WorldWideScience

Sample records for surface water dissolved

  1. Experimental study of water and dissolved pollutant runoffs on impervious surfaces

    Institute of Scientific and Technical Information of China (English)

    肖洋; 张涛涛

    2016-01-01

    The water and dissolved pollutant runoffs on impervious surfaces are the essential factor to be considered in design methods to minimize the impacts of the diffuse water pollution. In this paper, experiments are conducted to study the water and dissolved pollutant runoffs on impervious surfaces for different rainfall intensities and surface roughnesses. It is shown that a larger rainfall intensity and a smaller surface roughness reduce the time of concentration and increase the pollutant transport rate. Most of the pollutant runoffs take place at the initial stage of the rainfall. The pollutant transport rate rapidly reaches a peak and then gradually drops to zero.

  2. Reducing dissolved inorganic nitrogen in surface runoff water from sugarcane production systems.

    Science.gov (United States)

    Webster, A J; Bartley, R; Armour, J D; Brodie, J E; Thorburn, P J

    2012-01-01

    Nitrogen (N) lost from farms, especially as the highly bioavailable dissolved inorganic form, may be damaging Australia's Great Barrier Reef (GBR). As sugarcane is the dominant cropping system in GBR catchments, its N management practises are coming under increasing scrutiny. This study measured dissolved inorganic N lost in surface runoff water and sugarcane productivity over 3 years. The experiment compared the conventional fertiliser N application rate to sugarcane (average 180kg N/ha/year) and a rate based on replacing N exported in the previous crop (average 94kg N/ha/year). Dissolved inorganic N losses in surface water were 72%, 48% and 66% lower in the three monitored years in the reduced N fertiliser treatment. There was no significant difference in sugarcane yield between the two fertiliser N treatments, nor any treatment difference in soil mineral N - both of these results are indicators of the sustainability of the lower fertiliser N applications. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters

    DEFF Research Database (Denmark)

    Goncalves-Araujo, Rafael; Granskog, Mats A.; Bracher, Astrid

    2016-01-01

    Climate change affects the Arctic with regards to permafrost thaw, sea-ice melt, alterations to the freshwater budget and increased export of terrestrial material to the Arctic Ocean. The Fram and Davis Straits represent the major gateways connecting the Arctic and Atlantic. Oceanographic surveys...... were performed in the Fram and Davis Straits, and on the east Greenland Shelf (EGS), in late summer 2012/2013. Meteoric (f(mw)), sea-ice melt, Atlantic and Pacific water fractions were determined and the fluorescence properties of dissolved organic matter (FDOM) were characterized. In Fram Strait...... was correlated to apparent oxygen utilization (AOU) and traced deep-water DOM turnover. In surface waters FDOM characteristics could distinguish between surface waters from eastern (Atlantic + modified polar waters) and western (Canada-basin polar waters) Arctic sectors. The findings highlight the potential...

  4. Modeling the Effect of Dissolved Hydrogen Sulfide on Mg2+-water Complex on Dolomite {104} Surfaces

    CERN Document Server

    Shen, Zhizhang; Brown, Philip E; Szlufarska, Izabela; Xu, Huifang

    2016-01-01

    The key kinetic barrier to dolomite formation is related to the surface Mg2+-H2O complex, which hinders binding of surface Mg2+ ions to the CO3 2- ions in solution. It has been proposed that this reaction can be catalyzed by dissolved hydrogen sulfide. To characterize the role of dissolved hydrogen sulfide in the dehydration of surface Mg 2+ ions, ab initio simulations based on density functional theory (DFT) were carried out to study the thermodynamics of competitive adsorption of hydrogen sulfide and water on dolomite (104) surfaces from solution. We find that water is thermodynamically more stable on the surface with the difference in adsorption energy of -13.6 kJ/mol (in vacuum) and -12.8 kJ/mol (in aqueous solution). However, aqueous hydrogen sulfide adsorbed on the surface increases the Mg2+-H2O distances on surrounding surface sites. Two possible mechanisms were proposed for the catalytic effects of adsorbed hydrogen sulfide on the anhydrous Ca-Mg-carbonate crystallization at low temperature.

  5. Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters

    Science.gov (United States)

    Gonçalves-Araujo, Rafael; Granskog, Mats A.; Bracher, Astrid; Azetsu-Scott, Kumiko; Dodd, Paul A.; Stedmon, Colin A.

    2016-09-01

    Climate change affects the Arctic with regards to permafrost thaw, sea-ice melt, alterations to the freshwater budget and increased export of terrestrial material to the Arctic Ocean. The Fram and Davis Straits represent the major gateways connecting the Arctic and Atlantic. Oceanographic surveys were performed in the Fram and Davis Straits, and on the east Greenland Shelf (EGS), in late summer 2012/2013. Meteoric (fmw), sea-ice melt, Atlantic and Pacific water fractions were determined and the fluorescence properties of dissolved organic matter (FDOM) were characterized. In Fram Strait and EGS, a robust correlation between visible wavelength fluorescence and fmw was apparent, suggesting it as a reliable tracer of polar waters. However, a pattern was observed which linked the organic matter characteristics to the origin of polar waters. At depth in Davis Strait, visible wavelength FDOM was correlated to apparent oxygen utilization (AOU) and traced deep-water DOM turnover. In surface waters FDOM characteristics could distinguish between surface waters from eastern (Atlantic + modified polar waters) and western (Canada-basin polar waters) Arctic sectors. The findings highlight the potential of designing in situ multi-channel DOM fluorometers to trace the freshwater origins and decipher water mass mixing dynamics in the region without laborious samples analyses.

  6. 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.

  7. Dissolved organic matter in sea spray: a transfer study from marine surface water to aerosols

    Science.gov (United States)

    Schmitt-Kopplin, P.; Liger-Belair, G.; Koch, B. P.; Flerus, R.; Kattner, G.; Harir, M.; Kanawati, B.; Lucio, M.; Tziotis, D.; Hertkorn, N.; Gebefügi, I.

    2012-04-01

    Atmospheric aerosols impose direct and indirect effects on the climate system, for example, by absorption of radiation in relation to cloud droplets size, on chemical and organic composition and cloud dynamics. The first step in the formation of Organic primary aerosols, i.e. the transfer of dissolved organic matter from the marine surface into the atmosphere, was studied. We present a molecular level description of this phenomenon using the high resolution analytical tools of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and nuclear magnetic resonance spectroscopy (NMR). Our experiments confirm the chemoselective transfer of natural organic molecules, especially of aliphatic compounds from the surface water into the atmosphere via bubble bursting processes. Transfer from marine surface water to the atmosphere involves a chemical gradient governed by the physicochemical properties of the involved molecules when comparing elemental compositions and differentiating CHO, CHNO, CHOS and CHNOS bearing compounds. Typical chemical fingerprints of compounds enriched in the aerosol phase were CHO and CHOS molecular series, smaller molecules of higher aliphaticity and lower oxygen content, and typical surfactants. A non-targeted metabolomics analysis demonstrated that many of these molecules corresponded to homologous series of oxo-, hydroxy-, methoxy-, branched fatty acids and mono-, di- and tricarboxylic acids as well as monoterpenes and sugars. These surface active biomolecules were preferentially transferred from surface water into the atmosphere via bubble bursting processes to form a significant fraction of primary organic aerosols. This way of sea spray production leaves a selective biological signature of the surface water in the corresponding aerosol that may be transported into higher altitudes up to the lower atmosphere, thus contributing to the formation of secondary organic aerosol on a global scale or transported laterally with

  8. Dissolved Cu, Pb, Zn and Cd in the South China Sea surface waters

    Institute of Scientific and Technical Information of China (English)

    Huo Wenmian; Ji Weidong; Xu Kuncan

    2001-01-01

    A total of 106 surface water samples were collected in the South China Sea during two transects in June and December 1998. The samples were collected with strictly contamination free procedure and trace metals were measured by clean laboratory methods and GFAAS. The mean concentrations for the dissolved fractions are: Cu 0.100 μg/dm3, Pb 0.060 μg/dm3, Zn 0.086 μg/dm3, Cd 0.007 μg/dm3, which is close to the world open ocean's level. The spatial distribution of the trace heavy metals shows higher concentrations in offshore area and lower concentrations in the central in the South China Sea, and the concentrations decrease with the distance from the offshore, which suggests the existence of significant continental shelf input of the trace heavy metals. The correlationship among the elements is better in summer than that in winter. Cu is positively correlated with Cd in both seasons and it is also found for the first time that they are positively correlated with nutrients in the South China Sea surface waters which further indicate the biogeochemical cycle of these elements in the marine environment. The baseline value of Cu, Pb, Zn, Cd in the South China Sea surface waters is obtained through statistical analysis.

  9. Photomineralization and photomethanification of dissolved organic matter in Saguenay River surface water

    Science.gov (United States)

    Zhang, Y.; Xie, H.

    2015-11-01

    Rates and apparent quantum yields of photomineralization (AQYDOC) and photomethanification (AQYCH4) of chromophoric dissolved organic matter (CDOM) in Saguenay River surface water were determined at three widely differing dissolved oxygen concentrations ([O2]) (suboxic, air saturation, and oxygenated) using simulated-solar radiation. Photomineralization increased linearly with CDOM absorbance photobleaching for all three O2 treatments. Whereas the rate of photochemical dissolved organic carbon (DOC) loss increased with increasing [O2], the ratio of fractional DOC loss to fractional absorbance loss showed an inverse trend. CDOM photodegradation led to a higher degree of mineralization under suboxic conditions than under oxic conditions. AQYDOC determined under oxygenated, suboxic, and air-saturated conditions increased, decreased, and remained largely constant with photobleaching, respectively; AQYDOC obtained under air saturation with short-term irradiations could thus be applied to longer exposures. AQYDOC decreased successively from ultraviolet B (UVB) to ultraviolet A (UVA) to visible (VIS), which, alongside the solar irradiance spectrum, points to VIS and UVA being the primary drivers for photomineralization in the water column. The photomineralization rate in the Saguenay River was estimated to be 2.31 × 108 mol C yr-1, accounting for only 1 % of the annual DOC input into this system. Photoproduction of CH4 occurred under both suboxic and oxic conditions and increased with decreasing [O2], with the rate under suboxic conditions ~ 7-8 times that under oxic conditions. Photoproduction of CH4 under oxic conditions increased linearly with photomineralization and photobleaching. Under air saturation, 0.00057 % of the photochemical DOC loss was diverted to CH4, giving a photochemical CH4 production rate of 4.36 × 10-6 mol m-2 yr-1 in the Saguenay River and, by extrapolation, of (1.9-8.1) × 108 mol yr-1 in the global ocean. AQYCH4 changed little with

  10. Sampling and analysis for radon-222 dissolved in ground water and surface water

    Science.gov (United States)

    DeWayne, Cecil L.; Gesell, T.F.

    1992-01-01

    Radon-222 is a naturally occurring radioactive gas in the uranium-238 decay series that has traditionally been called, simply, radon. The lung cancer risks associated with the inhalation of radon decay products have been well documented by epidemiological studies on populations of uranium miners. The realization that radon is a public health hazard has raised the need for sampling and analytical guidelines for field personnel. Several sampling and analytical methods are being used to document radon concentrations in ground water and surface water worldwide but no convenient, single set of guidelines is available. Three different sampling and analytical methods - bubbler, liquid scintillation, and field screening - are discussed in this paper. The bubbler and liquid scintillation methods have high accuracy and precision, and small analytical method detection limits of 0.2 and 10 pCi/l (picocuries per liter), respectively. The field screening method generally is used as a qualitative reconnaissance tool.

  11. Effects of Dissolved Carbonate on Arsenate Adsorption and Surface Speciation at the Hematite-Water Interface

    Science.gov (United States)

    Arai, Y.; Sparks, D.L.; Davis, J.A.

    2004-01-01

    Effects of dissolved carbonate on arsenate [As(V)] reactivity and surface speciation at the hematite-water interface were studied as a function of pH and two different partial pressures of carbon dioxide gas [PCO2 = 10 -3.5 atm and ???0; CO2-free argon (Ar)] using adsorption kinetics, pseudo-equilibrium adsorption/titration experiments, extended X-ray absorption fine structure spectroscopic (EXAFS) analyses, and surface complexation modeling. Different adsorbed carbonate concentrations, due to the two different atmospheric systems, resulted in an enhanced and/or suppressed extent of As(V) adsorption. As(V) adsorption kinetics [4 g L -1, [As(V)]0 = 1.5 mM and / = 0.01 M NaCl] showed carbonate-enhanced As(V) uptake in the air-equilibrated systems at pH 4 and 6 and at pH 8 after 3 h of reaction. Suppressed As(V) adsorption was observed in the air-equilibrated system in the early stages of the reaction at pH 8. In the pseudo-equilibrium adsorption experiments [1 g L-1, [As(V)] 0 = 0.5 mM and / = 0.01 M NaCl], in which each pH value was held constant by a pH-stat apparatus, effects of dissolved carbonate on As(V) uptake were almost negligible at equilibrium, but titrant (0.1 M HCl) consumption was greater in the air-equilibrated systems (PCO2 = 10-3.5 atm)than in the CO2-free argon system at pH 4-7.75. The EXAFS analyses indicated that As(V) tetrahedral molecules were coordinated on iron octahedral via bidentate mononuclear (???2.8 A??) and bidentate binuclear (???3.3 A??) bonding at pH 4.5-8 and loading levels of 0.46-3.10 ??M m-2. Using the results of the pseudoequilibrium adsorption data and the XAS analyses, the pH-dependent As(V) adsorption under the PCO2 = 10-3.5 atm and the CO2-free argon system was modeled using surface complexation modeling, and the results are consistent with the formation of nonprotonated bidentate surface species at the hematite surfaces. The results also suggest that the acid titrant consumption was strongly affected by changes to

  12. Catalytic behavior of metallic particles in anisotropic etching of Ge(100) surfaces in water mediated by dissolved oxygen

    Science.gov (United States)

    Kawase, Tatsuya; Mura, Atsushi; Nishitani, Keisuke; Kawai, Yoshie; Kawai, Kentaro; Uchikoshi, Junichi; Morita, Mizuho; Arima, Kenta

    2012-06-01

    The authors demonstrate that Ge(100) surfaces containing metallic particles are etched anisotropically in water. This originates from the catalytic reduction of dissolved oxygen (O2) in water to water molecules (H2O) on the metallic particles, which is followed by the enhanced oxidation of Ge around the particles. The soluble nature of Ge oxide (GeO2) in water promotes the formation of inverted pyramidal etch pits composed of (111) microfacets. On the basis of the results, the authors propose strategies for avoiding unwanted surface roughening during the wet cleaning of Ge.

  13. The conservative behavior of dissolved organic carbon in surface waters of the southern Chukchi Sea, Arctic Ocean, during early summer

    Science.gov (United States)

    Tanaka, Kazuki; Takesue, Nobuyuki; Nishioka, Jun; Kondo, Yoshiko; Ooki, Atsushi; Kuma, Kenshi; Hirawake, Toru; Yamashita, Youhei

    2016-01-01

    The spatial distribution of dissolved organic carbon (DOC) concentrations and the optical properties of dissolved organic matter (DOM) determined by ultraviolet-visible absorbance and fluorescence spectroscopy were measured in surface waters of the southern Chukchi Sea, western Arctic Ocean, during the early summer of 2013. Neither the DOC concentration nor the optical parameters of the DOM correlated with salinity. Principal component analysis using the DOM optical parameters clearly separated the DOM sources. A significant linear relationship was evident between the DOC and the principal component score for specific water masses, indicating that a high DOC level was related to a terrigenous source, whereas a low DOC level was related to a marine source. Relationships between the DOC and the principal component scores of the surface waters of the southern Chukchi Sea implied that the major factor controlling the distribution of DOC concentrations was the mixing of plural water masses rather than local production and degradation. PMID:27658444

  14. Characterization of dissolved organic matter for prediction of trihalomethane formation potential in surface and sub-surface waters.

    Science.gov (United States)

    Awad, John; van Leeuwen, John; Chow, Christopher; Drikas, Mary; Smernik, Ronald J; Chittleborough, David J; Bestland, Erick

    2016-05-05

    Dissolved organic matter (DOM) in surface waters used for drinking purposes can vary markedly in character dependent on their sources within catchments. The character of DOM further influences the formation of disinfection by products when precursor DOM present in drinking water reacts with chlorine during disinfection. Here we report the development of models that describe the formation potential of trihalomethanes (THMFP) dependent on the character of DOM in waters from discrete catchments with specific land-use and soil textures. DOM was characterized based on UV absorbance at 254 nm, apparent molecular weight and relative abundances of protein-like and humic-like compounds. DOM character and Br concentration (up to 0.5 mg/L) were used as variables in models (R(2)>0.93) of THMFP, which ranged from 19 to 649 μg/L. Chloroform concentration (12-594 μg/L) and relative abundance (27-99%) were first modeled (R(2)>0.85) and from these, the abundances of bromodichloromethane and chlorodibromomethane estimated using power and exponential functions, respectively (R(2)>0.98). From these, the abundance of bromoform is calculated. The proposed model may be used in risk assessment of catchment factors on formation of trihalomethanes in drinking water, in context of treatment efficiency for removal of organic matter.

  15. Enzymatic scavenging of oxygen dissolved in water: Application of response surface methodology in optimization of conditions

    Directory of Open Access Journals (Sweden)

    Karimi Afzal

    2012-01-01

    Full Text Available In this work, removal of dissolved oxygen in water through reduction by glucose, which was catalyzed by glucose oxidase – catalase enzyme, was studied. Central composite design (CCD technique was applied to achieve optimum conditions for dissolved oxygen scavenging. Linear, square and interactions between effective parameters were obtained to develop a second order polynomial equation. The adequacy of the obtained model was evaluated by the residual plots, probability-value, coefficient of determination, and Fisher’s variance ratio test. Optimum conditions for activity of two enzymes in water deoxygenation were obtained as follows: pH=5.6, T=40°C, initial substrate concentration [S] = 65.5 mmol/L and glucose oxidase activity [E] = 252 U/Lat excess amount of catalase. The deoxygenation process during 30 seconds, in the optimal conditions, was predicted 98.2%. Practical deoxygenation in the predicted conditions was achieved to be 95.20% which was close to the model prediction.

  16. Water resources and effects of potential surface coal mining on dissolved solids in Hanging Woman Creek basin, southeastern Montana

    Science.gov (United States)

    Cannon, M.R.

    1989-01-01

    Groundwater resources of the Hanging Woman Creek basin, Montana include Holocene and Pleistocene alluvial aquifers and sandstone , coal, and clinker aquifers in the Paleocene Fort Union Formation. Surface water resources are composed of Hanging Woman Creek, its tributaries, and small stock ponds. Dissolved-solids concentrations in groundwater ranged from 200 to 11,00 mg/L. Generally, concentrations were largest in alluvial aquifers and smallest in clinker aquifers. Near its mouth, Hanging Woman Creek had a median concentration of about 1,800 mg/L. Mining of the 20-foot to 35-foot-thick Anderson coal bed and 3-foot to 16-foot thick Dietz coal bed could increase dissolved-solids concentrations in shallow aquifers and in Hanging Woman Creek because of leaching of soluble minerals from mine spoils. Analysis of saturated-paste extracts from 158 overburden samples indicated that water moving through mine spoils would have a median increase in dissolved-solids concentration of about 3,700 mg/L, resulting in an additional dissolved-solids load to Hanging Woman Creek of about 3.0 tons/day. Hanging Woman Creek near Birney could have an annual post-mining dissolved-solids load of 3,415 tons at median discharge, a 47% increase from pre-mining conditions load. Post-mining concentrations of dissolved solids, at median discharge, could range from 2,380 mg/L in March to 3,940 mg/L in August, compared to mean pre-mining concentrations that ranged from 1,700 mg/L in July, November, and December to 2,060 mg/L in May. Post-mining concentrations and loads in Hanging Woman Creek would be smaller if a smaller area were mined. (USGS)

  17. Concentration and characterization of dissolved organic matter in the surface microlayer and subsurface water of the Bohai Sea, China

    Science.gov (United States)

    Chen, Yan; Yang, Gui-Peng; Wu, Guan-Wei; Gao, Xian-Chi; Xia, Qing-Yan

    2013-01-01

    A total of 19 sea-surface microlayer and corresponding subsurface samples collected from the Bohai Sea, China in April 2010 were analyzed for chlorophyll a, dissolved organic carbon (DOC) and its major compound classes including total dissolved carbohydrates (TDCHO, including monosaccharides, MCHO, and polysaccharides, PCHO) and total hydrolysable amino acids (THAA, including dissolved free, DFAA, and combined fraction, DCAA). The concentrations of DOC in the subsurface water ranged from 130.2 to 407.7 μM C, with an average of 225.9±75.4 μM C, while those in the surface microlayer varied between 140.1 and 330.9 μM C, with an average of 217.8±56.8 μM C. The concentrations of chlorophyll a, DOC, TDCHO and THAA in the microlayer were, respectively correlated with their subsurface water concentrations, implying that there was a strong exchange effect between the microlayer and subsurface water. The concentrations of DOC and TDCHO were negatively correlated with salinity, respectively, indicating that water mixing might play an important role in controlling the distribution of DOC and TDCHO in the water column. Major constituents of DCAA and DFAA present in the study area were glycine, alanine, glutamic acid, serine and histidine. Principal component analysis (PCA) was applied to examine the complex compositional differences that existed among the sampling sites. Our results showed that DFAA had higher mole percentages of glycine, valine and serine in the microlayer than in the subsurface water, while DCAA tended to have higher mole percentages of glutamic acid, aspartic acid, threonine, arginine, alanine, tyrosine, phenylalanine and leucine in the microlayer. The yields of TDCHO and THAA exhibited similar trends between the microlayer and subsurface water. Carbohydrate species displayed significant enrichment in the microlayer, whereas the DFAA and DCAA exhibited non-uniform enrichment in the microlayer.

  18. Dissolved organic matter dynamics in surface waters affected by oil spill pollution: Results from the Serious Game exercise

    Science.gov (United States)

    Gonnelli, M.; Galletti, Y.; Marchetti, E.; Mercadante, L.; Retelletti Brogi, S.; Ribotti, A.; Sorgente, R.; Vestri, S.; Santinelli, C.

    2016-11-01

    Dissolved organic carbon (DOC), chromophoric and fluorescent dissolved organic matter (CDOM and FDOM, respectively) surface distribution was studied during the Serious Game exercise carried out in the Eastern Ligurian Sea, where an oil spill was localized by using satellite images and models. This paper reports the first DOC, CDOM and FDOM data for this area together with an evaluation of fluorescence as a fast and inexpensive tool for early oil spill detection in marine waters. The samples collected in the oil spill showed a fluorescence intensity markedly higher ( 5 fold) than all the other samples. The excitation-emission matrixes, coupled with parallel factor analysis (PARAFAC), allowed for the identification in the FDOM pool of a mixture of polycyclic aromatic hydrocarbons, humic-like and protein-like fluorophores.

  19. Assessment of dissolved Pb concentration and isotopic composition in surface waters of the modern global ocean

    Science.gov (United States)

    Pinedo-Gonzalez, P.; West, A. J.; Sanudo-Wilhelmy, S. A.

    2015-12-01

    Lead (Pb) produced by human activities, mainly from leaded gasoline combustion and high-temperature industries, dominates Pb in our present-day oceans. Previous studies have shown that surface ocean Pb concentrations and isotope ratios have varied in time and space, reflecting the changes in the amount of inputs and sources of anthropogenic Pb. However, data on surface ocean Pb is quite limited, especially for some basins like the Indian Ocean. In the present study, Pb concentrations and stable isotopes (208, 207, and 206) have been analyzed in surface water samples (3m depth) collected during the Malaspina Circumnavigation Expedition, 2010. Our results are compared with data from the literature to i) evaluate the changing status of metal contamination in surface waters of the global ocean over the last 30 years, and ii) propose potential sources of modern Pb to the oceans. Our results show that Pb concentrations in surface waters of the North Atlantic Ocean have decreased ~ 40% since 1975, attributable to the phase-out of leaded gasoline in North America. This result is corroborated by stable Pb isotope measurements. Furthermore, the isotopic gradient observed in surface waters of the studied transects in the north tropical and subtropical Atlantic Ocean can be attributed to simple mixing of European and African aerosols and Saharan Holocene loess. Results from an understudied transect in the Southern Indian Ocean give an indication of the source region of Pb delivered to this region. Although comparison with literature data is limited, mixing of Australian ores and African and Australian coals could potentially explain the measured Pb isotope composition. This study provides an opportunity to build on the work of previous oceanographic campaigns, enabling us to assess the impact of anthropogenic Pb inputs to the ocean and the relative importance of various Pb sources, providing new insights into the transport and fate of Pb in the oceans.

  20. Evidence for dissolved organic matter as the primary source and sink of photochemically produced hydroxyl radical in arctic surface waters.

    Science.gov (United States)

    Page, Sarah E; Logan, J Robert; Cory, Rose M; McNeill, Kristopher

    2014-04-01

    Hydroxyl radical (˙OH) is an indiscriminate oxidant that reacts at near-diffusion-controlled rates with organic carbon. Thus, while ˙OH is expected to be an important oxidant of dissolved organic matter (DOM) and other recalcitrant compounds, the role of ˙OH in the oxidation of these compounds in aquatic ecosystems is not well known due to the poorly constrained sources and sinks of ˙OH, especially in pristine (unpolluted) natural waters. We measured the rates of ˙OH formation and quenching across a range of surface waters in the Arctic varying in concentrations of expected sources and sinks of ˙OH. Photochemical formation of ˙OH was observed in all waters tested, with rates of formation ranging from 2.6 ± 0.6 to 900 ± 100 × 10(-12) M s(-1). Steady-state concentrations ranged from 2 ± 1 to 290 ± 60 × 10(-17) M, and overlapped with previously reported values in surface waters. While iron-mediated photo-Fenton reactions likely contributed to the observed ˙OH production, several lines of evidence suggest that DOM was the primary source and sink of photochemically produced ˙OH in pristine arctic surface waters. DOM from first-order or headwater streams was more efficient in producing ˙OH than what has previously been reported for DOM, and ˙OH formation decreased with increasing residence time of DOM in sunlit surface waters. Despite the ubiquitous formation of ˙OH in arctic surface waters observed in this study, photochemical ˙OH formation was estimated to contribute ≤4% to the observed photo-oxidation of DOM; however, key uncertainties in this estimate must be addressed before ruling out the role of ˙OH in the oxidation of DOM in these waters.

  1. 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.

  2. Impact of pH, dissolved inorganic carbon, and polyphosphates for the initial stages of water corrosion of copper surfaces investigated by AFM and NEXAFS

    Science.gov (United States)

    Nanoscale studies at the early stages of the exposure of copper surfaces after systematic treatments in synthesized water solutions can provide useful information about corrosion processes. The corrosion and passivation of copper surfaces as influenced by pH, dissolved inorganic ...

  3. Protein analysis in dissolved organic matter: what free proteins from soil leachate and surface water can tell us a perspective

    Science.gov (United States)

    Schulze, W.

    2004-12-01

    Mass spectrometry based analysis of proteins is widely used to study cellular processes in model organisms. However, it has not yet routinely been applied in environmental research. Based on observations that protein can readily be detected as a component of dissolved organic matter (DOM), this article gives an example about the possible use of protein analysis in ecology and environmental sciences focusing on different terrestrial ecosystems. At this stage, there are two areas of interest: (1) the identification of phylogenetic groups contributing to the DOM protein pool, and (2) identification of the organismic origin of specific enzymes that are important for ecosystem processes. In this paper, mass spectrometric protein analysis was applied to identify proteins from DOM and organism-free surface water samples derived from different environments. It is concluded, that mass spectrometric protein analysis is capable of distinguishing phylogenetic origin of proteins from leachates of different soil horizons, and from various sources of terrestrial surface water. Current limitation is imposed by the limited knowledge of complete genomes of soil organisms. The protein analysis allows to relate protein presence to biogeochemical processes, and to identify the source organisms for specific active enzymes. Further applications, such as in pollution research are conceivable. In summary, the analysis of proteins opens a new area of research between the fields of microbiology and biogeochemistry.

  4. Terpenoids as major precursors of dissolved organic matter in landfill leachates, surface water, and groundwater

    Science.gov (United States)

    Leenheer, J.A.; Nanny, M.A.; McIntyre, C.

    2003-01-01

    13C NMR analyses of hydrophobic dissolved organic matter (DOM) fractions isolated from a landfill leachate contaminated groundwater near Norman, OK; the Colorado River aqueduct near Los Angeles, CA; Anaheim Lake, an infiltration basin for the Santa Ana River in Orange County, CA; and groundwater from the Tomago Sand Beds, near Sydney, Australia, found branched methyl groups and quaternary aliphatic carbon structures that are indicative of terpenoid hydrocarbon precursors. Significant amounts of lignin precursors, commonly postulated to be the major source of DOM, were found only in trace quantities by thermochemolysis/gas chromatography/mass spectrometry of the Norman Landfill and Tomago Sand Bed hydrophobic DOM fractions. Electrospray/tandem mass spectrometry of the Tomago Sand Bed hydrophobic acid DOM found an ion series differing by 14 daltons, which is indicative of aliphatic and aryl-aliphatic polycarboxylic acids. The product obtained from ozonation of the resin acid, abietic acid, gave a similar ion series. Terpenoid precursors of DOM are postulated to be derived from resin acid paper sizing agents in the Norman Landfill, algal and bacterial terpenoids in the Colorado River and Anaheim Lake, and terrestrial plant terpenoids in the Tomago Sand Beds.

  5. Improved automation of dissolved organic carbon sampling for organic-rich surface waters.

    Science.gov (United States)

    Grayson, Richard P; Holden, Joseph

    2016-02-01

    In-situ UV-Vis spectrophotometers offer the potential for improved estimates of dissolved organic carbon (DOC) fluxes for organic-rich systems such as peatlands because they are able to sample and log DOC proxies automatically through time at low cost. In turn, this could enable improved total carbon budget estimates for peatlands. The ability of such instruments to accurately measure DOC depends on a number of factors, not least of which is how absorbance measurements relate to DOC and the environmental conditions. Here we test the ability of a S::can Spectro::lyser™ for measuring DOC in peatland streams with routinely high DOC concentrations. Through analysis of the spectral response data collected by the instrument we have been able to accurately measure DOC up to 66 mg L(-1), which is more than double the original upper calibration limit for this particular instrument. A linear regression modelling approach resulted in an accuracy >95%. The greatest accuracy was achieved when absorbance values for several different wavelengths were used at the same time in the model. However, an accuracy >90% was achieved using absorbance values for a single wavelength to predict DOC concentration. Our calculations indicated that, for organic-rich systems, in-situ measurement with a scanning spectrophotometer can improve fluvial DOC flux estimates by 6 to 8% compared with traditional sampling methods. Thus, our techniques pave the way for improved long-term carbon budget calculations from organic-rich systems such as peatlands.

  6. Groundwater and surface-water interaction, water quality, and processes affecting loads of dissolved solids, selenium, and uranium in Fountain Creek near Pueblo, Colorado, 2012–2014

    Science.gov (United States)

    Arnold, L. Rick; Ortiz, Roderick F.; Brown, Christopher R.; Watts, Kenneth R.

    2016-11-28

    In 2012, the U.S. Geological Survey, in cooperation with the Arkansas River Basin Regional Resource Planning Group, initiated a study of groundwater and surface-water interaction, water quality, and loading of dissolved solids, selenium, and uranium to Fountain Creek near Pueblo, Colorado, to improve understanding of sources and processes affecting loading of these constituents to streams in the Arkansas River Basin. Fourteen monitoring wells were installed in a series of three transects across Fountain Creek near Pueblo, and temporary streamgages were established at each transect to facilitate data collection for the study. Groundwater and surface-water interaction was characterized by using hydrogeologic mapping, groundwater and stream-surface levels, groundwater and stream temperatures, vertical hydraulic-head gradients and ratios of oxygen and hydrogen isotopes in the hyporheic zone, and streamflow mass-balance measurements. Water quality was characterized by collecting periodic samples from groundwater, surface water, and the hyporheic zone for analysis of dissolved solids, selenium, uranium, and other selected constituents and by evaluating the oxidation-reduction condition for each groundwater sample under different hydrologic conditions throughout the study period. Groundwater loads to Fountain Creek and in-stream loads were computed for the study area, and processes affecting loads of dissolved solids, selenium, and uranium were evaluated on the basis of geology, geochemical conditions, land and water use, and evapoconcentration.During the study period, the groundwater-flow system generally contributed flow to Fountain Creek and its hyporheic zone (as a single system) except for the reach between the north and middle transects. However, the direction of flow between the stream, the hyporheic zone, and the near-stream aquifer was variable in response to streamflow and stage. During periods of low streamflow, Fountain Creek generally gained flow from

  7. Copper toxicity in relation to surface water-dissolved organic matter: biological effects to Daphnia magna

    NARCIS (Netherlands)

    Kramer, K.J.M.; Jak, R.G.; Hattum, van B.; Hooftman, R.N.; Zwolsman, J.J.G.

    2004-01-01

    Water quality standards for copper are usually stated in total element concentrations. It is known, however, that a major part of the copper can be bound in complexes that are biologically not available. Natural organic matter, such as humic and fulvic acids, are strong complexing agents that may af

  8. A radiocarbon-based inventory of methane and inorganic carbon dissolved in surface lake waters in arctic Alaska, USA

    Science.gov (United States)

    Czimczik, Claudia; Clayton, Elder; Xu, Xiaomei; Lehman, Jennifer; Townsend-Small, Amy

    2014-05-01

    Major uncertainties in land-atmosphere carbon (C) exchange in the rapidly warming and wetting Arctic are 1) the magnitude and timing of net losses of ancient permafrost C to the atmosphere and 2) the relative changes of C exchange as carbon dioxide (CO2) or the more powerful greenhouse gas methane (CH4). For CH4, the role of diffusive fluxes versus plant-mediated and ebullition fluxes is poorly constrained. Radiocarbon (14C) is a unique tracer for distinguishing ancient permafrost C from C rapidly cycling between the land and atmosphere. In addition, stable isotope ratios (13C/12C and D/H) provide insight to trace gas production and consumption pathways. Previous measurements, however, have focused on CH4 from ebullition fluxes due to technical and logistical challenges in 14C-CH4 analysis. We quantified the 14C content and δ13C signatures of dissolved CH4 and DIC in lake surface waters along a north-south transect on the North Slope of Alaska, USA (69.9°N to 71.28°N, -156.12°W to -156.32°W). Samples were collected at the end of winter before ice break-up (April 2013) and during summer (August 2012 & 2013) in 1 L bottles. A subset of samples was also analyzed for CH4 and CO2 concentrations and stable isotope ratios by the Circumarctic Lakes Observation Network (CALON). In addition, in August 2013, we measured the 14C content and δ13C ratios of lake-atmosphere CH4 and CO2 exchange near Barrow, AK, USA (71°N, -156°W). We obtained dissolved CH4 and CO2 sufficient for 14C analysis from lakes with concentrations as low as 0.01 mg C /L) using a novel, in situ preconcentration method (liqui-cel, Membrana). And, we measured and collected isoflux samples of simulated, near-shore ebulltion-derived CH4 and CO2 using floating headspace chambers. Isotope samples were processed using a novel, flow-through vacuum line and analyzed at the KCCAMS facility at the University of California, Irvine, USA with accelerator (0.5MV 1.5SDH-2, National Electrostatics Corporation) and

  9. Mercury, monomethyl mercury, and dissolved organic carbon concentrations in surface water entering and exiting constructed wetlands treated with metal-based coagulants, Twitchell Island, California

    Science.gov (United States)

    Stumpner, Elizabeth B.; Kraus, Tamara E.C.; Fleck, Jacob A.; Hansen, Angela M.; Bachand, Sandra M.; Horwath, William R.; DeWild, John F.; Krabbenhoft, David P.; Bachand, Philip A.M.

    2015-09-02

    Coagulation with metal-based salts is a practice commonly employed by drinking-water utilities to decrease particle and dissolved organic carbon concentrations in water. In addition to decreasing dissolved organic carbon concentrations, the effectiveness of iron- and aluminum-based coagulants for decreasing dissolved concentrations both of inorganic and monomethyl mercury in water was demonstrated in laboratory studies that used agricultural drainage water from the Sacramento–San Joaquin Delta of California. To test the effectiveness of this approach at the field scale, nine 15-by-40‑meter wetland cells were constructed on Twitchell Island that received untreated water from island drainage canals (control) or drainage water treated with polyaluminum chloride or ferric sulfate coagulants. Surface-water samples were collected approximately monthly during November 2012–September 2013 from the inlets and outlets of the wetland cells and then analyzed by the U.S. Geological Survey for total concentrations of mercury and monomethyl mercury in filtered (less than 0.3 micrometers) and suspended-particulate fractions and for concentrations of dissolved organic carbon.

  10. Molecular weight and chemical reactivity of dissolved trace metals (Cd, Cu, Ni) in surface waters from the Mississippi River to Gulf of Mexico

    Science.gov (United States)

    Wen, Liang-Saw; Santschi, Peter H.; Warnken, Kent W.; Davison, William; Zhang, Hao; Li, Hsiu-Ping; Jiann, Kuo-Tung

    2011-05-01

    It is generally assumed that estuarine mixing is continuous for metals from terrestrial sources, gradually decreasing towards the open ocean endmember. Here we show that, chemical reactivity, determined by ion exchange method, and molecular weight distributions, obtained using cross-flow ultrafiltration, of dissolved Cd, Cu, and Ni in the surface waters of the Gulf of Mexico varied systematically across the estuarine mixing zone of the Mississippi River. Most size or chemical affinity fractions of dissolved metals (warm core ring in the Gulf of Mexico. Dissolved Cd was mostly present as a truly dissolved (behavior between Cu and the other two metals might indicate differences in the biopolymeric nature of the metal-organic chelates. In particular, the anionic-organic Cd fractions accounted for just 3 ± 1%, on average. However, for Cu, it was 24 ± 4%, and for Ni, it was 9 ± 6%. The fractions of the total dissolved metal fractions that were "inert" averaged 31 ± 10% for Cu and 29 ± 12% for Ni. Small but noticeable amounts (6 ± 3%) of dissolved inert Cd fractions were also present. Apparent non-local transport processes, likely associated with cross-shelf sediment resuspension processes, could have been responsible for the relatively high concentrations of 'inert' and 'anionic' metal fractions in high salinity coastal waters, and accounting for the persistence of metals bound to humic substances in the Gulf of Mexico.

  11. The effects of nutrient additions on particulate and dissolved primary production in surface waters of three Mediterranean eddies

    Science.gov (United States)

    Lagaria, A.; Psarra, S.; Lefèvre, D.; van Wambeke, F.; Courties, C.; Pujo-Pay, M.; Oriol, L.; Tanaka, T.; Christaki, U.

    2010-12-01

    The effects of additions of nitrogen (+N), phosphorus (+P), alone and in combination, were assessed during three microcosm experiments performed with surface waters of three anticyclonic eddies, located in the Western, Central and Eastern Mediterranean. We examined the effects of nutrient additions on rates of dissolved and particulate primary production and on metabolic rates of the osmotrophic community (phytoplankton and heterotrophic prokaryotes). The experiments were performed in June/July 2008 during the BOUM (Biogeochemistry from the Oligotrophic to the Ultra-oligotrophic Mediterranean) cruise. In all three experiments, particulate primary production was significantly stimulated by the additions of nitrogen (+N, +NP) while no effect was observed with the addition of phosphorus alone. Percent extracellular release (PER) showed an inverse relation with total primary production (PPtotal), displaying the lowest values (4-8%) in the +NP treatment. Among the three treatments, the +NP had the strongest effect on the community metabolic rates leading to positive net community production values (NCP>0). These changes of NCP were mainly due to enhanced gross community production (GCP) rather than lower respiration rates (CR). In +NP treatments autotrophic production (whether expressed as GCP or PPtotal) was high enough to fulfil the carbon requirements of the heterotrophic prokaryotes, with phytoplankton and heterotrophic prokaryote production positively correlated. Addition of nitrogen alone (+N) had a smaller effect on community production, resulting in metabolically balanced systems (NCP≍0). Finally, heterotrophic conditions persisted in the +P treatment at the central and eastern stations, and gross production was not sufficient to supply bacterial carbon demand, evidence of a decoupling of phytoplankton production and consumption by heterotrophic prokaryotes.

  12. Interfacial properties of dissolved crude oil components in produced water

    OpenAIRE

    Eftekhardadkhah, Mona

    2013-01-01

    Produced water is a mixture of water trapped in underground formations and injection water that is brought to the surface along with oil or gas. In general, produced water is a mixture of dispersed oil in water (o/w), dissolved organic compounds (including hydrocarbons), residual concentration of chemical additives from the production line, heavy metals, dissolved minerals and suspended solids.In the year 2011, 131 million m3 of produced water were discharged on the Norwegian Continental Shel...

  13. Distribution of dissolved labile and particulate iron and copper in Terra Nova Bay polynya (Ross Sea, Antarctica) surface waters in relation to nutrients and phytoplankton growth

    Science.gov (United States)

    Rivaro, Paola; Ianni, Carmela; Massolo, Serena; Abelmoschi, M. Luisa; De Vittor, Cinzia; Frache, Roberto

    2011-05-01

    The distribution of the dissolved labile and of the particulate Fe and Cu together with dissolved oxygen, nutrients, chlorophyll a and total particulate matter was investigated in the surface waters of Terra Nova Bay polynya in mid-January 2003. The measurements were conducted within the framework of the Italian Climatic Long-term Interactions of the Mass balance in Antarctica (CLIMA) Project activities. The labile dissolved fraction was operationally defined by employing the chelating resin Chelex-100, which retains free and loosely bound trace metal species. The dissolved labile Fe ranges from below the detection limit (0.15 nM) to 3.71 nM, while the dissolved labile Cu from below the detection limit (0.10 nM) to 0.90 nM. The lowest concentrations for both metals were observed at 20 m depth (the shallowest depth for which metals were measured). The concentration of the particulate Fe was about 5 times higher than the dissolved Fe concentration, ranging from 0.56 to 24.83 nM with an average of 6.45 nM. The concentration of the particulate Cu ranged from 0.01 to 0.71 nM with an average of 0.17 nM. The values are in agreement with the previous data collected in the same area. We evaluated the role of the Fe and Cu as biolimiting metals. The N:dissolved labile Fe ratios (18,900-130,666) would or would not allow a complete nitrate removal, on the basis of the N:Fe requirement ratios that we calculated considering the N:P and the C:P ratios estimated for diatoms. This finding partially agrees with the Si:N ratio that we found (2.29). Moreover we considered a possible influence of the dissolved labile Cu on the Fe uptake process.

  14. 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

  15. Simulated climate change impact on summer dissolved organic carbon release from peat and surface vegetation: implications for drinking water treatment.

    Science.gov (United States)

    Ritson, Jonathan P; Bell, Michael; Graham, Nigel J D; Templeton, Michael R; Brazier, Richard E; Verhoef, Anne; Freeman, Chris; Clark, Joanna M

    2014-12-15

    Uncertainty regarding changes in dissolved organic carbon (DOC) quantity and quality has created interest in managing peatlands for their ecosystem services such as drinking water provision. The evidence base for such interventions is, however, sometimes contradictory. We performed a laboratory climate manipulation using a factorial design on two dominant peatland vegetation types (Calluna vulgaris and Sphagnum Spp.) and a peat soil collected from a drinking water catchment in Exmoor National Park, UK. Temperature and rainfall were set to represent baseline and future conditions under the UKCP09 2080s high emissions scenario for July and August. DOC leachate then underwent standard water treatment of coagulation/flocculation before chlorination. C. vulgaris leached more DOC than Sphagnum Spp. (7.17 versus 3.00 mg g(-1)) with higher specific ultraviolet (SUVA) values and a greater sensitivity to climate, leaching more DOC under simulated future conditions. The peat soil leached less DOC (0.37 mg g(-1)) than the vegetation and was less sensitive to climate. Differences in coagulation removal efficiency between the DOC sources appears to be driven by relative solubilisation of protein-like DOC, observed through the fluorescence peak C/T. Post-coagulation only differences between vegetation types were detected for the regulated disinfection by-products (DBPs), suggesting climate change influence at this scale can be removed via coagulation. Our results suggest current biodiversity restoration programmes to encourage Sphagnum Spp. will result in lower DOC concentrations and SUVA values, particularly with warmer and drier summers.

  16. Dissolved iron in the Arctic shelf seas and surface waters of the central Arctic Ocean : Impact of Arctic river water and ice-melt

    NARCIS (Netherlands)

    Klunder, M. B.; Bauch, D.; Laan, P.; de Baar, H. J. W.; van Heuven, S.; Ober, S.

    2012-01-01

    Concentrations of dissolved (10 nM) in the bottom waters of the Laptev Sea shelf may be attributed to either sediment resuspension, sinking of brine or regeneration of DFe in the lower layers. A significant correlation (R-2 = 0.60) between salinity and DFe is observed. Using delta O-18, salinity, nu

  17. Human health risk assessment of dissolved metals in groundwater and surface waters in the Melen watershed, Turkey.

    Science.gov (United States)

    Çelebi, Ahmet; Sengörür, Bülent; Kløve, Bjørn

    2014-01-01

    Determination of metal risk levels in potable water and their effects on human health are vital in assessment of water resources. Risk assessment of metals to human health in a watershed, which has not been studied before, is the main objective of the present study. Surface and groundwater sampling was carried out between September 2010 and August 2011 in the Melen Watershed, Turkey, an important drinking water resource for millions of people. Metals were analyzed in the laboratory using inductively coupled plasma. Of the 26 different metals monitored, Al, B, Ba, Cr, Cu, Fe, Mn, Mo and V were found in surface water and As, B, Ba, Cr, Cu, Mn, Mo, V and Zn in groundwater. In groundwater, unitless hazard quotient (HQ) values were 6 for As, 2.7 for Mn and 1 for Zn, while in surface water all metals were below the risk level (HQ watersheds can pose a risk to human health and that potential carcinogenic impacts should receive more attention.

  18. Production and degradation of fluorescent dissolved organic matter in surface waters of the eastern north Atlantic ocean

    NARCIS (Netherlands)

    Lønborg, C.; Yokokawa, T.; Herndl, G.J.; Alvarez-Salgado, X.A.

    2015-01-01

    The distribution and fate of coloured dissolved organic matter (CDOM) in the epipelagic Eastern North Atlantic was investigated during a cruise in the summer 2009 by combining field observations and culture experiments. Dissolved organic carbon (DOC) and nitrogen (DON), the absorption spectra of

  19. Relating the Chemical Composition of Dissolved Organic Matter Draining Permafrost Soils to its Photochemical Degradation in Arctic Surface Waters.

    Science.gov (United States)

    Ward, C.; Cory, R. M.

    2015-12-01

    Thawing permafrost soils are expected to shift the chemical composition of DOM exported to and degraded in arctic surface waters. While DOM photo-degradation is an important component of the freshwater C cycle in the Arctic, the molecular controls on DOM photo-degradation remain poorly understood, making it difficult to predict how shifting chemical composition may alter DOM photo-degradation in arctic surface waters. To address this knowledge gap, we quantified the susceptibility of DOM draining the shallow organic mat and the deeper permafrost layer to complete photo-oxidation to CO₂ and partial photo-oxidation to compounds that remain in the DOM pool, and investigated changes in DOM chemical composition following sunlight exposure. DOM leached from the organic mat contained higher molecular weight, more oxidized and unsaturated aromatic species compared to permafrost DOM. Despite significant differences in initial chemical composition, permafrost and organic mat DOM had similar susceptibilities to complete photo-oxidation to CO₂. Concurrent losses of carboxyl moieties and shifts in chemical composition during photo-degradation indicated that carboxyl-rich tannin-like compounds in both DOM sources were likely photo-decarboxylated to CO₂. Permafrost DOM had a higher susceptibility to partial photo-oxidation compared to organic mat DOM, potentially due to a lower abundance of phenolic compounds that act as "antioxidants" and slow the oxidation of DOM. These results demonstrated how chemical composition controls the photo-degradation of DOM in arctic surface waters, and that DOM photo-degradation will likely remain an important component of the freshwater C budget in the Arctic with increased export of permafrost DOM to surface waters.

  20. Comparison of zinc complexation properties of dissolved organic matter from surface waters and wastewater treatment plant effluents

    Institute of Scientific and Technical Information of China (English)

    CHENG Tao

    2005-01-01

    Unlike natural organic matter(NOM), wastewater organic matter(WWOM) from wastewater treatment plant effluents has not been extensively studied with respect to complexation reactions with heavy metals such as copper or zinc. In this study, organic matter from surface waters and a wastewater treatment plant effluent were concentrated by reverse osmosis(RO) method. The samples were treated in the laboratory to remove trace metals and major cations. The zinc complexing properties of both NOM and the WWOM were studied by square wave anodic stripping voltammetry(SWASV). Experimental data were compared to predictions using the Windermere Humic Aqueous Model(WHAM) Version VI. We found that the zinc binding of WWOM was much stronger than that of NOM and not well predicted by WHAM. This suggests that in natural water bodies that receive wastewater treatment plant effluents the ratio of WWOM to NOM must be taken into account in order to accurately predict free zinc activities.

  1. Photo- and bio-reactivity patterns of dissolved organic matter from biomass and soil leachates and surface waters in a subtropical wetland.

    Science.gov (United States)

    Chen, Meilian; Jaffé, Rudolf

    2014-09-15

    Dissolved organic carbon (DOC) measurements and optical properties were applied to assess the photo- and bio-reactivity of dissolved organic matter (DOM) from different sources, including biomass leaching, soil leaching and surface waters in a subtropical wetland ecosystem. Samples were exposed to light and/or dark incubated through controlled laboratory experiments. Changes in DOC, ultraviolet (UV-Vis) visible absorbance, and excitation-emission matrix (EEM) fluorescence combined with parallel factor analysis (PARAFAC) were performed to assess sample degradation. Degradation experiments showed that while significant amounts of DOC were consumed during bio-incubation for biomass leachates, a higher degree of bio-recalcitrance for soil leachate and particularly surface waters was displayed. Photo- and bio-humification transformations were suggested for sawgrass, mangrove, and seagrass leachates, as compared to substantial photo-degradation and very little to almost no change after bio-incubation for the other samples. During photo-degradation in most cases the EEM-PARAFAC components displayed photo-decay as compared to a few cases which featured photo-production. In contrast during bio-incubation most EEM-PARAFAC components proved to be mostly bio-refractory although some increases and decreases in abundance were also observed. Furthermore, the sequential photo- followed by bio-degradation showed, with some exceptions, a "priming effect" of light exposure on the bio-degradation of DOM, and the combination of these two processes resulted in a DOM composition more similar to that of the natural surface water for the different sub-environments. In addition, for leachate samples there was a general enrichment of one of the EEM-PARAFAC humic-like component (Ex/Em: bio-degradation process. This study exemplifies the effectiveness of optical property and EEM-PARAFAC in the assessment of DOM reactivity and highlights the importance of the coupling of photo- and bio

  2. Analysis of total and dissolved heavy metals in surface water of a Mexican polluted river by total reflection X-ray fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zarazua, G. [Instituto Nacional de Investigaciones Nucleares, Gerencia de Ciencias Ambientales, Apartado Postal 18-1027, Mexico D.F., C.P. 11801 (Mexico)]. E-mail: gzo@nuclear.inin.mx; Avila-Perez, P. [Instituto Nacional de Investigaciones Nucleares, Gerencia de Ciencias Ambientales, Apartado Postal 18-1027, Mexico D.F., C.P. 11801 (Mexico); Tejeda, S. [Instituto Nacional de Investigaciones Nucleares, Gerencia de Ciencias Ambientales, Apartado Postal 18-1027, Mexico D.F., C.P. 11801 (Mexico); Barcelo-Quintal, I. [Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Mexico, D.F. (Mexico); Martinez, T. [Universidad Nacional Autonoma de Mexico, Facultad de Quimica, Mexico, D.F. (Mexico)

    2006-11-15

    The present area of study is located in the Upper Course of the Lerma River (UCLR). The Lerma is one of the most important rivers of Mexico, where it drains highly populated and industrialized regions. The aim of the present study is to determine the heavy metal concentration of Cr, Mn, Fe, Cu and Pb in dissolved and total phases of the UCLR by means of Total Reflection X-ray Fluorescence Spectrometry (TXRF). The surface water samples were collected at 8 sites distributed following the stream flow direction of the river. Four sampling campaigns were carried out in each site in a 1-year period. A sample preparation method was applied in order to obtain the total and dissolved fraction and to destroy the organic matter. The total heavy metal average concentration decrease in the following order: Fe (2566 {mu}g/L) > Mn (300 {mu}g/L) > Cu (66 {mu}g/L) > Cr (21 {mu}g/L) > Pb (15 {mu}g/L). In general, the heavy metal concentrations in water of the UCLR are below the maximum permissible limits.

  3. Analysis of total and dissolved heavy metals in surface water of a Mexican polluted river by total reflection X-ray fluorescence spectrometry

    Science.gov (United States)

    Zarazua, G.; Ávila-Pérez, P.; Tejeda, S.; Barcelo-Quintal, I.; Martínez, T.

    2006-11-01

    The present area of study is located in the Upper Course of the Lerma River (UCLR). The Lerma is one of the most important rivers of Mexico, where it drains highly populated and industrialized regions. The aim of the present study is to determine the heavy metal concentration of Cr, Mn, Fe, Cu and Pb in dissolved and total phases of the UCLR by means of Total Reflection X-ray Fluorescence Spectrometry (TXRF). The surface water samples were collected at 8 sites distributed following the stream flow direction of the river. Four sampling campaigns were carried out in each site in a 1-year period. A sample preparation method was applied in order to obtain the total and dissolved fraction and to destroy the organic matter. The total heavy metal average concentration decrease in the following order: Fe (2566 μg/L) > Mn (300 μg/L) > Cu (66 μg/L) > Cr (21 μg/L) > Pb (15 μg/L). In general, the heavy metal concentrations in water of the UCLR are below the maximum permissible limits.

  4. High resolution measurements of methane and carbon dioxide in surface waters over a natural seep reveal dynamics of dissolved phase air-sea flux.

    Science.gov (United States)

    Du, Mengran; Yvon-Lewis, Shari; Garcia-Tigreros, Fenix; Valentine, David L; Mendes, Stephanie D; Kessler, John D

    2014-09-01

    Marine hydrocarbon seeps are sources of methane and carbon dioxide to the ocean, and potentially to the atmosphere, though the magnitude of the fluxes and dynamics of these systems are poorly defined. To better constrain these variables in natural environments, we conducted the first high-resolution measurements of sea surface methane and carbon dioxide concentrations in the massive natural seep field near Coal Oil Point (COP), California. The corresponding high resolution fluxes were calculated, and the total dissolved phase air-sea fluxes over the surveyed plume area (∼363 km(2)) were 6.66 × 10(4) to 6.71 × 10(4) mol day(-1) with respect to CH4 and -6.01 × 10(5) to -5.99 × 10(5) mol day(-1) with respect to CO2. The mean and standard deviation of the dissolved phase air-sea fluxes of methane and carbon dioxide from the contour gridding analysis were estimated to be 0.18 ± 0.19 and -1.65 ± 1.23 mmol m(-2) day(-1), respectively. This methane flux is consistent with previous, lower-resolution estimates and was used, in part, to conservatively estimate the total area of the dissolved methane plume at 8400 km(2). The influx of carbon dioxide to the surface water refutes the hypothesis that COP seep methane appreciably influences carbon dioxide dynamics. Seeing that the COP seep field is one of the biggest natural seeps, a logical conclusion could be drawn that microbial oxidation of methane from natural seeps is of insufficient magnitude to change the resulting plume area from a sink of atmospheric carbon dioxide to a source.

  5. Correlation Between Surface Area and Dissolving Properties of Lead - A Step in the Investigation of Higher than Standard Lead Concentration in Drinking Water in Washington, D.C.

    Science.gov (United States)

    Hua, M.; Garduno, L.; Mondragon, J. D.; Cuff, K. E.

    2004-12-01

    Several recently published articles by the Washington Post exposing the alarming concentration of lead in drinking water from schools and homes in the Washington D.C. area sparked our interest in the correlation between lead-containing materials used in plumbing and rate of lead solubility. Elementary children who attend schools in various regions of the District were contacted by San Francisco Bay Area- based high school students who are participants in the NSF-sponsored Environmental Science Information Technology Activities (ESITA) project. After receiving a thorough explanation of required sampling procedures, the elementary school children sent 500 ml water samples from their homes and schools to Berkeley along with information on the locations from which the water samples were collected. These water samples were analyzed for lead content at the Environmental Science Research Program laboratory at Lawrence Hall of Science. The majority of the samples contained more than 15 ppb of lead, which is the EPA action level. We hypothesize that there are three possible sources of lead in the drinking water: 1) lead pipes in the water main; 2) lead pipes in the service main; and 3) lead soldering that was often previously used to connect piping. We chose to investigate the effect of lead-based solder on the overall lead concentration in water. Using a soldering iron, we melted lead solder to create discs ranging from one to five centimeter diameter and one to thirty-six grams of mass. These discs were then placed into a beaker with 500 ml of 7.1pH distilled water and allowed to stand for 48 hours. At the end of 48 hours, the water samples were prepared for analysis using the EPA approved lead-dithizone procedure. Results showed an exponential relationship between disc surface area and the concentration of dissolved lead measured in the sample. Therefore, lead-based solder can represent a possible major source of lead contamination.

  6. Distribution and sources of dissolved black carbon in surface waters of the Chukchi Sea, Bering Sea, and the North Pacific Ocean

    Science.gov (United States)

    Nakane, Motohiro; Ajioka, Taku; Yamashita, Youhei

    2017-05-01

    Pyrogenic carbon, also called black carbon (BC), is an important component in the global carbon cycle. BC produced by biomass burning or fossil fuel combustion is transported to oceans by the atmosphere or rivers. However, environmental dynamics (i.e., major sources and sinks) of BC in marine environments have not been well documented. In this study, dissolved BC (DBC) collected from surface waters of the Chukchi Sea, the Bering Sea, and the subarctic and subtropical North Pacific were analyzed using the benzene polycarboxylic acid (BPCA) method. The DBC concentration and the ratio of B5CA and B6CA to all BPCAs (an index of the DBC condensation degree) ranged from 4.8 to 15.5 µg-C L-1 and from 0.20 to 0.43, respectively, in surface waters of the Chukchi/Bering Seas and the North Pacific Ocean. The concentration and condensation degree of DBC in the Chukchi/Bering Seas were higher and more variable than those in the subarctic and subtropical North Pacific, which implies that the major factors controlling DBC distribution were different in these marine provinces. In the Chukchi/Bering Seas, the DBC concentration was negatively correlated to salinity but positively correlated to chromophoric dissolved organic matter (CDOM) quantity and total dissolved lignin phenol concentration estimated by CDOM parameters. These correlations indicated that the possible major source of DBC in the Chukchi/Bering Seas was Arctic rivers. However, in the North Pacific, where riverine inputs are negligible for most sampling sites, DBC was possibly derived from the atmosphere. Although spectral slopes of CDOM at 275-295 nm (an index of the photodegradation degree of CDOM) differed widely between the subarctic and subtropical North Pacific, the concentration and condensation degrees of DBC were similar between the subarctic and subtropical North Pacific, which suggests that photodegradation was not the only major factor controlling DBC distribution. Therefore, DBC distributions of the

  7. Distribution and Sources of Dissolved Black Carbon in Surface Waters of the Chukchi Sea, Bering Sea, and the North Pacific Ocean

    Directory of Open Access Journals (Sweden)

    Motohiro Nakane

    2017-05-01

    Full Text Available Pyrogenic carbon, also called black carbon (BC, is an important component in the global carbon cycle. BC produced by biomass burning or fossil fuel combustion is transported to oceans by the atmosphere or rivers. However, environmental dynamics (i.e., major sources and sinks of BC in marine environments have not been well-documented. In this study, dissolved BC (DBC collected from surface waters of the Chukchi Sea, the Bering Sea, and the subarctic and subtropical North Pacific were analyzed using the benzene polycarboxylic acid (BPCA method. The DBC concentration and the ratio of B5CA and B6CA to all BPCAs (an index of the DBC condensation degree ranged from 4.8 to 15.5 μg-C L−1 and from 0.20 to 0.43, respectively, in surface waters of the Chukchi/Bering Seas and the North Pacific Ocean. The concentration and condensation degree of DBC in the Chukchi/Bering Seas were higher and more variable than those in the subarctic and subtropical North Pacific, which implies that the major factors controlling DBC distribution were different in these marine provinces. In the Chukchi/Bering Seas, the DBC concentration was negatively correlated to salinity but positively correlated to chromophoric dissolved organic matter (CDOM quantity and total dissolved lignin phenol concentration estimated by CDOM parameters. These correlations indicated that the possible major source of DBC in the Chukchi/Bering Seas was Arctic rivers. However, in the North Pacific, where riverine inputs are negligible for most sampling sites, DBC was possibly derived from the atmosphere. Although spectral slopes of CDOM at 275–295 nm (an index of the photodegradation degree of CDOM differed widely between the subarctic and subtropical North Pacific, the concentration and condensation degrees of DBC were similar between the subarctic and subtropical North Pacific, which suggests that photodegradation was not the only major factor controlling DBC distribution. Therefore, DBC

  8. Fluorescence and absorption properties of chromophoric dissolved organic matter (CDOM in coastal surface waters of the northwestern Mediterranean Sea, influence of the Rhône River

    Directory of Open Access Journals (Sweden)

    J. Para

    2010-12-01

    Full Text Available Seawater samples were collected monthly in surface waters (2 and 5 m depths of the Bay of Marseilles (northwestern Mediterranean Sea; 5°17'30" E, 43°14'30" N during one year from November 2007 to December 2008 and studied for total organic carbon (TOC as well as chromophoric dissolved organic matter (CDOM optical properties (absorbance and fluorescence. The annual mean value of surface CDOM absorption coefficient at 350 nm [aCDOM(350] was very low (0.10 ± 0.02 m−1 in comparison to values usually found in coastal waters, and no significant seasonal trend in aCDOM(350 could be determined. By contrast, the spectral slope of CDOM absorption (SCDOM was significantly higher (0.023 ± 0.003 nm−1 in summer than in fall and winter periods (0.017 ± 0.002 nm−1, reflecting either CDOM photobleaching or production in surface waters during stratified sunny periods. The CDOM fluorescence, assessed through excitation emission matrices (EEMs, was dominated by protein-like component (peak T; 1.30–21.94 QSU and marine humic-like component (peak M; 0.55–5.82 QSU, while terrestrial humic-like fluorescence (peak C; 0.34–2.99 QSU remained very low. This reflected a dominance of relatively fresh material from biological origin within the CDOM fluorescent pool. At the end of summer, surface CDOM fluorescence was very low and strongly blue shifted, reinforcing the hypothesis of CDOM photobleaching. Our results suggested that unusual Rhône River plume eastward intrusion events might reach Marseilles Bay within 2–3 days and induce local phytoplankton blooms and subsequent fluorescent CDOM production (peaks M and T without adding terrestrial fluorescence signatures (peaks C and A. Besides Rhône River plumes, mixing events of the entire water column injected relative aged (peaks C and M CDOM from the bottom into the surface and thus appeared also as an important source

  9. Protein analysis in dissolved organic matter: What proteins from organic debris, soil leachate and surface water can tell us - a perspective

    Directory of Open Access Journals (Sweden)

    W. X. Schulze

    2005-01-01

    Full Text Available Mass spectrometry based analysis of proteins is widely used to study cellular processes in model organisms. However, it has not yet routinely been applied in environmental research. Based on observations that protein can readily be detected as a component of dissolved organic matter (DOM, this article gives an example about the possible use of protein analysis in ecology and environmental sciences focusing on different terrestrial ecosystems. At this stage, there are two areas of interest: (1 the identification of phylogenetic groups contributing to the environmental protein pool, and (2 identification of the organismic origin of specific enzymes that are important for ecosystem processes. In this paper, mass spectrometric protein analysis was applied to identify proteins from decomposing plant material and DOM of soil leachates and surface water samples derived from different environments. It is concluded, that mass spectrometric protein analysis is capable of distinguishing phylogenetic origin of proteins from litter protein extracts, leachates of different soil horizons, and from various sources of terrestrial surface water. Current limitation is imposed by the limited knowledge of complete genomes of soil organisms. The protein analysis allows to relate protein presence to biogeochemical processes, and to identify the source organisms for specific active enzymes. Further applications, such as in pollution research are conceivable. In summary, the analysis of proteins opens a new area of research between the fields of microbiology and biogeochemistry.

  10. Protein analysis in dissolved organic matter: What proteins from organic debris, soil leachate and surface water can tell us - a perspective

    Science.gov (United States)

    Schulze, W. X.

    Mass spectrometry based analysis of proteins is widely used to study cellular processes in model organisms. However, it has not yet routinely been applied in environmental research. Based on observations that protein can readily be detected as a component of dissolved organic matter (DOM), this article gives an example about the possible use of protein analysis in ecology and environmental sciences focusing on different terrestrial ecosystems. At this stage, there are two areas of interest: (1) the identification of phylogenetic groups contributing to the environmental protein pool, and (2) identification of the organismic origin of specific enzymes that are important for ecosystem processes. In this paper, mass spectrometric protein analysis was applied to identify proteins from decomposing plant material and DOM of soil leachates and surface water samples derived from different environments. It is concluded, that mass spectrometric protein analysis is capable of distinguishing phylogenetic origin of proteins from litter protein extracts, leachates of different soil horizons, and from various sources of terrestrial surface water. Current limitation is imposed by the limited knowledge of complete genomes of soil organisms. The protein analysis allows to relate protein presence to biogeochemical processes, and to identify the source organisms for specific active enzymes. Further applications, such as in pollution research are conceivable. In summary, the analysis of proteins opens a new area of research between the fields of microbiology and biogeochemistry.

  11. Protein analysis in dissolved organic matter: what free proteins from soil leachate and surface water can tell us – a perspective

    Directory of Open Access Journals (Sweden)

    W. Schulze

    2004-12-01

    Full Text Available Mass spectrometry based analysis of proteins is widely used to study cellular processes in model organisms. However, it has not yet routinely been applied in environmental research. Based on observations that protein can readily be detected as a component of dissolved organic matter (DOM, this article gives an example about the possible use of protein analysis in ecology and environmental sciences focusing on different terrestrial ecosystems. At this stage, there are two areas of interest: (1 the identification of phylogenetic groups contributing to the DOM protein pool, and (2 identification of the organismic origin of specific enzymes that are important for ecosystem processes. In this paper, mass spectrometric protein analysis was applied to identify proteins from DOM and organism-free surface water samples derived from different environments. It is concluded, that mass spectrometric protein analysis is capable of distinguishing phylogenetic origin of proteins from leachates of different soil horizons, and from various sources of terrestrial surface water. Current limitation is imposed by the limited knowledge of complete genomes of soil organisms. The protein analysis allows to relate protein presence to biogeochemical processes, and to identify the source organisms for specific active enzymes. Further applications, such as in pollution research are conceivable. In summary, the analysis of proteins opens a new area of research between the fields of microbiology and biogeochemistry.

  12. Distribution of dissolved organic carbon and metal-binding capacity among ultrafilterable fractions isolated from selected surface waters of the southeastern United States

    Science.gov (United States)

    Alberts, James J.; Giesy, John P.; Evans, David W.

    1984-06-01

    The binding capacities of surface waters for Cd, Cu, and Pb were determined for eight water samples representing four rivers and two swamps from Florida and Georgia in the southeastern United States The binding capacity ranges were CdBC=0 04 to 0 79 μg atm/L, CuBC=1 0 to 5 4 μg atm/L, and PbBC=5 0 to 17 8 μg atm/L Binding capacity values from the southeastern United States are shown to be in good agreement with values reported from the northeastern part of the country and northern Europe The CdBC was due primarily to inorganic ligand binding, while PbBC was predominantly a result of organic matter The CuBC was due to a complex function of both organic and inorganic binding Significant portions of the CuBC and PbBC could be removed from the waters by ultrafiltration of particles between 0·45 μm and 52 Å in diameter Ultrafiltration, even to removing particles > 13 Å diameter, did not affect the CdBC Distributional studies of the dissolved organic carbon in these systems reveal that significant fractions of the DOC are present in the ultrafilterable fraction which contains significant portions of the CuBC and PbBC

  13. Total dissolvable and dissolved iron isotopes in the water column of the Peru upwelling regime

    Science.gov (United States)

    Chever, Fanny; Rouxel, Olivier J.; Croot, Peter L.; Ponzevera, Emmanuel; Wuttig, Kathrin; Auro, Maureen

    2015-08-01

    Vertical distributions of iron (Fe) concentrations and isotopes were determined in the total dissolvable and dissolved pools in the water column at three coastal stations located along the Peruvian margin, in the core of the Oxygen Minimum Zone (OMZ). The shallowest station 121 (161 m total water depth) was characterized by lithogenic input from the continental plateau, yielding concentrations as high as 456 nM in the total dissolvable pool. At the 2 other stations (stations 122 and 123), Fe concentrations of dissolved and total dissolvable pools exhibited maxima in both surface and deep layers. Fe isotopic composition (δ56Fe) showed a fractionation toward lighter values for both physical pools throughout the water column for all stations with minimum values observed for the surface layer (between -0.64 and -0.97‰ at 10-20 m depth) and deep layer (between -0.03 and -1.25‰ at 160-300 m depth). An Fe isotope budget was established to determine the isotopic composition of the particulate pool. We observed a range of δ56Fe values for particulate Fe from +0.02 to -0.87‰, with lightest values obtained at water depth above 50 m. Such light values in the both particulate and dissolved pools suggest sources other than atmospheric dust deposition in the surface ocean, including lateral transport of isotopically light Fe. Samples collected at station 122 closest to the sediment show the lightest isotope composition in the dissolved and the particulate pools (-1.25 and -0.53‰ respectively) and high Fe(II) concentrations (14.2 ± 2.1 nM) consistent with a major reductive benthic Fe sources that is transferred to the ocean water column. A simple isotopic model is proposed to link the extent of Fe(II) oxidation and the Fe isotope composition of both particulate and dissolved Fe pools. This study demonstrates that Fe isotopic composition in OMZ regions is not only affected by the relative contribution of reductive and non-reductive shelf sediment input but also by

  14. Four-year survey of dissolved/dispersed petroleum hydrocarbons on surface waters of Admiralty Bay, King George Island, Antarctica

    Directory of Open Access Journals (Sweden)

    Márcia Caruso Bícego

    2003-01-01

    Full Text Available Seawater from 8 stations in Admiralty Bay was systematically sampled during the summer of 1994, 1995, 1996 and 1997 and analyzed by spectrofluorimetry to measure dissolved/dispersed petroleum hydrocarbons (DDPHs. The purpose of this study was to detect some temporal and spatial changes in terms of oil contamination of the region. The results indicate low levels of oil pollution with relatively high concentrations near the research stations located in the study area. During the summers of 1995 and 1996 the average concentrations for individual stations were low and below of 0.50 ¼g.L-1. Summers of 1994 and 1997 had relatively higher average concentrations (up to 1.57 ¼g.L-1, mainly in front of Arctowski and Ferraz Research Stations.Amostras de água na Baía do Almirantado, Península Antártica, foram sistematicamente coletadas em 8 estações durante os verões de 1994 a 1997 onde foram analisados hidrocarbonetos do petróleo dispersos e dissolvidos por espectrofluorescência. O objetivo foi avaliar variações temporais e espaciais em termos de contaminação por óleo na região. Os resultados em geral indicam baixos níveis de poluição embora tenham sido verificadas algumas concentrações relativamente maiores nas proximidades das estações de pesquisa fixadas na região de estudo. Durante os anos de 1995 e 1996 a média das concentrações foram baixas e menores que 0,50 ¼g.L-1 para os pontos individuais. Os verões de 1994 e 1997 tiveram concentrações médias mais elevadas (até 1,57 ¼g.L-1, e os maiores valores foram nas proximidades das estações brasileira e polonesa.

  15. Twentieth century δ13C variability in surface water dissolved inorganic carbon recorded by coralline algae in the northern North Pacific Ocean and the Bering Sea

    Directory of Open Access Journals (Sweden)

    W. Adey

    2010-07-01

    Full Text Available Oxygen isotopes and Mg/Ca ratios in long-lived coralline algae record ambient seawater temperature in their calcified tissues over time. Similarly, carbon stable isotopes (δ13C in the calcified tissue may record δ13C values of ambient seawater dissolved inorganic carbon. Here, we measured δ13C in the coralline algae Clathromorphum nereostratum to test the feasibility of reconstructing the intrusion of anthropogenic CO2 into the northern North Pacific Ocean and Bering Sea. δ13C was measured in the high Mg-calcite calcified tissue of three C. nereostratum specimens from two islands 500 km apart in the Aleutian archipelago. In the records spanning 1887 to 2003, the average rate of decline in δ13C values increased from 0.03‰ yr−1 in the 1960s to 0.1‰ yr−1 in the 1990s, which was higher than expected due to solely the δ13C-Suess effect. Deeper water in this region exhibits higher concentrations of CO2 and low δ13C values. Transport of deeper water into surface water (i.e., upwelling is increased when the Aleutian Low is intensified. We hypothesize that the acceleration of δ13C decline may result from an increase in upwelling from the 1960s to 1990s, which in turn was driven by an increase in the intensity of the Aleutian Low. Detrended δ13C records also vary on 4–7 years and bidecadal timescales supporting an atmospheric teleconnection of tropical climate patterns to the northern North Pacific Ocean and Bering Sea manifested as changes in upwelling.

  16. Twentieth century δ13C variability in surface water dissolved inorganic carbon recorded by coralline algae in the northern North Pacific Ocean and the Bering Sea

    Directory of Open Access Journals (Sweden)

    W. Adey

    2011-01-01

    Full Text Available The oxygen isotopic composition and Mg/Ca ratios in the skeletons of long-lived coralline algae record ambient seawater temperature over time. Similarly, the carbon isotopic composition in the skeletons record δ13C values of ambient seawater dissolved inorganic carbon. Here, we measured δ13C in the coralline alga Clathromorphum nereostratum to test the feasibility of reconstructing the intrusion of anthropogenic CO2 into the northern North Pacific Ocean and Bering Sea. The δ13C was measured in the high Mg-calcite skeleton of three C. nereostratum specimens from two islands 500 km apart in the Aleutian archipelago. In the records spanning 1887 to 2003, the average decadal rate of decline in δ13C values increased from 0.03‰ yr−1 in the 1960s to 0.095‰ yr−1 in the 1990s, which was higher than expected due to solely the δ13C-Suess effect. Deeper water in this region exhibits higher concentrations of CO2 and low δ13C values. Transport of deeper water into surface water (i.e., upwelling increases when the Aleutian Low is intensified. We hypothesized that the acceleration of the δ13C decline may result from increased upwelling from the 1960s to 1990s, which in turn was driven by increased intensity of the Aleutian Low. Detrended δ13C records also varied on 4–7 year and bidecadal timescales supporting an atmospheric teleconnection of tropical climate patterns to the northern North Pacific Ocean and Bering Sea manifested as changes in upwelling.

  17. Study on Dissolved Trace Metals in Sea Surface Microlayer in Daya Bay

    Institute of Scientific and Technical Information of China (English)

    张正斌; 刘春颖; 刘莲生; 于琳; 王肇鼎

    2004-01-01

    Glass-plate sampling during 1988-1999 in Daya Bay and suitable corresponding analytical methods were used for the measurement of dissolved trace metals, dissolved organic carbon, biological oxygen demand, chemical oxygen demand, salinity of the sea surface microlayer and subsurface water. Apparent enrichment mechanism and diurnal variation have been revealed for dissolved trace metals in the microlayer in Daya Bay. The more dissolved organic matter was enriched in the sea surface microlayer, the more dissolved trace metals were enriched in the layer. The organic matter played an important role in the enrichment process. The diurnal variations of dissolved trace metals showed that their concentration was apparently inversely related to the tide activity that the concentration was low during rising tide, but high during falling tide. The behavior of dissolved trace metals expressed by the diurnal variation was clearly opposite to that of salinity.

  18. 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...

  19. Stability of salt in the Permian salt basin of Kansas, Oklahoma, Texas and New Mexico, with a section on dissolved salts in surface water

    Science.gov (United States)

    Bachman, George Odell; Johnson, Ross Byron

    1973-01-01

    bedded salt from subsurface dissolution depends chiefly on the isolation of the salt from moving ground water that is not completely saturated with salt. Karst topography is a major criterion for recognizing areas where subsurface dissolution has been active in the past; therefore, the age of the karst development is needed to provide the most accurate estimate of the dissolution rate. The Ogallala Formation-of Pliocene age is probably the most widespread deposit in the Permian salt basin that can be used as a point of reference for dating the development of recent topography. It is estimated that salt has been dissolved laterally in the vicinity of Carlsbad, New Mexico, at an average rate of about 6-8 miles per million years. Estimates of future rates of salt dissolution and the resulting lateral retreat of the underground dissolution front can be projected with reasonable confidence for southeastern New Mexico on the assumption that the climatic changes there in the past 4 million years are representative of climatic changes that may be expected in the near future of geologic time. Large amounts of salt are carried by present-day rivers in the Permian salt basin; some of the salt is derived from subsurface salt beds, but dissolution is relatively slow. Ground-water movement through the Permian salt basin is also relatively slow.

  20. Measuring in-stream productivity: the potential of continuous chlorophyll and dissolved oxygen monitoring for assessing the ecological status of surface waters.

    Science.gov (United States)

    Jarvie, H P; Love, A J; Williams, R J; Neal, C

    2003-01-01

    Continuous (hourly) measurements of dissolved oxygen and chlorophyll (determined by fluorimetry) were made for an inter-linked lowland river and canal system. The dissolved oxygen data were used to estimate daily rates of re-aeration, photosynthesis and respiration, using a process-based analytical technique (the Delta method). In-situ fluorimeter measurements of chlorophyll were ground-truthed on a fortnightly basis using laboratory methanol extraction of chlorophyll and spectrophotometric analysis. Water samples were also analysed for algal species on a fortnightly basis. The river and canal exhibited very similar rates of photosynthesis and respiration during the summer of 2001, despite much higher chlorophyll concentrations and total algal counts, indicating that benthic algae and/or aquatic macrophytes may be making an important contribution to photosynthesis rates in the river. Suspended algal populations in the canal are dominated by planktonic species, whereas the river has a higher proportion of species which are predominantly benthic in habitat. The river exhibited higher rates of respiration, reflecting a higher organic loading from external (e.g. sewage effluent) sources.

  1. Seasonal variations of total {sup 234}Th and dissolved {sup 238}U concentration activities in surface water of Bransfield Strait, Antarctica, from March to October 2011

    Energy Technology Data Exchange (ETDEWEB)

    Lapa, Flavia V.; Oliveira, Joselene de; Costa, Alice M.R., E-mail: fvlapa@ipen.br, E-mail: jolivei@ipen.br, E-mail: lice_mrc@hotmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN-CNEN/SP), Sao Paulo, SP (Brazil). Laboratorio de Radiometria Ambiental; Braga, Elisabete S., E-mail: edsbraga@usp.br [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Inst. Oceanografico. Lab. de Nutrientes, Micronutrientes e Tracos nos Oceanos

    2013-07-01

    In this study the naturally occurring radionuclides {sup 234}Th and {sup 238}U were used to investigate the magnitude of upper ocean particulate organic carbon export in Bransfield Strait, Southern Ocean. This region is the largest oceanic high-nitrate low-chlorophyll (HNLC) area in the world and is known to contribute to regulate of the atmospheric CO{sub 2} via the biological pump. Due to its different geochemical behavior in seawater, the resulting U/Th disequilibria can be easily used to constrain the transport rates of particles and reaction processes between solution and particulate phases. Sampling occurred during the summer (March and November) 2011. Total {sup 234}Th activities in surface seawater samples ranged from 1.3 to 3.7 dpm L{sup -1} (station EB 011) during March/11 campaign, while in October/11 total {sup 234}Th activity concentrations varied from 1.4 to 2.9 dpm L{sup -1}. Highest total {sup 234}Th activities were found late in the austral summer season. Activity concentrations of dissolved {sup 238}U in surface seawater varied from 2.1 to 2.4 dpm L{sup -1}. Taking into account all sampling stations established in March and October/11 the relative variability of total {sup 234}Th distribution was 22%. (author)

  2. The spectral optical properties and relative radiant heating contribution of dissolved and particulate matter in the surface waters across the Fram Strait

    DEFF Research Database (Denmark)

    Pavlov, A.K.; Granskog, M.A.; Stedmon, Colin

    The Fram Strait is the key region for exchange processes between Arctic Ocean and North Atlantic. With two major near-surface currents, the warm and salty West Spitsbergen Current and cold low-salinity East Greenland Current, its waters encompass two distinct oceanographic environments. During...

  3. The spectral optical properties and relative radiant heating contribution of dissolved and particulate matter in the surface waters across the Fram Strait

    DEFF Research Database (Denmark)

    Pavlov, A.K.; Granskog, M.A.; Stedmon, Colin

    The Fram Strait is the key region for exchange processes between Arctic Ocean and North Atlantic. With two major near-surface currents, the warm and salty West Spitsbergen Current and cold low-salinity East Greenland Current, its waters encompass two distinct oceanographic environments. During...

  4. Optimization of a cloud point extraction procedure with response surface methodology for the quantification of dissolved iron in produced water from the petroleum industry using FAAS.

    Science.gov (United States)

    Gondim, Tamyris A; Guedes, Jhonyson A C; Ribeiro, Livia P D; Lopes, Gisele S; Matos, Wladiana O

    2017-01-30

    The characterization of inorganic elements in the produced water (PW) samples is a difficult task because of the complexity of the matrix. This work deals with a study of a methodology for dissolved Fe quantification in PW from oil industry by flame atomic absorption spectrometry (FAAS) after cloud point extraction (CPE). The procedure is based on the CPE using PAN as complexing agent and Triton X-114 as surfactant. The best conditions for Fe extraction parameters were studied using a Box-Behnken design. The proposed method presented a LOQ of 0.010μgmL(-1) and LOD of 0.003μgmL(-1). The precision of the method was evaluated in terms of repeatability, obtaining a coefficient of variation of 2.54%. The accuracy of the method was assessed by recovery experiments of Fe spiked that presented recovery of 103.28%. The method was applied with satisfactory performance to determine Fe by FAAS in PW samples.

  5. Total dissolved gas, barometric pressure, and water temperature data, lower Columbia River, Oregon and Washington, 1996

    Science.gov (United States)

    Tanner, Dwight Q.; Harrison, Howard E.; McKenzie, Stuart W.

    1996-01-01

    Increased levels of total dissolved gas pressure can cause gas-bubble trauma in fish downstream from dams on the Columbia River. In cooperation with the U.S. Army Corps of Engineers, the U.S. Geological Survey collected data on total dissolved gas pressure, barometric pressure, water temperature, and dissolved oxygen pressure at 11 stations on the lower Columbia River from the John Day forebay (river mile 215.6) to Wauna Mill (river mile 41.9) from March to September 1996. Methods of data collection, review, and processing are described in this report. Summaries of daily minimum, maximum, and mean hourly values are presented for total dissolved gas pressure, barometric pressure, and water temperature. Hourly values for these parameters are presented graphically. Dissolved oxygen data are not presented in this report because the quality-control data show that the data have poor precision and high bias. Suggested changes to monitoring procedures for future studies include (1) improved calibration procedures for total dissolved gas and dissolved oxygen to better define accuracy at elevated levels of supersaturation and (2) equipping dissolved oxygen sensors with stirrers because river velocities at the shoreline monitoring stations probably cannot maintain an adequate flow of water across the membrane surface of the dissolved oxygen sensor.

  6. Water quality: determination of dissolved oxygen : electrochemical probe method

    National Research Council Canada - National Science Library

    2012-01-01

    ISO 5814:2012 specifies an electrochemical method for the determination of dissolved oxygen in water by means of an electrochemical cell which is isolated from the sample by a gas permeable membrane...

  7. Real Time Monitoring of Dissolved Organic Carbon Concentration and Disinfection By-Product Formation Potential in a Surface Water Treatment Plant with Simulaneous UV-VIS Absorbance and Fluorescence Excitation-Emission Mapping

    Science.gov (United States)

    Gilmore, A. M.

    2015-12-01

    This study describes a method based on simultaneous absorbance and fluorescence excitation-emission mapping for rapidly and accurately monitoring dissolved organic carbon concentration and disinfection by-product formation potential for surface water sourced drinking water treatment. The method enables real-time monitoring of the Dissolved Organic Carbon (DOC), absorbance at 254 nm (UVA), the Specific UV Absorbance (SUVA) as well as the Simulated Distribution System Trihalomethane (THM) Formation Potential (SDS-THMFP) for the source and treated water among other component parameters. The method primarily involves Parallel Factor Analysis (PARAFAC) decomposition of the high and lower molecular weight humic and fulvic organic component concentrations. The DOC calibration method involves calculating a single slope factor (with the intercept fixed at 0 mg/l) by linear regression for the UVA divided by the ratio of the high and low molecular weight component concentrations. This method thus corrects for the changes in the molecular weight component composition as a function of the source water composition and coagulation treatment effects. The SDS-THMFP calibration involves a multiple linear regression of the DOC, organic component ratio, chlorine residual, pH and alkalinity. Both the DOC and SDS-THMFP correlations over a period of 18 months exhibited adjusted correlation coefficients with r2 > 0.969. The parameters can be reported as a function of compliance rules associated with required % removals of DOC (as a function of alkalinity) and predicted maximum contaminant levels (MCL) of THMs. The single instrument method, which is compatible with continuous flow monitoring or grab sampling, provides a rapid (2-3 minute) and precise indicator of drinking water disinfectant treatability without the need for separate UV photometric and DOC meter measurements or independent THM determinations.

  8. 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...

  9. 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.

  10. Effect of dissolved oxygen content on stress corrosion cracking of a cold worked 316L stainless steel in simulated pressurized water reactor primary water environment

    Science.gov (United States)

    Zhang, Litao; Wang, Jianqiu

    2014-03-01

    Stress corrosion crack growth tests of a cold worked nuclear grade 316L stainless steel were conducted in simulated pressurized water reactor (PWR) primary water environment containing various dissolved oxygen (DO) contents but no dissolved hydrogen. The crack growth rate (CGR) increased with increasing DO content in the simulated PWR primary water. The fracture surface exhibited typical intergranular stress corrosion cracking (IGSCC) characteristics.

  11. Investigating Factors that Affect Dissolved Oxygen Concentration in Water

    Science.gov (United States)

    Jantzen, Paul G.

    1978-01-01

    Describes activities that demonstrate the effects of factors such as wind velocity, water temperature, convection currents, intensity of light, rate of photosynthesis, atmospheric pressure, humidity, numbers of decomposers, presence of oxidizable ions, and respiration by plants and animals on the dissolved oxygen concentration in water. (MA)

  12. Benthic flux of dissolved nickel into the water column of south San Francisco Bay

    Science.gov (United States)

    Topping, B.R.; Kuwabara, J.S.; Parcheso, Francis; Hager, S.W.; Arnsberg, A.J.; Murphy, Fred

    2001-01-01

    Field and laboratory studies were conducted between April, 1998 and May, 1999 to provide the first direct measurements of the benthic flux of dissolved (0.2-micron filtered) nickel between the bottom sediment and water column at three sites in the southern component of San Francisco Bay (South Bay), California. Dissolved nickel and predominant ligands (represented by dissolved organic carbon, and sulfides) were the solutes of primary interest, although a variety of ancillary measurements were also performed to provide a framework for interpretation. Results described herein integrate information needs identified by the State Water Resources Control Board and local stakeholders with fundamental research associated with the U.S. Geological Survey Toxic Substances Hydrology Program. Dissolved-Ni concentrations in the bottom water over the three sampling dates ranged from 34 to 43 nanomoles per liter. Dissolved-macronutrient concentrations in the bottom water were consistently higher (frequently by orders of magnitude) than surface-water determinations reported for similar times and locations (Regional Monitoring Program, 2001). This is consistent with measured positive benthic fluxes for the macronutrients. Benthic-flux estimates for dissolved nickel from core-incubations, when areally averaged over the South Bay, were significant (that is, of equivalent or greater order of magnitude) relative to previously reported freshwater point and non-point sources. This observation is consistent with previous determinations for other metals, and with the potential remobilization of sediment-associated metals that have been ubiquitously distributed in the South Bay. Similar to dissolved-nickel results, benthic flux of macronutrients was also consistently significant relative to surface-water inputs. These results add to a growing body of knowledge that strongly suggests a need to consider contaminant transport across the sediment-water interface when establishing future

  13. Investigation of a fiber optic surface plasmon spectroscopy in conjunction with conductivity as an in situ method for simultaneously monitoring changes in dissolved organic carbon and salinity in coastal waters.

    Science.gov (United States)

    Kim, Yoon-Chang; Cramer, Jeffrey A; Booksh, Karl S

    2011-10-21

    A combination surface plasmon resonance (SPR) and conductivity sensor array was developed and implemented to demonstrate the ability to differentiate among changes in dissolved organic carbon (DOC) and salinity in coastal water. The array is capable of achieving sufficient spatial and temporal data density to better understand the cycling and fate of terrestrial DOC in coastal areas. DOC is the second largest source of bioreactive carbon in the environment and plays a key role in mediating microbial activity and generation of atmospheric CO(2). In the coastal areas, the salinity is also an important property in many applications, such as leak detection for landfill liners, saltwater intrusion to drinking water, marine environment monitoring, and seasonal climate prediction. Conductivity sensors are the industry standard for determining salinity in ocean systems. However, both conductivity and refractive index sensors, such as SPR spectroscopy based sensors, respond to salinity and DOC levels. To demonstrate the capability of the SPR sensor and a conductivity sensor to collect complimentary data useful in discrimination of salinity and DOC in coastal zone water, conductivity, SPR, and temperature data were collected during passage from the Juan de Fuca ridge area returning to the University of Washington docks.

  14. Dissolved organic matter in anoxic pore waters from Mangrove Lake, Bermuda

    Science.gov (United States)

    Orem, W.H.; Hatcher, P.G.; Spiker, E. C.; Szeverenyi, N.M.; Maciel, G.E.

    1986-01-01

    Dissolved organic matter and dissolved inorganic chemical species in anoxic pore water from Mangrove Lake, Bermuda sediments were studied to evaluate the role of pore water in the early diagenesis of organic matter. Dissolved sulphate, titration alkalinity, phosphate, and ammonia concentration versus depth profiles were typical of many nearshore clastic sediments and indicated sulphate reduction in the upper 100 cm of sediment. The dissolved organic matter in the pore water was made up predominantly of large molecules, was concentrated from large quantities of pore water by using ultrafiltration and was extensively tudied by using elemental and stable carbon isotope analysis and high-resolution, solid state 13C nuclear magnetic resonance and infrared spectroscopy. The results indicate that this material has a predominantly polysaccharide-like structure and in addition contains a large amount of oxygen-containing functional groups (e.g., carboxyl groups). The 13C nulcear magnetic resonance spectra of the high-molecular-weight dissolved organic matter resemble those of the organic matter in the surface sediments of Mangrove Lake. We propose that this high-molecular-weight organic matter in pore waters represents the partially degraded, labile organic components of the sedimentary organic matter and that pore waters serve as a conduit for removal of these labile organic components from the sediments. The more refractory components are, thus, selectively preserved in the sediments as humic substances (primarily humin). ?? 1986.

  15. Selected methods for dissolved iron (II, III) and dissolved sulfide (-II) determinations in geothermal waters

    Science.gov (United States)

    Vivit, D.V.; Jenne, E.A.

    1985-01-01

    Dissolved sulfide (-II) and dissolved iron (II, III) were determined in geothermal well water samples collected at Cerro Prieto, Mexico. Most samples consisted of liquid and gas (two phases) at the instant of collection; and a subset of samples, referred to as ' flashed ' samples, consisted of pressurized steam samples which were allowed to condense. Sulfide was determined by sulfide specific ion electrode; Fe(II) and Fe(III) plus Fe(II) were determined spectrophotometrically. The precision and accuracy of the methods were evaluated for these high-silica waters with replicate analyses, spike recoveries, and an alternate method. Direct current (d.c.) argon plasma emission spectrometry was the alternate method used for Fe(III)-plus-Fe(II) analyses. Mean dissolved iron concentrations ranged from 20.2 to 834 micrograms/L (ug/L) as Fe(II) and 26.8 to 904 ug/L as Fe(III) plus Fe(II). Mean sulfide concentrations ranged from about 0.01 to 5.3 mg/L (S-II) Generally, higher S(-II) values and larger Fe(II)/Fe(III) ratios were found in the two-phase samples. These findings suggest that the ' flashed ' samples are at a less reduced state than the two-phase samples. (Author 's abstract)

  16. The Biogeochemistry of Chromophoric Dissolved Organic Matter in Coastal Waters

    Science.gov (United States)

    2016-06-07

    The Biogeochemistry of Chromophoric Dissolved Organic Matter in Coastal Waters Robert F. Chen Environmental , Coastal and Ocean Sciences University of...properties to governing physical processes in high energy environments such as coastal seas. In addition, large spatial coverage over a wide range of...optical measurements of CDOM. In order to reliably predict the important photochemical, biological, and chemical processes governing CDOM, and hence its

  17. Mechanisms and solubility equations of gas dissolving in water

    Institute of Scientific and Technical Information of China (English)

    付晓泰; 王振平; 卢双舫

    1996-01-01

    The two mechanisms of gas dissolving in water, interstice filling and aquation, are proposed. General equations of gas solubility have been deduced from the mechanisms and experimental observations. Dependence of Henry’s coefficient on temperature, pressure, aquation equilibrium constant and gas molecular wlume is discussed. The theoretical equations were verified by experimental data, which shows that the theoretical results of the solubility of methane are in good agreement with the experimental data in the range of 20 -160℃ and under a pressure of less than 60 MPa.

  18. Experimental study on total dissolved gas supersaturation in water

    Directory of Open Access Journals (Sweden)

    Lu QU

    2011-12-01

    Full Text Available More and more high dams have been constructed and operated in China. The total dissolved gas (TDG supersaturation caused by dam discharge leads to gas bubble disease or even death of fish. Through a series of experiments, the conditions and requirements of supersaturated TDG generation were examined in this study. The results show that pressure (water depth, aeration, and bubble dissolution time are required for supersaturated TDG generation, and the air-water contact area and turbulence intensity are the main factors that affect the generation rate of supersaturated TDG. The TDG supersaturation levels can be reduced by discharging water to shallow shoals downstream of the dam or using negative pressure pipelines. Furthermore, the TDG supersaturation levels in stilling basins have no direct relationship with those in reservoirs. These results are of great importance for further research on the prediction of supersaturated TDG generation caused by dam discharge and aquatic protection.

  19. Storm dissolved organic matter : surface and sub-surface erosion controls its composition

    Science.gov (United States)

    Denis, Marie; Jeanneau, Laurent; Gruau, Gérard; Petitjean, Patrice; Pierson-Wickmann, Anne-Catherine

    2016-04-01

    In headwater catchments, flood events are responsible for exportation of the major part of DOM (dissolved organic matter) during the hydrological year. During these hot moments, the increased flow at the outlet is accompanied with an increase of DOM concentrations, implying the mobilisation of additional DOM sources which could have a different composition than DOM exported during base-flow. Molecular analysis performed on samples coming from the outlet of the Kervidy-Naizin catchment, an agricultural catchment located in France (Critical Zone Observatory AgrHyS) revealed a modification in the distribution of lignin compounds during flood events. This DOM, less biodegraded, could be produced by partition between particulate and dissolved phases when the soil/water ratio is low, that is to say when soil particles are isolated in water. The evolution of DOM composition during storm events has been assumed to reflect a combination of in-stream and in-soil erosion processes. So how soil erosion could be responsible for production of less degraded DOM? And is the composition of soil DOM modified during a storm event? Those questions were investigated during two flood events, by sampling soil solutions with high frequency in riparian soils equipped with zero-tension lysimeters in the Kervidy-Naizin catchment. In the same time stream DOM was sampled at the outlet of the watershed and runoff were investigated. Samples have been filtered at 0.2μm, analysed for DOC and freeze-dried for molecular analysis (thermally assisted hydrolysis methylation - gas chromatography / mass spectrometry). The hydraulic gradient was monitored every 15 minutes using piezometers implemented in the riparian soils and higher up in the toposequence. At the beginning of the events, hydraulic gradient increased rapidly and stayed high during several days. Modification of DOM composition in soil solution were recorded during the hydraulic gradient rise with an increase in the proportion of less

  20. Chemosensory deprivation in juvenile coho salmon exposed to dissolved copper under varying water chemistry conditions.

    Science.gov (United States)

    McIntyre, Jenifer K; Baldwin, David H; Meador, James P; Scholz, Nathaniel L

    2008-02-15

    Dissolved copper is an important nonpoint source pollutant in aquatic ecosystems worldwide. Copper is neurotoxic to fish and is specifically known to interfere with the normal function of the peripheral olfactory nervous system. However,the influence of water chemistry on the bioavailability and toxicity of copper to olfactory sensory neurons is not well understood. Here we used electrophysiological recordings from the olfactory epithelium of juvenile coho salmon (Oncorhynchus kisutch) to investigate the impacts of copper in freshwaters with different chemical properties. In low ionic strength artificial fresh water, a short-term (30 min) exposure to 20 microg/L dissolved copper reduced the olfactory response to a natural odorant (10(-5) M L-serine) by 82%. Increasing water hardness (0.2-1.6 mM Ca) or alkalinity (0.2-3.2 mM HCO3-) only slightly diminished the inhibitory effects of copper. Moreover, the loss of olfactory function was not affected by a change in pH from 8.6 to 7.6. By contrast, olfactory capacity was partially restored by increasing dissolved organic carbon (DOC; 0.1-6.0 mg/L). Given the range of natural water quality conditions in the western United States, water hardness and alkalinity are unlikelyto protect threatened or endangered salmon from the sensory neurotoxicity of copper. However, the olfactory toxicity of copper may be partially reduced in surface waters that have a high DOC content.

  1. Epstein-Plesset theory based measurements of concentration of nitrogen gases dissolved in aerated water

    Science.gov (United States)

    Sasaki, Masashi; Yamashita, Tatsuya; Ando, Keita

    2016-11-01

    Microbubble aeration is used to dissolved gases into water and is an important technique in agriculture and industry. We can measure concentration of dissolved oxygen (DO) in aerated water by commercial DO meters. However, there do not exist commercially available techniques to measure concentration to dissolved nitrogen (DN). In the present study, we propose the method to measure DN in aerated water with the aid of Epstein-Plesset-type analysis. Gas-supersaturated tap water is produced by applying aeration with micro-sized air bubbles and is then stored in a glass container open to the atmosphere. Diffusion-driven growth of bubbles nucleated at the container surface is recorded with a video camera. The bubble growth rate is compare to the extended Epstein-Plesset theory that models mass transfer of both DO and DN into the surface-attached bubbles base on the diffusion equation. Given the DO measurements, we can obtain the DN level by fitting in the comparison.

  2. Temporal and spatial distribution of dissolved copper,lead,zinc and cadmium in the Changjiang Estuary and its adjacent waters

    Institute of Scientific and Technical Information of China (English)

    WANG Changyou; WANG Xiulin; WANG Baodong; ZHANG Chuansong; SHI Xiaoyong; ZHU Chenjian

    2008-01-01

    Heavy metal concentrations were measured in the Changjiang Estuary and its adjacent waters.Results from a systematic survey in April 2002 to March 2003 indicate that the ranges of the concentrations of dissolved copper,lead,zinc and cadmium in the study waters are 1.01~6.86,0.10~0.39,3.17~9.12 and 0.011~0.049 μg/dm3,respectively.Similar to zinc,the behavior of dissolved copper Was essentially conservative,but high seatter has been observed for high salinity samples,which can be attribu-ted to the decomposition or mineralization of organic matter by bacteria.Dissolved lead may have active behavior with an addition at high salinity.Overall concentrations of dissolved cadmium increase with salinity.The mean values of these dissolved metals cal-culated for the surface waters were highcr than those for the middle and bottom ones.External inputs of dissolved heavy metals to the surface waters were the likely explanation for these higher values.The maximum seasonal average values of dissolved copper and zinc were flound in summer,reflecting higher amounts of riverine input in this season.In contrast,the maximum seasonal av-erage values of dissolved lead and copper were found in winter and the lowest ones in summer,respectively,which might be asso-ciated with a combination of low concentration with heterogeneous scavenging.Concentrations of these dissolved metals found for the Changjiang Estuary fall in the range observed for the other estuaries but are noticeably higher than those from uncontaminated rivers,except for cadmium.Compared with observations for the Changjiang Estuary in the last two deeades.it is clear that the Changjiang estuarine waters has been contaminated with copper,lead,zinc and cadmium during China's industuialization,but concentrations of them have decreased in the last few years.

  3. Observation of water dangling OH bonds around dissolved nonpolar groups.

    Science.gov (United States)

    Perera, P N; Fega, K R; Lawrence, C; Sundstrom, E J; Tomlinson-Phillips, J; Ben-Amotz, Dor

    2009-07-28

    We report the experimental observation of water dangling OH bonds in the hydration shells around dissolved nonpolar (hydrocarbon) groups. The results are obtained by combining vibrational (Raman) spectroscopy and multivariate curve resolution (MCR), to reveal a high-frequency OH stretch peak arising from the hydration shell around nonpolar (hydrocarbon) solute groups. The frequency and width of the observed peak is similar to that of dangling OH bonds previously detected at macroscopic air-water and oil-water interfaces. The area of the observed peak is used to quantify the number of water dangling bonds around hydrocarbon chains of different length. Molecular dynamics simulation of the vibrational spectra of water molecules in the hydration shell around neopentane and benzene reveals high-frequency OH features that closely resemble the experimentally observed dangling OH vibrational bands around neopentyl alcohol and benzyl alcohol. The red-shift of approximately 50 cm(-1) induced by aromatic solutes is similar to that previously observed upon formation of a pi-H bond (in low-temperature benzene-water clusters).

  4. Removing Dissolved Silica from Waste Water with Catechol and Active Carbon

    Energy Technology Data Exchange (ETDEWEB)

    Sasan, Koroush [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Nanoscale Sciences Dept.; Brady, Patrick [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Nuclear Energy Program; Krumhansl, James L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Geosciences Dept.; Nenoff, Tina M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Physical Chemical and Nano Sciences Center

    2017-01-01

    Fresh water scarcity is going to be a global great challenge in the near future because of the increasing population. Our water resources are limited and, hence, water treatment and recycling methods are the only alternatives for fresh water procurement in the upcoming decades. Water treatment and recycling methods serve to remove harmful or problematic constituents from ground, surface and waste waters prior to its consumption, industrial supply, or other uses. Scale formation in industrial and domestic installations is still an important problem during water treatment. In water treatment, silica scaling is a real and constant concern for plant operations. The focus of this study is on the viability of using a combination of catechol and active carbon to remove dissolved silica from concentrated cooling tower water (CCTW). Various analytical methods, such as ICP-MS and UV-vis, were used to understand the structure-property relationship between the material and the silica removal results. UV-Vis indicates that catechol can react with silica ions and form a silica-catecholate complex. The speciation calculation of catechol and silica shows that catechol and silica bind in the pH range of 8 – 10; there is no evidence of linkage between them in neutral and acidic pHs. The silica removal results indicate that using ~4g/L of catechol and 10g/L active carbon removes up to 50% of the dissolved silica from the CCTW.

  5. Contribution of dissolved sulfates and sulfites in hydrogen sulfide emission from stagnant water bodies in Sri Lanka.

    Science.gov (United States)

    Kularatne, K I A; Dissanayake, D P; Mahanama, K R R

    2003-08-01

    Accumulation of sulfur-containing compounds and their bacterial mediated reductions have led to the emission of pungent odors from stagnant water bodies. This study is focused on the contribution of inorganic sulfur compounds in the emission of hydrogen sulfide. The measured dissolved oxygen levels have demonstrated good negative correlations with the dissolved sulfide levels implying the oxygen deficiency is the key for the reduction of sulfate ion and sulfite ion to sulfide ion. Particularly, the dissolved molar fractions of sulfide from the total dissolved sulfur compounds (sulfates, sulfites and sulfides) have a very good correlation with the dissolved oxygen for the stagnant water bodies except the artificially aerated prawn farms. For the stagnant water bodies with significant correlations, linear regressions are reported for them to be utilized in estimating one component of the regression from the measurement of the other. The measured data were further utilized to estimate the levels of hydrogen sulfide gas. The pH of the water bodies has confined much of the dissolved sulfides in the form of bisulfide ion and they can be easily escaped to the atmosphere upon acidification due to industrial discharges and/or acidic precipitations. The estimated levels of hydrogen sulfide just above the water surface were plotted for the most polluted stagnant water body in Sri Lanka for the pH range of 5-10 and temperature range of 25-35 degrees C.

  6. Long-term dynamics of dissolved organic carbon: implications for drinking water supply.

    Science.gov (United States)

    Ledesma, José L J; Köhler, Stephan J; Futter, Martyn N

    2012-08-15

    Surface waters are the main source of drinking water in many regions. Increasing organic carbon concentrations are a cause for concern in Nordic countries since both dissolved and particulate organic carbon can transport contaminants and adversely affect drinking water treatment processes. We present a long-term study of dynamics of total (particulate and dissolved) organic carbon (TOC) concentrations in the River Fyris. This river supplies drinking water to approximately 200000 people in Uppsala, Sweden. The River Fyris is a main tributary to Lake Mälaren, which supplies drinking water to approximately 2 million people in the greater Stockholm area. Utilities responsible for drinking water supply in both Uppsala and Stockholm have expressed concerns about possible increases in TOC. We evaluate organic carbon dynamics within the Fyris catchment by calculating areal mass exports using observed TOC concentrations and modeled flows and by modeling dissolved organic carbon (as a proxy for TOC) using the dynamic, process based INCA-C model. Exports of TOC from the catchment ranged from 0.8 to 5.8 g m(-2) year(-1) in the period 1995-2010. The variation in annual exports was related to climatic variability which influenced seasonality and amount of runoff. Exports and discharge uncoupled at the end of 2008. A dramatic increase in TOC concentrations was observed in 2009, which gradually declined in 2010-2011. INCA-C successfully reproduced the intra- and inter-annual variation in concentrations during 1996-2008 and 2010-2011 but failed to capture the anomalous increase in 2009. We evaluated a number of hypotheses to explain the anomaly in 2009 TOC values, ultimately none proved satisfactory. We draw two main conclusions: there is at least one unknown or unmeasured process controlling or influencing surface water TOC and INCA-C can be used as part of the decision-making process for current and future use of rivers for drinking water supply.

  7. Behavior of dissolved radiocesium in river water in a forested watershed in Fukushima Prefecture

    Science.gov (United States)

    Tsuji, H.; Nishikiori, T.; Yasutaka, T.; Watanabe, M.; Ito, S.; Hayashi, S.

    2016-10-01

    Dissolved radiocesium concentrations in river water in a high-dose-rate forest watershed in Fukushima Prefecture were investigated under base flow and storm flow conditions. Under base flow conditions, dissolved 137Cs concentrations in water (Bq/L) were relatively high in summer, and these levels were higher than particulate 137Cs concentrations (Bq/L). Under storm flow, particulate 137Cs concentration became dominant as the suspended solid concentration increased. Throughout the monitoring period, dissolved 137Cs concentrations in water (Bq/L) were higher under storm flow than base flow conditions and were positively correlated with runoff intensity. Factors influencing changes in dissolved 137Cs concentrations were investigated by measuring the 137Cs concentration of suspended solid (Bq/kg) and dissolved 137Cs of unsaturated soil water, throughfall, and rainfall, together with other main solute concentrations. The 137Cs concentration per unit weight of suspended solids in river water was not strongly correlated with runoff intensity. Additionally, dissolved 137Cs concentrations of soil water, groundwater, and rainfall were not detected, while higher dissolved 137Cs concentrations were detected in throughfall than river water. K+ concentrations were higher under storm flow than base flow, and dissolved organic carbon increased toward the peak flow rate. These findings suggested that one main factor influencing generation of dissolved 137Cs in the river water was leaching from organic material in flooded areas. However, further investigation is needed to clarify the dominant source of dissolved 137Cs in river water.

  8. Dissolved aluminium in the surface microlayer of the eastern Arabian Sea

    Digital Repository Service at National Institute of Oceanography (India)

    Narvekar, P.V.; Singbal, S.Y.S.

    in the rest of the water column (up to 3000 m), indicating that much of the dissolved aerosal Al was removed in the upper few metres of the water column. The non-nutrient-type behaviour of dissolved Al did not support a mechanism of Al removal by biological...

  9. Fe-binding dissolved organic ligands in the oxic and suboxic waters of the Black Sea

    Directory of Open Access Journals (Sweden)

    Loes J.A. Gerringa

    2016-05-01

    Full Text Available In the oxygen-rich layer of the Black Sea, above the permanent halocline, the Fe and nitrate concentrations are low where fluorescence is relatively high , indicating uptake by phytoplankton. In this study we used ligand exchange adsorptive cathodic stripping voltammetry (CLE-aCSV, using 2-(2-Thiazolylazo-p-cresol (TAC as measuring ligand, to investigate the role of Fe-binding dissolved organic ligands in keeping Fe in the dissolved phase and potentially biologically available. The conditional stability constant, logK´, was between 21 and 22 in most samples, which is on average lower than in ocean water. The Fe-binding dissolved organic ligand concentrations varied between 0.35 and 4.81 nEq of M Fe, which was higher than the dissolved concentration of Fe (DFe as found in most samples. At two stations ligands were saturated in the surface. At one station ligands were saturated near the oxycline, where ligand concentrations seemed to increase, indicating that they play a role in keeping Fe in the dissolved phase across the redox gradient. At the fluorescence maximum (between 40 and 50 m, the dissolved organic ligand binding capacity (alphaFeL=K´*[L´] of Fe was at its highest while the concentration DFe was at its lowest. Here, we find a statistically significant, positive relationship between fluorescence and the logarithm of alphaFeL, along with fluorescence and the ratio of the total ligand concentration over DFe. These relationships are best explained by phytoplankton utilizing Fe from Fe-binding organic ligands, resulting in an increase in free Fe-binding ligands.

  10. Drainage, rupture, and lifetime of deionized water films: effect of dissolved gases?

    Science.gov (United States)

    Nguyen, Phong T; Nguyen, Anh V

    2010-03-02

    Gas bubbles coalesce in deionized (DI) water because the water (foam) films between the bubbles are not stable. The so-called hydrophobic attraction has been suggested as the cause of the film instability and the bubble coalescence. In this work, microinterferometry experiments show that foam films of ultrapure DI water can last up to 10 s and the contact time between the two gas bubble surfaces at close proximity (approximately 1 microm separation distance) significantly influences the film drainage, rupture, and lifetime. Specifically, when the two bubbles were first brought into contact, the films instantly ruptured at 0.5 microm thickness. However, the film drainage rate and rupture thickness sharply decreased and the film lifetime steeply increased with increasing contact time up to 10 min, but then they leveled off. The constant thickness of film rupture was around 35 nm. Possible contamination was vigorously investigated and ruled out. It is argued that migration of gases inherently dissolved in water might cause the transient behavior of the water films at the short contact time. The film drainage rate and instability at the long contact time were analyzed employing Eriksson et al.'s phenomenological theory of long-range hydrophobic attraction (Eriksson, J. C.; Ljunggren, S.; Claesson, P. M., J. Chem. Soc., Faraday Trans. 2 1989, 85, 163-176) and the hypothesis of water molecular structure modified by dissolved gases, and the extended Stefan-Reynolds theory by incorporating the mobility of the air-DI-water interfaces.

  11. Chemical characterization of high molecular weight dissolved organic matter in fresh and marine waters

    Science.gov (United States)

    Repeta, Daniel J.; Quan, Tracy M.; Aluwihare, Lihini I.; Accardi, AmyMarie

    2002-03-01

    The high molecular weight fraction of dissolved organic matter in a suite of lakes, rivers, seawater, and marine sediment interstitial water samples was collected by ultrafiltration and characterized by molecular level and spectroscopic techniques. Proton nuclear magnetic resonance spectra of all samples show a high degree of similarity, with major contributions from carbohydrates, bound acetate, and lipids. Molecular level analyses of neutral sugars show seven monosaccharides, rhamnose, fucose, arabinose, xylose, mannose, glucose, and galactose, to be abundant, and to occur in comparable relative amounts in each sample. Previous studies have emphasized the distinctive composition of dissolved humic substances in fresh and marine waters, and have attributed these differences to sources and transformations of organic matter unique to each environment. In contrast we find a large fraction of freshwater high molecular weight dissolved organic matter (HMWDOM; > 1kD) to be indistinguishable from marine HMWDOM in bulk and molecular-level chemical properties. Aquatic HMWDOM is similar in chemical composition to biologically derived acylated heteropolysaccharides isolated from marine algal cultures, suggesting a biological source for some fraction of persistent HMWDOM. High molecular weight DOC contributes 51 ± 26% of the total DOC, and monosaccharides 18 ± 8% of the total HMWDOC in our freshwater samples. These contributions are on average higher and more variable, but not significantly different than for surface seawater (30% and 16% respectively). Biogeochemical processes that produce, accumulate, and recycle DOM may therefore share important similarities and be broadly comparable across a range of environmental settings.

  12. Differences in dissolved organic matter between reclaimed water source and drinking water source.

    Science.gov (United States)

    Hu, Hong-Ying; Du, Ye; Wu, Qian-Yuan; Zhao, Xin; Tang, Xin; Chen, Zhuo

    2016-05-01

    Dissolved organic matter (DOM) significantly affects the quality of reclaimed water and drinking water. Reclaimed water potable reuse is an effective way to augment drinking water source and de facto reuse exists worldwide. Hence, when reclaimed water source (namely secondary effluent) is blended with drinking water source, understanding the difference in DOM between drinking water source (dDOM) and reclaimed water source (rDOM) is essential. In this study, composition, transformation, and potential risk of dDOM from drinking water source and rDOM from secondary effluent were compared. Generally, the DOC concentration of rDOM and dissolved organic nitrogen (DON) content in reclaimed water source were higher but rDOM exhibited a lower aromaticity. Besides, rDOM comprises a higher proportion of hydrophilic fractions and more low-molecular weight compounds, which are difficult to be removed during coagulation. Although dDOM exhibited higher specific disinfection byproducts formation potential (SDBPFP), rDOM formed more total disinfection byproducts (DBPs) during chlorination including halomethanes (THMs) and haloacetic acids (HAAs) due to high DOC concentration. Likewise, in consideration of DOC basis, rDOM contained more absolute assimilable organic carbon (AOC) despite showing a lower specific AOC (normalized AOC per unit of DOC). Besides, rDOM exhibited higher biotoxicity including genotoxicity and endocrine disruption. Therefore, rDOM presents a greater potential risk than dDOM does. Reclaimed water source needs to be treated carefully when it is blended with drinking water source.

  13. 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).

  14. Student Misconceptions in Writing Balanced Equations for Dissolving Ionic Compounds in Water

    Science.gov (United States)

    Naah, Basil M.; Sanger, Michael J.

    2012-01-01

    The goal of this study was to identify student misconceptions and difficulties in writing symbolic-level balanced equations for dissolving ionic compounds in water. A sample of 105 college students were asked to provide balanced equations for dissolving four ionic compounds in water. Another 37 college students participated in semi-structured…

  15. Major ion chemistry of the Son River, India: Weathering processes, dissolved fluxes and water quality assessment

    Indian Academy of Sciences (India)

    Chinmaya Maharana; Sandeep Kumar Gautam; Abhay Kumar Singh; Jayanth K Tripathi

    2015-08-01

    River Son, draining diverse lithologies in the subtropical climate of the peninsular sub-basin of the Ganga basin, is one of the major tributaries of the Ganga River. The chemistry of major ions in the surface water of the Son River was studied in detail to determine various source(s) and processes controlling its water chemistry, seasonal and spatial variations in water chemistry, dissolved fluxes and chemical denudation rate (CDR). The study shows that Ca2+, Mg2+ and HCO$^{-}_{3}$ are major ionic species in the river water. Most of the measured parameters exhibit a relatively lower concentration in the post-monsoon as compared to pre-monsoon season. The water chemistry highlights the influence of continental weathering aided by secondary contributions from ground water, saline/alkaline soils and anthropogenic activities in the catchment. Results also reflect the dominance of carbonate weathering over silicate weathering in controlling water composition. The Son River delivers about 4.2 million tons of dissolved loads annually to the Ganga River, which accounts for ∼6% of the total annual load carried by the Ganga River to the Bay of Bengal. The average CDR of the Son River is 59.5 tons km−2 yr−1, which is less than the reported 72 tons km−2 yr−1 of the Ganga River and higher than the global average of 36 tons km−2 yr−1. The water chemistry for the pre-monsoon and post-monsoon periods shows a strong seasonal control on solute flux and CDR values. The water chemistry indicates that the Son River water is good to excellent in quality for irrigation and also suitable for drinking purposes.

  16. Dynamics of altered surface layer formation on dissolving silicates

    Science.gov (United States)

    Daval, Damien; Bernard, Sylvain; Rémusat, Laurent; Wild, Bastien; Guyot, François; Micha, Jean Sébastien; Rieutord, François; Magnin, Valérie; Fernandez-Martinez, Alejandro

    2017-07-01

    .g., the (0 1 0) face), the dissolution of other faces is hampered by passivating ASSLs within a few hours. The observed passivation is suggested to originate from the progressive densification of the ASSL, which limits the transport of reactive species from and to the dissolving wollastonite surface, as evidenced by the estimated diffusivity of the ASSLs. Because the apparent face-specific diffusivity of the ASSLs is correlated with the face-specific initial (i.e., ASSL-free) dissolution rate of wollastonite, we propose that the extent of ASSL densification (and the resulting impact on ion transport) is (at least partly) controlled by the absolute mineral dissolution rate. Overall, this study argues that the formation and microstructural evolution of ASSLs are likely candidates for mineral ageing, highlighting the need for determining the parameters controlling the spontaneous changes of ASSL diffusivity as a function of the reaction progress.

  17. 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.

  18. Water and dissolved carbon transport in an eroding soil landscape using column experiments

    DEFF Research Database (Denmark)

    Rieckh, Helene; Gerke, Horst; Glæsner, Nadia;

    2014-01-01

    boundary. Breakthrough curves for a pre-applied tracer (Br-) on the soil surface and a tracer applied with irrigation water (3H2O) were modeled analytically using CXTFIT. The heterogeneity of the Luvisol horizons was generally higher than that of the Regosol horizons, which relates to the higher......In the hummocky ground moraine soil landscape, a spatial continuum of more or less eroded soils developed from till under intensive agricultural cultivation. Water flow and solute transport are affected by the variable soil structural and pedological developments, which are posing a challenge...... for flux estimation. The objective of this study was to investigate transport of water, dissolved organic (DOC), and particulate carbon (PC) through soil profiles of an eroded Haplic Luvisol and a heavily eroded Haplic Regosol. We studied 5 soil horizons in three replicates each: Ap (0-20 cm) and E (20...

  19. Uptake of dissolved Ag, Cd, and Co by the clam, Macoma balthica: relative importance of overlying water, oxic pore water, and burrow water.

    Science.gov (United States)

    Griscom, Sarah B; Fisher, Nicholas S

    2002-06-01

    The facultative deposit-feeding clam Macoma balthica is used as a bioindicator organism for assessing coastal metal contamination. Previous work has evaluated the assimilation of metals from different possible food sources for this clam, but no studies have measured the uptake rates of metals from different dissolved sources. This study specifically compares three different dissolved sources: overlying water (SW), oxic pore water (OPW) from a depth of deposit feeding), and burrow water (BW) (a mixture of anoxic pore water and overlying water). Uptake rates of dissolved Ag, Cd, and Co in M. balthica were measured in short-term laboratory experiments using radiotracers. Clams were exposed to metals in water only for SW and surface OPW treatments. In the BW treatment, metal uptake was compared in clams placed in radiolabeled organic-poor or organic-rich sediment under conditions in which feeding was inhibited. Uptake rate constantsfrom SW for Ag, Cd, and Co were 0.35, 0.033, and 0.035 L g(-1) day(-1), respectively. Lower uptake of dissolved metals from OPW was noted but was only significant for Co. Metal uptake from BW and SW were also comparable; however, the trend showed lower Ag and higher Co uptake from BW. Metal distributions and concentrations in the two radiolabeled sediments were affected by active irrigation of SW into the burrows; dissolved metal concentrations in BW were approximately 30% lower than that in the bulk pore water concentrations. In the organic-rich sediment, Cd and Ag partitioned more in the dissolved phase (sensitivity analysis using measured rate constants for uptake and a range of metal concentrations from field studies suggested that, under most conditions, uptake of dissolved Ag is primarily from OPW, Co is mostly from BW, and Cd uptake varies depending on its concentration in each compartment. Little Co or Ag is likely to be taken up from SW, whereas 20-50% of Cd may be accumulated from this source. Thus, SW, OPW, and BW are all

  20. Growth inhibition of phytoplankton populations cultured in disphotic zone water by insufficient amounts of dissolved organic carbon

    Energy Technology Data Exchange (ETDEWEB)

    Toyota, T. [Japan Marine Science and Technology Center, Kanagawa (Japan)

    1994-10-01

    Phytoplankton cultures in disphotic zone water were performed, to examine dissolved organic carbon (DOC) as a controlling agent of the initial lag period and growth rate. Culture media with various concentrations of DOC were prepared by mixing low DOC disphotic zone water with high DOC surface water. Natural phytoplankton populations exhibited strong correlations to the lag period with DOC concentrations and to the population growth rate. Similar tendencies were also confirmed as to a marine diatom dominating in the disphotic zone by culture experiments. By reducing DOC concentrations in seawater samples through pretreatments with ultraviolet radiation, charcoal adsorption and Amberlite resin adsorption, lag periods of diatom increased. Consequently, it was found that the lag period is prolonged in low DOC water. It was suggested that the essential substance to shorten lag periods of phytoplankton cultured in disphotic zone water is a portion of dissolved organic matter. 35 refs., 6 figs., 5 tabs.

  1. Sonication-Aided Formation of Hollow Hybrid Nanoparticles as High-Efficiency Absorbents for Dissolved Toluene in Water.

    Science.gov (United States)

    Huang, Ting; Xu, Liju; Wang, Chen; Yin, Zheng; Qiu, Dong

    2016-01-01

    A surfactant-free emulsion polymerization process was developed to produce hollow hybrid nanoparticles (HHNP thereafter). Ultrasonication was found not only to help the generation of nanosized monomer droplets but also to generate surface active species through mediating the hydrolysis of the monomer, 3-(methacryloyloxy) propyltrimethoxysilane (MPS), thus stabilizing the oil/water interface. The hollow structure was formed based on a soft template approach, where the partially hydrolyzed monomer served as emulsifier and polymerized at the interface to form a hybrid shell. These HHNPs were used to absorb dissolved toluene in water and it was found they could reduce the toluene level down to zero, a level hardly being achieved by other methods. Combined with their good colloidal stability in water, these HHNPs are very promising colloidal collectors for dissolved organic solvents, in order to generate high quality water from contaminated water. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Freely dissolved concentrations and sediment-water activity ratios of PCDD/Fs and PCBs in the open Baltic Sea.

    Science.gov (United States)

    Cornelissen, Gerard; Wiberg, Karin; Broman, Dag; Arp, Hans Peter H; Persson, Ylva; Sundqvist, Kristina; Jonsson, Per

    2008-12-01

    Aqueous concentrations of polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs) as well as polychlorinated biphenyls (PCBs) in the open sea have heretofore been measured by filtering and extracting large amounts of water. Measurement of freely dissolved concentrations with this technique is difficult because of corrections for sorption to dissolved organic matter. In this study we use a novel, more economic technique using equilibrium passive samplers consisting of 17-microm thin polyoxymethylene (POM-17), capable of measuring freely dissolved aqueous concentrations (Cw) in pristine (i.e., background) locations. POM-17 was employed in an extensive field campaign at five stations in the open Baltic sea to obtain Cw at two depths (1 m above the seafloor and 25 m below the surface). Median Cw in the overlying water was 2.3 pg toxic equivalents (TEQ)/m3 PCDD/Fs and 15 pg/L sum 7-PCB, with generally less than a factor two variation among sites and depths. Also freely dissolved concentrations of native compounds in the surface sediment porewater (C(PW)) were determined in laboratory batch experiments. The data were used to derive sediment-water activity ratios, which indicate the diffusive flux direction. It was found that the PCDD/Fs and PCBs were in close equilibrium between the sediment porewater and the overlying water. Comparison of C(PW) with total sediment concentrations indicated that more than 90% of the compounds were sorbed to sedimentary black carbon.

  3. The dynamics of dissolved oxygen concentration for water quality monitoring and assessment in polder ditches

    NARCIS (Netherlands)

    Veeningen, R.

    1983-01-01

    This study deals with the use of the dynamics of dissolved oxygen concentration for water quality assessment in polder ditches. The dynamics of the dissolved oxygen concentration, i.e. the temporal and spatial variations in a few polder ditches under a range of natural, pollution and management

  4. Experimental evidence of dust-induced shaping of surface dissolved organic matter in the oligotrophic ocean

    Science.gov (United States)

    Pulido-Villena, Elvira; Djaoudi, Kahina; Barani, Aude; Charrière, Bruno; Delmont, Anne; Hélias-Nunige, Sandra; Marc, Tedetti; Wambeke France, Van

    2016-04-01

    Recent research has shown that dust deposition may impact the functioning of the microbial loop. On one hand, it enhances bacterial mineralization of dissolved organic matter (DOM), and so may limit the carbon export. On the other hand, the interaction between heterotrophic bacteria and DOM in the surface ocean can increase the residence time of DOM, promoting its export and sequestration in the deep ocean. The main goal of this study was to experimentally assess whether the bacterial response to dust deposition is prone to have an effect on the residence time of the DOM pool by modifying its bioavailability. The bacterial degradation of DOM was followed on dust-amended and control treatments during long-term incubations. Dissolved organic carbon concentration decreased by 9 μmol L-1 over the course of the experiment in both control and dust-enriched conditions, with no significant differences between treatments. However, significant differences in DOM optical properties appeared at the latest stage of the incubations suggesting an accumulation of DOM of high molecular weight in the dust-amended treatment. At the end of the incubations, the remaining water was filtered and re-used as a new culture medium for a bacterial natural assemblage. Bacterial abundance and production was lower in the treatment previously submitted to dust enrichment, suggesting a decrease in DOM lability after a dust deposition event. These preliminary results point to a new link between dust and ocean carbon cycle through the modification of the residence time of the DOM pool.

  5. Numerical simulation of dissolved oxygen concentration in water flow over stepped spillways.

    Science.gov (United States)

    Cheng, Xiangju; Chen, Xuewei

    2013-05-01

    This study developed an improved Eulerian model for the simulation of an air-water flow field over stepped spillways. The improved drag model applied different drag coefficients for bubbles and for free surface flows or gas cavities. Void fraction and turbulence correction were used in determining the bubble drag coefficient. The calculated air entrainment and air-water velocity could be adapted using these parameters. With the improved drag model, the Eulerian simulations predicted the location of the inception point, the distributions of air void fraction, velocity distributions, and pressure distributions. The change in the dissolved oxygen (DO) concentration from upstream of the stepped spillways, to downstream, was simulated based on the improved computational fluid dynamics model and the transport equation for DO transferring. The numerical DO concentration coincided with the experimental results. Therefore, the improved CFD model and the numerical methods presented here can provide possible optimization tools for strong air entrainment flows.

  6. Water quality and processes affecting dissolved oxygen concentrations in the Blackwater River, Canaan Valley, West Virginia

    Science.gov (United States)

    Waldron, M.C.; Wiley, J.B.

    1996-01-01

    The water quality and environmental processes affecting dissolved oxygen were determined for the Blackwater River in Canaan Valley, West Virginia. Canaan Valley is oval-shaped (14 miles by 5 miles) and is located in the Allegheny Mountains at an average elevation of 3,200 feet above sea level. Tourism, population, and real estate development have increased in the past two decades. Most streams in Canaan Valley are a dilute calcium magnesium bicarbonate-type water. Streamwater typicaly was soft and low in alkalinity and dissolved solids. Maximum values for specific conductance, hardness, alkalinity, and dissolved solids occurred during low-flow periods when streamflow was at or near baseflow. Dissolved oxygen concentrations are most sensitive to processes affecting the rate of reaeration. The reaeration is affected by solubility (atmospheric pressure, water temperature, humidity, and cloud cover) and processes that determine stream turbulence (stream depth, width, velocity, and roughness). In the headwaters, photosynthetic dissolved oxygen production by benthic algae can result in supersaturated dissolved oxygen concentrations. In beaver pools, dissolved oxygen consumption from sediment oxygen demand and carbonaceous biochemical oxygen demand can result in dissolved oxygen deficits.

  7. Fluorescent dissolved organic matter in the continental shelf waters of western Bay of Bengal

    Indian Academy of Sciences (India)

    N V H K Chari; P Sudarsana Rao; Nittala S Sarma

    2013-10-01

    Fluorescent dissolved organic matter (FDOM) of southwestern Bay of Bengal surface water during southwest monsoon consisted five fluorophores, three humic-like and two protein-like. The humification index (HIX) and humic fluorophores, viz., visible (C), marine (M) and UV (A) humic-likes indicated, better than biogeochemical constituents analyzed, that the northern-half region of the study area which is closer to the head bay (less salinity) is distinctly more terrestrially influenced. Similarly, the southernhalf region (less dissolved oxygen) is indicated as more in situ influenced. This region is enriched with tyrosine protein-like fluorophore (B), an indicator of bacterial metabolism in some of its samples due to upwelled water. Although chlorophyll is less in this (southern) region, the fluorescence based biological index (BIX) which is an index of recent phytoplankton production is about the same in the two regions, and the lower chlorophyll of southern region is attributed to greater grazing pressure. Fluorescence properties, e.g., BIX are more informative about phytoplankton production than chlorophyll .

  8. The isotopic composition of dissolved cadmium in the water column of the West Philippine Sea

    Directory of Open Access Journals (Sweden)

    Shun-Chung eYang

    2014-11-01

    Full Text Available The dissolved concentration and isotopic compositions of cadmium (Cd in the seawater of the West Philippine Sea were determined. In general, Cd isotopic composition in the water column decreased with depth, with ε114/110Cd (ε114/110Cd = [(114Cd/110Cdsample / (114Cd/110CdNIST 3108 - 1]×10000 ranging from +7.2 to +10.1 in the top 60 m, from +4.8 to +5.1 between 100 and 150 m, peaking at +8.2 at 200 m, decreasing from +4.5 to +3.3 from 400 to 1000 m, and remaining constant at +3.0 from 1000 m and deeper. Different to a Rayleigh fractionation model, the isotopic composition and log scale concentrations of Cd do not exhibit a linear relationship. However, from the deep water to thermocline, the variations in Cd concentration and ε114/110Cd are relevant to the variations of temperature and salinity, indicating that water mixing is the dominant processes determining the concentration and isotopic composition in the interval. At 200 m where North Pacific Tropic Water dominates the water mass, the elevated ε114/110Cd could be linked to the composition in the upper portions of the water mass. In the top 150 m, the ε114/110Cd varies similarly to the phytoplankton community structures, implying that Cd uptake by various phytoplankton species may be associated with the isotopic variation. However, the effects of atmospheric inputs to the ε114/110Cd in the surface water cannot be excluded. A box model calculation is used to constrain the contributions of various processes to the Cd isotopes of surface water, and the results indicate that the Cd concentration and isotopic composition in most of the water body of the region are controlled by physical mixing, while the effects of biological fractionation and atmospheric inputs are limited in the euphotic zone.

  9. Land management impacts on dairy-derived dissolved organic carbon in ground water.

    Science.gov (United States)

    Chomycia, Jill C; Hernes, Peter J; Harter, Thomas; Bergamaschi, Brian A

    2008-01-01

    Dairy operations have the potential to elevate dissolved organic carbon (DOC) levels in ground water, where it may interact with organic and inorganic contaminants, fuel denitrification, and may present problems for drinking water treatment. Total and percent bioavailable DOC and total and carbon-specific trihalomethane (THM) formation potential (TTHMFP and STHMFP, respectively) were determined for shallow ground water samples from beneath a dairy farm in the San Joaquin Valley, California. Sixteen wells influenced by specific land management areas were sampled over 3 yr. Measured DOC concentrations were significantly elevated over the background as measured at an upgradient monitoring well, ranging from 13 to 55 mg L(-1) in wells downgradient from wastewater ponds, 8 to 30 mg L(-1) in corral wells, 5 to 12 mg L(-1) in tile drains, and 4 to 15 mg L(-1) in wells associated with manured fields. These DOC concentrations were at the upper range or greatly exceeded concentrations in most surface water bodies used as drinking water sources in California. DOC concentrations in individual wells varied by up to a factor of two over the duration of this study, indicating a dynamic system of sources and degradation. DOC bioavailability over 21 d ranged from 3 to 10%, comparable to surface water systems and demonstrating the potential for dairy-derived DOC to influence dissolved oxygen concentrations (nearly all wells were hypoxic to anoxic) and denitrification. TTHMFP measurements across all management units ranged from 141 to 1731 microg L(-1), well in excess of the maximum contaminant level of 80 microg L(-1) established by the Environmental Protection Agency. STHMFP measurements demonstrated over twofold variation ( approximately 4 to approximately 8 mmol total THM/mol DOC) across the management areas, indicating the dependence of reactivity on DOC composition. The results indicate that land management strongly controls the quantity and quality of DOC to reach shallow

  10. Land management impacts on dairy-derived dissolved organic carbon in ground water

    Science.gov (United States)

    Chomycia, J.C.; Hernes, P.J.; Harter, T.; Bergamaschi, B.A.

    2008-01-01

    Dairy operations have the potential to elevate dissolved organic carbon (DOC) levels in ground water, where it may interact with organic and inorganic contaminants, fuel denitrification, and may present problems for drinking water treatment. Total and percent bioavailable DOC and total and carbon-specific trihalomethane (THM) formation potential (TTHMFP and STHMFP, respectively) were determined for shallow ground water samples from beneath a dairy farm in the San Joaquin Valley, California. Sixteen wells influenced by specific land management areas were sampled over 3 yr. Measured DOC concentrations were significantly elevated over the background as measured at an upgradient monitoring well, ranging from 13 to 55 mg L-1 in wells downgradient from wastewater ponds, 8 to 30 mg L-1 in corral wells, 5 to 12 mg L-1 in tile drains, and 4 to 15 mg L-1 in wells associated with manured fields. These DOC concentrations were at the upper range or greatly exceeded concentrations in most surface water bodies used as drinking water sources in California. DOC concentrations in individual wells varied by up to a factor of two over the duration of this study, indicating a dynamic system of sources and degradation. DOC bioavailability over 21 d ranged from 3 to 10%, comparable to surface water systems and demonstrating the potential for dairy-derived DOC to influence dissolved oxygen concentrations (nearly all wells were hypoxic to anoxic) and denitrification. TTHMFP measurements across all management units ranged from 141 to 1731 ??g L-1, well in excess of the maximum contaminant level of 80 ??g L-1 established by the Environmental Protection Agency. STHMFP measurements demonstrated over twofold variation (???4 to ???8 mmol total THM/mol DOC) across the management areas, indicating the dependence of reactivity on DOC composition. The results indicate that land management strongly controls the quantity and quality of DOC to reach shallow ground water and hence should be considered

  11. Techniques for the conversion to carbon dioxide of oxygen from dissolved sulfate in thermal waters

    Science.gov (United States)

    Nehring, N.L.; Bowen, P.A.; Truesdell, A.H.

    1977-01-01

    The fractionation of oxygen isotopes between dissolved sulfate ions and water provides a useful geothermometer for geothermal waters. The oxygen isotope composition of dissolved sulfate may also be used to indicate the source of the sulfate and processes of formation. The methods described here for separation, purification and reduction of sulfate to prepare carbon dioxide for mass spectrometric analysis are modifications of methods by Rafter (1967), Mizutani (1971), Sakai and Krouse (1971), and Mizutani and Rafter (1969). ?? 1976.

  12. Relationships between secchi disk visibility, water temperature and dissolved oxygen in freshwater fishpond

    OpenAIRE

    M. H. Ali; Cagauan, A.G.

    2007-01-01

    A study was conducted to determine the relationships between secchi disk variability, water temperature and dissolved oxygen in fish ponds. Multiple regression correlation analysis was done to evaluate the relationships between the variables. Results indicated that the ranges of secchi disk visibility, water temperature and dissolved oxygen in the study ponds were just within the ranges of the variables for tilapia culture. Multiple regression correlation showed no (or insignificant) relation...

  13. SAMPLING AND ANALYTICAL METHOD FOR GEOCHEMICAL SURVEY OF DISSOLVED GASES IN BRACKISH THERMAL WATERS

    OpenAIRE

    Liotta, Marcello; Martelli, Mauro

    2011-01-01

    Dissolved gases are often utilized in geochemical studies for investigating hydrothermal and/or magmatic contributions to shallow aquifers. Between the several methods applied for analyzing dissolved gases in water, the head space equilibration technique is probably the most used because it does not require any strain before or during the water sampling in the field and can be adapted to various aims in the laboratory, with multispecies analysis by common gas chromatography. This type of tech...

  14. Characterization of Dissolved Organic Matter in River Water by Conventional Methods and Direct Sample Analysis-Time of Flight-Mass Spectrometry

    Directory of Open Access Journals (Sweden)

    T. Garrido Reyes

    2016-01-01

    Full Text Available The dissolved organic matter in surface waters is composed of fractions of different molecular weight and polarity, characteristics that determine their capacity for complexing different types of pollutants and their environmental impact. In this study, the dissolved organic matter in the surface water of the Bio-Bio River (Central Region of Chile was characterized chemically and spectroscopically after fractionating by molecular weight and polarity. The technique of direct sample analysis-time of flight-mass spectrometry (DSA-TOF-MS was used to obtain more information on the composition of dissolved organic matter. It is concluded that dissolved organic matter found in the water of the river from the site of minor human impact (Rucalhue has a predominantly natural origin, with a high content of aromatic carbon, in contrast to dissolved organic matter found in the waters of the sites that have higher human impact (Laja and Concepción, characterized by a greater molecular size and higher organic carbon content. These results are consistent with those obtained from DSA-TOF-MS, where higher correlation was observed between the mass spectrum of the standard commercial humic acid and dissolved organic matter found in the sectors of Laja and Concepción, unlike the spectrum mass of lignin which is more like dissolved organic matter found in the sector Rucalhue.

  15. 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.

  16. Toxicity of methylmercury injected into eggs when dissolved in water versus corn oil

    Science.gov (United States)

    Heinz, G.H.; Hoffman, D.J.; Klimstra, J.D.; Stebbins, K.R.; Kondrad, S.L.

    2011-01-01

    In a previous study, the embryotoxicity of methylmercury dissolved in corn oil was compared among 26 species of birds. Corn oil is not soluble in the water-based matrix that constitutes the albumen of an egg. To determine whether the use of corn oil limited the usefulness of this earlier study, a comparison was made of the embryotoxicity of methylmercury dissolved in corn oil versus water. Mallard (Anas platyrhynchos) and chicken (Gallus gallus) eggs were injected with methylmercury chloride dissolved in corn oil or water to achieve concentrations of 0, 0.2, 0.4, 0.8, and 1.6??g/g mercury in the egg on a wet weight basis. Hatching success at each dose of mercury was compared between the two solvents. For mallards, 16.4% of the eggs injected with 1.6??g/g mercury dissolved in water hatched, which was statistically lower than the 37.6% hatch rate of eggs injected with 1.6??g/g mercury dissolved in corn oil, but no differences in hatching success were observed between corn oil and water at any of the other doses. With chicken eggs, no significant differences occurred in percentage hatch of eggs between corn oil and water at any of the mercury doses. Methylmercury dissolved in corn oil seems to have a toxicity to avian embryos similar to that of does methylmercury dissolved in water. Consequently, the results from the earlier study that described the toxicity of methylmercury dissolved in corn oil to avian embryos were probably not compromised by the use of corn oil as a solvent. ?? 2011 SETAC.

  17. Measurement and interpretation of low levels of dissolved oxygen in ground water

    Science.gov (United States)

    White, A.F.; Peterson, M.L.; Solbau, R.D.

    1990-01-01

    A Rhodazine-D colorimetric technique was adapted to measure low-level dissolved oxygen concentrations in ground water. Prepared samples containing between 0 and 8.0 ??moles L-1 dissolved oxygen in equilibrium with known gas mixtures produced linear spectrophotometric absorbance with a lower detection limit of 0.2 ??moles L-1. Excellent reproducibility was found for solutions ranging in composition from deionized water to sea water with chemical interferences detected only for easily reduced metal species such as ferric ion, cupric ion, and hexavalent chromium. Such effects were correctable based on parallel reaction stoichiometries relative to oxygen. The technique, coupled with a downhole wire line tool, permitted low-level monitoring of dissolved oxygen in wells at the selenium-contaminated Kesterson Reservoir in California. Results indicated a close association between low but measurable dissolved oxygen concentrations and mobility of oxidized forms of selenium. -from Authors

  18. Bacterial community structure and dissolved organic matter in repeatedly flooded subsurface karst water pools.

    Science.gov (United States)

    Shabarova, Tanja; Villiger, Jörg; Morenkov, Oleg; Niggemann, Jutta; Dittmar, Thorsten; Pernthaler, Jakob

    2014-07-01

    Bacterial diversity, community assembly, and the composition of the dissolved organic matter (DOM) were studied in three temporary subsurface karst pools with different flooding regimes. We tested the hypothesis that microorganisms introduced to the pools during floods faced environmental filtering toward a 'typical' karst water community, and we investigated whether DOM composition was related to floodings and the residence time of water in stagnant pools. As predicted, longer water residence consistently led to a decline of bacterial diversity. The microbial assemblages in the influx water harbored more 'exotic' lineages with large distances to known genotypes, yet these initial communities already appeared to be shaped by selective processes. β-Proteobacterial operational taxonomic units (OTUs) closely related to microbes from subsurface or surface aquatic environments were mainly responsible for the clustering of samples according to water residence time in the pools. By contrast, several Cytophagaceae and Flavobacteriaceae OTUs were related to different floodings, which were also the main determinants of DOM composition. A subset of compounds distinguishable by molecular mass and O/C content were characteristic for individual floods. Moreover, there was a transformation of DOM in stagnant pools toward smaller and more aromatic compounds, potentially also reflecting microbial utilization. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

  19. Distribution and biological turnover of dissolved organic compounds in the water column of the Black Sea

    Science.gov (United States)

    Mopper, Kenneth; Kieber, David J.

    Water column concentrations and turnover rates were determined for a suite of low molecular weight organic compounds in the Black Sea. The classes of compounds studied included amino acids, simple sugars, α-keto acids, aldehydes, ketones, carboxylic acids, flavins and thiols. Our study yielded some new insights, as well as a few surprising discoveries, regarding the composition and cycling of organic matter in the Black Sea. (1) Uptake rates of organic compounds were from 2 to 4640 times faster in oxic surface waters than in anoxic waters. (2) Sharp maxima or minima in concentrations of organic compounds coincided with zones of enhanced microbial activities, especially in the vicinity of the oxic-suboxic and suboxic-anoxic interfaces. (3) The benthic boundary layer, 300-400 m thick, had a markedly different organic composition and substantially higher concentrations of organic acids, and to a lesser extent sugars and thiols, than the overlying water. (4) A dramatic change in the composition and concentration of dissolved free amino acids occurred in the water column during the cruise and appeared to be related to biological patchiness. (5) Organic thiols constituted a significant portion (e.g. 10-20%) of the total reduced sulfur near the top of the sulfidic zone, and may contribute to the origin of hydrogen sulfide in this zone. (6) Major unknown amine and carbonyl compounds were discovered in the anoxic zone, providing evidence that the Black Sea contains unique anaerobic bacteria with possibly new biochemical pathways.

  20. Rainbow trout responses to water temperature and dissolved oxygen stress in two southern California stream pools

    Science.gov (United States)

    K.R. Matthews; N.H. Berg

    1997-01-01

    Habitat use by rainbow trout Oncorhynchus mykiss is described for a southern California stream where the summer water temperatures typically exceed the lethal limits for trout (>25) C). During August 1994, water temperature, dissolved oxygen (DO), and trout distribution were monitored in two adjacent pools in Sespe Creek, Ventura County, where summer water...

  1. Dissolved Organic Carbon as a Drinking Water Constituent of Concern in California Agricultural Watersheds

    Science.gov (United States)

    Pellerin, B. A.; Bergamaschi, B. A.; Downing, B. D.; Bachand, P. A.; Deverel, S.; Kendall, C.

    2007-12-01

    Dissolved organic carbon (DOC) from the breakdown of plant and animal material is a concern for drinking water quality in California due to the potential formation of carcinogenic byproducts during disinfection. Agricultural DOC loading to surface water is a significant concern, but the sources and reactivity in agricultural runoff remains poorly understood. Here we present data on DOC dynamics in surface water from the Willow Slough watershed, a 425\\- km2 agricultural catchment in the Sacramento Valley, California. Samples collected weekly during 2006 and 2007 were analyzed for DOC concentration, optical properties (UV absorbance and fluorescence), 13C\\- DOC isotopes, and trihalomethane formation potential (a regulated disinfection byproduct formed during chlorination). DOC concentrations at the watershed mouth ranged from 2 to 4 mg/L during winter and spring, with a clear increase in DOC concentrations to more than 7 mg L following the onset of summer irrigation. The 13C\\- DOC values revealed a large range (-19 to -27 ‰), with lowest values during winter baseflow and higher values during summer and winter storms. Spectral slopes also varied seasonally (0.012 to 0.020), with steeper slopes during winter baseflow. Both isotopic and optical data provide evidence for algal\\- derived DOC during the winter baseflow and terrestrial sources during winter storms and summer irrigation. Total THM formation potential was higher in winter than summer, and is strongly correlated to DOC concentrations in surface waters (r2 = 0.87). In contrast to the total THM formation potential, the specific THM formation potential (e.g., total THM normalized to DOC) decreased during the summer irrigation season, suggesting a change in reactivity related to DOC source or degradation. Additional data from plant leachates and ground water will be discussed, as well as the implications of watershed management on DOC dynamics and reactivity in agriculturally-dominated landscapes.

  2. Assessing the Effects of Water Rights Purchases on Dissolved Oxygen, Stream Temperatures, and Fish Habitat

    Science.gov (United States)

    Mouzon, N. R.; Null, S. E.

    2014-12-01

    Human impacts from land and water development have degraded water quality and altered the physical, chemical, and biological integrity of Nevada's Walker River. Reduced instream flows and increased nutrient concentrations affect native fish populations through warm daily stream temperatures and low nightly dissolved oxygen concentrations. Water rights purchases are being considered to maintain instream flows, improve water quality, and enhance habitat for native fish species, such as Lahontan cutthroat trout. This study uses the River Modeling System (RMSv4), an hourly, physically-based hydrodynamic and water quality model, to estimate streamflows, temperatures, and dissolved oxygen concentrations in the Walker River. We simulate thermal and dissolved oxygen changes from increased streamflow to prioritize the time periods and locations that water purchases most enhance native trout habitat. Stream temperatures and dissolved oxygen concentrations are proxies for trout habitat. Monitoring results indicate stream temperature and dissolved oxygen limitations generally exist in the 115 kilometers upstream of Walker Lake (about 37% of the study area) from approximately May through September, and this reach currently acts as a water quality barrier for fish passage.

  3. Using the soil and water assessment tool to estimate dissolved inorganic nitrogen water pollution abatement cost functions in central portugal.

    Science.gov (United States)

    Roebeling, P C; Rocha, J; Nunes, J P; Fidélis, T; Alves, H; Fonseca, S

    2014-01-01

    Coastal aquatic ecosystems are increasingly affected by diffuse source nutrient water pollution from agricultural activities in coastal catchments, even though these ecosystems are important from a social, environmental and economic perspective. To warrant sustainable economic development of coastal regions, we need to balance marginal costs from coastal catchment water pollution abatement and associated marginal benefits from coastal resource appreciation. Diffuse-source water pollution abatement costs across agricultural sectors are not easily determined given the spatial heterogeneity in biophysical and agro-ecological conditions as well as the available range of best agricultural practices (BAPs) for water quality improvement. We demonstrate how the Soil and Water Assessment Tool (SWAT) can be used to estimate diffuse-source water pollution abatement cost functions across agricultural land use categories based on a stepwise adoption of identified BAPs for water quality improvement and corresponding SWAT-based estimates for agricultural production, agricultural incomes, and water pollution deliveries. Results for the case of dissolved inorganic nitrogen (DIN) surface water pollution by the key agricultural land use categories ("annual crops," "vineyards," and "mixed annual crops & vineyards") in the Vouga catchment in central Portugal show that no win-win agricultural practices are available within the assessed BAPs for DIN water quality improvement. Estimated abatement costs increase quadratically in the rate of water pollution abatement, with largest abatement costs for the "mixed annual crops & vineyards" land use category (between 41,900 and 51,900 € tDIN yr) and fairly similar abatement costs across the "vineyards" and "annual crops" land use categories (between 7300 and 15,200 € tDIN yr).

  4. Interactions Between Prokaryotes and Dissolved Organic Matter in Marine Waters

    DEFF Research Database (Denmark)

    Traving, Sachia Jo

    Microscopic unicellular organisms display a wealth of diversity, and occupy many different roles on Earth. Due to their ubiquitous distribution and high numbers, what they do and when they do it are of vital importance for the biogeochemical cycles on Earth. A large and important group of microbes...... are the heterotrophic bacteria and archaea, from here on collectively referred to as prokaryotes. They are specialized in consuming and re-mineralize organic material converting it into biomass and inorganic nutrients and carbon. The oceans function as a vast reservoir of dissolved organic matter (DOM), which contain...... extracellular enzymes as a key trait of the prokaryote-DOM interface. Understanding the chemical ecology of extracellular enzymes may reveal new insights to DOM cycling in the oceans....

  5. Dissolved oxygen and water temperature dynamics in lowland rivers over various timescales

    Directory of Open Access Journals (Sweden)

    Rajwa-Kuligiewicz Agnieszka

    2015-12-01

    Full Text Available The impact of floodplain hydrology on the in-stream dissolved oxygen dynamics and the relation between dissolved oxygen and water temperature are investigated. This has been done by examining the time series of dissolved oxygen and water temperature coupled with meteorological and hydrological data obtained from two lowland rivers having contrasting hydrological settings. Spectral analysis of long-term oxygen variations in a vegetated river revealed a distinct scaling regime with slope ‘–1’ indicating a self-similar behaviour. Identical slopes were obtained for water temperature and water level. The same power-law behaviour was observed for an unvegetated river at small timescales revealing the underlying scaling behaviour of dissolved oxygen regime for different types of rivers and over various time scales. The results have shown that the oxygenation of a vegetated river is strongly related to its thermal regime and flow conditions. Moreover, analysis of short-term fluctuations in the unvegetated river demonstrated that physical factors such as rainfall and backwaters play a substantial role in the functioning of this ecosystem. Finally, the results show that the relation between water temperature and dissolved oxygen concentration at the diurnal timescale exhibits a looping behaviour on the variable plot. The findings of this study provide an insight into the sensitivity of rivers to changing hydro-physical conditions and can be useful in the assessment of environmental variability.

  6. Remote Sensing of Dissolved Oxygen and Nitrogen in Water using Raman Spectroscopy

    Science.gov (United States)

    De Young, R.; Ganoe, R.

    2013-12-01

    The health of an estuarine ecosystem is largely driven by the abundance of dissolved oxygen and nitrogen available for maintenance of plant and animal life. An investigation was conducted to quantify the concentration of dissolved molecular oxygen and nitrogen in water by means of Raman spectroscopy. This technique is proposed for the remote sensing of dissolved oxygen in the Chesapeake Bay, which will be utilized by aircraft in order to survey large areas in real-time. A proof of principle experiment has demonstrated the ability to remotely detect dissolved oxygen and nitrogen in pure water (also Chesapeake Bay water) using a 355nm Nd:YAG laser and a simple monochromater to detect the shifted Raman oxygen and nitrogen backscattered signals at 376.2 and 387.5 nm respectively. The theoretical basis for the research, components of the experimental system, and key findings are presented. A 1.3-m water cell had an attached vertical column to house a Troll 9500 dissolved oxygen in-situ monitor (In-Situ Inc Troll 9500). The Raman oxygen signal could be calibrated with this devise. While Raman backscattered water signals are low a potential aircraft remote system was designed and will be presented.

  7. Collective and convective effects compete in patterns of dissolving surface droplets

    NARCIS (Netherlands)

    Laghezaa, G.; Dietrich, E.; Yeomans, J.M.; Ledesma-Aguilar, R.A.; Kooij, Ernst S.; Zandvliet, Henricus J.W.; Lohse, Detlef

    2016-01-01

    The effects of neighboring droplets on the dissolution of a sessile droplet, i.e. collective effects, are investigated both experimentally and numerically. On the experimental side small approximately 20 nL mono-disperse surface droplets arranged in an ordered pattern were dissolved and their size

  8. Collective and convective effects compete in patterns of dissolving surface droplets

    NARCIS (Netherlands)

    Laghezaa, G.; Dietrich, E.; Yeomans, J.M.; Ledesma-Aguilar, R.A.; Kooij, E.S.; Zandvliet, H.J.W.; Lohse, D.

    2016-01-01

    The effects of neighboring droplets on the dissolution of a sessile droplet, i.e. collective effects, are investigated both experimentally and numerically. On the experimental side small approximately 20 nL mono-disperse surface droplets arranged in an ordered pattern were dissolved and their size e

  9. Dissolved organic nutrients and phytoplankton production in the Mandovi estuary and coastal waters of Goa

    Digital Repository Service at National Institute of Oceanography (India)

    Verlecar, X.N.

    Total organic nitrogen (TON) and dissolved organic phosphorus (DOP) in the coastal and estuarine waters of Goa, India varied from 0.6 to 47.1 mu g-at N 1-1 and 0.12 to 3.49 mu g-at P l-1 respectively. The chlorophyll content of these waters...

  10. Dissolved platinum in rainwater, river water and seawater around Tokyo Bay and Otsuchi Bay in Japan

    Science.gov (United States)

    Mashio, Asami Suzuki; Obata, Hajime; Tazoe, Hirofumi; Tsutsumi, Makoto; Ferrer i Santos, Antoni; Gamo, Toshitaka

    2016-10-01

    Platinum, among the rarest elements in the earth's crust, is now widely used in various products such as catalytic converters in automobiles and anticancer drugs. Consequently, the concentration of Pt in urban aquatic environments might be increasing. However, little is known about the distributions and geochemical cycles of Pt in aquatic environments because its overall concentration remains low. In this study, we examined dissolved Pt in river water and seawater around Tokyo Bay and Otsuchi Bay (Iwate Prefecture, Japan) and rainwater in the Tokyo area. To determine sub-picomolar levels of dissolved Pt, we used isotope-dilution Inductively Coupled Plasma Mass Spectrometry (ICP-MS) after column preconcentration with an anion exchange resin. We observed seasonal variation in the dissolved Pt concentrations in Tokyo rainwater in 2002; higher concentrations were found from January to March, which might be related to the pH of rainwaters. At the source of the Arakawa River in the greater Tokyo area, the dissolved Pt concentration was found to be similar to that in rainwater. Further downstream, the dissolved Pt concentration increased sharply, which seemingly reflects the anthropogenic input of Pt into the river. In a rural area in Japan (Otsuchi Bay), the dissolved Pt concentrations were lower than in Tokyo Bay. In this area, a sharp increase in dissolved Pt concentrations was observed in a high salinity region. Contrasting Pt distribution patterns between urban and rural areas indicate that strong anthropogenic Pt sources exist in urban estuaries and that geochemical processes within estuaries affect the Pt distribution.

  11. Indications for a ubiquitous dissolved pigment degradation product in subsurface waters of the global ocean

    Directory of Open Access Journals (Sweden)

    R. Röttgers

    2011-10-01

    Full Text Available Measurements of light absorption by chromophoric dissolved organic matter (CDOM from sub-surface waters of the tropical Atlantic and Pacific showed a distinct absorption shoulder at 410–415 nm, indicating an underlying absorption of a pigment. A similar absorption maximum at ~410 nm was also found in the particulate fraction and is usually attributed to absorption by respiratory pigments of heterotrophic unicellular organisms. The CDOM absorption shoulder was described earlier in the Indian Ocean at 600 m depth and was related to a "deep red fluorescence" found in the same depth, i.e. in the oxygen minimum zone (Breves et al., 2003; Broenkow et al., 1983. In our study, fluorescence measurements of pre-concentrated DOM samples confirmed that the absorption at ~410 nm was related to a specific fluorescence at 650 nm. The absorption characteristic of this specific fluorophor was examined by fluorescence emission/excitation analysis and this showed a clear excitation maximum at 415 nm (in methanol that can explain the absorption shoulder in the CDOM spectra. The spectral characteristics of the substance found in the dissolved and particulate fraction did not match with those of chlorophyll a degradation products (as found in a sample from the sea surface but can be explained by the occurrence of respiratory pigments from heterotrophs. Combining the observations of the "deep red fluorescence" and the 410 nm-absorption shoulder suggests that there are high concentrations of a pigment degradation product (cytochrome c in DOM of all major oceans. Most pronouncedly we found this signal in the deep chlorophyll maximum and the oxygen minimum zone of tropical regions. The origin, chemical nature, turn-over rate, and fate of this molecule is so far unknown.

  12. Differentiating sources of dissolved lead in mine waters using lead isotope techniques, Sullivan Mine, British Columbia

    Science.gov (United States)

    Lepitre, M. E.; Allen, D. M.; Mortensen, J. K.; Gabites, J. E.

    2003-01-01

    This study investigates the use of Pb isotopes in acid rock drainage studies and outlines a protocol for sampling and analysis of dissolved Pb in mine waters. Groundwaters and surface waters were sampled at the Sullivan Mine, British Columbia, to quantify Pb isotope ratios and to identify possible sources of Pb in mine effluent and back groundwaters, respectively. The Sullivan Deposit is a sediment-hosted Fe-Pb-Zn massive sulphide deposit with a well-defined homogeneous Pb isotopic composition, which provided a suitable end-member for the isotopic study. The Pb isotopic compositions of water samples define a mixing line between the homogeneous Pb isotopic signature of the Sullivan Ore and at least one other more radiogenic end-member. This end-member may correspond to Pb in the host rocks (Aldridge Formation), Pb from aerosols that have infiltrated the local surficial deposits with recharge, or Pb from the surficial deposits themselves. Further study is needed to more completely characterize the composition of potential isotopic end-members in the study area. The study demonstrates that different source regions for Pb have distinct and measurable isotopic compositions, which enable "fingerprinting" sources of Pb contamination that result from ore deposits or from other sources.

  13. In situ speciation of dissolved inorganic antimony in surface waters and sediment porewaters: development of a thiol-based diffusive gradients in thin films technique for Sb(III).

    Science.gov (United States)

    Bennett, William W; Arsic, Maja; Welsh, David T; Teasdale, Peter R

    2016-08-10

    Antimony is a priority environmental contaminant typically present as either the trivalent (Sb(III)) or the pentavalent (Sb(V)) oxidation state in aquatic systems. Both the toxicity and mobility of antimony are affected by its speciation, and thus the accurate measurement of antimony speciation is essential for investigating the behaviour of this contaminant in aquatic systems. Here we present a diffusive gradients in thin films (DGT) technique, which utilises a binding layer containing a thiol-based adsorbent (3-mercaptopropyl functionalised silica gel), for the selective measurement of Sb(III) in surface waters and sediment porewaters. We also evaluated the Metsorb DGT technique, which has been previously reported to accurately measure Sb(V), for its ability to accumulate Sb(III) and thus allow the measurement of total inorganic antimony. Both the mercapto-silica and Metsorb DGT techniques showed a high affinity for Sb(III), with uptake efficiencies >97%. Elution efficiencies of 86.9 ± 2.6% and 88.1 ± 1.2% were obtained for mercapto-silica and Metsorb, respectively, with 1 mol L(-1) H2O2 in 1 mol L(-1) NaOH. The accumulation of Sb(III) by these DGT techniques was linear with time (R(2) > 0.99) and unaffected by pH (4.07-8.05), ionic strength (0.001-1.0 mol L(-1) NaCl), bicarbonate (1-15 mmol L(-1)), and an artificial seawater matrix (pH 8.34; salinity 34.8). Finally, the mercapto-silica DGT technique was applied to measure porewater concentrations of Sb(III) and As(III) in a contaminated freshwater sediment at high resolution.

  14. Puget Sound Dissolved Oxygen Modeling Study: Development of an Intermediate Scale Water Quality Model

    Energy Technology Data Exchange (ETDEWEB)

    Khangaonkar, Tarang; Sackmann, Brandon S.; Long, Wen; Mohamedali, Teizeen; Roberts, Mindy

    2012-10-01

    The Salish Sea, including Puget Sound, is a large estuarine system bounded by over seven thousand miles of complex shorelines, consists of several subbasins and many large inlets with distinct properties of their own. Pacific Ocean water enters Puget Sound through the Strait of Juan de Fuca at depth over the Admiralty Inlet sill. Ocean water mixed with freshwater discharges from runoff, rivers, and wastewater outfalls exits Puget Sound through the brackish surface outflow layer. Nutrient pollution is considered one of the largest threats to Puget Sound. There is considerable interest in understanding the effect of nutrient loads on the water quality and ecological health of Puget Sound in particular and the Salish Sea as a whole. The Washington State Department of Ecology (Ecology) contracted with Pacific Northwest National Laboratory (PNNL) to develop a coupled hydrodynamic and water quality model. The water quality model simulates algae growth, dissolved oxygen, (DO) and nutrient dynamics in Puget Sound to inform potential Puget Sound-wide nutrient management strategies. Specifically, the project is expected to help determine 1) if current and potential future nitrogen loadings from point and non-point sources are significantly impairing water quality at a large scale and 2) what level of nutrient reductions are necessary to reduce or control human impacts to DO levels in the sensitive areas. The project did not include any additional data collection but instead relied on currently available information. This report describes model development effort conducted during the period 2009 to 2012 under a U.S. Environmental Protection Agency (EPA) cooperative agreement with PNNL, Ecology, and the University of Washington awarded under the National Estuary Program

  15. Raman Spectroscopic Measurements of Co2 Dissolved in Seawater for Laser Remote Sensing in Water

    Directory of Open Access Journals (Sweden)

    Somekawa Toshihiro

    2016-01-01

    Full Text Available We examined the applicability of Raman lidar technique as a laser remote sensing tool in water. The Raman technique has already been used successfully for measurements of CO2 gas dissolved in water and bubbles. Here, the effect of seawater on CO2 Raman spectra has been evaluated. A frequency doubled Q-switched Nd:YAG laser (532 nm was irradiated to CO2 gas dissolved in a standard seawater. In seawater, the Raman signals at 984 and 1060-1180 cm-1 from SO42- were detected, which shows no spectral interference caused by Raman signals derived from CO2.

  16. Cavitation Rates in Water with Dissolved Gas and Other Impurities

    Institute of Scientific and Technical Information of China (English)

    Patrik Zima; Frantisek Marsík; Milan Sedlár

    2003-01-01

    Our objective is a better understanding of the role of physical properties of real fluids in the thermodynamics of cavitation in impure water. An extension to the classical homogenous nucleation theory suitable for mixtures is presented in attempt to address the discrepancy between the theoretical predictions and practical observations of cavitation rates in water at normal temperatures.The extension takes into account the non—equilibrium (dissipative) effects involved in nuclei formation through a substance dependent correction coefficient to be determined experimentally.The theory of thermodynamic fluctuations is applied to derive the work of formation of a bubble nucleus.The value of the correction coefficient is estimated using preliminary experimental data from a convergent-divergent nozzle. An application of the results to the numerical prediction of the cavitation zones in a radial-flow water pump is shown.

  17. Coloured Dissolved Organic Matter (CDOM) dynamics in small surface reservoirs in semiarid Brazil

    Science.gov (United States)

    Coelho, Christine; Foerster, Saskia; Heim, Birgit; de Araujo, Jose Carlos

    2016-04-01

    Coloured Dissolved Organic Matter (CDOM) is one of the major light absorbing constituents in freshwaters. Supplied from degradation of components of the aquatic environment, it consists mainly of humic substances and its concentration is strongly related to primary production, often associated to macrophytes. It plays a central role in several biological and chemical processes affecting the bioavailability of nutrients in aquatic ecosystems. Therefore CDOM can be regarded as a water quality indicator. We used the spectral absorption and spectral slope for understanding CDOM dynamics in surface reservoirs in the Brazilian semiarid region. The analysis was based on water samples collected in three reservoirs in a total of ten sampling locations in the period June 2014 to November 2015 with monthly to bi-monthly intervals totaling 120 samples. The collected water samples were filtered through cellulose acetate membrane filters. Subsequently, spectral absorbance was measured in a Lambda 950 UV-VIS spectrometer in the spectral range 250 to 800 nm using a quartz cuvette with 5 cm optical path. From the absorbance measurement, we obtained CDOM content using the specific absorption coefficient at 440nm as well as spectral slope. The average slope for the entire period for all reservoirs is 0,018, but we found a considerable increase in spectral slope values after the wet period (between February 2014 and June 2014) for the reservoirs São Nicolau and Paus Branco while Marengo reservoir showed only slight variations during this period, but exhibited an increase only in the dry period. Regarding aCDOM(440), the average was equal to 2,55 for Marengo, 5,70 for São Nicolau, and 3,53 for Paus Branco reservoir indicating different characteristics of these reservoirs. We noticed a decrease in the absorption coefficient for São Nicolau and Paus Branco reservoirs at the end of the wet period whereas for Marengo reservoir this value showed a different behavior. Spectral slope and

  18. Interactions Between Prokaryotes and Dissolved Organic Matter in Marine Waters

    DEFF Research Database (Denmark)

    Traving, Sachia Jo

    the key to understanding the mechanisms controlling the cycling of DOM within marine waters. In the thesis presented here, the aim was to investigate the activity and composition of prokaryotes to determine their functional role in DOM utilization. The thesis incorporates a range of study systems...... organic bound carbon equal in size to atmospheric carbon dioxide. Prokaryotes mediate the fate of a large part of marine DOM, which is their principal source of energy and substrate. However, a large fraction is also left behind in the water column persisting for millennia, and prokaryotes may hold...... – ranging from bacterioplankton communities in seasonally variable coastal ecosystems, a manipulated pelagic food web, to a mathematical model of free-living prokaryotes and extracellular enzyme strategies. The results characterize links between community dynamics and function in prokaryotes, and emphasize...

  19. Study on the oscillation dissolved behavior of oxysophocarpine in water

    Energy Technology Data Exchange (ETDEWEB)

    Li, Z.X., E-mail: mingtian8001@163.com [Department of Chemistry and Chemical Engineering, Baoji University of Arts and Science, Baoji, Shaanxi 721013 (China); Zhao, W.W.; Pu, X.H. [Department of Chemistry and Chemical Engineering, Baoji University of Arts and Science, Baoji, Shaanxi 721013 (China)

    2012-06-10

    Highlights: Black-Right-Pointing-Pointer The dissolution enthalpies of oxysophocarpine in water was measured using a RD496-2000 Calvet microcalorimeter. Black-Right-Pointing-Pointer The results show that the dissolution process possessed an endothermic and exothermic oscillation behavior. Black-Right-Pointing-Pointer A series of thermodynamics functions and half-life period were obtained from thermodynamic and kinetic calculations. - Abstract: In this paper, the enthalpies of dissolution of oxysophocarpine in water were measured using a RD496-2000 Calvet microcalorimeter at 298.15 K under atmospheric pressure, showing that the dissolution process was an endothermic and exothermic oscillation behavior. A series of thermodynamics functions and the half-life were obtained by thermodynamic and kinetic methods. The results show that this work not only provide a simple method for the determination of the half-life for a drug but also offer a theoretical reference for the clinical application of resveratrol.

  20. Fluoride, Nitrate, and Dissolved-Solids Concentrations in Ground Waters of Washington

    Science.gov (United States)

    Lum, W. E.; Turney, Gary L.

    1984-01-01

    This study provides basic data on ground-water quality throughout the State. It is intended for uses in planning and management by agencies and individuals who have responsibility for or interest in, public health and welfare. It also provides a basis for directing future studies of ground-water quality toward areas where ground-water quality problems may already exist. The information presented is a compilation of existing data from numerous sources including: the Washington Departments of Ecology and Social and Health Services, the Environmental Protection Agency, as well as many other local, county, state and federal agencies and private corporations. Only data on fluoride, nitrate, and dissolved-solids concentrations in ground water are presented, as these constituents are among those commonly used to determine the suitability of water for drinking or other purposes. They also reflect both natural and man-imposed effects on water quality and are the most readily available water-quality data for the State of Washington. The percentage of wells with fluoride, nitrate, or dissolved-solids concentrations exceeding U.S. Environmental Protection Agency Primary and Secondary Drinking Water Regulations were about 1, about 3, and about 3, respectively. Most high concentrations occurred in widely separated wells. Two exceptions were: high concentrations of nitrate and dissolved solids in wells on the Hanford Department of Energy Facility and high concentrations of nitrate in the lower Yakima River basin. (USGS)

  1. Dissolved organic matter fluorescence at wavelength 275/342 nm as a key indicator for detection of point-source contamination in a large Chinese drinking water lake.

    Science.gov (United States)

    Zhou, Yongqiang; Jeppesen, Erik; Zhang, Yunlin; Shi, Kun; Liu, Xiaohan; Zhu, Guangwei

    2016-02-01

    Surface drinking water sources have been threatened globally and there have been few attempts to detect point-source contamination in these waters using chromophoric dissolved organic matter (CDOM) fluorescence. To determine the optimal wavelength derived from CDOM fluorescence as an indicator of point-source contamination in drinking waters, a combination of field campaigns in Lake Qiandao and a laboratory wastewater addition experiment was used. Parallel factor (PARAFAC) analysis identified six components, including three humic-like, two tryptophan-like, and one tyrosine-like component. All metrics showed strong correlation with wastewater addition (r(2) > 0.90, p water quality in surface drinking water sources.

  2. Microbial activities and dissolved organic matter dynamics in oil-contaminated surface seawater from the Deepwater Horizon oil spill site.

    Directory of Open Access Journals (Sweden)

    Kai Ziervogel

    Full Text Available The Deepwater Horizon oil spill triggered a complex cascade of microbial responses that reshaped the dynamics of heterotrophic carbon degradation and the turnover of dissolved organic carbon (DOC in oil contaminated waters. Our results from 21-day laboratory incubations in rotating glass bottles (roller bottles demonstrate that microbial dynamics and carbon flux in oil-contaminated surface water sampled near the spill site two weeks after the onset of the blowout were greatly affected by activities of microbes associated with macroscopic oil aggregates. Roller bottles with oil-amended water showed rapid formation of oil aggregates that were similar in size and appearance compared to oil aggregates observed in surface waters near the spill site. Oil aggregates that formed in roller bottles were densely colonized by heterotrophic bacteria, exhibiting high rates of enzymatic activity (lipase hydrolysis indicative of oil degradation. Ambient waters surrounding aggregates also showed enhanced microbial activities not directly associated with primary oil-degradation (β-glucosidase; peptidase, as well as a twofold increase in DOC. Concurrent changes in fluorescence properties of colored dissolved organic matter (CDOM suggest an increase in oil-derived, aromatic hydrocarbons in the DOC pool. Thus our data indicate that oil aggregates mediate, by two distinct mechanisms, the transfer of hydrocarbons to the deep sea: a microbially-derived flux of oil-derived DOC from sinking oil aggregates into the ambient water column, and rapid sedimentation of the oil aggregates themselves, serving as vehicles for oily particulate matter as well as oil aggregate-associated microbial communities.

  3. Dissolved oxygen

    National Research Council Canada - National Science Library

    1981-01-01

    Dissolved oxygen concentrations in the waters of Botany Bay and Georges and Cooks Rivers vary mainly as a result of tidal water movements, algal and macrophytic growth and decay, and effects of storms...

  4. ANALYSIS OF DISSOLVED METHANE, ETHANE, AND ETHYLENE IN GROUND WATER BY A STANDARD GAS CHROMATOGRAPHIC TECHNIQUE

    Science.gov (United States)

    The measurement of dissolved gases such as methane, ethane, and ethylene in ground water is important in determining whether intrinsic bioremediation is occurring in a fuel- or solvent-contaminated aquifer. A simple procedure is described for the collection and subsequent analys...

  5. A Simplified and Inexpensive Method for Measuring Dissolved Oxygen in Water.

    Science.gov (United States)

    Austin, John

    1983-01-01

    A modified Winkler method for determining dissolved oxygen in water is described. The method does not require use of a burette or starch indicator, is simple and inexpensive and can be used in the field or laboratory. Reagents/apparatus needed and specific procedures are included. (JN)

  6. Distribution of dissolved boron in the waters of the Zuari estuary (Goa)

    Digital Repository Service at National Institute of Oceanography (India)

    Rajagopal, M.D.; Rajendran, A.; Reddy, C.V.G.

    Dissolved boron varies from 0.02 to 5.42mg/kg along the length of the estuary.The data suggest that a considerable portion of boron is removed from the waters by sedimentary uptake during monsoon and postmonsoon seasons. There is also a variation...

  7. A simple device for the collection of water and dissolved gases at defined depths

    Science.gov (United States)

    A device, consisting of a jar fitted with an inlet comprised of a gas-tight check valve and 2-way ball valve outlet connected via tubing to a portable peristaltic pump, was constructed to collect water samples without atmospheric contamination or loss of dissolved gases. A headspace void for dissol...

  8. DISSOLVED OXYGEN AND METHANE IN WATER BY A GC HEADSPACE EQUILIBRATION TECHNIQUE

    Science.gov (United States)

    An analytical procedure is described for the determination of dissolved oxygen and methane in groundwater samples. The method consists of generating a helium gas headspace in a water filled bottle, and analysis of the headspace by gas chromatography. Other permanent gases such as...

  9. ANALYSIS OF DISSOLVED METHANE, ETHANE, AND ETHYLENE IN GROUND WATER BY A STANDARD GAS CHROMATOGRAPHIC TECHNIQUE

    Science.gov (United States)

    The measurement of dissolved gases such as methane, ethane, and ethylene in ground water is important in determining whether intrinsic bioremediation is occurring in a fuel- or solvent-contaminated aquifer. A simple procedure is described for the collection and subsequent analys...

  10. 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.

  11. Equilibrator-based measurements of dissolved methane in the surface ocean using an integrated cavity output laser absorption spectrometer

    Institute of Scientific and Technical Information of China (English)

    LI Yuhong; ZHAN Liyang; ZHANG Jiexia; CHEN Liqi

    2015-01-01

    A new off-axis integrated cavity output spectroscopy (ICOS) is coupled to Weiss equilibrator for continuous high-resolution dissolved methane measurement in the surface ocean. The time constant for the equilibrator in freshwater at room temperature is determined via dis-equilibration and re-equilibration experiments. The constant for methane is about 40 min. The system is calibrated using a standard gas of 3.980×10–6, and the precision of the ICOS for methane is 0.07%. This system is equipped onboard to measure the spatial distribution in methane concentrations of South Yellow Sea (SYS) along the cruise track from Shanghai to Qingdao. Result shows that the methane concentration varies from 2.79 to 36.36 nmol/L, reveals a significant pattern of methane source in SYS, and a distinct decreasing trend from south to north. The peak value occurs at the coast area outside mouth of the Changjiang River, likely to be affected by the Changjiang diluted water mass dissolving a large amount of rich in methane. Moreover, all the surface waters are oversaturated, air-to-sea fluxes range from 98.59 to 5 485.35 μmol/(m2·d) (average value (1 169.74±1 398.46) μmol/(m2·d)), indicating a source region for methane to the atmosphere.

  12. Near-surface Heating of Young Rift Sediment Causes Mass Production and Discharge of Reactive Dissolved Organic Matter.

    Science.gov (United States)

    Lin, Yu-Shih; Koch, Boris P; Feseker, Tomas; Ziervogel, Kai; Goldhammer, Tobias; Schmidt, Frauke; Witt, Matthias; Kellermann, Matthias Y; Zabel, Matthias; Teske, Andreas; Hinrichs, Kai-Uwe

    2017-03-22

    Ocean margin sediments have been considered as important sources of dissolved organic carbon (DOC) to the deep ocean, yet the contribution from advective settings has just started to be acknowledged. Here we present evidence showing that near-surface heating of sediment in the Guaymas Basin, a young extensional depression, causes mass production and discharge of reactive dissolved organic matter (DOM). In the sediment heated up to ~100 °C, we found unexpectedly low DOC concentrations in the pore waters, reflecting the combined effect of thermal desorption and advective fluid flow. Heating experiments suggested DOC production to be a rapid, abiotic process with the DOC concentration increasing exponentially with temperature. The high proportions of total hydrolyzable amino acids and presence of chemical species affiliated with activated hydrocarbons, carbohydrates and peptides indicate high reactivity of the DOM. Model simulation suggests that at the local scale, near-surface heating of sediment creates short and massive DOC discharge events that elevate the bottom-water DOC concentration. Because of the heterogeneous distribution of high heat flow areas, the expulsion of reactive DOM is spotty at any given time. We conclude that hydrothermal heating of young rift sediments alter deep-ocean budgets of bioavailable DOM, creating organic-rich habitats for benthic life.

  13. Near-surface Heating of Young Rift Sediment Causes Mass Production and Discharge of Reactive Dissolved Organic Matter

    Science.gov (United States)

    Lin, Yu-Shih; Koch, Boris P.; Feseker, Tomas; Ziervogel, Kai; Goldhammer, Tobias; Schmidt, Frauke; Witt, Matthias; Kellermann, Matthias Y.; Zabel, Matthias; Teske, Andreas; Hinrichs, Kai-Uwe

    2017-03-01

    Ocean margin sediments have been considered as important sources of dissolved organic carbon (DOC) to the deep ocean, yet the contribution from advective settings has just started to be acknowledged. Here we present evidence showing that near-surface heating of sediment in the Guaymas Basin, a young extensional depression, causes mass production and discharge of reactive dissolved organic matter (DOM). In the sediment heated up to ~100 °C, we found unexpectedly low DOC concentrations in the pore waters, reflecting the combined effect of thermal desorption and advective fluid flow. Heating experiments suggested DOC production to be a rapid, abiotic process with the DOC concentration increasing exponentially with temperature. The high proportions of total hydrolyzable amino acids and presence of chemical species affiliated with activated hydrocarbons, carbohydrates and peptides indicate high reactivity of the DOM. Model simulation suggests that at the local scale, near-surface heating of sediment creates short and massive DOC discharge events that elevate the bottom-water DOC concentration. Because of the heterogeneous distribution of high heat flow areas, the expulsion of reactive DOM is spotty at any given time. We conclude that hydrothermal heating of young rift sediments alter deep-ocean budgets of bioavailable DOM, creating organic-rich habitats for benthic life.

  14. Isotopic tracing of clear water sources in an urban sewer: A combined water and dissolved sulfate stable isotope approach.

    Science.gov (United States)

    Houhou, J; Lartiges, B S; France-Lanord, C; Guilmette, C; Poix, S; Mustin, C

    2010-01-01

    This paper investigates the potential of stable isotopes of both water (deltaD and deltaOH(2)O18) and dissolved sulfate (delta(34)S and deltaOSO(4)18) for determining the origin and the amount of clear waters entering an urban sewer. The dynamics of various hydrological processes that commonly occur within the sewer system such as groundwater infiltration, rainwater percolation, or stormwater release from retention basins, can be readily described using water isotope ratios. In particular, stable water isotopes indicate that the relative volumes of infiltrated groundwater and sewage remain approximately constant and independent of wastewater flow rate during the day, thus demonstrating that the usual quantification of parasitic discharge from minimal nocturnal flow measurements can lead to completely erroneous results. The isotopic signature of dissolved sulfate can also provide valuable information about the nature of water inputs to the sewage flow, but could not be used in our case to quantify the infiltrating water. Indeed, even though the microbial activity had a limited effect on the isotopic composition of dissolved sulfate at the sampling sites investigated, the dissolved sulfate concentration in sewage was regulated by the formation of barite and calcium-phosphate mineral species. Sulfate originating from urine was also detected as a source using the oxygen isotopic composition of sulfate, which suggests that deltaOSO(4)18 might find use as a urine tracer.

  15. 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

  16. Influence of dissolved humic substances on the mass transfer of organic compounds across the air-water interface.

    Science.gov (United States)

    Ramus, Ksenia; Kopinke, Frank-Dieter; Georgi, Anett

    2012-01-01

    The effect of dissolved humic substances (DHS) on the rate of water-gas exchange of two volatile organic compounds was studied under various conditions of agitation intensity, solution pH and ionic strength. Mass-transfer coefficients were determined from the rate of depletion of model compounds from an apparatus containing a stirred aqueous solution with continuous purging of the headspace above the solution (dynamic system). Under these conditions, the overall transfer rate is controlled by the mass-transfer resistance on the water side of the water-gas interface. The experimental results show that the presence of DHS hinders the transport of the organic molecules from the water into the gas phase under all investigated conditions. Mass-transfer coefficients were significantly reduced even by low, environmentally relevant concentrations of DHS. The retardation effect increased with increasing DHS concentration. The magnitude of the retardation effect on water-gas exchange was compared for Suwannee River fulvic and humic acids, a commercially available leonardite humic acid and two synthetic surfactants. The observed results are in accordance with the concept of hydrodynamic effects. Surface pressure forces due to surface film formation change the hydrodynamic characteristics of water motion at the water-air interface and thus impede surface renewal.

  17. Analysis of Dissolved Organic Nutrients in the Interstitial Water of Natural Biofilms.

    Science.gov (United States)

    Tsuchiya, Yuki; Eda, Shima; Kiriyama, Chiho; Asada, Tomoya; Morisaki, Hisao

    2016-07-01

    In biofilms, the matrix of extracellular polymeric substances (EPSs) retains water in the interstitial region of the EPS. This interstitial water is the ambient environment for microorganisms in the biofilms. The nutrient condition in the interstitial water may affect microbial activity in the biofilms. In the present study, we measured the concentrations of dissolved organic nutrients, i.e., saccharides and proteins, contained in the interstitial water of biofilms formed on the stones. We also analyzed the molecular weight distribution, chemical species, and availability to bacteria of some saccharides in the interstitial water. Colorimetric assays showed that the concentrations of saccharides and proteins in the biofilm interstitial water were significantly higher (ca. 750 times) than those in the surrounding lake waters (p interstitial waters were mainly of low molecular-weight saccharides such as glucose and maltose, while proteins in the interstitial water were high molecular-weight proteins (over 7000 Da). Bacterial growth and production of EPS occurred simultaneously with the decrease in the low molecular-weight saccharide concentrations when a small portion of biofilm suspension was inoculated to the collected interstitial water, suggesting that the dissolved saccharides in the interstitial water support bacterial growth and formation of biofilms.

  18. A preliminary evaluation model for reservoir hydrocarbon-generating potential established based on dissolved hydrocarbons in oilfield water

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A large number of oilfield water samples were analyzed in this work. Research on the relationship between the concentrations and distribution of dissolved hydrocarbons sug gested that the contents and composition of dissolved hydrocarbons varied with the hydrocar bon-generating potential of reservoirs. The concentrations of dissolved hydrocarbons were low in dry layers, water layers and gas-water layers, but high in gas reservoirs and oil reservoirs, especially in gas reservoirs with condensed oil. Series of carbon-number alkanes were usually absent in oilfield water from dry layers, water layers and gas-water layers but abundant in oil field water from oil-water reservoirs, gas reservoirs and oil reservoirs, whose carbon numbers varied most widely in oil reservoirs and least in gas reservoirs. A preliminary evaluation model for reservoir hydrocarbon-generating potential was established based on the characteristics of dissolved hydrocarbons in oilfield water to assist hydrocarbon exploration.

  19. Remote Sensing of Dissolved Oxygen and Nitrogen in Water Using Raman Spectroscopy

    Science.gov (United States)

    Ganoe, Rene; DeYoung, Russell J.

    2013-01-01

    The health of an estuarine ecosystem is largely driven by the abundance of dissolved oxygen and nitrogen available for maintenance of plant and animal life. An investigation was conducted to quantify the concentration of dissolved molecular oxygen and nitrogen in water by means of Raman spectroscopy. This technique is proposed for the remote sensing of dissolved oxygen in the Chesapeake Bay, which will be utilized by aircraft in order to survey large areas in real-time. A proof of principle system has been developed and the specifications are being honed to maximize efficiency for the final application. The theoretical criteria of the research, components of the experimental system, and key findings are presented in this report

  20. Comparison of absorption properties of colored dissolved organic matter in six different case 2 water bodies

    Science.gov (United States)

    Nima, Ciren; Frette, Øyvind; Hamre, Børge; Erga, Svein Rune; Chen, Yi-Chun; Zhao, Lu; Muyimbwa, Dennis; Ssenyonga, Taddeo; Ssebiyonga, Nicolausi; Okullo, Willy; Stamnes, Knut; Stamnes, Jakob J.

    2017-02-01

    Colored Dissolved Organic Matter (CDOM) is one of the main factors controlling the penetration of solar radiation in Case 2 water and affecting satellite-based estimation of ocean color. We present absorption properties of CDOM sampled in 6 water bodies including three in Norway (Røst coastal water, Samnangerfjord, Lysefjord), two in China (Bohai Sea, Lake Namtso), and one in Africa (Lake Victoria). These locations, which range from near the equator to subarctic regions, include water types from oligotrophic to eutrophic, and altitudes from sea level to 4,700 m above sea level.

  1. Medidas da concentração de oxigênio dissolvido na superfície da água Measurements of dissolved oxygen concentration at water surface

    Directory of Open Access Journals (Sweden)

    Johannes Gerson Janzen

    2008-09-01

    Full Text Available A transferência de gases através da interface ar-água é um processo importante para ciclos climáticos de grande escala e para sistemas ambientais menores como rios, lagos, córregos e estações de tratamento de esgoto. Para avançar no entendimento dos princípios básicos envolvidos no fenômeno é necessária a utilização de técnicas e aparatos experimentais adequados. Neste estudo, foram realizadas medidas de concentração através da utilização de micro sonda de oxigênio, em tanque de grade oscilante. A dimensão do elemento sensor da micro sonda é da ordem de alguns micra. Os resultados demonstram a possibilidade de medir, sob condições turbulentas controladas similares às encontradas no ambiente, as flutuações de concentração de oxigênio no interior da camada limite existente imediatamente abaixo da interface ar-água.Gas transfer across the air-water interface is an important process for large-scale climate cycles as well as smaller environmental systems such as rivers, lakes, streams, and wastewater treatment basins. To improve the understanding of the basic principles involved in this phenomenon it is necessary to use suitable apparatus and experimental techniques. In this study, a microprobe has been used for measurements of oxygen concentration in an oscillating-grid tank. The microprobe has tip dimensions of the order of a few microns. The results demonstrate that it is feasible to measure, under controlled turbulence conditions that are representative for environmental situations, the fluctuating oxygen concentrations that take place in a boundary layer below the air-water interface.

  2. Water and dissolved gas geochemistry of the monomictic Paterno sinkhole (central Italy

    Directory of Open Access Journals (Sweden)

    Matteo Nocentini

    2012-07-01

    Full Text Available This paper describes the chemical and isotope features of water and dissolved gases from lake Paterno (max. depth 54 m, a sinkhole located in the NE sector of the S. Vittorino plain (Rieti, Central Italy, where evidences of past and present hydrothermal activity exists. In winter (February 2011 lake Paterno waters were almost completely mixed, whereas in summer time (July 2011 thermal and chemical stratifications established. During the stratification period, water and dissolved gas chemistry along the vertical water column were mainly controlled by biological processes, such as methanogenesis, sulfate-reduction, calcite precipitation, denitrification, and NH4 and H2 production. Reducing conditions at the interface between the bottom sediments and the anoxic waters are responsible for the relatively high concentrations of dissolved iron (Fe and manganese (Mn, likely present in their reduced oxidation state. Minerogenic and biogenic products were recognized at the lake bottom even during the winter sampling. At relatively shallow depth the distribution of CH4 and CO2 was controlled by methanotrophic bacteria and photosynthesis, respectively. The carbon isotope signature of CO2 indicates a significant contribution of deep-originated inorganic CO2 that is related to the hydrothermal system feeding the CO2-rich mineralized springs discharging in the surrounding areas of lake Paterno. The seasonal lake stratification likely controls the vertical and horizontal distribution of fish populations in the different periods of the year.

  3. Determination of dissolved methane in natural waters using headspace analysis with cavity ring-down spectroscopy.

    Science.gov (United States)

    Roberts, Hannah M; Shiller, Alan M

    2015-01-26

    Methane (CH4) is the third most abundant greenhouse gas (GHG) but is vastly understudied in comparison to carbon dioxide. Sources and sinks to the atmosphere vary considerably in estimation, including sources such as fresh and marine water systems. A new method to determine dissolved methane concentrations in discrete water samples has been evaluated. By analyzing an equilibrated headspace using laser cavity ring-down spectroscopy (CRDS), low nanomolar dissolved methane concentrations can be determined with high reproducibility (i.e., 0.13 nM detection limit and typical 4% RSD). While CRDS instruments cost roughly twice that of gas chromatographs (GC) usually used for methane determination, the process presented herein is substantially simpler, faster, and requires fewer materials than GC methods. Typically, 70-mL water samples are equilibrated with an equivalent amount of zero air in plastic syringes. The equilibrated headspace is transferred to a clean, dry syringe and then drawn into a Picarro G2301 CRDS analyzer via the instrument's pump. We demonstrate that this instrument holds a linear calibration into the sub-ppmv methane concentration range and holds a stable calibration for at least two years. Application of the method to shipboard dissolved methane determination in the northern Gulf of Mexico as well as river water is shown. Concentrations spanning nearly six orders of magnitude have been determined with this method.

  4. 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.

  5. Influence of dissolved oxygen on silver nanoparticle mobility and dissolution in water-saturated quartz sand

    Energy Technology Data Exchange (ETDEWEB)

    Mittelman, Anjuliee M.; Taghavy, Amir; Wang, Yonggang; Abriola, Linda M.; Pennell, Kurt D., E-mail: kurt.pennell@tufts.edu [Tufts University, Department of Civil and Environmental Engineering (United States)

    2013-07-15

    The influence of dissolved oxygen (DO) on the transport behavior and dissolution kinetics of silver nanoparticles (nAg) was explored through a combination of experimental and mathematical modeling studies. One-dimensional column experiments were conducted with water-saturated 40-50 mesh Ottawa sand, operated at pH 4 or 7 under three DO conditions (8.9, 2, or <0.2 mg/L). The experimental protocol consisted of a nAg deposition phase, designed to assess nanoparticle mobility as a function of DO level, followed by a dissolution phase, to evaluate the release of Ag{sup +} from retained nanoparticles. Experimental observations revealed that the mobility of nAg increased by 15 % when the DO level was reduced from 8.9 to <0.2 mg/L at pH 4, and that, once retained by the quartz sand, the fraction of nAg mass eluted as Ag{sup +} decreased from 21.6 to 13.5 to 11.3 % with decreasing oxygen level (8.9, 2, and <0.2 mg/L, respectively). In both batch and column studies, rates of nAg dissolution decreased over time, behavior attributed to aging of the nanoparticle surface due to oxidation. A hybrid Eulerian-Lagrangian nanoparticle transport model was developed and implemented to simulate the mobility of nAg, subject to DO-dependent dissolution kinetics and particle aging. Model simulations accurately captured nAg transport and dissolution as a function of pH and DO level, and demonstrate the importance of considering nanoparticle surface aging to accurately predict Ag{sup +} release over time.

  6. Geochemical processes controlling dissolved selenium in the Changjiang (Yangtze) Estuary and its adjacent waters

    Institute of Scientific and Technical Information of China (English)

    WU Xiaodan; SONG Jinming; WU Bin; LI Tiegang; LI Xuegang

    2014-01-01

    Dissolved selenium in the Changjiang (Yangtze) Estuary and its adjacent waters was determined by hy-dride generation atomic fluorescence spectrometry to elucidate the source, behavior in estuary, adsorp-tion-desorption process and biological role. In surface water, Se(IV ) concentration ranged 0.05-1.14 nmol/L and Se(VI) concentration varied 0.01-1.20 nmol/L, with the means of 0.76 and 0.49 nmol/L, respectively. In bottom water, Se(IV) content varied 0.03-0.27 nmol/L and Se(VI) content ranged 0.04-0.85 nmol/L, with the averages of 0.10 and 0.40 nmol/L, respectively. High level of Se(IV ) was observed near the shore with a significant decrease towards the open sea, suggesting the continental input from the adjacent rivers. Large value of Se( VI) was found in bottom water, reflecting the release from suspended sediment. Besides, high value appeared in the same latitude of the Changjiang Estuary and Hangzhou Bay illustrated the effect of lat-eral mixing and the long-distance transport of selenium. Se(VI), more soluble, occupied higher percentage in aqueous environment. The presence of Se(IV ) resulted from the degradation of residue and the reduction of Se(VI) under anaerobic condition. The positive relationship to suspended particulate material (SPM) and negative correlation to depth indicated that Se(IV ) tended to be released from the high density particulate matter. Instead, Se(VI) content did not significantly relate to SPM since it generally formed inner-sphere complex to iron hydroxide. Se(IV ) content negatively varied to salinity and largely depended on the fresh-water dilution and physical mixing. While, Se( VI) level deviated from the dilution line due to the in situ bio-geochemical process such as removal via phytoplankton uptake and inputs via organic matter regeneration. As the essential element, Se(IV) was confirmed more bioavailable to phytoplankton growth than Se(VI), and moreover, seemed to be more related to phosphorus than to nitrogen.

  7. Elucidating mechanisms of toxic action of dissolved organic chemicals in oil sands process-affected water (OSPW).

    Science.gov (United States)

    Morandi, Garrett D; Wiseman, Steve B; Guan, Miao; Zhang, Xiaowei W; Martin, Jonathan W; Giesy, John P

    2017-08-08

    Oil sands process-affected water (OSPW) is generated during extraction of bitumen in the surface-mining oil sands industry in Alberta, Canada, and is acutely and chronically toxic to aquatic organisms. It is known that dissolved organic compounds in OSPW are responsible for most toxic effects, but knowledge of the specific mechanism(s) of toxicity, is limited. Using bioassay-based effects-directed analysis, the dissolved organic fraction of OSPW has previously been fractionated, ultimately producing refined samples of dissolved organic chemicals in OSPW, each with distinct chemical profiles. Using the Escherichia coli K-12 strain MG1655 gene reporter live cell array, the present study investigated relationships between toxic potencies of each fraction, expression of genes and characterization of chemicals in each of five acutely toxic and one non-toxic extract of OSPW derived by use of effects-directed analysis. Effects on expressions of genes related to response to oxidative stress, protein stress and DNA damage were indicative of exposure to acutely toxic extracts of OSPW. Additionally, six genes were uniquely responsive to acutely toxic extracts of OSPW. Evidence presented supports a role for sulphur- and nitrogen-containing chemical classes in the toxicity of extracts of OSPW. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Diffusion Kinetics of Carbonate Hydroxyapatite (CHAP) for Adsorbing F- Dissolved in Water

    Institute of Scientific and Technical Information of China (English)

    HUANG Zhiliang; ZHANG Lianmeng; LIU Yu; WANG Qilin; HE Qianjun; CHEN Wei

    2006-01-01

    A systematic research was performed about diffusion kinetics of adsorbing F- dissolved in water for carbonate hydroxyapatite (CHAP) from the natural hydroxyapatite which was modified by adulterating with CO32-. The result shows that the speed of F- adsorption is controlled by membrane diffusion when F- concentration is relatively low, which is expressed by the kinetic equation of diffusion Q=0.0005(Ci-C)(t-ti)+0.3967, or by vacancy diffusion when F- concentration is relatively high, which is expressed by the kinetic equation of diffusion In[C(o, t)]=8.4718-0.5048Int. Based on the feature of CHAP for adsorbing F- dissolved in water and its special channel of the structure of CO32-- modified hydroxyapatite, models of vacancy diffusion and membrane diffusion were established.

  9. 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...

  10. 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...

  11. 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...

  12. Improved speciation of dissolved organic nitrogen in natural waters: amide hydrolysis with fluorescence derivatization

    Institute of Scientific and Technical Information of China (English)

    Ryan L.Firnmen; Tamara D.Trouts; Daniel D.Richter Jr.; Dharni Vasudevan

    2008-01-01

    The objective of this study was to improve primary-amine nitrogen (1°-N) quantification in dissolved organic matter (DOM)originating from natural waters where inorganic forms of N, which may cause analytical interference, are commonly encountered.Efforts were targeted at elucidating organic-N structural criteria influencing the response of organic amines to known colorimetric andfluorescent reagents and exploring the use of divalent metal-assisted amide hydrolysis in combination with fluorescence analyses.We found that reaction of o-phthaldialdehyde (OPA) with primary amines is significantly influenced by steric factors, whereasfluorescamine (FLU) lacks sensitivity to steric factors and allows for the detection of a larger suite of organic amines, includingdi- and tri-peptides and sterically hindered 1°-N. Due to the near quantitative recovery of dissolved peptides with the FLU reagent andlack of analytical response to inorganic nitrogen, we proposed that FLU be utilized for the quantification of primary amine nitrogen.In exploring the application of divalent metal promoted peptide hydrolysis to the analysis of organic forms of nitrogen in DOM, wefound that Zn(Ⅱ) reaction increased the total fraction of organic-N detectable by both OPA and FLU reagents. Zn-hydrolysis improvedrecovery of organic-N in natural waters from<5% to 35%. The above method, coupled with standard inorganic-N analyses, allows forenhanced resolution of dissolved organic nitrogen (DON) speciation in natural waters.

  13. Effect of dissolved oxygen in alcoholic beverages and drinking water on alcohol elimination in humans.

    Science.gov (United States)

    Rhee, Su-jin; Chae, Jung-woo; Song, Byung-jeong; Lee, Eun-sil; Kwon, Kwang-il

    2013-02-01

    Oxygen plays an important role in the metabolism of alcohol. An increased dissolved oxygen level in alcoholic beverages reportedly accelerates the elimination of alcohol. Therefore, we evaluated the effect of dissolved oxygen in alcohol and the supportive effect of oxygenated water on alcohol pharmacokinetics after the excessive consumption of alcohol, i.e., 540 ml of 19.5% alcohol (v/v). Fifteen healthy males were included in this randomized, 3 × 3 crossover study. Three combinations were tested: X, normal alcoholic beverage and normal water; Y, oxygenated alcoholic beverage and normal water; Z, oxygenated alcoholic beverage and oxygenated water. Blood alcohol concentrations (BACs) were determined by conversion of breath alcohol concentrations. Four pharmacokinetic parameters (C(max), T(max), K(el), and AUCall) were obtained using non-compartmental analysis and the times to reach 0.05% and 0.03% BAC (T(0.05%) and T(0.03%)) were compared using one-way analysis of variance (ANOVA) and Duncan's post hoc test. With combination Z, the BAC decreased to 0.05% significantly faster (p water augments the effect of oxygen in the alcoholic beverage in alcohol elimination. Therefore, it is necessary to investigate the supportive effect of ingesting additional oxygenated water after heavy drinking of normal alcoholic beverages.

  14. Evolution of Pretreatment Methods for Nanofiltration Membrane Used for Dissolved Organic Matter Removal in Raw Water Supply

    Directory of Open Access Journals (Sweden)

    Sirikul Siriraksophon

    2016-07-01

    Full Text Available Coagulation and microfiltration using polyaluminium chloride (PACl were investigated as a pretreatment process by nanofiltration to reduce dissolved organic matter in both raw water and treated water at water treatment plants. The dissolved organic matter in the raw water supply may be a precursor of carcinogens produced during the disinfection process. Raw water from pumping stations and treated water from Hat Yai Provincial Waterworks Authority, Songkhla Province, Thailand were used as samples for this study. Fractionation of raw water samples by DAX-8 and XAD-4 resin revealed that they contained hydrophilic, transphilic and hydrophobic groups with hydrophilic the major organic component. PACl coagulation resulted in a higher dissolved organic matter removal than microfiltration techniques. A hybrid coagulation-nanofiltration process was studied. This effectively reduced dissolved organic matter as dissolved organic carbon and UV-254 by 86% and 94% respectively. The hybrid coagulation-nanofiltration process reduced dissolved organic carbons of the hydrophobic group more effectively than the hydrophilic group. Chloroform and bromodichloroform were the two major species of the trihalomethane group produced when raw water reacted with chlorine. The hybrid coagulation-nanofiltration process reduced the trihalomethane formation potential (THMFP in raw water samples by up to 90%

  15. Relationship between precipitation quality, shallow ground-water geochemistry, and dissolved aluminum in eastern Maryland. Final report, November 1983-April 1985

    Energy Technology Data Exchange (ETDEWEB)

    Bachman, L.J.; Katz, B.G.

    1986-04-01

    Precipitation, surface water, and shallow ground-water samples were collected in eastern Maryland to determine if acidic precipitation is affecting the chemical quality of water in the Columbia aquifer--an unconsolidated sand and gravel deposit. Thirty-eight water samples were collected from 11 wells, and 9 samples from 3 stream sites between February and June 1984. Ground-water and surface-water samples contained chemical species with significantly different concentration from those of precipitation. Ground-water samples were enriched with bicarbonate, silica, potassium, chloride, and sulfate and had lower hydrogen-ion concentrations than precipitation. Dissolved aluminum in most of the other ground-water samples was at or near the detection limit of 0.01 mg/l.

  16. Dissolved inorganic carbon isotopic composition of the Gulf of Mexico deep-water masses.

    Science.gov (United States)

    Quintanilla-Terminel, J. G.; Herguera, J. C.; Ferreira-Bartrina, V.; Hernández-Ayón, J. M.; Camacho-Ibar, V.

    2014-12-01

    This study provides new data for the establishment of a carbon biogeochemical dynamics baseline in the deep Gulf of Mexico (GM) based on carbon isotopes in dissolved inorganic carbon. Water samples from 40 deep-water stations south of 25˚N were collected during XIXIMI-2 cruise, July 2011, aboard BO/Justo Sierra. Vertical profiles of temperature, salinity and dissolved oxygen (DO) were further measured in each station. In the Stable Isotopes Laboratory at CICESE we determined the carbon isotopic composition of the dissolved inorganic carbon (DIC) (δ13CDIC). Remarkably, density, DO and δ13CCID profiles showed a clear difference between the Loop current and the deep-waters of the GM south of 25˚N. We found the following average δ13CCID values in the Loop current and in the deep-waters of the Gulf: subtropical underwater (SUW): 0.73±0.06‰ and 0.86±0.04‰; 18 degree water (18W): 0.76 ± 0.08‰ and 0.58± 0.06‰; North Atlantic central water (NACW): 0.77 ± 0.05‰ and 0.71 ± 0.09‰; South Atlantic central water (SACW): 0.80 ± 0.08‰ and 0.77 ± 0.07‰; Antartic intermediate water (AAIW): 1.00 ± 0.06‰ and 0.90 ± 0.08‰; North Atlantic deep water (NADW): 1.03 ± 0.06‰ and 1.01 ± 0.10‰. We will discuss how the biological component, δ13CCID-BIO, of subsurface water masses match very closely the apparent oxygen utilization relation described by Kroopnick, 1985, with the exception of SUW, and as a consequence the 18W is probably the water mass most affected by organic carbon remineralization processes in the GM south of 25˚N. We further show how these waters seem to store a larger proportion of anthropogenic carbon than the deeper water masses.

  17. Method for the determination of dissolved chloride, nitrate, and sulfate in natural water using ion chromatography

    Science.gov (United States)

    Brinton, Terry I.; Antweiler, Ronald C.; Taylor, Howard E.

    1996-01-01

    Ion chromatography was used for the determination of dissolved chloride, nitrate and sulfate in natural water where concentrations ranged from a detection limit of 0.02 milligrams per liter to 80 milligrams per liter for chloride, to 18 milligrams per liter for nitrate, and to 280 milligrams per liter for sulfate. Specific conductance was the mode of detection used. Three analytical sample size loops of 11, 61, and 250 microliters, were used to include the analytical ranges described. U.S. Geological Survey Standard Reference Water Samples were analyzed to test the precision and accuracy of the analyses.

  18. Dissolved rhenium in river waters: Insight into the chemical weathering of fossil organic carbon?

    Science.gov (United States)

    Hilton, Robert; Gaillardet, Jerome

    2010-05-01

    The store of carbon in rock as fossil organic matter represents ~15x1021 g, which is almost 400 times the total amount of carbon present in the oceans and atmosphere. Oxidation of fossil organic carbon (FOC) during chemical weathering returns CO2 that was sequestered from the atmosphere in the geological past, back into the contemporary carbon cycle. Despite this recognition, the natural rates of FOC weathering are poorly constrained in the modern environment, as are the precise controls on its variability. This is primarily due to the difficultly in tracking the dissolved and gaseous carbon produced during FOC weathering, where biology and carbonate weathering mask its influence at a catchment-scale. Here we investigate the use of rhenium (Re) as a tracer of FOC weathering, focusing on a series of mountain catchments in Taiwan. We present dual methodology for determining dissolved Re content in river waters by ICP-MS, using pre-concentration and matrix removal via anion exchange chemistry and by direct analysis through standard-addition. Precision (2sigma) and accuracy at the ppt level are found to be better than 7%. In the 16 sampled catchments, the dissolved Re concentrations span the entire range from the published literature. We investigate the source of dissolved Re in the catchments using measurements of bedrocks and river sediments, and the comparative behavior of Re to major dissolved phases. A preliminary estimate of the Re budget derived from the weathering of FOC is presented, and the implications for the rates of FOC weathering discussed.

  19. Dissolved and particulate organic carbon in the melt water of Icelandic glaciers

    Science.gov (United States)

    Chifflard, Peter; Reiss, Martin

    2017-04-01

    Recently, glaciers have been recognized as unique ecosystems with potential effects on the global carbon cycle. Among other transport processes organic carbon stored in glacier ecosystems is released from the glaciers through melt at the glaciers surface that discharges into proglacial streams and finally into the ocean. Nevertheless, the potential role of glaciers in the carbon cycle remains poorly understood (Hood et al. 2015). One particular problem in this respect is that there is a lack in regional and global analysis of the total amount of organic carbon released from glaciers. Although, the release of organic carbon has been investigated in proglacial streams in Alaska, the European Alps and Greenland, to our knowledge, there is no information available for Icelandic proglacial streams. Thus, the aims of this study are: 1) to develop a first base information about the concentration of dissolved and particulate organic carbon (DOC and POC) in several Icelandic proglacial streams and 2) to detect the variability of DOC and POC along a proglacial stream from the glacier source to the mouth into the Atlantic Ocean. Therefore, a field trip was conducted between 23 and 31 July 2016, whereby, 25 water samples were taken. The sampling points cover melt water from the following Icelandic glaciers Vatnajökull, Langjökull, Hofsjökull, Myrdalsjökull and Tungnafellsjökull. Further water samples were taken along the river Hvitá starting at the glacier Langjökull and ending at the mouth into the Atlantic ocean in the southwest of Iceland. At every sample point electrical conductivity, water temperate and the pH-value were measured in situ using a calibrated portable water quality meter (Hanna Combo HI98129). The water samples (130 ml) were filtered using pre-combusted GF/F filters (Whatman, pore sizes 0.7 µm) and stored in a cooling box until the shipment to the laboratory of the Department for Geography, Philipps-University of Marburg. The DOC concentrations in

  20. Removal of fluorescence and ultraviolet absorbance of dissolved organic matter in reclaimed water by solar light.

    Science.gov (United States)

    Wu, Qianyuan; Li, Chao; Wang, Wenlong; He, Tao; Hu, Hongying; Du, Ye; Wang, Ting

    2016-05-01

    Storing reclaimed water in lakes is a widely used method of accommodating changes in the consumption of reclaimed water during wastewater reclamation and reuse. Solar light serves as an important function in degrading pollutants during storage, and its effect on dissolved organic matter (DOM) was investigated in this study. Solar light significantly decreased the UV254 absorbance and fluorescence (FLU) intensity of reclaimed water. However, its effect on the dissolved organic carbon (DOC) value of reclaimed water was very limited. The decrease in the UV254 absorbance intensity and FLU excitation-emission matrix regional integration volume (FLU volume) of reclaimed water during solar light irradiation was fit with pseudo-first order reaction kinetics. The decrease of UV254 absorbance was much slower than that of the FLU volume. Ultraviolet light in solar light had a key role in decreasing the UV254 absorbance and FLU intensity during solar light irradiation. The light fluence-based removal kinetic constants of the UV254 and FLU intensity were independent of light intensity. The peaks of the UV254 absorbance and FLU intensity with an apparent molecular weight (AMW) of 100Da to 2000Da decreased after solar irradiation, whereas the DOC value of the major peaks did not significantly change.

  1. Survey of Arsenic Removal fromWater by Coagulation and Dissolved Air Floatation Method

    Directory of Open Access Journals (Sweden)

    E Bazrafshan

    2010-10-01

    Full Text Available "n "nBackgrounds and Objectives:Arsenic is one of the most toxic and dangerous elements in drinking  water that with increase in its application in agriculture, development of applications in agriculture, livestock, medicine, industry and other cases its entry to water resources and environment is much easier.Arsenic is a poisonous, cumulative substance and inhibitor of SH group enzymes and various studies revealed a significant correlation between high concentrations of arsenic in drinking water and liver cancer, nasal cavity cancer, lungs, skin, bladder and kidney cancer in men and women and prostate and liver in men. The aim of this was survey of arsenic removed from water using dissolved air floatation mechanism."nMaterials and Methods: At present study in first step for determination best conditions of arsenic removal by dissolved air floatation method, optimum amount of coagulants determined and then synthetic solution of arsenic (50, 100 and 200 µg/L prepared using sodium arsenate. In third step arsenic removal efficiency under various variables such as arsenic concentration, flocculation and floatation time and saturation pressure were analyzed. Finally residual arsenic concentration was determined by the silver diethyl dithiocarbamate method."nResults:Effect of optimum condition on arsenic removal efficiency at various initial concentration 50, 100 and 200 µg/Lshowed that the best coagulant for removal of arsenic is polyaluminumchloride. Also maximum efficiency (99.4% was obtained in initial concentration equal 200 µg/L."nConclusion: It can be concluded that dissolved air floatation method with poly aluminum chloride as coagulant have high efficiency for arsenic removal even at high concentrations and therefore this method can be used for removal of arsenic from water as a suitable and safe option.

  2. Tracing water and suspended matter in Raritan and Lower New York Bays using dissolved and particulate elemental concentrations

    Science.gov (United States)

    Paulson, A.J.

    2005-01-01

    Geochemical tracers were used to examine the mixing of water and particles in Lower New York and Raritan Bays in August 1999 during low-flow conditions. Four brackish water masses (20 ≤ S ≤ 28) originating in the Raritan and Shrewsbury Rivers, Arthur Kill, and Upper New York Bay were characterized by their dissolved metals concentrations. The mixing lines of dissolved Cu, Ni, and Pb in Lower New York Bay were similar to those in Upper New York Bay, the source of most of the freshwater to the system. Dissolved Cd and Mn seemed to have been removed by particles in several regions of the study. Dissolved Cu, Ni and Pb in the Raritan River fell below the mixing lines of the Lower New York Bay. In contrast, the concentrations of dissolved Co and Mn in the Raritan River were distinctly higher than those in the Lower New York Bay, while dissolved Cu and Ni were elevated in the Arthur Kill. A plot of dissolved Co versus dissolved Ni clearly differentiated among three water masses: (1) Upper and Lower New York Bays and Sandy Hood Bay, (2) the Raritan River, and (3) Arthur Kill–Raritan Bay–Shrewsbury River.

  3. Surface evolution of dissolving minerals investigated with a kinetic Ising model

    Science.gov (United States)

    Bandstra, Joel Z.; Brantley, Susan L.

    2008-06-01

    In natural weathering systems, both the chemistry and the topography of mineral surfaces change as rocks and minerals equilibrate to surface conditions. Most geochemical research has focused on changes in solution chemistry over time; however, temporal changes in surface topography may also yield information about rates and mechanisms of dissolution. We use stochastic dissolution simulations of a regular 2-D lattice with reaction mechanisms defined in terms of nearest neighbor interactions to elucidate how the surface area and reactivity of a crystal evolve during dissolution. Despite the simplicity of the model, it reproduces key features observed or inferred for mineral dissolution. Our model results indicate that: (i) dissolving surfaces reach a steady-state conformation after sufficient dissolution time, (ii) linear defects cause surface area and dissolution rate to vary in concert with one another, (iii) sigmoidal and non-sigmoidal rate vs. free-energy of reaction (Δ Grxn) behavior can be rationalized in terms of the multiple steps occurring during dissolution, and (iv) surface roughness as a function of Δ Grxn is highly sensitive to the reaction mechanism. When simulated times to reach steady-state are compared to published time series rate data using suitable scaling, good agreement is found for silicate minerals while the model significantly over-predicts the duration of the transient for Fe and Al oxides. The implication of our simple model is that many aspects of mineral dissolution behavior, including approach to steady-state, sigmoidal vs. non-sigmoidal rate vs. Δ Grxn behavior, and development of rougher surfaces in conditions further from equilibrium can be explained by nearest neighbor interactions and simple Kossel-type models where reactivity of a surface is defined in terms of perfect surface, step, and kink sites.

  4. Titania/C{sub n}TAB Nanoskeleton as adsorbent and photocatalyst for removal of alkylphenols dissolved in water

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Toshio, E-mail: tsakai@shinshu-u.ac.jp [Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan); Da Loves, Albar; Okada, Tomohiko; Mishima, Shozi [Department of Chemistry and Material Engineering, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan)

    2013-03-15

    Highlights: ► Removal of alkylphenols from water by TiO{sub 2}/C{sub n}TAB Nanoskeleton. ► No significant adsorption of alkylphenols onto calcined TiO{sub 2}/C{sub n}TAB Nanoskeleton. ► Adsorption dominated by hydrophobic interaction between alkylphenols and C{sub n}TAB. ► Adsorption of alkylphenols promoted with C{sub n}TAB content in TiO{sub 2}/C{sub n}TAB Nanoskeleton. ► Complete removal of alkylphenols by adsorption and photocatalytic degradation. -- Abstract: We report here on the removal of alkylphenols (phenol, 4-n-propylphenol, 4-n-heptylphenol and 4-nonylphenol) dissolved in water using the composite particles of nanocrystalline titania and alkyltrimethylammonium bromide (C{sub n}H{sub 2n+1}N(CH{sub 3}){sub 3}Br, C{sub n}TAB; n = 12, 14, 16 and 18) (named as TiO{sub 2}/C{sub n}TAB Nanoskeleton) as adsorbents and photocatalysts. In particular, the adsorption of alkylphenols onto TiO{sub 2}/C{sub n}TAB Nanoskeleton in water was investigated in terms of hydrophobic interaction between alkylphenols and C{sub n}TAB, surface area, pore structure and crystal size of TiO{sub 2}/C{sub n}TAB Nanoskeleton. We revealed that C{sub n}TAB incorporated in the TiO{sub 2}/C{sub n}TAB Nanoskeleton promotes the adsorption of alkylphenols onto TiO{sub 2}/C{sub n}TAB Nanoskeleton due to the hydrophobic interaction between alkylphenols and C{sub n}TAB. On the other hand, the surface area, pore structure and crystal size of TiO{sub 2}/C{sub n}TAB Nanoskeleton did not affect the adsorption of alkylphenols onto TiO{sub 2}/C{sub n}TAB Nanoskeleton. We also found that the alkylphenols dissolved in water were completely removed by the combination of adsorption and photocatalytic degradation by the TiO{sub 2}/C{sub n}TAB Nanoskeleton under UV irradiation. These results prove that the TiO{sub 2}/C{sub n}TAB Nanoskeleton acts as in tandem an adsorbent and a photocatalyst for removal of alkylphenols dissolved in water.

  5. Influence of dissolved organic matter on nickel bioavailability and toxicity to Hyalella azteca in water-only exposures.

    Science.gov (United States)

    Doig, Lorne E; Liber, Karsten

    2006-03-10

    Dissolved organic matter (DOM) is known to reduce the bioavailability of metals in aquatic systems. This study evaluated the effects of DOM from various sources (e.g., Little Bear Lake sediment, Suwannee River, peat moss) and various DOM fractions (humic acids, HA; fulvic acids, FA) on the bioavailability of nickel (Ni) to Hyalella azteca, a common freshwater benthic invertebrate. In particular, this study was conducted to evaluate the effect of surficial sediment DOM on Ni bioavailability. Short-term (48 h) acute toxicity tests with H. azteca conducted in synthetic water demonstrated that the aqueous Ni concentrations required for lethality were greater than what could be significantly complexed by environmentally relevant concentrations of dissolved organic carbon (DOC: 0.6-30.4 mg/L). At Ni concentrations sublethal to H. azteca (500 microg/L), the bioavailability of Ni was significantly reduced in the presence of representative surface water DOC concentrations regardless of DOC source or fraction. DOC fraction (i.e., FA and HA) differentially affected Ni speciation, but had little or no effect on Ni accumulation by H. azteca. Tissue Ni was found to be strongly dependent upon the Ni(2+) concentration in the exposure solutions and the Ni:DOC ratio. Overall, the concentration of DOC played a greater role than either DOC source or fraction in determining Ni speciation and hence bioavailability and toxicity to H. azteca.

  6. New method for the direct determination of dissolved Fe(III) concentration in acid mine waters

    Science.gov (United States)

    To, T.B.; Nordstrom, D.K.; Cunningham, K.M.; Ball, J.W.; McCleskey, R.B.

    1999-01-01

    A new method for direct determination of dissolved Fe(III) in acid mine water has been developed. In most present methods, Fe(III) is determined by computing the difference between total dissolved Fe and dissolved Fe(II). For acid mine waters, frequently Fe(II) >> Fe(III); thus, accuracy and precision are considerably improved by determining Fe(III) concentration directly. The new method utilizes two selective ligands to stabilize Fe(III) and Fe(II), thereby preventing changes in Fe reduction-oxidation distribution. Complexed Fe(II) is cleanly removed using a silica-based, reversed-phase adsorbent, yielding excellent isolation of the Fe(III) complex. Iron(III) concentration is measured colorimetrically or by graphite furnace atomic absorption spectrometry (GFAAS). The method requires inexpensive commercial reagents and simple procedures that can be used in the field. Calcium(II), Ni(II), Pb(II), AI(III), Zn(II), and Cd(II) cause insignificant colorimetric interferences for most acid mine waters. Waters containing >20 mg of Cu/L could cause a colorimetric interference and should be measured by GFAAS. Cobalt(II) and Cr(III) interfere if their molar ratios to Fe(III) exceed 24 and 5, respectively. Iron(II) interferes when its concentration exceeds the capacity of the complexing ligand (14 mg/L). Because of the GFAAS elemental specificity, only Fe(II) is a potential interferent in the GFAAS technique. The method detection limit is 2 ??g/L (40 nM) using GFAAS and 20 ??g/L (0.4 ??M) by colorimetry.A new method for direct determination of dissolved Fe(III) in acid mine water has been developed. In most present methods, Fe(III) is determined by computing the difference between total dissolved Fe and dissolved Fe(II). For acid mine waters, frequently Fe(II)???Fe(III); thus, accuracy and precision are considerably improved by determining Fe(III) concentration directly. The new method utilizes two selective ligands to stabilize Fe(III) and Fe(II), thereby preventing changes

  7. The radiocarbon age of calcite dissolving at the sea floor: Estimates from pore water data

    Science.gov (United States)

    Martin, W. R.; McNichol, A. P.; McCorkle, D. C.

    2000-04-01

    We measured the radiocarbon content and stable isotopic composition of pore water and bottom water ΣCO 2, sedimentary organic carbon, and CaCO 3 at two sites on the Ceara Rise, one underlying bottom water that is supersaturated with respect to calcite (Site B), the other underlying undersaturated bottom water (Site G). The results were combined with pore water O 2, ΣCO 2, and Ca 2+ profiles (Martin and Sayles, 1996) to estimate the radiocarbon content of the CaCO 3 that is dissolving in the sediment mixed layer. At Site G, the CaCO 3 that is dissolving in the upper 2 cm of the sediments is clearly younger (richer in 14C) than the bulk sedimentary CaCO 3, indicating that nonhomogeneous CaCO 3 dissolution occurs there. The case for nonhomogeneous dissolution is much weaker at the site underlying supersaturated bottom water. The results indicate that nonhomogeneous dissolution occurs in sediments underlying undersaturated bottom water, that the dissolution is rapid relative to the rate of homogenization of the CaCO 3 in the mixed layer by bioturbation, and that the dissolution rate of CaCO 3 decreases as it ages in the sediment mixed layer. The results support the hypothesis, based on solid phase analyses, that the preferential dissolution of young (i.e., radiocarbon-rich) CaCO 3 leads to a pattern of increasing radiocarbon age of mixed-layer CaCO 3 as the degree of undersaturation of bottom water increases (Keir, 1984; Broecker et al., 1991).

  8. Estimating dissolved organic carbon concentration in turbid coastal waters using optical remote sensing observations

    Science.gov (United States)

    Cherukuru, Nagur; Ford, Phillip W.; Matear, Richard J.; Oubelkheir, Kadija; Clementson, Lesley A.; Suber, Ken; Steven, Andrew D. L.

    2016-10-01

    Dissolved Organic Carbon (DOC) is an important component in the global carbon cycle. It also plays an important role in influencing the coastal ocean biogeochemical (BGC) cycles and light environment. Studies focussing on DOC dynamics in coastal waters are data constrained due to the high costs associated with in situ water sampling campaigns. Satellite optical remote sensing has the potential to provide continuous, cost-effective DOC estimates. In this study we used a bio-optics dataset collected in turbid coastal waters of Moreton Bay (MB), Australia, during 2011 to develop a remote sensing algorithm to estimate DOC. This dataset includes data from flood and non-flood conditions. In MB, DOC concentration varied over a wide range (20-520 μM C) and had a good correlation (R2 = 0.78) with absorption due to coloured dissolved organic matter (CDOM) and remote sensing reflectance. Using this data set we developed an empirical algorithm to derive DOC concentrations from the ratio of Rrs(412)/Rrs(488) and tested it with independent datasets. In this study, we demonstrate the ability to estimate DOC using remotely sensed optical observations in turbid coastal waters.

  9. Simultaneous analysis of noble gases, sulfur hexafluoride, and other dissolved gases in water.

    Science.gov (United States)

    Brennwald, Matthias S; Hofer, Markus; Kipfer, Rolf

    2013-08-06

    We developed an analytical method for the simultaneous measurement of dissolved He, Ne, Ar, Kr, Xe, SF6, N2, and O2 concentrations in a single water sample. The gases are extracted from the water using a head space technique and are transferred into a vacuum system for purification and separation into different fractions using a series of cold traps. Helium is analyzed using a quadrupole mass spectrometer (QMS). The remaining gas species are analyzed using a gas chromatograph equipped with a mass spectrometer (GC-MS) for analysis of Ne, Ar, Kr, Xe, N2, and O2 and an electron capture detector (GC-ECD) for SF6 analysis. Standard errors of the gas concentrations are approximately 8% for He and 2-5% for the remaining gas species. The method can be extended to also measure concentrations of chlorofluorocarbons (CFCs). Tests of the method in Lake Lucerne (Switzerland) showed that dissolved gas concentrations agree with measurements from other methods and concentrations of air saturated water. In a small artificial pond, we observed systematic gas supersaturations, which seem to be linked to adsorption of solar irradiation in the pond and to water circulation through a gravel bed.

  10. New nutrients exert fundamental control on dissolved organic carbon accumulation in the surface Atlantic Ocean

    Science.gov (United States)

    Romera-Castillo, Cristina; Letscher, Robert T.; Hansell, Dennis A.

    2016-09-01

    The inventories of carbon residing in organic matter dissolved in the ocean [dissolved organic carbon (DOC)] and in the atmosphere as CO2 are of the same order of magnitude, such that small changes in the DOC pool could have important consequences in atmospheric carbon and thus climate. DOC in the global ocean is largely formed in the sunlit euphotic zone, but identifying predictable controls on that production is an important yet unrealized goal. Here, we use a testable and causative correlation between the net production of DOC and the consumption of new nutrients in the euphotic zone of the Atlantic Ocean. We demonstrate that new nutrients introduced to the euphotic zone by upwelling in divergence zones and by winter convective overturn of the water column, and the primary production associated with those nutrients, are the ultimate driver of DOC distributions across the Atlantic basins. As new nutrient input will change with a changing climate, the role of DOC in the ocean’s biological pump should likewise be impacted.

  11. Benthic Fluxes of Dissolved Macro- and Micronutrients to the Water Column of Upper Klamath Lake, Oregon

    Science.gov (United States)

    Kuwabara, J. S.; Topping, B. R.; Lynch, D. D.; Murphy, F.; Carter, J. L.; Lindenberg, M.

    2007-12-01

    Hypoxic, environmentally stressful conditions for endangered fish populations have been generated over the past century by an annual phytoplankton bloom in Upper Klamath Lake, OR. The bloom is consistently dominated by the nitrogen-fixing cyanophyte Aphanizomenon flos-aquae (AFA), thus a quantitative understanding of processes affecting the transport of biologically available phosphorus (P), presumably the limiting nutrient, is critical for resource management in the lake. This work was undertaken to help develop sound remediation or restoration strategies, and to set realistic expectations for water-quality improvements. Particle-reactive phosphate can adsorb or complex onto particles that settle and accumulate in the lake bed. Biogeochemical processes near the sediment-water interface can remobilize particle-bound P and generate a benthic flux of bioavailable P. This study provides estimates of the benthic flux of dissolved macronutrients (i.e., phosphorus and nitrogen species) before, during and after the period of: (1) increased water-column nutrient concentrations that cannot be accounted for by riverine inputs, and (2) the annual bloom of AFA. Benthic flux of dissolved orthophosphate was consistently positive (i.e., out of the sediment into the overlying water column) and ranged between 0.5 and 6.1 mg m-2 d-1. Assuming a lake area of 200 km2, this converts to a mass flux to the entire lake of 8,000 to 100,000 kg over a 3-month AFA bloom season which is comparable in magnitude to riverine inputs. An additional concern related to fish toxicity was that dissolved ammonium also displayed consistently positive benthic fluxes of 4 to 100 mg m-2 d-1; also comparable to riverine inputs. In contrast, dissolved nitrate exhibited a consistently negative flux (consumed by the sediment) with values ranging between -20 to -0.1 mg m-2 d-1. Macroinvertebrate densities of the order of 105 individuals-m-2 suggest that the diffusive-flux estimates may be significantly lower

  12. The wide spectrum high biocidal potency of Bioxy formulation when dissolved in water at different concentrations

    Science.gov (United States)

    Dagher, Fadi

    2017-01-01

    Traditional surface disinfectants that have long been applied in medicine, animal husbandry, manufacturing and institutions are inconvenient at best and dangerous at worst. Moreover, some of these substances have adverse environmental impacts: for example, quaternary ammonium compounds (“quats”) are reproductive toxicants in both fish and mammals. Halogens are corrosive both to metals and living tissues, are highly reactive, can be readily neutralized by metals, and react with organic matter to form toxic, persistent by-products such as dioxins and furans. Aldehydes may be carcinogenic to both human and animals upon repeated exposures, are corrosive, cross-link living tissues and many synthetic materials, and may lose efficacy when pathogens enzymatically adapt to them. Alcohols are flammable and volatile and can be enzymatically degraded by certain bacterial pathogens. Quats are highly irritating to mucous membranes and over time can induce pathogen resistance, especially if they are not alternated with functionally different disinfectants. In contrast, peracetic acid (PAA), a potent oxidizer, liberates hydrogen peroxide (itself a disinfectant), biodegrades to carbon dioxide, water and oxygen, and is at least as efficacious as contact biocides e.g., halogens and aldehydes. Nevertheless, the standard form of liquid PAA is highly corrosive, is neutralized by metals and organic matter, gives off noxious odours and must be stored in vented containers. For the reasons stated above, Bioxy formulations were developed, a series of powder forms of PAA, which are odourless, stable in storage and safe to transport and handle. They generate up to 10% PAA in situ when dissolved in water. A 0.2% aqueous solution of Bioxy (equivalent to 200 ppm PAA) effected a 6.76 log reduction in Methicillin-resistant Staphylococcus aureus (MRSA) within 2 minutes after application. A 5% aqueous solution of Bioxy achieved a 3.93 log reduction in the bovine tuberculosis bacillus

  13. 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...

  14. 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...

  15. Formulation and optimization of fast dissolving intraoral drug delivery system for clobazam using response surface methodology.

    Science.gov (United States)

    Bala, Rajni; Khanna, Sushil; Pawar, Pravin K

    2013-07-01

    Clobazam is a newer 1,5-benzodiazepine used for the treatment of epilepsy. It is better tolerated and less sedating than other benzodiazepines. Absorption of the drug can be impacted by oral fast dissolving dosage form; this may have implications for epilepsy in pediatrics and those having difficulty in swallowing tablets/capsules resulting in improved patient compliance. The purpose of the present investigation was to formulate and optimize clobazam oro-dissolving tablets by direct compression method using response surface methodology (RSM). Oro-dispersible tablets of clobazam were prepared by direct compression method using crospovidone (2-6%) as a superdisintegrant, microcrystalline cellulose (MCC) (20-40%) was used as diluents along with directly compressible mannitol to enhance mouth feel. A 3(2) full factorial design was applied to investigate the combined effect of two formulation variables: amount of crospovidone and MCC over the independent variables disintegration time, wetting time and percent drug release. Disintegration time showed by all formulations was found to be in the range of 24.3-193 s based on evaluation parameters the formulation containing 6% of crospovidone and 30% of MCC showed promising performance against all other formulations. The results demonstrated that the RSM could efficiently be applied for the formulation of clobazam oro-dispersible tablets; therefore, constitute an advance in the management of epileptic attacks.

  16. Formulation and optimization of fast dissolving intraoral drug delivery system for clobazam using response surface methodology

    Directory of Open Access Journals (Sweden)

    Rajni Bala

    2013-01-01

    Full Text Available Clobazam is a newer 1,5-benzodiazepine used for the treatment of epilepsy. It is better tolerated and less sedating than other benzodiazepines. Absorption of the drug can be impacted by oral fast dissolving dosage form; this may have implications for epilepsy in pediatrics and those having difficulty in swallowing tablets/capsules resulting in improved patient compliance. The purpose of the present investigation was to formulate and optimize clobazam oro-dissolving tablets by direct compression method using response surface methodology (RSM. Oro-dispersible tablets of clobazam were prepared by direct compression method using crospovidone (2-6% as a superdisintegrant, microcrystalline cellulose (MCC (20-40% was used as diluents along with directly compressible mannitol to enhance mouth feel. A 3 2 full factorial design was applied to investigate the combined effect of two formulation variables: amount of crospovidone and MCC over the independent variables disintegration time, wetting time and percent drug release. Disintegration time showed by all formulations was found to be in the range of 24.3-193 s based on evaluation parameters the formulation containing 6% of crospovidone and 30% of MCC showed promising performance against all other formulations. The results demonstrated that the RSM could efficiently be applied for the formulation of clobazam oro-dispersible tablets; therefore, constitute an advance in the management of epileptic attacks.

  17. Purging dissolved oxygen by nitrogen bubble aeration

    Science.gov (United States)

    Yamashita, Tatsuya; Ando, Keita

    2016-11-01

    We apply aeration with nitrogen microbubbles to water in order to see whether oxygen gas originally dissolved in the water at one atmosphere is purged by the aeration. The concentration of dissolved oxygen (DO) is detected by a commercial DO meter. To detect the dissolved nitrogen (DN) level, we observe the growth of millimetre-sized bubbles nucleated at glass surfaces in contact with the aerated water and compare it with the Epstein-Plesset theory that accounts for DO/DN diffusions and the presence of the glass surfaces. Comparisons between the experiment and the theory suggest that the DO in the water are effectively purged by the aeration.

  18. Using water chemistry time series to model dissolved inorganic carbon dynamics in the western Amazon basin

    Science.gov (United States)

    Vihermaa, Leena; Waldron, Susan; Newton, Jason

    2013-04-01

    Two small streams (New Colpita and Main Trail) and two rivers (Tambopata and La Torre), in the Tambopata National Reserve, Madre de Dios, Peru, were sampled for water chemistry (conductivity, pH and dissolved oxygen) and hydrology (stage height and flow velocity). In the small streams water chemistry and hydrology variables were logged at 15 minute intervals from Feb 2011 to November 2012. Water samples were collected from all four channels during field campaigns spanning different seasons and targeting the hydrological extremes. All the samples were analysed for dissolved inorganic carbon (DIC) concentration and δ13C (sample size ranging from 77 to 172 depending on the drainage system) and a smaller subset for dissolved organic carbon (DOC) and particulate organic carbon (POC) concentrations. Strong positive relationships were found between conductivity and both DIC concentration and δ13C in the New Colpita stream and the La Torre river. In Tambopata river the trends were less clear and in the Main Trail stream there was very little change in DIC and isotopic composition. The conductivity data was used to model continuous DIC time series for the New Colpita stream. The modelled DIC data agreed well with the measurements; the concordance correlation coefficients between predicted and measured data were 0.91 and 0.87 for mM-DIC and δ13C-DIC, respectively. The predictions of δ13C-DIC were improved when calendar month was included in the model, which indicates seasonal differences in the δ13C-DIC conductivity relationship. At present, continuous DIC sampling still requires expensive instrumentation. Therefore, modelling DIC from a proxy variable which can be monitored continuously with ease and at relatively low cost, such as conductivity, provides a powerful alternative method of DIC determination.

  19. Dissolved organic phosphorus speciation in the waters of the Tamar estuary (SW England)

    Science.gov (United States)

    Monbet, Phil; McKelvie, Ian D.; Worsfold, Paul J.

    2009-02-01

    The speciation of dissolved organic phosphorus (DOP) in the temperate Tamar estuary of SW England is described. Eight stations from the riverine to marine end-members were sampled during four seasonal campaigns in 2007 and the DOP pool in the water column and sediment porewater was characterized and quantified using a flow injection manifold after sequential enzymatic hydrolysis. This enabled the enzymatically hydrolysable phosphorus (EHP) fraction and its component labile monoester phosphates, diester phosphates and a phytase-hydrolysable fraction that includes myo-inositol hexakisphosphate (phytic acid), to be determined and compared with the total DOP, dissolved reactive phosphorus (DRP) and total dissolved phosphorus (TDP) pools. The results showed that the DOP pool in the water column varied temporally and spatially within the estuary (1.1-22 μg L -1) and constituted 6-40% of TDP. The EHP fraction of DOP ranged from 1.1-15 μg L -1 and represented a significant and potentially bioavailable phosphorus fraction. Furthermore the spatial profiles of the three components of the EHP pool generally showed non-conservative behavior along the salinity gradient, with apparent internal estuarine sources. Porewater profiles followed broadly similar trends but were notably higher at the marine station throughout the year. In contrast to soil organic phosphorus profiles, the labile monoester phosphate fraction was the largest component, with diester phosphates also prevalent. Phytic acid concentrations were higher in the lower estuary, possibly due to salinity induced desorption processes. The EHP fraction is not commonly determined in aquatic systems due to the lack of a suitable measurement technique and the Tamar results reported here have important implications for phosphorus biogeochemistry, estuarine ecology and the development of efficient strategies for limiting the effects of phosphorus on water quality.

  20. THE STRENGTH OF THE DISSOLVED OXYGEN MAXIMUM IN THE VERTICAL DISTRIBUTION OF N ANSHA ISLANDS WATERS

    Institute of Scientific and Technical Information of China (English)

    林洪瑛; 程赛伟; 韩舞鹰

    2002-01-01

    Observation data from a cruise in the Nansha Islands, in May to June 1990, Decem ber, 1993, September to October 1994, and July, 1999, respectively, were used to develop the method presented here to indicate the existing strength of the diss ol ved oxygen maximum in the vertical distribution of Nansha Islands waters. Its se asonal variation and regional distribution are discussed in this paper. Analysis results showed that the distribution of the strength of dissolved oxygen maximum (Domax-Dosur) was closely related to the upper layer circulation and the bioactivity of Nansha Islands seawater.

  1. Diel Production and Microheterotrophic Utilization of Dissolved Free Amino Acids in Waters Off Southern California

    OpenAIRE

    Carlucci, A. F.; Craven, D. B.; Henrichs, S. M.

    1984-01-01

    Diel patterns of dissolved free amino acid (DFAA) concentration and microheterotrophic utilization were examined in the spring and fall of 1981 in euphotic waters from the base of the mixed layer off the southern California coast. The average depths of the isotherms sampled were 19.2 m for spring and 9.0 m for fall. Total DFAA levels were generally higher in the spring than in the fall, 18 to 66 nM and 14 to 20 nM, respectively. Two daily concentration maxima and minima were observed for tota...

  2. Early diagenetic production and sediment-water exchange of fluorescent dissolved organic matter in the coastal environment

    Science.gov (United States)

    Skoog, Annelie; Hall, Per O. J.; Hulth, Stefan; Paxéus, Nicklas; Van Der Loeff, Michiel Rutgers; Westerlund, Stig

    1996-10-01

    Fluorescence at wavelengths characteristic of humic substances (excitation 350 nm, emission 450 nm) have been used in this study to approximate concentrations of fluorescent dissolved organic material (FDOM). In situ regulated and unregulated benthic chambers, sediment cores, and laboratory tank incubations were used to study early diagenesis of FDOM in coastal marine sediments of the Gullmar Fjord, western Sweden. In the regulated in situ chambers, pH and oxygen were kept at relatively stable levels, while in the unregulated in situ chambers, pH and oxygen were left to decrease as a result of biological activity. FDOM porewater distributions and correlation between FDOM and parameters indicating mineralization showed that FDOM was formed in the sediment and should flux across the sediment-water interface. A substantial flux of FDOM was also observed during winter and spring conditions and during anoxic conditions fall. However, no flux was observed during oxic conditions fall. Modeling indicated that oxygen penetration depth was deeper during winter than during fall, i.e., the oxygen penetration depth increased during fall towards winter values. We suggest that as FeOOH was formed when oxygen penetration depths increased, FROM was sorbed to newly formed FeOOH, inhibiting FDOM flux over the sediment-water interface. In addition, at onset of anoxic conditions in the sediment surface layer in fall incubations, FDOM flux from sediment to overlying water increased substantially. Increases in anoxic FDOM fluxes were accompanied by increases in Fe and phosphate fluxes. We suggest that reductively dissolved FeOOH released sorbed FDOM. FDOM released from FeOOH by anoxic conditions was not resorbed when oxic conditions were resumed. This could be an effect of higher pH in overlying water as compared with porewater, inhibiting FeOOH sorption of FDOM.

  3. Titanium distribution in swimming pool water is dominated by dissolved species.

    Science.gov (United States)

    David Holbrook, R; Motabar, Donna; Quiñones, Oscar; Stanford, Benjamin; Vanderford, Brett; Moss, Donna

    2013-10-01

    The increased use of titanium dioxide nanoparticles (nano-TiO2) in consumer products such as sunscreen has raised concerns about their possible risk to human and environmental health. In this work, we report the occurrence, size fractionation and behavior of titanium (Ti) in a children's swimming pool. Size-fractionated samples were analyzed for Ti using ICP-MS. Total titanium concentrations ([Ti]) in the pool water ranged between 21 μg/L and 60 μg/L and increased throughout the 101-day sampling period while [Ti] in tap water remained relatively constant. The majority of [Ti] was found in the dissolved phase (pool water is minimal. Published by Elsevier Ltd.

  4. Attractive forces between hydrophobic solid surfaces measured by AFM on the first approach in salt solutions and in the presence of dissolved gases.

    Science.gov (United States)

    Azadi, Mehdi; Nguyen, Anh V; Yakubov, Gleb E

    2015-02-17

    Interfacial gas enrichment of dissolved gases (IGE) has been shown to cover hydrophobic solid surfaces in water. The atomic force microscopy (AFM) data has recently been supported by molecular dynamics simulation. It was demonstrated that IGE is responsible for the unexpected stability and large contact angle of gaseous nanobubbles at the hydrophobic solid-water interface. Here we provide further evidence of the significant effect of IGE on an attractive force between hydrophobic solid surfaces in water. The force in the presence of dissolved gas, i.e., in aerated and nonaerated NaCl solutions (up to 4 M), was measured by the AFM colloidal probe technique. The effect of nanobubble bridging on the attractive force was minimized or eliminated by measuring forces on the first approach of the AFM probe toward the flat hydrophobic surface and by using high salt concentrations to reduce gas solubility. Our results confirm the presence of three types of forces, two of which are long-range attractive forces of capillary bridging origin as caused by either surface nanobubbles or gap-induced cavitation. The third type is a short-range attractive force observed in the absence of interfacial nanobubbles that is attributed to the IGE in the form of a dense gas layer (DGL) at hydrophobic surfaces. Such a force was found to increase with increasing gas saturation and to decrease with decreasing gas solubility.

  5. Electrochemically reduced water exerts superior reactive oxygen species scavenging activity in HT1080 cells than the equivalent level of hydrogen-dissolved water

    Science.gov (United States)

    Hamasaki, Takeki; Harada, Gakuro; Nakamichi, Noboru; Kabayama, Shigeru; Teruya, Kiichiro; Fugetsu, Bunshi; Gong, Wei; Sakata, Ichiro; Shirahata, Sanetaka

    2017-01-01

    Electrochemically reduced water (ERW) is produced near a cathode during electrolysis and exhibits an alkaline pH, contains richly dissolved hydrogen, and contains a small amount of platinum nanoparticles. ERW has reactive oxygen species (ROS)-scavenging activity and recent studies demonstrated that hydrogen-dissolved water exhibits ROS-scavenging activity. Thus, the antioxidative capacity of ERW is postulated to be dependent on the presence of hydrogen levels; however, there is no report verifying the role of dissolved hydrogen in ERW. In this report, we clarify whether the responsive factor for antioxidative activity in ERW is dissolved hydrogen. The intracellular ROS scavenging activity of ERW and hydrogen-dissolved water was tested by both fluorescent stain method and immuno spin trapping assay. We confirm that ERW possessed electrolysis intensity-dependent intracellular ROS-scavenging activity, and ERW exerts significantly superior ROS-scavenging activity in HT1080 cells than the equivalent level of hydrogen-dissolved water. ERW retained its ROS-scavenging activity after removal of dissolved hydrogen, but lost its activity when autoclaved. An oxygen radical absorbance capacity assay, the 2,2-diphenyl-1-picrylhydrazyl assay and chemiluminescence assay could not detect radical-scavenging activity in both ERW and hydrogen-dissolved water. These results indicate that ERW contains electrolysis-dependent hydrogen and an additional antioxidative factor predicted to be platinum nanoparticles. PMID:28182635

  6. Electrochemically reduced water exerts superior reactive oxygen species scavenging activity in HT1080 cells than the equivalent level of hydrogen-dissolved water.

    Science.gov (United States)

    Hamasaki, Takeki; Harada, Gakuro; Nakamichi, Noboru; Kabayama, Shigeru; Teruya, Kiichiro; Fugetsu, Bunshi; Gong, Wei; Sakata, Ichiro; Shirahata, Sanetaka

    2017-01-01

    Electrochemically reduced water (ERW) is produced near a cathode during electrolysis and exhibits an alkaline pH, contains richly dissolved hydrogen, and contains a small amount of platinum nanoparticles. ERW has reactive oxygen species (ROS)-scavenging activity and recent studies demonstrated that hydrogen-dissolved water exhibits ROS-scavenging activity. Thus, the antioxidative capacity of ERW is postulated to be dependent on the presence of hydrogen levels; however, there is no report verifying the role of dissolved hydrogen in ERW. In this report, we clarify whether the responsive factor for antioxidative activity in ERW is dissolved hydrogen. The intracellular ROS scavenging activity of ERW and hydrogen-dissolved water was tested by both fluorescent stain method and immuno spin trapping assay. We confirm that ERW possessed electrolysis intensity-dependent intracellular ROS-scavenging activity, and ERW exerts significantly superior ROS-scavenging activity in HT1080 cells than the equivalent level of hydrogen-dissolved water. ERW retained its ROS-scavenging activity after removal of dissolved hydrogen, but lost its activity when autoclaved. An oxygen radical absorbance capacity assay, the 2,2-diphenyl-1-picrylhydrazyl assay and chemiluminescence assay could not detect radical-scavenging activity in both ERW and hydrogen-dissolved water. These results indicate that ERW contains electrolysis-dependent hydrogen and an additional antioxidative factor predicted to be platinum nanoparticles.

  7. Nutrient and dissolved organic carbon removal from natural waters using industrial by-products.

    Science.gov (United States)

    Wendling, Laura A; Douglas, Grant B; Coleman, Shandel; Yuan, Zheng

    2013-01-01

    Attenuation of excess nutrients in wastewater and stormwater is required to safeguard aquatic ecosystems. The use of low-cost, mineral-based industrial by-products with high Ca, Mg, Fe or Al content as a solid phase in constructed wetlands potentially offers a cost-effective wastewater treatment option in areas without centralised water treatment facilities. Our objective was to investigate use of water treatment residuals (WTRs), coal fly ash (CFA), and granular activated carbon (GAC) from biomass combustion in in-situ water treatment schemes to manage dissolved organic carbon (DOC) and nutrients. Both CaO- and CaCO(3)-based WTRs effectively attenuated inorganic N species but exhibited little capacity for organic N removal. The CaO-based WTR demonstrated effective attenuation of DOC and P in column trials, and a high capacity for P sorption in batch experiments. Granular activated carbon proved effective for DOC and dissolved organic nitrogen (DON) removal in column trials, but was ineffective for P attenuation. Only CFA demonstrated effective removal of a broad suite of inorganic and organic nutrients and DOC; however, Se concentrations in column effluents exceeded Australian and New Zealand water quality guideline values. Water treated by filtering through the CaO-based WTR exhibited nutrient ratios characteristic of potential P-limitation with no potential N- or Si-limitation respective to growth of aquatic biota, indicating that treatment of nutrient-rich water using the CaO-based WTR may result in conditions less favourable for cyanobacterial growth and more favourable for growth of diatoms. Results show that selected industrial by-products may mitigate eutrophication through targeted use in nutrient intervention schemes.

  8. Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer

    Directory of Open Access Journals (Sweden)

    I. Grefe

    2013-07-01

    Full Text Available A laser-based analyser for nitrous oxide, carbon monoxide and water vapour was coupled to an equilibrator for continuous high-resolution dissolved gas measurements in the surface ocean. Results for nitrous oxide measurements from laboratory tests and field deployments are presented here. Short-term precision for 10 s-average N2O mole fractions at an acquisition rate of 1 Hz was better than 0.2 nmol mol−1 for standard gases and equilibrator measurements. The same precision was achieved for replicate standard gas analyses within 1 h of each other. The accuracy of the equilibrator measurements was verified by comparison with purge-and-trap GC-MS measurements of N2O concentrations in discrete samples from the Southern Ocean and showed agreement to within the 2% measurement uncertainty of the GC-MS method. Measured atmospheric N2O mole fractions agreed with AGAGE values to within 0.4%. The equilibrator response time to concentration changes in water was 142 to 203 s, depending on the headspace flow rate. The system was tested at sea during a north-to-south transect of the Atlantic Ocean. While the subtropical gyres were slightly undersaturated, the equatorial region was a source of nitrous oxide to the atmosphere. The ability to measure at high temporal and spatial resolution revealed sub-mesoscale variability in dissolved N2O concentrations. The magnitude of the observed saturation is in agreement with published data. Mean sea-to-air fluxes in the tropical and subtropical Atlantic ranged between −1.6 and 0.11 μmol m−2d−1 and confirm that the subtropical Atlantic is not an important source region for N2O to the atmosphere, compared to average global fluxes of 0.6 to 2.4 μmol m−2d−1. The system can be easily modified for autonomous operation on voluntary observing ships (VOS. Further work should include an interlaboratory comparison exercise with other methods of dissolved N2O analyses.

  9. 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.

  10. Role of dissolved gas in optical breakdown of water: differences between effects due to helium and other gases.

    Science.gov (United States)

    Bunkin, N F; Ninham, B W; Babenko, V A; Suyazov, N V; Sychev, A A

    2010-06-17

    It is shown that water contains defects in the form of heterogeneous optical breakdown centers. Long-living complexes composed of gas and liquid molecules may serve as nuclei for such centers. A new technique for removing dissolved gas from water is developed. It is based on a "helium washing" routine. The structure of helium-washed water is very different from that of water containing dissolved atmospheric gas. It is able to withstand higher optical intensities and temperatures of superheating compared with the nonprocessed ones. The characteristics of plasma spark and values of the breakdown thresholds for processed and nonprocessed samples are given.

  11. A study on the photocatalytic decomposition reactions of organics dissolved in water (II)

    Energy Technology Data Exchange (ETDEWEB)

    Sung, K. W.; Na, J. W.; Cho, Y. H.; Chung, H. H

    2001-01-01

    Experiments on aqueous TiO{sup 2} photocatalytic reaction characteristics of 4 nitrogen-containing and 12 aromatic organic compounds were carried out. Based on the values calculated for the distribution of ionic species and atomic charge, the characteristics of their photocatalytic decomposition were estimated. It was shown that the dependence of decomposition of the N-containing compounds were linearly proportional to their nitrogen atomic charge values, while that of the aromatic compounds were inversely proportional. The effects of aqueous pH, oxygen content and concentration on the TiO{sup 2} photocatalytic characteristics of EDTA-Cu(II) and EDTA-Fe(III) were experimentally investigated. All EDTA systems were decomposed better in the pH range of 2.5{approx}3.0 and with more dissolved oxygen. These results could be applied to a unit process for removal of organic impurities dissolved in a source water of the system water, and for treatment of EDTA-containing liquid waste produced by chemical cleaning process in the domestic NPPs.

  12. Photo-production of dissolved inorganic carbon from dissolved organic matter in contrasting coastal waters in the southwestern Taiwan Strait, China

    Institute of Scientific and Technical Information of China (English)

    Weidong Guo; Liyang Yang; Xiangxiang Yu; Weidong Zhai; Huasheng Hong

    2012-01-01

    Photo-production of dissolved inorganic carbon (DIC) from chromophoric dissolved organic matter (CDOM) is an important transformation process in marine carbon cycle,but little is known about this process in Chinese coastal systems.This study investigated an estuarine water sample and a coastal seawater sample from the subtropical waters in southeast of China.Water samples were exposed to natural sunlight and the absorption and fluorescence of CDOM as well as the DIC concentration were measured in the summer of 2009.The estuarine water had higher CDOM level,molecular weight and proportion of humic-like fluorescent components than the seawater that exhibited abundant tryptophan-like fluorescent component.After a 3-day irradiation,the CDOM level decreased by 45% in the estuarine water and 20% in the seawater,accompanied with a decrease in the molecular weight and aromaticity of DOM which was inferred from an incrcase in the absorption spectral slope parameter.The photo-degradation rates of all the five fluorescent components were also notable,in particular two humic-like components (C4 and C5) were removed by 78% and 69% in the estuarine water and by 69% and 56% in the seawater.The estuarine water had a higher photo-production rate of DIC than the seawater (4.4vs.2.5 tmol/(L.day)),in part due to its higher CDOM abundance.The differences in CDOM compositions between the two types of waters might be responsible for the higher susceptibility of the estuarine water to photo-degradation and hence could also affect the photo-production process of DIC.

  13. Photo-production of dissolved inorganic carbon from dissolved organic matter in contrasting coastal waters in the southwestern Taiwan Strait, China.

    Science.gov (United States)

    Guo, Weidong; Yang, Liyang; Yu, Xiangxiang; Zhai, Weidong; Hong, Huasheng

    2012-01-01

    Photo-production of dissolved inorganic carbon (DIC) from chromophoric dissolved organic matter (CDOM) is an important transformation process in marine carbon cycle, but little is known about this process in Chinese coastal systems. This study investigated an estuarine water sample and a coastal seawater sample from the subtropical waters in southeast of China. Water samples were exposed to natural sunlight and the absorption and fluorescence of CDOM as well as the DIC concentration were measured in the summer of 2009. The estuarine water had higher CDOM level, molecular weight and proportion of humic-like fluorescent components than the seawater that exhibited abundant tryptophan-like fluorescent component. After a 3-day irradiation, the CDOM level decreased by 45% in the estuarine water and 20% in the seawater, accompanied with a decrease in the molecular weight and aromaticity of DOM which was inferred from an increase in the absorption spectral slope parameter. The photo-degradation rates of all the five fluorescent components were also notable, in particular two humic-like components (C4 and C5) were removed by 78% and 69% in the estuarine water and by 69% and 56% in the seawater. The estuarine water had a higher photo-production rate of DIC than the seawater (4.4 vs. 2.5 micromol/(L x day)), in part due to its higher CDOM abundance. The differences in CDOM compositions between the two types of waters might be responsible for the higher susceptibility of the estuarine water to photo-degradation and hence could also affect the photo-production process of DIC.

  14. Measurement of 222Rn dissolved in water at the Sudbury Neutrino Observatory

    Science.gov (United States)

    Blevis, I.; Boger, J.; Bonvin, E.; Cleveland, B. T.; Dai, X.; Dalnoki-Veress, F.; Doucas, G.; Farine, J.; Fergani, H.; Grant, D.; Hahn, R. L.; Hamer, A. S.; Hargrove, C. K.; Heron, H.; Jagam, P.; Jelley, N. A.; Jillings, C.; Knox, A. B.; Lee, H. W.; Levine, I.; Liu, M.; Majerus, S.; McDonald, A.; McFarlane, K.; Mifflin, C.; Noble, A. J.; Noël, S.; Novikov, V. M.; Rowley, J. K.; Shatkay, M.; Simpson, J. J.; Sinclair, D.; Sur, B.; Wang, J.-X.; Yeh, M.; Zhu, X.

    2004-01-01

    The technique used at the Sudbury Neutrino Observatory (SNO) to measure the concentration of 222Rn in water is described. Water from the SNO detector is passed through a vacuum degasser (in the light water system) or a membrane contact degasser (in the heavy water system) where dissolved gases, including radon, are liberated. The degasser is connected to a vacuum system which collects the radon on a cold trap and removes most other gases, such as water vapor and N 2. After roughly 0.5 tonnes of H 2O or 6 tonnes of D 2O have been sampled, the accumulated radon is transferred to a Lucas cell. The cell is mounted on a photomultiplier tube which detects the α-particles from the decay of 222Rn and its progeny. The overall degassing and concentration efficiency is about 38% and the single-α counting efficiency is approximately 75%. The sensitivity of the radon assay system for D 2O is equivalent to ˜3×10 -15 g U/g water. The radon concentration in both the H 2O and D 2O is sufficiently low that the rate of background events from U-chain elements is a small fraction of the interaction rate of solar neutrinos by the neutral current reaction.

  15. (222)Rn, (220)Rn and other dissolved gases in mineral waters of southeast Brazil.

    Science.gov (United States)

    Bonotto, Daniel Marcos

    2014-06-01

    This paper describes the natural radioactivity due to (222)Rn and (220)Rn in mineral waters occurring at São Paulo and Minas Gerais states, Brazil, that are extensively used for drinking in public places, bottling and bathing purposes, among other. The measurements of these alpha-emitting radionuclides were also accompanied by the monitoring of temperature and some dissolved gases (O2, CO2 and H2S) in 75 water sources located in 14 municipalities of those states. Eight water sources yielded (220)Rn activity concentration values below the detection limit of 4 mBq/L. On other hand, (222)Rn activity concentration values exceeding the WHO guidance level of 100 Bq/L in drinking-water for public water supplies were found in two springs, named Villela and Dona Beja, whose discharge occurs in areas characterized by the presence of enhanced levels of natural radioelements in rocks. The obtained results were compared with the guidelines of the Brazilian Code of Mineral Waters (BCMW) that was established in 1945 and is still in force in the country. The (222)Rn and (220)Rn activity concentration data allowed perform dose radiation calculations based on the potential alpha energy concentration (PAEC), whose implications for health risk have been also considered in this paper. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Measurement of 222Rn dissolved in water at the Sudbury Neutrino Observatory

    CERN Document Server

    Blevis, I

    2004-01-01

    The technique used at the Sudbury Neutrino Observatory (SNO) to measure the concentration of 222Rn in water is described. Water from the SNO detector is passed through a vacuum degasser (in the light water system) or a membrane contact degasser (in the heavy water system) where dissolved gases, including radon, are liberated. The degasser is connected to a vacuum system which collects the radon on a cold trap and removes most other gases, such as water vapor and nitrogen. After roughly 0.5 tons of H2O or 6 tons of D2O have been sampled, the accumulated radon is transferred to a Lucas cell. The cell is mounted on a photomultiplier tube which detects the alpha particles from the decay of 222Rn and its daughters. The overall degassing and concentration efficiency is about 38% and the single-alpha counting efficiency is approximately 75%. The sensitivity of the radon assay system for D2O is equivalent to ~3 E(-15) g U/g water. The radon concentration in both the H2O and D2O is sufficiently low that the rate of ba...

  17. Removal of dissolved oxygen from water using a Pd-resin based catalytic reactor

    Institute of Scientific and Technical Information of China (English)

    Wenxin SHI; Chongwei CUI; Liye ZHAO; Shuili YU; Xia YUN

    2009-01-01

    The removal of dissolved oxygen (DO) from water was studied experimentally in a Pd-resin base catalyst reactor using purified hydrogen gas as a reducing agent. The effects of various operating conditions, such as hydrogen and water flow rates, height of the catalytic resin bed, temperature, pH value and nan time, on the removal of DO, had been studied extensively. The results shows that DO could be removed by the reactor from ppm to ppb levels at ambient temperature. Increases of temperature, H2gas rate and the height of the catalytic resin were helpful to improve the DO removal rate. The change of pH value fom 4 to 12 resulted in no effect on DO removal. Reaction time was the key factor to control the DO removal efficiency. Only when the reaction time was longer than 2.3 minutes under the experimental conditions, could a very low DO level be achieved.

  18. Hydrogeochemical processes controlling water and dissolved gas chemistry at the Accesa sinkhole (southern Tuscany, central Italy

    Directory of Open Access Journals (Sweden)

    Franco Tassi

    2014-05-01

    Full Text Available The 38.5 m deep Lake Accesa is a sinkhole located in southern Tuscany (Italy that shows a peculiar water composition, being characterized by relatively high total dissolved solids (TDS values (2 g L-1 and a Ca(Mg-SO4 geochemical facies. The presence of significant amounts of extra-atmospheric gases (CO2 and CH4, which increase their concentrations with depth, is also recognized. These chemical features, mimicking those commonly shown by volcanic lakes fed by hydrothermal-magmatic reservoirs, are consistent with those of mineral springs emerging in the study area whose chemistry is produced by the interaction of meteoric-derived waters with Mesozoic carbonates and Triassic evaporites. Although the lake has a pronounced thermocline, water chemistry does not show significant changes along the vertical profile. Lake water balance calculations demonstrate that Lake Accesa has >90% of its water supply from sublacustrine springs whose subterranean pathways are controlled by the local structural assessment that likely determined the sinking event, the resulting funnel-shape being then filled by the Accesa waters. Such a huge water inflow from the lake bottom (~9·106 m3 yr-1 feeds the lake effluent (Bruna River and promotes the formation of water currents, which are able to prevent the establishment of a vertical density gradient. Consequently, a continuous mixing along the whole vertical water column is established. Changes of the drainage system by the deep-originated waters in the nearby former mining district have strongly affected the outflow rates of the local mineral springs; thus, future intervention associated with the ongoing remediation activities should carefully be evaluated to preserve the peculiar chemical features of Lake Accesa.

  19. Predicting Impact of Climate Change on Water Temperature and Dissolved Oxygen in Tropical Rivers

    Directory of Open Access Journals (Sweden)

    Al-Amin Danladi Bello

    2017-07-01

    Full Text Available Predicting the impact of climate change and human activities on river systems is imperative for effective management of aquatic ecosystems. Unique information can be derived that is critical to the survival of aquatic species under dynamic environmental conditions. Therefore, the response of a tropical river system under climate and land-use changes from the aspects of water temperature and dissolved oxygen concentration were evaluated. Nine designed projected climate change scenarios and three future land-use scenarios were integrated into the Hydrological Simulation Program FORTRAN (HSPF model to determine the impact of climate change and land-use on water temperature and dissolved oxygen (DO concentration using basin-wide simulation of river system in Malaysia. The model performance coefficients showed a good correlation between simulated and observed streamflow, water temperature, and DO concentration in a monthly time step simulation. The Nash–Sutcliffe Efficiency for streamflow was 0.88 for the calibration period and 0.82 for validation period. For water temperature and DO concentration, data from three stations were calibrated and the Nash–Sutcliffe Efficiency for both water temperature and DO ranged from 0.53 to 0.70. The output of the calibrated model under climate change scenarios show that increased rainfall and air temperature do not affects DO concentration and water temperature as much as the condition of a decrease in rainfall and increase in air temperature. The regression model on changes in streamflow, DO concentration, and water temperature under the climate change scenarios illustrates that scenarios that produce high to moderate streamflow, produce small predicted change in water temperatures and DO concentrations compared with the scenarios that produced a low streamflow. It was observed that climate change slightly affects the relationship between water temperatures and DO concentrations in the tropical rivers that we

  20. Dissolved organic compounds in reused process water for steam-assisted gravity drainage oil sands extraction.

    Science.gov (United States)

    Kawaguchi, Hideo; Li, Zhengguo; Masuda, Yoshihiro; Sato, Kozo; Nakagawa, Hiroyuki

    2012-11-01

    The in situ oil sands production method called steam-assisted gravity drainage (SAGD) reuses process wastewater following treatment. However, the treatment and reuse processes concentrate contaminants in the process water. To determine the concentration and dynamics of inorganic and organic contaminants, makeup water and process water from six process steps were sampled at a facility employing the SAGD process in Alberta, Canada. In the groundwater used for the makeup water, the total dissolved organic carbon (DOC) content was 4 mg/L. This significantly increased to 508 mg/L in the produced water, followed by a gradual increase with successive steps in subsequent water treatments. The concentrations and dynamics of DOC constituents in the process water determined by gas chromatography-mass spectrometry showed that in the produced water, volatile organic compounds (VOCs) such as acetone (33.1 mg/L) and 2-butanone (13.4 mg/L) predominated, and there were significant amounts of phenolic compounds (total 9.8 mg/L) and organic acids including naphthenic acids (NAs) corresponding to the formula C(n)H(2n+Z)O(X) for combinations of n = 4 to 18, Z = 0 and -2, and X = 2 to 4 (53 mg/L) with trace amounts of polycyclic aromatic hydrocarbons (PAHs) such as naphthalene and phenanthrene. No organic contaminants, except for saturated fatty acids, were detected in the groundwater. The concentration of DOC in the recycled water was 4.4-fold higher than that in the produced water. Likewise, the total concentrations of phenols and organic acids in the recycled water were 1.7- and 4.5-fold higher than in the produced water, whereas the total concentrations of VOCs and PAHs in the recycled water were reduced by over 80%, suggesting that phenols and organic acids are selectively concentrated in the process water treatment. This comprehensive chemical analysis thus identified organic constituents that were concentrated in the process water and which interfere with subsequent

  1. Measurement of dissolved Cs-137 in stream water, soil water and groundwater at Headwater Forested Catchment in Fukushima after Fukushima Dai-ichi Nuclear Power Plant Accident

    Science.gov (United States)

    Iwagami, Sho; Tsujimura, Maki; Onda, Yuichi; Sakakibara, Koichi; Konuma, Ryohei; Sato, Yutaro

    2016-04-01

    Radiocesium migration from headwater forested catchment is important perception as output from the forest which is also input to the subsequent various land use and downstream rivers after Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. In this study, dissolved Cs-137 concentration of stream water, soil water and groundwater were measured. Observations were conducted at headwater catchment in Yamakiya district, located 35 km northwest of FDNPP from April 2014 to November 2015. Stream water discharge was monitored and stream water samples were taken at main channel and sub channel. Stream water discharge was monitored by combination of parshallflume and v-notch weir. Stream water was sampled manually at steady state condition in 3-4 month interval and also intense few hours interval sampling were conducted during rainfall events using automated water sampler. Around the sub channel, it is found that there is a regularly saturated area at the bottom of the slope, temporary saturated area which saturate during the rainy season in summer and regularly dry area. 6 interval cameras were installed to monitor the changing situation of saturated area. Suction lysimeters were installed at three areas (regularly saturated area, temporary saturated area and dry area) for sampling soil water in depth of 0.1 m and 0.3 m. Boreholes were installed at three points along the sub channel. Three boreholes with depth of 3 m, 5 m and 10 m were installed at temporary saturated area, 20 m upstream of sub channel weir. Another three boreholes with depth of 3 m, 5 m and 10 m were installed at dry area, 40 m upstream of sub channel weir. And a borehole with depth of 20 m was installed at ridge of sub catchment, 52 m upstream of sub channel weir. Groundwater was sampled by electrically powered pump and groundwater level was monitored. Also suction-free lysimeter was installed at temporary saturated area for sampling the near surface subsurface water. Soil water samples were collected

  2. Hydrophobically-associating cationic polymers as micro-bubble surface modifiers in dissolved air flotation for cyanobacteria cell separation.

    Science.gov (United States)

    Yap, R K L; Whittaker, M; Diao, M; Stuetz, R M; Jefferson, B; Bulmus, V; Peirson, W L; Nguyen, A V; Henderson, R K

    2014-09-15

    Dissolved air flotation (DAF), an effective treatment method for clarifying algae/cyanobacteria-laden water, is highly dependent on coagulation-flocculation. Treatment of algae can be problematic due to unpredictable coagulant demand during blooms. To eliminate the need for coagulation-flocculation, the use of commercial polymers or surfactants to alter bubble charge in DAF has shown potential, termed the PosiDAF process. When using surfactants, poor removal was obtained but good bubble adherence was observed. Conversely, when using polymers, effective cell removal was obtained, attributed to polymer bridging, but polymers did not adhere well to the bubble surface, resulting in a cationic clarified effluent that was indicative of high polymer concentrations. In order to combine the attributes of both polymers (bridging ability) and surfactants (hydrophobicity), in this study, a commercially-available cationic polymer, poly(dimethylaminoethyl methacrylate) (polyDMAEMA), was functionalised with hydrophobic pendant groups of various carbon chain lengths to improve adherence of polymer to a bubble surface. Its performance in PosiDAF was contrasted against commercially-available poly(diallyl dimethyl ammonium chloride) (polyDADMAC). All synthesised polymers used for bubble surface modification were found to produce positively charged bubbles. When applying these cationic micro-bubbles in PosiDAF, in the absence of coagulation-flocculation, cell removals in excess of 90% were obtained, reaching a maximum of 99% cell removal and thus demonstrating process viability. Of the synthesised polymers, the polymer containing the largest hydrophobic functionality resulted in highly anionic treated effluent, suggesting stronger adherence of polymers to bubble surfaces and reduced residual polymer concentrations.

  3. Isotopic Tracers for Delineating Non-Point Source Pollutants in Surface Water

    Energy Technology Data Exchange (ETDEWEB)

    Davisson, M L

    2001-03-01

    This study tested whether isotope measurements of surface water and dissolved constituents in surface water could be used as tracers of non-point source pollution. Oxygen-18 was used as a water tracer, while carbon-14, carbon-13, and deuterium were tested as tracers of DOC. Carbon-14 and carbon-13 were also used as tracers of dissolved inorganic carbon, and chlorine-36 and uranium isotopes were tested as tracers of other dissolved salts. In addition, large databases of water quality measurements were assembled for the Missouri River at St. Louis and the Sacramento-San Joaquin Delta in California to enhance interpretive results of the isotope measurements. Much of the water quality data has been under-interpreted and provides a valuable resource to investigative research, for which this report exploits and integrates with the isotope measurements.

  4. Temporal and spatial variation of hardness and total dissolved solids concentration in drinking water resources of Ilam City using Geographic Information System

    Directory of Open Access Journals (Sweden)

    Zabihollah Yousefi

    2015-12-01

    Full Text Available Background: In recent times, the decreasing groundwater reserves due to over-consumption of water resources and the unprecedented reduction of precipitation, during the past 1 decades, have resulted in a change in the volume and quality of water with time. The aim of this study was to determine the spatial and temporal variations of hardness and total dissolved solids in drinking water resources of Ilam city, using the GIS system. Methods: This cross-sectional study was carried out on 20 sources of drinking water in Ilam and the results of 5 years archived by the Water and Sewage Co were analyzed using geographic information system (GIS software version 9.3, SPSS version 16 and one-way analysis of variance (ANOVA. The sampling and measurement were also performed in this study based on the Standard Method book. Results: The ordinary kriging method and spherical model are the best interpolation methods for hardness and total dissolved solid, due to the normal distribution of data. The highest values of parameters in most cases are related to the western parts based on maps. The one-way ANOVA test showed that the average amount of total hardness (P = 0.68 and total dissolved solids (P = 0.6 in different seasons of the year are the same. Conclusion: Overuse of groundwater due to illegal digging and permanent easy access to water, increased the salinity of water in the central sections of the studied area. Proper planning that allows the withdrawal of water from authorized underground aquifers or water supply from surface water or dams should be done to overcome this problem.

  5. A study on the photo catalytic decomposition reactions of organics dissolved in water (II)

    Energy Technology Data Exchange (ETDEWEB)

    Sung, K.W.; Na, J. W.; Cho, Y. H.; Chung, H. H

    2000-01-01

    Experiments on aqueous TiO{sub 2} photo catalytic reaction of nitrogen containing organic compounds such as ethylamine, phenylhydrazine, pyridine, urea and EDTA were carried out. Based on the values calculated for the distribution of ionic species and atomic charge, the characteristics of their photo catalytic decomposition were estimated. It was shown that the decomposition characteristics was linearly proportional to nitrogen atomic charge value. On the other hand, the effects of aqueous pH, oxygen content and concentration on the TiO{sub 2} photo catalytic characteristics of EDTA, EDTA-Cu(II) and EDTA-Fe(III) were experimentally investigated. All EDTA systems were decomposed better in the pH range of 2.5-3.0 and with more dissolved oxygen. These results could be applied to construction of a process for removal of organic impurities dissolved in a source of system water, or for treatment of EDTA-containing liquid waste produced by a chemical cleaning in the domestic NPPs. (author)

  6. FORMULATION AND EVALUATION OF FAST DISSOLVING TABLETS OF CYCLODEXTRIN INCLUSION COMPLEXED WATER INSOLUBLE DRUG: GLIMIPIRIDE

    Directory of Open Access Journals (Sweden)

    Shirse Prabhakar

    2012-06-01

    Full Text Available Glimepiride (GMP is a Third Generation Sulphonylureas used for treatment of type 2 diabetes. Poor water solubility is the main constraint for its oral bioavailability. The rationale of this study was to enhance the solubility and dissolution of the drug by preparing its complex with β-cyclodextrin and Hydroxypropyl Betacyclodextrin-β-cyclodextrin. In the present study attempt has been made to prepare, formulate and characterize inclusion complexes of Glimepiride with β-cyclodextrin and Hydroxypropyl Betacyclodextrin-β-cyclodextrin. The inclusion complexes were prepared by three different methods viz. Physical, Kneading and Co-precipitation method. The inclusion complex containing Glimepiride: β-cyclodextrin and Hydroxypropyl Betacyclodextrin-β-cyclodextrin was further formulated into Fast Dissolving Tablets (FDT by Direct Compression Technique using Super-disintegrants like Crosscarmelose Sodium, Crospovidone and Sodium Starch Glycolate were used. The prepared Complexes were characterized using FT-IR and Differential Scanning Calorimetry and finally the prepared Fast Dissolving Tablets were Evaluated for various pharmaceutical characteristics viz. Hardness, % Friability, Weight Variation, Wetting Time, Drug Content and In-vitro Dissolution profiles. The results of stability studies revealed no change in physical appearance, hardness, drug content and in-vitro dissolution profiles, thus indicating that formulation was stable.

  7. Comparison of Dissolved Air Flotation and Sedimentation in Treatment of Typical North China Source Water

    Institute of Scientific and Technical Information of China (English)

    刘善培; 王启山; 何文杰; 韩宏大; 樊雪红; 耿天甲

    2007-01-01

    The treatment of typical north China water by dissolved air flotation (DAF) and sedimentation process was examined. A pilot plant with a water treatment capacity of 120 m3/d constructed in the Jieyuan Water Treatment Plant (JWTP) of Tianjin, China, was utilized for the comparison of the two processes. The results show that during the pilot test, DAF process can remove particles and organic mater more efficiently than sedimentation process. The removal rate for turbidity by DAF process is 5.5% higher than that by sedimentation in normal turbidity period, and 40% higher in low turbidity period, it is 5%~10% higher for removals of algae, total organic carbon (TOC), trihalomethane formation potential (THMFP) and bacteria in all periods. The removal rates for turbidity, TOC, THMFP, algae and bacteria by DAF process can reach 95%, 30%, 20%, 94% and 97% respectively. From the results of the pilot test, it can be concluded that DAF is a feasible clarification process, especially for source water with low turbidity and high algal blooming.

  8. Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa

    Energy Technology Data Exchange (ETDEWEB)

    Borysow, Jacek, E-mail: jborysow@mtu.edu; Rosso, Leonardo del; Celli, Milva; Ulivi, Lorenzo, E-mail: lorenzo.ulivi@isc.cnr.it [Consiglio Nazionale delle Ricerche, Istituto dei Sistemi Complessi, Via Madonna del piano 10, I-50019 Sesto Fiorentino (Italy); Moraldi, Massimo [Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Via Sansone 1, I-50019 Sesto Fiorentino (Italy)

    2014-04-28

    We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines were narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Q-branch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule.

  9. Water mass age and aging driving chromophoric dissolved organic matter in the dark global ocean

    Science.gov (United States)

    Catalá, T. S.; Reche, I.; Álvarez, M.; Khatiwala, S.; Guallart, E. F.; Benítez-Barrios, V. M.; Fuentes-Lema, A.; Romera-Castillo, C.; Nieto-Cid, M.; Pelejero, C.; Fraile-Nuez, E.; Ortega-Retuerta, E.; Marrasé, C.; Álvarez-Salgado, X. A.

    2015-07-01

    The omnipresence of chromophoric dissolved organic matter (CDOM) in the open ocean enables its use as a tracer for biochemical processes throughout the global overturning circulation. We made an inventory of CDOM optical properties, ideal water age (τ), and apparent oxygen utilization (AOU) along the Atlantic, Indian, and Pacific Ocean waters sampled during the Malaspina 2010 expedition. A water mass analysis was applied to obtain intrinsic, hereinafter archetypal, values of τ, AOU, oxygen utilization rate (OUR), and CDOM absorption coefficients, spectral slopes and quantum yield for each one of the 22 water types intercepted during this circumnavigation. Archetypal values of AOU and OUR have been used to trace the differential influence of water mass aging and aging rates, respectively, on CDOM variables. Whereas the absorption coefficient at 325 nm (a325) and the fluorescence quantum yield at 340 nm (Φ340) increased, the spectral slope over the wavelength range 275-295 nm (S275-295) and the ratio of spectral slopes over the ranges 275-295 nm and 350-400 nm (SR) decreased significantly with water mass aging (AOU). Combination of the slope of the linear regression between archetypal AOU and a325 with the estimated global OUR allowed us to obtain a CDOM turnover time of 634 ± 120 years, which exceeds the flushing time of the dark ocean (>200 m) by 46%. This positive relationship supports the assumption of in situ production and accumulation of CDOM as a by-product of microbial metabolism as water masses turn older. Furthermore, our data evidence that global-scale CDOM quantity (a325) is more dependent on aging (AOU), whereas CDOM quality (S275-295, SR, Φ340) is more dependent on aging rate (OUR).

  10. Spectroscopic and thermodynamic properties of molecular hydrogen dissolved in water at pressures up to 200 MPa.

    Science.gov (United States)

    Borysow, Jacek; del Rosso, Leonardo; Celli, Milva; Moraldi, Massimo; Ulivi, Lorenzo

    2014-04-28

    We have measured the Raman Q-branch of hydrogen in a solution with water at a temperature of about 280 K and at pressures from 20 to 200 MPa. From a least-mean-square fitting analysis of the broad Raman Q-branch, we isolated the contributions from the four lowest individual roto-vibrational lines. The vibrational lines were narrower than the pure rotational Raman lines of hydrogen dissolved in water measured previously, but significantly larger than in the gas. The separations between these lines were found to be significantly smaller than in gaseous hydrogen and their widths were slightly increasing with pressure. The lines were narrowing with increasing rotational quantum number. The Raman frequencies of all roto-vibrational lines were approaching the values of gas phase hydrogen with increasing pressure. Additionally, from the comparison of the integrated intensity signal of Q-branch of hydrogen to the integrated Raman signal of the water bending mode, we have obtained the concentration of hydrogen in a solution with water along the 280 K isotherm. Hydrogen solubility increases slowly with pressure, and no deviation from a smooth behaviour was observed, even reaching thermodynamic conditions very close to the transition to the stable hydrogen hydrate. The analysis of the relative hydrogen concentration in solution on the basis of a simple thermodynamic model has allowed us to obtain the molar volume for the hydrogen gas/water solution. Interestingly, the volume relative to one hydrogen molecule in solution does not decrease with pressure and, at high pressure, is larger than the volume pertinent to one molecule of water. This is in favour of the theory of hydrophobic solvation, for which a larger and more stable structure of the water molecules is expected around a solute molecule.

  11. Modeling the simultaneous transport of silver nanoparticles and dissolved silver ions in water-saturated sand columns

    Science.gov (United States)

    Taghavy, A.; Wang, Y.; Mittelman, A.; Becker, M. D.; Pennell, K. D.; Abriola, L. M.

    2011-12-01

    Concerns over the potential adverse impacts of nanosilver particles (nAg) on human health and the environment have arisen based upon their widespread use in various commercial and biomedical products. In addition, in situ dissolution of deposited nAg could enhance its environmental impact through the formation of dissolved silver ion (Ag+) plumes. A hybrid mathematical model is presented that simulates the simultaneous reactive transport of nAg/Ag+ in porous media. The simulator couples a Lagrangian Random Walk-based Particle Tracking (RWPT) method for nAg transport with a conventional Eulerian Finite Differencing (FD) scheme for the reactive transport of dissolved solutes. In the absence of oxidants other than dissolved oxygen (DO), nAg is assumed to dissolve via a cooperative oxidation reaction with DO and proton ions (H+), and dissolution is modeled by a first-order kinetic expression. An existing empirical correlation is implemented for evaluation of the dissolution rate constant from physiochemical characteristics of the system and nanoparticles, including solution pH, particle specific surface area (SSA), and temperature. The hybrid modeling approach enables the consideration of different particle size classes and the associated particle-specific dissolution rates. The utility of simulator is demonstrated by modeling results obtained from nAg/ Ag+ transport studies performed in ca. 10.8-cm long borosilicate glass columns with an inside diameter of 2.5 cm. Three column experiments were performed at a constant flow rate, yielding a particle approach velocity of 7.68±0.04 m/day, at dissolved oxygen concentrations ranging from 1.65 mg/L to 8.99 mg/L. A 3 pore volume pulse of nAg suspension, containing 3.17±0.07 mg/L total Ag and 10mM NaNO3 at pH 7.07, was injected into water-saturated columns packed with washed 40-50 mesh Ottawa sand. Following nAg injection, the columns were flushed with nAg-free background solution for an additional 3 pore volumes, which

  12. Microanalysis of dissolved iron and phosphate in pore waters of hypersaline sediment

    Science.gov (United States)

    Haddad, R.; Shaw, T.

    1985-01-01

    Diurnal fluctuations of reduced iron concentrations, expected to occur in reduced sediments in the photic zone, were studied. Iron concentration was compared to O2-H2S, a microcanalysis of sulfate reduction was performed, as well as an examination of diurnal concentration of dissolved phosphate and changes in interstitial CO2. The iron profiles suggest a strong correlation between iron remobilization and processes occurring in the light. Phosphate profiles suggest the removal of phosphate is strongly correlated with precipitation of oxidized iron in the upper 2 mm to 5 mm of the sediments. Pore water CO2 concentrations and carbon isotope ratios are presented. These data are from the analyses of minisediment cores collected from the 42 per mil salt pond and incubated in the laboratory under light and dark conditions.

  13. An improved biofilter to control the dissolved organic nitrogen concentration during drinking water treatment.

    Science.gov (United States)

    Zhang, Huining; Gu, Li; Liu, Bing; Gan, Huihui; Zhang, Kefeng; Jin, Huixia; Yu, Xin

    2016-09-01

    Dissolved organic nitrogen (DON) is a key precursor of numerous disinfection by-products (DBPs), especially nitrogenous DBPs (N-DBPs) formed during disinfection in drinking water treatment. To effectively control DBPs, reduction of the DON concentration before the disinfection process is critical. Traditional biofilters can increase the DON concentration in the effluent, so an improved biofilter is needed. In this study, an improved biofilter was set up with two-layer columns using activated carbon and quartz sand under different influent patterns. Compared with the single-layer filter, the two-layer biofilter controlled the DON concentration more efficiently. The two-point influent biofilter controlled the DON concentration more effectively than the single-point influent biofilter. The improved biofilter resulted in an environment (including matrix, DO, and pH) suitable for microbial growth. Along the depth of the biofilter column, the environment affected the microbial biomass and microbial activity and thus affected the DON concentration.

  14. Controls on stream water dissolved mercury in three mid-Appalachian forested headwater catchments

    Science.gov (United States)

    Riscassi, Ami L.; Scanlon, Todd M.

    2011-12-01

    Determining the controls on dissolved mercury (HgD) transport is necessary to improve estimations of export from unmonitored watersheds and to forecast responses to changes in deposition and other environmental forcings. Stream water HgD and dissolved organic carbon (DOC) were evaluated over a range of discharge conditions in three streams within Shenandoah National Park, VA. Watersheds are distinguished by stream water pH (ranging from neutral to acidic) and soil size fractioning (ranging from clays to sands). At all sites, discharge was a significant but poor predictor of HgD concentrations (r2 from 0.13-0.52). HgD was strongly coupled with DOC at all sites (r2 from 0.74-0.89). UV absorbance at 254 nm (UV254), a proxy for DOC quantity and quality, slightly improved the predictions of HgD. Mean DOC quality differed between streams, with less aromatic DOC mobilized from the more acidic watershed. The site with less aromatic DOC and sandy soils mobilized more Hg to the stream for the same quantity and quality of DOC, likely due to the reduced capacity of the larger-grained soils to retain Hg, leaving a greater fraction associated with the organic matter. A similar amount of 0.54 ng HgD/mg DOC is transported at all sites, suggesting the less aromatic DOC transports less Hg per unit DOC, offsetting the effects of soil type. This research demonstrates that soil composition and DOC quality influence HgDexport. We also provide evidence that soil organic carbon is a primary control on Hg-DOC ratios (0.12-1.4 ng mg-1) observed across the U.S. and Sweden.

  15. Biologically labile photoproducts from riverine non-labile dissolved organic carbon in the coastal waters

    Directory of Open Access Journals (Sweden)

    V. Kasurinen

    2015-06-01

    Full Text Available In order to assess the production of biologically labile photoproducts (BLPs from non-labile riverine dissolved organic carbon (DOC, we collected water samples from ten major rivers, removed labile DOC and mixed the residual non-labile DOC with artificial seawater for microbial and photochemical experiments. Bacteria grew on non-labile DOC with a growth efficiency of 11.5% (mean; range from 3.6 to 15.3%. Simulated solar radiation transformed a part of non-labile DOC into BLPs, which stimulated bacterial respiration and production, but did not change bacterial growth efficiency (BGE compared to the non-irradiated dark controls. In the irradiated water samples, the amount of BLPs stimulating bacterial production depended on the photochemical bleaching of chromophoric dissolved organic matter (CDOM. The apparent quantum yields for BLPs supporting bacterial production ranged from 9.5 to 76 (mean 39 (μmol C mol photons−1 at 330 nm. The corresponding values for BLPs supporting bacterial respiration ranged from 57 to 1204 (mean 320 (μmol C mol photons−1. According to the calculations based on spectral apparent quantum yields and local solar radiation, the annual production of BLPs ranged from 21 (St. Lawrence to 584 (Yangtze mmol C m−2 yr−1 in the plumes of the examined rivers. Complete photobleaching of riverine CDOM in the coastal ocean was estimated to produce 10.7 Mt C BLPs yr−1 from the rivers examined in this study and globally 38 Mt yr−1 (15% of riverine DOC flux from all rivers, which support 4.1 Mt yr−1 of bacterial production and 33.9 Mt yr−1 bacterial respiration.

  16. Optical assessment of colored dissolved organic matter and its related parameters in dynamic coastal water systems

    Science.gov (United States)

    Shanmugam, Palanisamy; Varunan, Theenathayalan; Nagendra Jaiganesh, S. N.; Sahay, Arvind; Chauhan, Prakash

    2016-06-01

    Prediction of the curve of the absorption coefficient of colored dissolved organic matter (CDOM) and differentiation between marine and terrestrially derived CDOM pools in coastal environments are hampered by a high degree of variability in the composition and concentration of CDOM, uncertainties in retrieved remote sensing reflectance and the weak signal-to-noise ratio of space-borne instruments. In the present study, a hybrid model is presented along with empirical methods to remotely determine the amount and type of CDOM in coastal and inland water environments. A large set of in-situ data collected on several oceanographic cruises and field campaigns from different regional waters was used to develop empirical methods for studying the distribution and dynamics of CDOM, dissolved organic carbon (DOC) and salinity. Our validation analyses demonstrated that the hybrid model is a better descriptor of CDOM absorption spectra compared to the existing models. Additional spectral slope parameters included in the present model to differentiate between terrestrially derived and marine CDOM pools make a substantial improvement over those existing models. Empirical algorithms to derive CDOM, DOC and salinity from remote sensing reflectance data demonstrated success in retrieval of these products with significantly low mean relative percent differences from large in-situ measurements. The performance of these algorithms was further assessed using three hyperspectral HICO images acquired simultaneously with our field measurements in productive coastal and lagoon waters on the southeast part of India. The validation match-ups of CDOM and salinity showed good agreement between HICO retrievals and field observations. Further analyses of these data showed significant temporal changes in CDOM and phytoplankton absorption coefficients with a distinct phase shift between these two products. Healthy phytoplankton cells and macrophytes were recognized to directly contribute to the

  17. Chemical and Isotopic Composition of Waters and Dissolved Gases in Some Thermal Springs of Sicily and Adjacent Volcanic Islands, Italy

    Science.gov (United States)

    Grassa, Fausto; Capasso, Giorgio; Favara, Rocco; Inguaggiato, Salvatore

    2006-04-01

    Hydrochemical (major and some minor constituents), stable isotope ([InlineMediaObject not available: see fulltext.] and [InlineMediaObject not available: see fulltext.], δ13CTDIC total dissolved inorganic carbon) and dissolved gas composition have been determined on 33 thermal discharges located throughout Sicily (Italy) and its adjacent islands. On the basis of major ion contents, four main water types have been distinguished: (1) a Na-Cl type; (2) a Ca-Mg > Na-SO4-Cl type; (3) a Ca-Mg-HCO3 type and (4) a Na-HCO3 type water. Most waters are meteoric in origin or resulting from mixing between meteoric water and heavy-isotope end members. In some samples, δ 18O values reflect the effects of equilibrium processes between thermal waters and rocks (positive 18O-shift) or thermal waters and CO2 (negative 18O-shift). Dissolved gas composition indicates the occurrence of gas/water interaction processes in thermal aquifers. N2/O2 ratios higher than air-saturated water (ASW), suggest the presence of geochemical processes responsible for dissolved oxygen consumption. High CO2 contents (more than 3000 cc/litre STP) dissolved in the thermal waters indicate the presence of an external source of carbon dioxide-rich gas. TDIC content and δ 13C TDIC show very large ranges from 4.6 to 145.3 mmol/Kg and from 10.0‰ and 2.8‰, respectively. Calculated values indicate the significant contribution from a deep source of carbon dioxide inorganic in origin. Interaction with Mediterranean magmatic CO2 characterized by heavier carbon isotope ratios ([InlineMediaObject not available: see fulltext.] value from -3 to 0‰ vs V-PDB (CAPASSO et al., 1997, GIAMMANCO et al., 1998; INGUAGGIATO et al., 2000) with respect to MORB value and/or input of CO2-derived from thermal decomposition of marine carbonates have been inferred.

  18. Understanding Your Watershed Fact Sheet: Dissolved Oxygen

    OpenAIRE

    Mesner, Nancy; Geiger, John

    2010-01-01

    Dissolved oxygen describes oxygen molecules which have actually dissolved in water. Sometimes people confuse bubbles in water with dissolved oxygen, but in reality the dissolved form of oxygen cannot be seen.

  19. Precise calibration of equilibrium oxygen isotope fractionations between dissolved phosphate and water from 3 to 37 °C

    Science.gov (United States)

    Chang, Sae Jung; Blake, Ruth E.

    2015-02-01

    The stable oxygen isotope composition of orthophosphate (δ18OPO4) is a widely used (paleo)temperature indicator and more recently, a useful tracer of phosphorus-cycling. In natural aqueous systems (e.g., oceans, rivers, soil/ground water) the largest reactive phosphorus pool is dissolved inorganic phosphate. Here, we present a new experimentally-determined equation for thermodynamic equilibrium O-isotope fractionations between dissolved phosphate and water, catalyzed by the enzyme inorganic pyrophosphatase (PPase) between 3 and 37 °C;

  20. Water Temperature, Specific Conductance, pH, and Dissolved-Oxygen Concentrations in the Lower White River and the Puyallup River Estuary, Washington, August-October 2002

    Science.gov (United States)

    Ebbert, James C.

    2003-01-01

    lower limit allowed by the water-quality standard is 8 mg/L. Concentrations of dissolved oxygen measured in a cross section of the Puyallup River estuary at high tide on September 12, 2002, ranged from 9.9 to 10.2 mg/L in fresh water at the surface and from 8.1 to 8.4 mg/L in salt water near the riverbed. These values were within limits set by Washington State water-quality standards for dissolved oxygen of 8 mg/L in fresh water and 6 mg/L in marine water.

  1. Water temperature, specific conductance, pH, and dissolved-oxygen concentrations in the lower White River and the Puyallup River estuary, Washington, August-October 2002

    Science.gov (United States)

    Ebbert, James C.

    2003-01-01

    lower limit allowed by the water-quality standard is 8 mg/L. Concentrations of dissolved oxygen measured in a cross section of the Puyallup River estuary at high tide on September 12, 2002, ranged from 9.9 to 10.2 mg/L in fresh water at the surface and from 8.1 to 8.4 mg/L in salt water near the riverbed. These values were within limits set by Washington State water-quality standards for dissolved oxygen of 8 mg/L in fresh water and 6 mg/L in marine water.

  2. Variations in dissolved organic nitrogen concentration in biofilters with different media during drinking water treatment.

    Science.gov (United States)

    Zhang, Huining; Zhang, Kefeng; Jin, Huixia; Gu, Li; Yu, Xin

    2015-11-01

    Dissolved organic nitrogen (DON) is potential precursor of disinfection byproducts (DBPs), especially nitrogenous DBPs. In this study, we investigated the impact of biofilters on DON concentration changes in a drinking water plant. A small pilot plant was constructed next to a sedimentation tank in a drinking water plant and included activated carbon, quartz sand, anthracite, and ceramsite biofilters. As the biofilter layer depth increased, the DON concentration first decreased and then increased, and the variation in DON concentration differed among the biofilters. In the activated carbon biofilter, the DON concentration was reduced by the largest amount in the first part of the column and increased by the largest amount in the second part of the column. The biomass in the activated carbon filter was less than that in the quartz sand filter in the upper column. The heterotrophic bacterial proportion among bacterial flora in the activated carbon biofilter was the largest, which might be due to the significant reduction in DON in the first part of the column. Overall, the results indicate that the DON concentration in biofiltered water can be controlled via the selection of appropriate biofilter media. We propose that a two-layer biofilter with activated carbon in the upper layer and another media type in the lower layer could best reduce the DON concentration. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. 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.

  4. Spatial distribution of dissolved neodymium and ɛNd in the Bay of Bengal: Role of particulate matter and mixing of water masses

    Science.gov (United States)

    Singh, Satinder Pal; Singh, Sunil Kumar; Goswami, Vineet; Bhushan, Ravi; Rai, Vinai Kumar

    2012-10-01

    The concentration and isotope composition of dissolved Nd have been measured in the water column along an 87°E transect (GIO1 section of International GEOTRACES Program) in the Bay of Bengal (BoB) to investigate the effect of water mass mixing and Nd release from particulate matter in determining these properties. The concentration of Nd in surface waters of the BoB shows a North-South decreasing non-linear trend (˜46 to ˜22 pmol/kg) with salinity, whereas its depth profiles typically show a high value in surface waters, a minimum (˜15 to ˜23 pmol/kg) in the shallow subsurface (˜50-200 m), followed by a gradual increase with depth. The Nd concentration of BoB waters is generally higher than that in nearby oceanic basins. On the other hand, the ɛNd values in the BoB are less radiogenic compared to those reported for other regions of the global oceans (except Baffin Bay, the North Atlantic Subpolar Gyre and the Niger delta margin), and show a greater variation in the upper water column. Surface waters of the southernmost profile (˜6°N) show a more radiogenic ɛNd value ˜-8, which decreases to -15 in the northernmost profile (˜20°N), close to the values for dissolved and particulate phases of the Ganga-Brahmaputra (G-B) Rivers. This latitudinal trend is most likely a result of variations in mixing proportion between the more radiogenic Indonesian Throughflow surface waters (IW) and unradiogenic BoB low salinity water; the former's signature being more clearly discernible in surface waters of the two southernmost profiles (˜6°N and ˜8.5°N). Attempts to balance the Nd budget in the water column based on an inversion model, suggest that in addition to water masses other source(s) is required, the strength of which is estimated to vary from 1% to 65% of the measured Nd concentration. The calculations also show that the ɛNd of this additional source(s) has to be in the range of ˜-16 ± 2, typical of G-B river sediments. These observations, coupled with

  5. Determination of colloidal and dissolved silver in water samples using colorimetric solid-phase extraction.

    Science.gov (United States)

    Hill, April A; Lipert, Robert J; Porter, Marc D

    2010-03-15

    The increase in bacterial resistance to antibiotics has led to resurgence in the use of silver as a biocidal agent in applications ranging from washing machine additives to the drinking water treatment system on the International Space Station (ISS). However, growing concerns about the possible toxicity of colloidal silver to bacteria, aquatic organisms and humans have led to recently issued regulations by the US EPA and FDA regarding the usage of silver. As part of an ongoing project, we have developed a rapid, simple method for determining total silver, both ionic (silver(I)) and colloidal, in 0.1-1mg/L aqueous samples, which spans the ISS potable water target of 0.3-0.5mg/L (total silver) and meets the US EPA limit of 0.1mg/L in drinking water. The method is based on colorimetric solid-phase extraction (C-SPE) and involves the extraction of silver(I) from water samples by passage through a solid-phase membrane impregnated with the colorimetric reagent DMABR (5-[4-(dimethylamino)benzylidene]rhodanine). Silver(I) exhaustively reacts with impregnated DMABR to form a colored compound, which is quantified using a handheld diffuse reflectance spectrophotometer. Total silver is determined by first passing the sample through a cartridge containing Oxone, which exhaustively oxidizes colloidal silver to dissolved silver(I). The method, which takes less than 2 min to complete and requires only approximately 1 mL of sample, has been validated through a series of tests, including a comparison with the ICP-MS analysis of a water sample from ISS that contained both silver(I) and colloidal silver. Potential earth-bound applications are also briefly discussed.

  6. Transport and Transformation of Dissolved Organic Matter in Soil Interstitial Water Across Forested, Montane Hillslopes

    Science.gov (United States)

    Burns, M. A.; McKnight, D. M.; Gabor, R. S.; Brooks, P. D.; Barnard, H. R.

    2013-12-01

    Dissolved organic matter (DOM) is a ubiquitous mixture of compounds formed from the degradation of both terrestrial and microbial material. The abundance and composition of the DOM present in stream water is important to stream processes such as UV light attenuation, nutrient supply and metal sorption. However, an excess of DOM can cause reactions with chlorination compounds at drinking water treatment plants, creating potentially harmful disinfection byproducts. Currently, little is known regarding the influence of soil interstitial water on stream DOM composition. In this study, we explore the role of interstitial water on DOM transport and transformation from the hillslope to the stream in a montane catchment within the Boulder Creek Critical Zone Observatory in Colorado. We installed a suite of tension lysimeters located within the rooting zone across representative north- and south-facing slopes. Interstitial water and stream samples were collected daily for approximately seven weeks during the 2013 spring snow melt period and analyzed for DOM composition using fluorescence spectroscopy. To date, we have used fluorescence index (FI) to evaluate differences between microbial and terrestrial DOM inputs and humification index (HIX) to assess degree of humification undergone by the DOM. Preliminary results indicate that FI was significantly correlated with hillslope aspect (pwater inputs into the stream during snowmelt. These preliminary results suggest that changes in DOM composition through the catchment during snowmelt can be linked to hydrologic transport. Further site specific model development will reveal explicit changes in the DOM chemistry and will increase our understanding of fundamental nutrient cycling processes at the hillslope to catchment scale.

  7. Effects of different water storage procedures on the dissolved Fe concentration and isotopic composition of chemically contrasted waters from the Amazon River Basin.

    Science.gov (United States)

    Mulholland, Daniel S; Poitrasson, Franck; Boaventura, Geraldo R

    2015-11-15

    Although recent studies have investigated the Fe isotopic composition of dissolved, colloidal and particulate phases from continental and oceanic natural waters, few efforts have been made to evaluate whether water sample storage and the separation of different pore-size fractions through filtration can cause any change to the Fe isotopic compositions. The present study investigates the possible biases introduced by different water storage conditions on the dissolved Fe concentration and isotopic composition of chemically different waters. Water samples were collected from an organic-rich river and from mineral particulate-rich rivers. Filtered and unfiltered water samples were stored either at room temperature or frozen at -18°C in order to assess possible biases due to (i) different water storage temperature, and (ii) storage of bulk (unfiltered) vs filtered water. Iron isotope measurements were performed by Multicollector Inductively Coupled Plasma Mass Spectrometry with a Thermo Electron Neptune instrument, after Fe purification using anion-exchange resins. Our data reveal that bulk water storage at room temperature without filtration produces minor changes in the dissolved Fe isotopic composition of mineral particulate-rich waters, but significant isotopic composition changes in organic-rich waters. In both cases, however, the impact of the different procedures on the Fe concentrations was strong. On the other hand, the bulk water stored frozen without filtration produced more limited changes in the dissolved Fe concentrations, and also on isotopic compositions, relative to the samples filtered in the field. The largest effect was again observed for the organic-rich waters. These findings suggest that a time lag between water collection and filtration may cause isotopic exchanges between the dissolved and particulate Fe fractions. When it is not possible to filter the samples in the field immediately after collection, the less detrimental approach is to

  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. 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

  11. 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

  12. Will enhanced turbulence in inland waters result in elevated production of autochthonous dissolved organic matter?

    Science.gov (United States)

    Zhou, Yongqiang; Zhou, Jian; Jeppesen, Erik; Zhang, Yunlin; Qin, Boqiang; Shi, Kun; Tang, Xiangming; Han, Xiaoxia

    2016-02-01

    Biological activity in lakes is strongly influenced by hydrodynamic conditions, not least turbulence intensity; which increases the encounter rate between plankter and nutrient patches. To investigate whether enhanced turbulence in shallow and eutrophic lakes may result in elevated biological production of autochthonous chromophoric dissolved organic matter (CDOM), a combination of field campaigns and mesocosm experiments was used. Parallel factor analysis identified seven components: four protein-like, one microbial humic-like and two terrestrial humic-like components. During our field campaigns, elevated production of autochthonous CDOM was recorded in open water with higher wind speed and wave height than in inner bays, implying that elevated turbulence resulted in increased production of autochthonous CDOM. Confirming the field campaign results, in the mesocosm experiment enhanced turbulence resulted in a remarkably higher microbial humic-like C1 and tryptophan-like C3 (pproduction of autochthonous CDOM. This is consistent with the significantly higher mean concentrations of chlorophyll-a (Chl-a) and dissolved organic carbon (DOC) and the enhanced phytoplanktonic alkaline phosphatase activity (PAPA) recorded in the experimental turbulence groups than in the control group (p<0.05). The C:N ratio (from 3.34 to 25.72 with a mean of 13.13±4.08) for the mesocosm CDOM samples further suggested their probable autochthonous origin. Our results have implications for the understanding of CDOM cycling in shallow aquatic ecosystems influenced by wind-induced waves, in which the enhanced turbulence associated with extreme weather conditions may be further stimulated by the predicted global climate change.

  13. 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...

  14. 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...

  15. 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...

  16. Depressurization and two-phase flow of water containing high levels of dissolved nitrogen gas

    Science.gov (United States)

    Simoneau, R. J.

    1981-01-01

    Depressurization of water containing various concentrations of dissolved nitrogen gas was studied. In a nonflow depressurization experiment, water with very high nitrogen content was depressurized at rates from 0.09 to 0.50 MPa per second and a metastable behavior which was a strong function of the depressurization rate was observed. Flow experiments were performed in an axisymmetric, converging diverging nozzle, a two dimensional, converging nozzle with glass sidewalls, and a sharp edge orifice. The converging diverging nozzle exhibited choked flow behavior even at nitrogen concentration levels as low as 4 percent of the saturation level. The flow rates were independent of concentration level. Flow in the two dimensional, converging, visual nozzle appeared to have a sufficient pressure drop at the throat to cause nitrogen to come out of solution, but choking occurred further downstream. The orifice flow motion pictures showed considerable oscillation downstream of the orifice and parallel to the flow. Nitrogen bubbles appeared in the flow at back pressures as high as 3.28 MPa, and the level at which bubbles were no longer visible was a function of nitrogen concentration.

  17. Water Dynamics and Its Role in Structural Hysteresis of Dissolved Organic Matter.

    Science.gov (United States)

    Conte, Pellegrino; Kucerik, Jiri

    2016-03-01

    Knowledge of structural dynamics of dissolved organic matter (DOM) is of paramount importance for understanding DOM stability and role in the fate of solubilized organic and inorganic compounds (e.g., nutrients and pollutants), either in soils or aquatic systems. In this study, fast field cycling (FFC) (1)H NMR relaxometry was applied to elucidate structural dynamics of terrestrial DOM, represented by two structurally contrasting DOM models such as Suwanee River (SRFA) and Pahokee peat (PPFA) fulvic acids purchased by the International Humic Substance Society. Measurement of NMR relaxation rate of water protons in heating-cooling cycles revealed structural hysteresis in both fulvic acids. In particular, structural hysteresis was related to the delay in re-establishing water network around fulvic molecules as a result of temperature fluctuations. The experiments revealed that the structural temperature dependency and hysteresis were more pronounced in SRFA than in PPFA. This was attributed to the larger content of hydrogel-like structure in SRFA stabilized, at a larger extent, by H-bonds between carboxylic and phenolic groups. Moreover, results supported the view that terrestrial DOM consist of a hydrophobic rigid core surrounded by progressively assembling amphiphilic and polar molecules, which form an elastic structure that can mediate reactivity of the whole DOM.

  18. Determination of dissolved naphthenic acids in natural waters by using negative-ion electrospray mass spectrometry.

    Science.gov (United States)

    Headley, John V; Peru, Kerry M; McMartin, Dena W; Winkler, Marcus

    2002-01-01

    Naphthenic acids (NAs) have been implicated as some of the most toxic substances in oil sands leachates and identified as priority substances impacting on aquatic environments. As a group of compounds, NAs are not well characterized and comprise a large group of saturated aliphatic and alicyclic carboxylic acids found in hydrocarbon deposits (petroleum, oil sands bitumen, and crude oils). Described is an analytical method using negative-ion electrospray ionization mass spectrometry (ES/MS) of extracts. Preconcentration was achieved by using a solid-phase extraction procedure utilizing a crosslinked polystyrene-based polymer with acetonitrile elution. Recovery of the Fluka Chemicals NA mixture was highly pH-dependent, with 100% recovery at pH 3.0, but only 66 and 51% recoveries at pHs 7 and 9, respectively. The dissolved phase of the NA was very dependent on sample pH. It is thus critical to measure the pH and determine the appropriate mass profiles to identify NAs in natural waters. The ES/MS analytical procedure proved to be a fast and sensitive method for the recovery and detection of NAs in natural waters, with a detection limit of 0.01 mg/L.

  19. High-resolution passive sampling of dissolved methane in the water column of lakes in Greenland

    Science.gov (United States)

    Goldman, A. E.; Cadieux, S. B.; White, J. R.; Pratt, L. M.

    2013-12-01

    Arctic lakes are important participants in the global carbon cycle, releasing methane in a warming climate and contributing to a positive feedback to climate change. In order to yield detailed methane budgets and understand the implications of warming on methane dynamics, high-resolution profiles revealing methane behavior within the water column need to be obtained. Single day sampling using disruptive techniques has the potential to result in biases. In order to obtain high-resolution, undisturbed profiles of methane concentration and isotopic composition, this study evaluates a passive sampling method over a multi-day equilibration period. Selected for this study were two small lakes (Gatos Research Methane Carbon Isotope Analyzer. PDB sampling and pump sampling resulted in statistically similar concentrations (R2=0.89), ranging from 0.85 to 135 uM from PDB and 0.74 to 143 uM from pump sampling. In anoxic waters of the lake, where concentrations were high enough to yield robust isotopic results on the LGR MCIA, δ13C were also similar between the two methods, yielding -73‰ from PDB and -74‰ from pump sampling. Further investigation will produce results for a second lake and methane carbon and hydrogen isotopic composition for both lakes. Preliminary results for this passive sampling method are promising. We envision the use of this technique in future studies of dissolved methane and expect that it will provide a more finely resolved vertical profile, allowing for a more complete understanding of lacustrine methane dynamics.

  20. Evaluation of dissolved oxygen in water by artificial neural network and sample optimization

    Institute of Scientific and Technical Information of China (English)

    陈丽华; 李丽

    2008-01-01

    Three important factors influencing directly the dissolved oxygen (DO) of river including the outflow, the water temperature and the pH, were used as input parameters to set up a BP neural network based on Levenberg-Marquant algorithm. The neural network model was proposed to evaluate DO in water. The model contains two parts: firstly, the learning sample is unified; secondly, the neural network is used to train the unified samples to ensure the best node number of hidden layer. The proposed model is applied to assessing the DO concentration of the Yellow River in Lanzhou city. The evaluation result is compared with that by the neural network method and the reported result in Lanzhou city. The comparison result indicates that the performance of the neural network model is practically feasible in the assessment of DO. At the same time, the linear interpolation method can add the number of network’s learning sample to improve the prediction precision of the network.

  1. Spectroscopic Evidence of Anthropogenic Compounds Extraction from Polymers by Fluorescent Dissolved Organic Matter in Natural Water

    Science.gov (United States)

    Miranda, M.; Trojzuck, A.; Voss, D.; Gassmann, S.; Zielinski, O.

    2016-04-01

    FDOM is one of the most important carriers of anthropogenic compounds in natural waters. It can combine with environmental contaminants and polymers to form diverse chemical structures. To this end, here a microfluidic chip was designed for the analysis of these changes in fluorescent dissolved organic matter (FDOM) fingerprints due to thermal treatment and varying time intervals of exposure. Excitation Emission Matrix Spectroscopy (EEMS) approach was utilized to detect and identify the inherent compounds in sampled FDOM. Strong direct correlations were founded, Spearman rank correlation values (ρ = 0.85 at α = 0.1, n = 4) and linear correlation R2 = 0.8359 were noted between thermal treatment pattern 2 and fluorescence intensity of samples. Materials, acrylic based glue and cyclic olefin copolymer (COC) polymer, used to design the microfluidic sensor were determined to possess unique spectral features in the ultraviolet to green spectrum using EEMS. The study therefore provides an insight on methods to identify contaminants in natural waters. This underlines the potential of optical sensors providing measurements at fast intervals, enabling environmental monitoring.

  2. Pesticide leaching FOCUS scenarios if only dissolved pesticides degrade: re-assessing the importance of soil water flow

    Science.gov (United States)

    Te Brake, B.; van der Zee, S. E. A. T. M.; Verhoef, A.

    2009-04-01

    Although the pesticide screening policies assume that both dissolved and adsorbed pesticides are subject to transformation (or degradation), it is debatable whether this assumption is correct. Instead, it has been proposed that only dissolved pesticides may degrade, in line with the consensus on other organic contaminants for which only the dissolved or easily accessible fractions are biodegradable. If only dissolved pesticide fractions can degrade, this has major impacts on the pesticide risk assessment in the EU, which so far assumes all pesticide can degrade, whatever their chemical forms. In particular, if only dissolved pesticide degrades, the sorption process becomes completely irrelevant for the long term leached fraction: both regarding its (non)equilibrium and its (non)linearity assumptions. If sorption as such becomes less important, other processes should become more important for the leached fraction, and water flow as the major driving force is a logical candidate. Indeed, the rate of leaching can be shown to depend significantly on the net precipitation, with some prominent adjustments, if sorption becomes less dominant than in the current pesticide screening approaches. It will be shown that the celerity of leaching depends differently on the water flow, than does the leached fraction (which is crucial for pesticide admission policies). Therefore, a reconsideration of EU pesticide screening and admission policies may be necessary.

  3. 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.

  4. Major and trace element partitioning between dissolved and particulate phases in Antarctic surface snow.

    Science.gov (United States)

    Grotti, M; Soggia, F; Ardini, F; Magi, E

    2011-09-01

    In order to provide a new insight into the Antarctic snow chemistry, partitioning of major and trace elements between dissolved and particulate (i.e. insoluble particles, >0.45 μm) phases have been investigated in a number of coastal and inland snow samples, along with their total and acid-dissolvable (0.5% nitric acid) concentrations. Alkaline and alkaline-earth elements (Na, K, Ca, Mg, Sr) were mainly present in the dissolved phase, while Fe and Al were predominantly associated with the particulate matter, without any significant difference between inland and coastal samples. On the other hand, partitioning of trace elements depended on the sampling site position, showing a general decrease of the particulate fraction by moving from the coast to the plateau. Cd, Cu, Pb and Zn were for the most part in the dissolved phase, while Cr was mainly associated with the particulate fraction. Co, Mn and V were equally distributed between dissolved and particulate phases in the samples collected from the plateau and preferentially associated with the particulate in the coastal samples. The correlation between the elements and the inter-sample variability of their concentration significantly decreased for the plateau samples compared to the coastal ones, according to a change in the relative contribution of the metal sources and in good agreement with the estimated marine and crustal enrichment factors. In addition, samples from the plateau were characterised by higher enrichment factors of anthropogenic elements (Cd, Cr, Cu, Pb and Zn), compared to the coastal area. Finally, it was observed that the acid-dissolvable metal concentrations were generally lower than the total concentration values, showing that the acid treatment can dissolve only a given fraction of the metal associated with the particulate (<20% for iron and aluminium).

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. The effects of continental margins and water mass circulation on the distribution of dissolved aluminum and manganese in Drake Passage

    NARCIS (Netherlands)

    Middag, R.; de Baar, H. J. W.; Laan, P.; Huhn, O.

    2012-01-01

    A total of 232 samples were analyzed for concentrations of dissolved aluminum ([Al]) and manganese ([Mn]) in Drake Passage. Both [Al] and [Mn] were extremely low (similar to 0.3 and 0.1 nM, respectively) in the surface layer of the middle Drake Passage, most likely due to limited input and

  11. Pencil lead scratches on steel surfaces as a substrate for LIBS analysis of dissolved salts in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Jijon, D; Costa, C, E-mail: judijival@hotmail.com [Departamento de Fisica, Escuela Politecnica Nacional, Ladron de Guevara E11-256, Apartado 17-12-866, Quito (Ecuador)

    2011-01-01

    A new substrate for the quantitative analysis of salts dissolved in liquids with Laser-induced Breakdown Spectroscopy (LIBS) is introduced for the first time. A steel surface scratched with HB pencil lead is introduced as a very efficient and sensitive substrate for quantitative analysis of dissolved salts in liquids. In this work we demonstrate the analytical quality of this system with the analysis of the crystalline deposits formed by the dried aqueous solutions of salts. We focused on analytical parameters such as sensitivity and linearity for the salt cations in each case. Four salts were studied (Sr(NO{sub 3}){sub 2}, LiSO{sub 4}, RbCl and BaCl), at nine different concentrations each. To improve linearity and lower the overall error in the calibration curves, we introduce a novel outlier removal method that takes into account the homogeneity of the dry deposits on the analytical surface.

  12. A vibrational spectroscopic study of structure evolution of water dissolved in supercritical carbon dioxide under isobaric heating.

    Science.gov (United States)

    Oparin, R; Tassaing, T; Danten, Y; Besnard, M

    2004-06-08

    A combination of Raman scattering spectroscopy and infrared absorption was applied to investigate the structural evolution of water dissolved in supercritical carbon dioxide under isobaric heating (T=40-340 degrees C, P=250 bar). Quantitative analysis of experimental spectra allowed us to determine that at relatively moderate temperatures water dissolved in CO(2)-rich phase exists only under monomeric form (solitary water surrounding by CO(2) molecules), but hydrogen-bonded species, namely, dimers, begin to appear upon heating. At the same time, the ratio of dimers to monomers concentration increases with further temperature increase and at temperatures close to the temperature of total miscibility of the mixture (T=366 degrees C, P=250 bar), water dimers only are present in the CO(2)-rich phase. (c) 2004 American Institute of Physics.

  13. Bacterial production in the water column of small streams highly depends on terrestrial dissolved organic carbon

    Science.gov (United States)

    Graeber, Daniel; Poulsen, Jane R.; Rasmussen, Jes J.; Kronvang, Brian; Zak, Dominik; Kamjunke, Norbert

    2016-04-01

    In the recent years it has become clear that the largest part of the terrestrial dissolved organic carbon (DOC) pool is removed on the way from the land to the ocean. Yet it is still unclear, where in the freshwater systems terrestrial DOC is actually taken up, and for streams DOC uptake was assumed to happen mostly at the stream bottom (benthic zone). However, a recent monitoring study implies that water column but not benthic bacteria are strongly affected by the amount and composition of DOM entering streams from the terrestrial zone. We conducted an experiment to compare the reaction of the bacterial production and heterotrophic uptake in the water column and the benthic zone to a standardized source of terrestrial DOC (leaf leachate from Beech litter). In detail, we sampled gravel and water from eight streams with a gradient in stream size and land use. For each stream four different treatments were incubated at 16°C for three days and each stream: filtered stream water with gravel stones (representing benthic zone bacteria) or unfiltered stream water (representing water column bacteria), both either with (n = 5) or, without (n = 3) leaf leachate. We found that the bacterial uptake of leaf litter DOC was higher for the benthic zone likely due to the higher bacterial production compared to the water column. In contrast, the bacterial production per amount of leaf leachate DOC taken up was significantly higher for the bacteria in the water column than for those in the benthic zone. This clearly indicates a higher growth efficiency with the leaf leachate DOC for the bacteria in the water column than in the benthic zone. We found a high variability for the growth efficiency in the water column, which was best explained by a negative correlation of the DOC demand with stream width (R² = 0.86, linear correlation of log-transformed data). This was not the case for the benthic zone bacteria (R² = 0.02). This implies that water column bacteria in very small streams

  14. Molecular dynamics simulations of the surface tension of oxygen-supersaturated water

    Directory of Open Access Journals (Sweden)

    S. Jain

    2017-04-01

    Full Text Available In this work, non-reactive molecular dynamic simulations were conducted to determine the surface tension of water as a function of the concentration of the dissolved gaseous molecules (O2, which would in turn help to predict the pressure inside the nanobubbles under supersaturation conditions. Knowing the bubble pressure is a prerequisite for understanding the mechanisms behind the spontaneous combustion of the H2/O2 gases inside the nanobubbles. First, the surface tension of pure water was determined using the planar interface method and the Irving and Kirkwood formula. Next, the surface tension of water containing four different supersaturation concentrations (S of O2 gas molecules was computed considering the curved interface of a nanobubble. The surface tension of water was found to decrease with an increase in the supersaturation ratio or the concentration of the dissolved O2 gas molecules.

  15. Deep water circulation and composition in the Arctic Ocean by dissolved barium, aluminium and silicate

    NARCIS (Netherlands)

    Roeske, T.; Rutgers van der Loeff, M.; Middag, R.; Bakker, K.

    2012-01-01

    As part of the ARK-XXII/2 Polarstern expedition in summer 2007, dissolved Ba was analyzed in the Eurasian Basins and the Makarov Basin including the Alpha and Mendeleyev Ridges as well as on the adjacent shelves. The data was compared with data of dissolved Al and Si from the same cruise. Superimpos

  16. Indirect photochemistry in sunlit surface waters: photoinduced production of reactive transient species.

    Science.gov (United States)

    Vione, Davide; Minella, Marco; Maurino, Valter; Minero, Claudio

    2014-08-18

    This paper gives an overview of the main reactive transient species that are produced in surface waters by sunlight illumination of photoactive molecules (photosensitizers), such as nitrate, nitrite, and chromophoric dissolved organic matter (CDOM). The main transients (˙OH, CO3(-˙) , (1)O2, and CDOM triplet states) are involved in the indirect phototransformation of a very wide range of persistent organic pollutants in surface waters.

  17. The Appearance, Taste, and Concentrations of Zolpidem Dissolved in Still Water and Carbonated Beverages.

    Science.gov (United States)

    Heide, Gunhild; Hjelmeland, Knut; Brochmann, Gerd-Wenche; Karinen, Ritva; Høiseth, Gudrun

    2017-08-15

    Zolpidem is a sedative that could be used to drug victims, but its suitability to dissolve in drinks is unknown. In this small study, we added either crushed or whole tablets of zolpidem hemitartrate to carbonated beverages or still water to observe how this affected the taste and appearance. Also, concentrations were measured by ultra-high performance liquid chromatography tandem mass spectrometry at different time intervals. Two crushed tablets (20 mg) in cider (250 mL) lead to a maximum concentration of 84 mg/L zolpidem base after 30 min, while the corresponding concentration after adding fifteen tablets (150 mg) was 467 mg/L. There was little change in taste, but froth and turbidity were observed when adding high doses to carbonated beverages. Carbonated beverages spiked with 20 mg of crushed zolpidem hemitartrate tablets reached concentrations that could cause impairment. Spiking with 150 mg could possibly be lethal if several mouthfuls were ingested. © 2017 American Academy of Forensic Sciences.

  18. Dissolved organic matter conformation and its interaction with pyrene as affected by water chemistry and concentration.

    Science.gov (United States)

    Pan, Bo; Ghosh, Saikat; Xing, Baoshan

    2008-03-01

    Water chemistry and concentration of dissolved organic matter (DOM) have been reported to affect DOM conformation and binding properties with hydrophobic organic contaminants (HOCs). However, relationship between DOM conformation and its binding properties remains unclear. We designed a multibag equilibration system (MBES) to investigate the variation of carbon-normalized sorption coefficients (K(DOC)) of pyrene at different DOM concentrations based on an identical free solute concentration at different pHs and in the presence of Al ions. In addition, we studied the conformation of DOM under different conditions via atomic force microscopy (AFM) imaging, dynamic light scattering, and zeta potential measurements. Zeta potential measurements indicated that intra- and intermolecular interaction was facilitated at low pH or with the presence of Al ions, and a more organized molecular aggregate (such as a micelle-like structure) could form, thus, enhancing K(DOC). As DOM concentration increased, DOM molecular aggregation was promoted in a way reducing K(DOC). This research is a first attempt to correlate DOM conformation with K(DOC). Aggregation of DOM molecules resulting from increased zeta potential (less negative) generally led to an increased K(DOC). Further study in this area will provide valuable information on HOC-DOM interactions, thus, leading to more accurate predictions of K(DOC).

  19. Optical Proxies for Terrestrial Dissolved Organic Matter in Estuaries and Coastal Waters

    Directory of Open Access Journals (Sweden)

    Christopher L. Osburn

    2016-01-01

    Full Text Available Optical proxies, especially DOM fluorescence, were used to track terrestrial DOM fluxes through estuaries and coastal waters by comparing models developed for several coastal ecosystems. Key to using optical properties is validating and calibrating them with chemical measurements, such as lignin-derived phenols - a proxy to quantify terrestrial DOM. Utilizing parallel factor analysis (PARAFAC, and comparing models statistically using the OpenFluor database (http://www.openfluor.org we have found common, ubiquitous fluorescing components which correlate most strongly with lignin phenol concentrations in several estuarine and coastal environments. Optical proxies for lignin were computed for the following regions: Mackenzie River Estuary, Atchafalaya River Estuary, Charleston Harbor, Chesapeake Bay, and Neuse River Estuary. The slope of linear regression models relating CDOM absorption at 350 nm (a350 to DOC and to lignin, varied 5 to 10 fold among systems. Where seasonal observations were available from a region, there were distinct seasonal differences in equation parameters for these optical proxies. Despite variability, overall models using single linear regression were developed that related dissolved organic carbon (DOC concentration to CDOM (DOC = 40×a350+138; R2 = 0.77; N = 130 and lignin (Σ8 to CDOM (Σ8 = 2.03×a350-0.5; R2 = 0.87; N = 130. This wide variability suggested that local or regional optical models should be developed for predicting terrestrial DOM flux into coastal oceans and taken into account when upscaling to remote sensing observations and calibrations.

  20. An overview of dissolved organic carbon in groundwater and implications for drinking water safety

    Science.gov (United States)

    Regan, S.; Hynds, P.; Flynn, R.

    2017-06-01

    Dissolved organic carbon (DOC) is composed of a diverse array of compounds, predominantly humic substances, and is a near ubiquitous component of natural groundwater, notwithstanding climatic extremes such as arid and hyper-arid settings. Despite being a frequently measured parameter of groundwater quality, the complexity of DOC composition and reaction behaviour means that links between concentration and human health risk are difficult to quantify and few examples are reported in the literature. Measured concentrations from natural/unpolluted groundwater are typically below 4 mg C/l, whilst concentrations above these levels generally indicate anthropogenic influences and/or contamination issues and can potentially compromise water safety. Treatment processes are effective at reducing DOC concentrations, but refractory humic substance reaction with chlorine during the disinfection process produces suspected carcinogenic disinfectant by-products (DBPs). However, despite engineered artificial recharge systems being commonly used to remove DOC from recycled treated wastewaters, little research has been conducted on the presence of DBPs in potable groundwater systems. In recent years, the capacity to measure the influence of organic matter on colloidal contaminants and its influence on the mobility of pathogenic microorganisms has aided understanding of transport processes in aquifers. Additionally, advances in polymerase chain reaction techniques used for the detection, identification, and quantification of waterborne pathogens, provide a method to confidently investigate the behaviour of DOC and its effect on contaminant transfer in aquifers. This paper provides a summary of DOC occurrence in groundwater bodies and associated issues capable of indirectly affecting human health.

  1. Effect of dissolved organic matter on mercury release from water body

    Institute of Scientific and Technical Information of China (English)

    Yutao Zhang; Xi Chen; Yongkui Yang; Dingyong Wang; Xiao Liu

    2011-01-01

    Dissolved organic matter (DOM) plays an important role in the process of mercury release from water body. In this study, the influence of DOM from different sources (DOMR, DOMs and DOMH, extracted from rice straw, compost and humic soil respectively)on mercury reduction was investigated. The molecular weight distribution and chemical composition of DOM from each source were determined using ultrafiltration membrane technique and elemental analysis respectively. The result showed that mercury release from DOM-added samples was much lower than the control; the lowest mercury release flux was observed in the treatment of DOMH,25.02% of the control, followed by DOMs and DOMR, 62.46% and 64.95% of the control, respectively. The higher saturation degree and lower molecular weight of DOMH was responsible for the highest inhibition degree on the mercury release. The link between DOMH, concentration and mercury flux was also estimated and the result showed that mercury flux was increased with DOMH at lower concentration, while decreased with DOMH at higher concentration. Different mechanism dominated the influence of DOM on mercury release with variation of DOM concentration.

  2. Assessment of the colored dissolved organic matter in coastal waters from ocean color remote sensing.

    Science.gov (United States)

    Loisel, Hubert; Vantrepotte, Vincent; Dessailly, David; Mériaux, Xavier

    2014-06-02

    Knowledge on absorption by colored dissolved organic matter, a(cdom), spatio-temporal variability in coastal areas is of fundamental importance in many field of researches related to biogeochemical cycles studies, coastal areas management, as well as land and water interactions in the coastal domain. A new method, based on the theoretical link between the vertical attenuation coefficient, K(d), and the absorption coefficient, has been developed to assess a(cdom). This method, confirmed from radiative transfer simulations and in situ measurements, and tested on an independent in situ data set (N = 126), allows a(cdom) to be assessed with a Mean Relative Absolute Difference, MRAD, of 33% over two order of magnitude (from 0.01 to 1.16 m(-1)). In the frame of ocean color observation, K(d) is not directly measured but estimated from the remote sensing reflectance, R(rs). Based on 109 satellite (SeaWiFS) and in situ coincident (i.e. match-up) data points a(cdom) is retrieved with a MRAD value of 37%. This simple model generally presents slightly better performances than recently developed empirical or semi-analytical algorithms.

  3. 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.

  4. 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...

  5. Partitioning of the pesticide trifluralin between dissolved organic matter and water using automated SPME-GC/MS

    KAUST Repository

    Caupos, Emilie

    2014-10-04

    Solid-phase microextraction (SPME) was used to determine the equilibrium association constant for a pesticide, trifluralin (TFR), with dissolved organic matter (DOM). After optimization of the SPME method for the analysis of TFR, partition coefficients (K DOM) with three different sources of DOM were determined in buffered solutions at pH 7. Commercial humic acids and DOM fractions isolated from two surface waters were used. The values of log K DOMvaried from 4.3 to 5.8, depending on the nature of the organic material. A good correlation was established between log K DOMand DOM properties (as measured with the H/O atomic ratio and UV absorbance), in agreement with literature data. This is consistent with the effect of polarity and aromaticity for governing DOM-pollutant associations, regardless of the origin of DOM. This association phenomenon is relevant to better understand the behavior of pesticides in the environment since it controls part of pesticide leaching and fate in aquatic systems.

  6. Surface distribution of dissolved trace metals in the oligotrophic ocean and their influence on phytoplankton biomass and productivity

    KAUST Repository

    Pinedo-González, Paulina

    2015-10-25

    The distribution of bioactive trace metals has the potential to enhance or limit primary productivity and carbon export in some regions of the world ocean. To study these connections, the concentrations of Cd, Co, Cu, Fe, Mo, Ni, and V were determined for 110 surface water samples collected during the Malaspina 2010 Circumnavigation Expedition (MCE). Total dissolved Cd, Co, Cu, Fe, Mo, Ni, and V concentrations averaged 19.0 ± 5.4 pM, 21.4 ± 12 pM, 0.91 ± 0.4 nM, 0.66 ± 0.3 nM, 88.8 ± 12 nM, 1.72 ± 0.4 nM, and 23.4 ± 4.4 nM, respectively, with the lowest values detected in the Central Pacific and increased values at the extremes of all transects near coastal zones. Trace metal concentrations measured in surface waters of the Atlantic Ocean during the MCE were compared to previously published data for the same region. The comparison revealed little temporal changes in the distribution of Cd, Co, Cu, Fe, and Ni over the last 30 years. We utilized a multivariable linear regression model to describe potential relationships between primary productivity and the hydrological, biological, trace nutrient and macronutrient data collected during the MCE. Our statistical analysis shows that primary productivity in the Indian Ocean is best described by chlorophyll a, NO3, Ni, temperature, SiO4, and Cd. In the Atlantic Ocean, primary productivity is correlated with chlorophyll a, NO3, PO4, mixed layer depth, Co, Fe, Cd, Cu, V, and Mo. The variables salinity, temperature, SiO4, NO3, PO4, Fe, Cd, and V were found to best predict primary productivity in the Pacific Ocean. These results suggest that some of the lesser studied trace elements (e.g., Ni, V, Mo, and Cd) may play a more important role in regulating oceanic primary productivity than previously thought and point to the need for future experiments to verify their potential biological functions.

  7. Dissolved lipid production in the Northern Adriatic (Mediterranean) in response to sea surface warmin

    Science.gov (United States)

    Gasparovic, Blazenka; Novak, Tihana; Godrijan, Jelena; Mlakar, Marina; MAric, Daniela; Djakovac, Tamara

    2017-04-01

    Marine dissolved organic matter (OM) represents one of the largest active pools of organic carbon in the global carbon cycle. Oceans and seas are responsible for half of global primary production. Ocean warming caused by climate change is already starting to impact the marine life that necessary will have impact on ocean productivity. The partition of OM production by phytoplankton (major OM producer in seas and ocens) in the conditions of rising temperatures may considerably change. This has implications for the export of organic matter from the photic zone. In this study, we set out to see how annual temperature changes between 10 and 30 C in the Northern Adriatic (Mediterranean) affect production of DOM and particularly dissolved lipids and lipid classes. We have sampled at two stations being oligotrophic and mesotrophic where we expected different system reaction to temperature changes. In addition, we performed microcosm incubations covering temperature range of the NA with nutrient amendments to test whether changes in the available nutrients would reflect those of dissolved OM in the NA. We have selected to work with extracellular OM produced during growth of diatom Chaetoceros curvisetus cultures according to the criteria that genera Chaetoceros are important component of the phytoplankton in the NA and are often among bloom-forming taxa. Details on the dissolved lipid and lipid classes production as plankton responce to rising temperature will be discussed.

  8. Simultaneous effect of dissolved organic carbon, surfactant, and organic acid on the desorption of pesticides investigated by response surface methodology

    DEFF Research Database (Denmark)

    Trinh, Ha Thu; Duong, Hanh Thi; Ta, Thao Thi

    2017-01-01

    Desorption of pesticides (fenobucarb, endosulfan, and dichlorodiphenyltrichloroethane (DDT)) from soil to aqueous solution with the simultaneous presence of dissolved organic carbon (DOC), sodium dodecyl sulfate (SDS), and sodium oxalate (Oxa) was investigated in batch test by applying a full fac...... characteristics of flooding and irrigation water in rice fields, and surfactants from pollution increase the problem with desorption of legacy pesticides in the rice fields....... caused the minimum desorption. This point at conditions of concern for flooding water is high content of organic compounds causing potentially high contamination by desorption, and the remarkably lower desorption at organic matter-free conditions. The suspended organic matter is one of the common...

  9. 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.

  10. Effect of water hardness and dissolved-solid concentration on hatching success and egg size in bighead carp

    Science.gov (United States)

    Chapman, Duane C.; Deters, Joseph E.

    2009-01-01

    Bighead carp Hypophthalmichthys nobilis is an Asian species that has been introduced to the United States and is regarded as a highly undesirable invader. Soft water has been said to cause the bursting of Asian carp eggs and thus has been suggested as a factor that would limit the spread of this species. To evaluate this, we subjected fertilized eggs of bighead carp to waters with a wide range of hardness and dissolved-solid concentrations. Hatching rate and egg size were not significantly affected by the different water qualities. These results, combined with the low hardness (28–84 mg/L) of the Yangtze River (the primary natal habitat of Hypophthalmichthys spp.), suggest that managers and those performing risk assessments for the establishment of Hypophthalmichthys spp. should be cautious about treating low hardness and dissolved-solid concentrations as limiting factors.

  11. A novel isotopic fractionation during dissolved oxygen consumption in mesopelagic waters inferred from observation and model simulation of dissolved oxygen δ18O in open oceanic regions

    Science.gov (United States)

    Nakayama, N.; Oka, A.; Gamo, T.

    2012-12-01

    Oxygen isotopic ratio (δ18O) of dissolved oxygen is a useful for bioactive tracer of the subsurface aphotic (mesopelagic) ocean since it varies nonlinearly related to oxygen consumption via stoichiometry of organic matter decomposition. Therefore, along with global circulation model (GCM), observed δ18O and their vertical/geographical distribution can be effectively used to quantitatively determine how marine biological and ocean physical processes contribute to varying dissolved oxygen (DO) concentration in the ocean, in particular mesopelagic zone where pronounced biological activity alters DO concentration significantly. In the central north Pacific Ocean and Indian Ocean, including Arabian Sea, one of the few regions in the open ocean which has oxygen minimum zone (OMZ, a layer with severely depleted DO), vertical profiles of DO and δ18O were observed. These observed data are compared with a GCM simulation in which a constant isotopic fractionation factor of DO by marine biological respiration and a fixed Redfield molar ratio between P and O are assumed. Even in the Arabian Sea OMZ, relationship between DO and δ18O was found to be similar to those observed in other open oceans, indicating that no specific oxygen consumption process occurred in the OMZ. Using the GCM model, we attempted to reproduce the observed overall relationship between DO and δ18O, but it failed when we adopted the previously reported isotopic fractionation factor: Discrepancy became larger when oxygen saturation level decreased, in particular in thermocline water (at 20% oxygen saturation level, modeled δ18O was heavier than observed values by +7‰). Sensitivity simulations with the GCM model revealed that (1) simply changing the intensity of oxygen consumption by respiration/organic matter decomposition nor physical processes (diffusion and/or advection) could explain the observed relationship between DO and δ18O, (2) applying a smaller isotopic fractionation for deep waters

  12. Effects of Environmental Oxygen Content and Dissolved Oxygen on the Surface Tension and Viscosity of Liquid Nickel

    Science.gov (United States)

    SanSoucie, M. P.; Rogers, J. R.; Kumar, V.; Rodriguez, J.; Xiao, X.; Matson, D. M.

    2016-07-01

    The NASA Marshall Space Flight Center's electrostatic levitation (ESL) laboratory has recently added an oxygen partial pressure controller. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled in the range from approximately 10^{-28} {to} 10^{-9} bar, while in a vacuum atmosphere. The oxygen control system installed in the ESL laboratory's main chamber consists of an oxygen sensor, oxygen pump, and a control unit. The sensor is a potentiometric device that determines the difference in oxygen activity in two gas compartments (inside the chamber and the air outside of the chamber) separated by an electrolyte. The pump utilizes coulometric titration to either add or remove oxygen. The system is controlled by a desktop control unit, which can also be accessed via a computer. The controller performs temperature control for the sensor and pump, has a PID-based current loop and a control algorithm. Oxygen partial pressure has been shown to play a significant role in the surface tension of liquid metals. Oxide films or dissolved oxygen may lead to significant changes in surface tension. The effects on surface tension and viscosity by oxygen partial pressure in the surrounding environment and the melt dissolved oxygen content will be evaluated, and the results will be presented. The surface tension and viscosity will be measured at several different oxygen partial pressures while the sample is undercooled. Surface tension and viscosity will be measured using the oscillating droplet method.

  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. Tidal Marsh Outwelling of Dissolved Organic Matter and Resulting Temporal Variability in Coastal Water Optical and Biogeochemical Properties

    Science.gov (United States)

    Tzortziou, Maria; Neale, Patrick J.; Megonigal, J. Patrick; Butterworth, Megan; Jaffe, Rudolf; Yamashita, Youhei

    2010-01-01

    Coastal wetlands are highly dynamic environments at the land-ocean interface where human activities, short-term physical forcings and intense episodic events result in high biological and chemical variability. Long being recognized as among the most productive ecosystems in the world, tidally-influenced coastal marshes are hot spots of biogeochemical transformation and exchange. High temporal resolution observations that we performed in several marsh-estuarine systems of the Chesapeake Bay revealed significant variability in water optical and biogeochemical characteristics at hourly time scales, associated with tidally-driven hydrology. Water in the tidal creek draining each marsh was sampled every hour during several semi-diurnal tidal cycles using ISCO automated samplers. Measurements showed that water leaving the marsh during ebbing tide was consistently enriched in dissolved organic carbon (DOC), frequently by more than a factor of two, compared to water entering the marsh during flooding tide. Estimates of DOC fluxes showed a net DOC export from the marsh to the estuary during seasons of both low and high biomass of marsh vegetation. Chlorophyll amounts were typically lower in the water draining the marsh, compared to that entering the marsh during flooding tide, suggesting that marshes act as transformers of particulate to dissolved organic matter. Moreover, detailed optical and compositional analyses demonstrated that marshes are important sources of optically and chemically distinctive, relatively complex, high molecular weight, aromatic-rich and highly colored dissolved organic compounds. Compared to adjacent estuarine waters, marsh-exported colored dissolved organic matter (CDOM) was characterized by considerably stronger absorption (more than a factor of three in some cases), larger DOC-specific absorption, lower exponential spectral slope, larger fluorescence signal, lower fluorescence per unit absorbance, and higher fluorescence at visible wavelengths

  15. 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.

  16. Monitoring of the radiocesium in river water in Fukushima using rapid and simultaneous monitoring of particulate and dissolved radiocesium in water with nonwoven fabric cartridge filters

    Energy Technology Data Exchange (ETDEWEB)

    Tsuji, H.; Yasutaka, T. [National Institute of Advanced Industrial Science and Technology (Japan); Kondo, Y. [Japan Vilene Company, Ltd (Japan); Suzuki, Y. [Fukushima Agricultural Technology Centre (Japan)

    2014-07-01

    The environmental monitoring of dissolved and particulate radiocesium in river became important after the accident of TEPCO Fukushima Daiichi Nuclear Power Plant. Traditional monitoring methods, such as evaporative concentration, require time for pre-processing because the concentration of dissolved radiocesium of river water in Fukushima prefecture is currently very low, averagely 0.001 - 0.1 Bq/L. Our research group has developed a monitoring method to investigate the radiocesium concentration in water by each existence form. Yasutaka et al. (2013) and Tsuji et al.(2013) developed a method for rapid and simultaneous monitoring of particulate and dissolved radiocesium in water with nonwoven fabric cartridge filters. This method uses pleated polypropylene nonwoven fabric filter with a pore size of 1-μm to collect particulate radiocesium, and nonwoven fabric impregnated with Prussian blue (PB) to absorb dissolved radiocesium. The fabric was placed into cylindrical plastic cartridges (SS-cartridge and PB-cartridge). This method could catch the 99% of the suspended solid (SS) and absorb 95% of dissolved radiocesium separately in 20 L water within 40 minutes. This device was applied to monitor the water in Abukuma River (January 2013) and upper area of Kuchibuto river (May 2013) at 12 locations, and the results were compared with those obtained by the filtrating and evaporative concentration method. The SS concentration and radioactivity of SS in the Abukuma river water, calculated by weight gain of the SS-cartridge and by sediment weight after filtration with a 0.45-μm membrane filter, agreed well without one location.The radioactivity of the dissolved {sup 137}Cs also agreed well between these two methods. In the Abukuma River, dissolved {sup 137}Cs was 0.006-0.025 Bq/L and particulate {sup 137}Cs was 0.008-0.070 Bq/L by the presented method in January 2013. In addition, the required time for pre-processing was reduced by more than 10 times that by filtrating and

  17. Arsenic and major cation hydrogeochemistry of the Central Victorian (Australia) surface waters

    Institute of Scientific and Technical Information of China (English)

    Khawar SULTAN; Kim DOWLING

    2006-01-01

    This paper reports on the major cations(Ca, Mg, Na and K) and arsenic(As) compositions of surface waters collected from major creeks, rivers and lakes in Central Victoria (Australia). The surface waters were found to be neutral to alkaline (pH 6.7-9.4),oxidised (average redox potential (Eh) about 130 mV) and showed variable concentrations of dissolved ions (EC, about 51-4386 μS/cm). The concen- trations of dissolved major cations in surface waters were found to be in the order of Na>>Mg>Ca>K and in soils the contents of metals followed an order of abundance as: Ca>Mg>>K>Na. While Na was the least abundant in soils, it registered the highest dissolved cation in surface waters. Of the four major cations, the average concentration ofNa(98.7 mg/L) was attributed to the weathering of feldspars and atmospheric input. Relatively highly dissolved concentrations of Na and Mg compared with the world average values of rivers reflected the weathering of rock and soil minerals within the catchments.The As soil level is naturally high(linked to lithology) as reflected by high background soil values and mining operations are also considered to be a contributory factor. Under relatively alkaline-oxidative conditions low mobility of dissolved As (average about 7.9 μg/L) was observed in most of the surface waters with a few higher values(>15 μg/L) around a sewage disposal site and mine tailings.Arsenic in soils is slowly released into water under alkaline and/or lower Eh conditions. The efficient sink of Fe, Al and Mn oxides acts as a barrier against the As release under near neutral-oxidising conditions. High As content (average about 28.3 mg/kg) in soils was found to be associated with Fe-hydroxides as revealed by XRD and SEM analysis. The dissolved As concentration was found to be below the recommended maximum levels for recreational water in all surface waters(lakes and rivers) in the study area. Catchment lithology exerted the fundamental control on surface water chemistry

  18. Influential factors on the exchange rate of dissolved inorganic nutrients at the sediment-water interface in Jiaozhou Bay, China

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Incubation experiments are carried out to study the exchange rates of dissolved inorganic nutrients including silicate, phosphate, ammonium, nitrite, and nitrate (vSiO3-Si, vPO4-P, vNH4-N, vNO2-N and vNO3-N) at the sediment-water interface in the Jiaozhou Bay. Major factors influencing the exchange rates are discussed in detail, which include the dissolved inorganic nutrient concentrations in porewater (Cpw), water and clay contents,and grain size of the sediments (CH2O, Cclay and GSsed). The results may provide insight into the dynamics of nutrient transport and the environmental capacity of nutrients in Jiaozhou Bay, and should be beneficial to solving the problems caused by excessive nutrient input this area.

  19. 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.

  20. Spatial variations in the molecular diversity of dissolved organic matter in water moving through a boreal forest in eastern Finland

    Science.gov (United States)

    Ide, Jun’ichiro; Ohashi, Mizue; Takahashi, Katsutoshi; Sugiyama, Yuko; Piirainen, Sirpa; Kortelainen, Pirkko; Fujitake, Nobuhide; Yamase, Keitaro; Ohte, Nobuhito; Moritani, Mina; Hara, Miyako; Finér, Leena

    2017-01-01

    Dissolved organic matter (DOM) strongly affects water quality within boreal forest ecosystems. However, how the quality of DOM itself changes spatially is not well understood. In this study, to examine how the diversity of DOM molecules varies in water moving through a boreal forest, the number of DOM molecules in different water samples, i.e., rainwater, throughfall, soil water, groundwater, and stream water was determined using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) in Norway spruce and Scots pine stands in eastern Finland during May and June 2010. The number of molecular compounds identified by FT-ICR MS (molecular diversity) ranged from 865 to 2,194, revealing large DOM molecular diversity in the water samples. Additionally, some of the molecular compounds were shared between different water samples. The DOM molecular diversity linearly correlated with the number of low-biodegradable molecules, such as, lignin-like molecules (lignins), but not with dissolved organic carbon concentration. The number of lignins shared between different sampling locations was larger than that of any other biomolecular class. Our results suggest that low-biodegradable molecules, especially lignins, regulate spatial variations in DOM molecular diversity in boreal forests. PMID:28186141

  1. Chemistry and dissolved gases of matrix pore water and fluid inclusions in Olkiluoto bedrock from drillhole ONK-PH9

    Energy Technology Data Exchange (ETDEWEB)

    Eichinger, F.; Haemmerli, J.; Waber, H.N.; Diamond, L.W. [Univ. of Bern (Switzerland). Inst. of Geological Sciences; Smellie, J.A.T. [Conterra AB, Stockholm (Sweden)

    2013-05-15

    Matrix pore water and gas dissolved in matrix pore water in drillcore samples from drillhole ONK-PH9 have been successfully characterised for their chemical and isotopic composition. Based on the comparison of natural tracers in matrix pore water and adjacent fracture groundwater, conclusions about the palaeohydrogeological history of the encountered system are drawn. The investigations are based on naturally saturated core samples from the subhorizontal drillhole ONK-PH9 which was drilled from the ONKALO access tunnel at a vertical depth of 306 m into the bedrock intersecting the water-conducting hydrogeological zone HZ20B. Pore water samples were taken from this highly transmissive water-conducting zone and the adjacent low transmissive bedrock along a continuous eleven metre long profile. Additional samples have been collected at intervals between five and ten metres until 100 m drillhole length (DHL)

  2. 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

  3. Treatment of produced water: targeting dissolved compounds to meet a zero harmful discharge in oil and gas production

    Energy Technology Data Exchange (ETDEWEB)

    Scurtu, Ciprian Teodor

    2009-06-15

    High amounts of dissolved compounds are discharged into the sea with the produced water generated from the offshore oil and gas platforms. Some of these compounds are toxic to the environment, having important contributions to the environmental impact factors (EIF) calculated for produced water discharges. No performance standards currently exist for the removal of dissolved compounds from produced water. However, the overall goals for oil, natural components and chemicals in produced water require reducing the input into the sea of oil and other substances resulting from produced water from offshore installations. The ultimate aim is to eliminate pollution from those sources and ensure that effort is made to give priority to actions related to the most harmful components of produced water. The goal of this study is to acquire further knowledge and technology to attain the 'Zero Harmful Discharge' policy initiated by the Norwegian authorities. The ambition is to study a treatment method to meet the requirements of the future performance standards for the removal of harmful dissolved organic compounds. The dissolved compounds can be removed by physical/chemical methods such as stripping, oxidation, membrane technology, extraction, sorption as well as biological treatment. Required process size is a key factor limiting the application of several of the alternatives described above, especially if very low effluent concentrations must be achieved. Handling of the 'waste' stream that could be spent sorption media, off-gas that requires further treatment or concentrate from a membrane process, is another common limitation. The scope of this study was to investigate the feasibility of a treatment concept that combines selective in-line sorption of selected dissolved compounds (BTX) coupled with biological regeneration of the spent media in a fluidized bed reactor (FBR). The research work was focused on the following issues: selective sorption of

  4. 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.

  5. Isotopic, chemical and dissolved gas constraints on spring water from Popocatepetl volcano (Mexico): evidence of gas water interaction between magmatic component and shallow fluids

    Science.gov (United States)

    Inguaggiato, S.; Martin-Del Pozzo, A. L.; Aguayo, A.; Capasso, G.; Favara, R.

    2005-03-01

    Geochemical research was carried out on cold and hot springs at Popocatepetl (Popo) volcano (Mexico) in 1999 to identify a possible relationship with magmatic activity. The chemical and isotopic composition of the fluids is compatible with strong gas-water interaction between deep and shallow fluids. In fact, the isotopic composition of He and dissolved carbon species is consistent with a magmatic origin. The presence of a geothermal system having a temperature of 80-100° C was estimated on the basis of liquid geothermometers. A large amount of dissolved CO 2 in the springs was also detected and associated with high CO 2 degassing.

  6. 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...

  7. Dramatic enhancement of solar disinfection (SODIS) of wild Salmonella sp. in PET bottles by H2O2 addition on natural water of Burkina Faso containing dissolved iron.

    Science.gov (United States)

    Sciacca, Frédéric; Rengifo-Herrera, Juliàn A; Wéthé, Joseph; Pulgarin, César

    2010-02-01

    Disinfection of surface water containing dissolved iron (0.3 mg L(-1)) at natural neutral pH ( approximately 7.5) was carried out via solar disinfection (SODIS) treatment in PET bottles with H(2)O(2) (10 mg L(-1)). Wild coliforms and Salmonella sp. were monitored for 6 h of sunlight irradiation and 72 h of dark post-treatment period. In our conditions, SODIS treatment could not avoid Salmonella sp. re-growth during dark storage, meanwhile the addition of 10 mg L(-1) of H(2)O(2) showed a strong enhancement of the inactivation rate without any re-growth of both bacteria. Finally, total coliforms (Escherichia coli included) demonstrated to be an inappropriate indicator for monitoring bacterial contamination in water during solar disinfection processes.

  8. 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...

  9. Feasibility Study of Reducing the Total Dissolved Solids (TDS from Contaminated Water in Radish Plant (Raphanus Sativus Using Nano Activated Carbon and Zeolite

    Directory of Open Access Journals (Sweden)

    S. Hassanpour Aslani

    2013-06-01

    Full Text Available Applying Nanoporous Materials is an appropriate method for improving chemical quality of the water due to high surface area, internal porous structure (porosity, high absorption capability of harmful gases and liquids, and capability of reactivating the surface. Therefore, actions were carried out in order to investigate the effect of Activated carbon and Zeolite on reducing the total dissolved solids in water to perform experiment in a randomized complete block design with four treatments and three replications in greenhouse. Results indicated that there are significant differences among various treatments of water in terms of change in the concentrations of chemical elements in water. Subsequently, we measured some traits in plant samples in order to evaluate the reaction of the radish plant related to changes in water quality resulting from use of these absorbers. Other characteristics did not show remarkable differences with the control sample based on the results of variance analysis related to plant samples with the exception of shoot’s chloride.

  10. Year-round record of dissolved and particulate metals in surface snow at Dome Concordia (East Antarctica).

    Science.gov (United States)

    Grotti, Marco; Soggia, Francesco; Ardini, Francisco; Magi, Emanuele; Becagli, Silvia; Traversi, Rita; Udisti, Roberto

    2015-11-01

    From January to December 2010, surface snow samples were collected with monthly resolution at the Concordia station (75°06'S, 123°20'E), on the Antarctic plateau, and analysed for major and trace elements in both dissolved and particulate (i.e. insoluble particles, >0.45 μm) phase. Additional surface snow samples were collected with daily resolution, for the determination of sea-salt sodium and not-sea-salt calcium, in order to support the discussion on the seasonal variations of trace elements. Concentrations of alkaline and alkaline-earth elements were higher in winter (April-October) than in summer (November-March) by a factor of 1.2-3.3, in agreement with the higher concentration of sea-salt atmospheric particles reaching the Antarctic plateau during the winter. Similarly, trace elements were generally higher in winter by a factor of 1.2-1.5, whereas Al and Fe did not show any significant seasonal trend. Partitioning between dissolved and particulate phases did not change with the sampling period, but it depended only on the element: alkaline and alkaline-earth elements, as well as Co, Cu, Mn, Pb and Zn were for the most part (>80%) in the dissolved phase, whereas Al and Fe were mainly associated with the particulate phase (>80%) and Cd, Cr, V were nearly equally distributed between the phases. Finally, the estimated marine and crustal enrichment factors indicated that Cd, Cr, Cu, Pb and Zn have a dominant anthropogenic origin, with a possible contribution from the Concordia station activities.

  11. Evaluation of acute copper toxicity to larval fathead minnows (Pimephales promelas) in soft surface waters.

    Science.gov (United States)

    Van Genderen, Eric J; Ryan, Adam C; Tomasso, Joseph R; Klaine, Stephen J

    2005-02-01

    The hardness-based regulatory approach for Cu prescribes an extrapolation of the toxicity-versus-hardness relationship to low hardness (hardness surface waters. Seasonal water sampling was conducted at 24 sites throughout South Carolina, USA, to determine the site-specific influences of soft surface-water conditions on acute Cu toxicity. Concurrent toxicity tests in laboratory water, matched for hardness and alkalinity (modified method), also were conducted to allow calculation of water-effect ratios (WERs). In addition, tests were conducted at recommended hardness levels (recommended method) for comparison of WER methodology in soft water. Surface-water conditions (average+/-standard deviation, n = 53) were hardness of 16+/-8 mg/L as CaCO3, alkalinity of 18+/-11 mg/L as CaCO3, and dissolved organic carbon of 6+/-4 mg/L. Dissolved Cu 48-h median lethal concentration (LC50) values varied nearly 45-fold across the dataset and greater than four-fold at individual sites. Spatial (p hardness-based equation for Cu at 50 mg/L or less as CaCO3 would adequately protect fathead minnow populations in soft surface waters. The WER results presented here demonstrate the inconsistency between hardness-based criteria and the methodology for deriving site-specific water-quality criteria in low-hardness waters.

  12. Laboratory studies of dissolved radiolabelled microcystin-LR in lake water

    DEFF Research Database (Denmark)

    Hyenstrand, Per; Rohrlack, Thomas; Beattie, Kenneth A

    2003-01-01

    in May before the cyanobacterial bloom season and low increases in the radioactivity of particulate fractions occurred with an approx. halving of the cyano-toxin during 4 days. The radioactivity of the dissolved fraction remained stable and there was no significant formation of radiolabelled inorganic...

  13. Development and application of a shipboard method for spectrophotometric determination of trace dissolved manganese in estuarine and coastal waters

    Science.gov (United States)

    Feng, Sichao; Huang, Yongming; Yuan, Dongxing; Zhu, Yong; Zhou, Tingjin

    2015-01-01

    A shipboard method for the determination of trace dissolved manganese in estuarine and coastal waters was developed using a technique of reverse flow injection analysis, which adopted a 1-m liquid waveguide capillary cell and spectrophotometric detection of manganese derivation with 1-(2-pyridylazo)-2-naphthol (PAN). The design of dual-sample-carrier speeded up the sample throughput and eliminated the Schlieren effect. The salinity of estuarine and coastal waters caused a huge increase in the blank absorption value at the maximum absorption wavelength; therefore, a less sensitive detection wavelength was selected to achieve a low blank value while the method sensitivity was not significantly decreased. Method parameters were optimized. The salinity effect from estuarine and coastal waters was carefully investigated, and interference from iron was evaluated. The proposed method had high sensitivity with a detection limit of 3.0 nmol L-1 and a wide linear range of 10-1500 nmol L-1 for dissolved manganese in seawater (S=35). The analytical results of five water samples with different salinities obtained using the proposed method showed good agreement with those using a reference ICP-MS method. The sample throughput of the proposed method was 120 h-1, which was capable of obtaining high spatial and temporal resolution data in shipboard analysis. The proposed method had the advantages of convenient application in estuarine and coastal waters with different salinities, low detection limit, as well as high sample throughput. The proposed method was successfully applied to a 24 h on-line analysis and a shipboard underway analysis of dissolved manganese in the Jiulongjiang Estuary.

  14. Water chemistry of surface waters affected by the Fourmile Canyon wildfire, Colorado, 2010-2011

    Science.gov (United States)

    McCleskey, R. Blaine; Writer, Jeffrey H.; Murphy, Sheila F.

    2012-01-01

    In September 2010, the Fourmile Canyon fire burned about 23 percent of the Fourmile Creek watershed in Boulder County, Colo. Water-quality sampling of Fourmile Creek began within a month after the wildfire to assess its effects on surface-water chemistry. Water samples were collected from five sites along Fourmile Creek (above, within, and below the burned area) monthly during base flow, twice weekly during snowmelt runoff, and at higher frequencies during storm events. Stream discharge was also monitored. Water-quality samples were collected less frequently from an additional 6 sites on Fourmile Creek, from 11 tributaries or other inputs, and from 3 sites along Boulder Creek. The pH, electrical conductivity, temperature, specific ultraviolet absorbance, total suspended solids, and concentrations (dissolved and total) of major cations (calcium, magnesium, sodium, and potassium), anions (chloride, sulfate, alkalinity, fluoride, and bromide), nutrients (nitrate, ammonium, and phosphorus), trace metals (aluminum, arsenic, boron, barium, beryllium, cadmium, cobalt, chromium, copper, iron, mercury, lithium, manganese, molybdenum, nickel, lead, rubidium, antimony, selenium, strontium, vanadium, and zinc), and dissolved organic carbon are here reported for 436 samples collected during 2010 and 2011.

  15. 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.

  16. Measuring water quality from individual fractures in open wellbores using hydraulic isolation and the dissolved oxygen alteration method

    Science.gov (United States)

    Vitale, Sarah A.; Robbins, Gary A.

    2017-08-01

    This study describes a low-cost method for sampling individual fractures in open wellbores in crystalline bedrock utilizing naturally occurring flow conditions in the well. The method entails using the dissolved oxygen alteration method (DOAM) to identify transmissive fractures and vertical flow direction. After obtaining information about relative hydraulic gradients, flow direction in the well is modified using a single control pump to isolate fractures of interest for sampling. Additional dissolved oxygen, injected during the DOAM procedure, serves as a tracer to ensure the water quality in the sampling zone is characteristic of the fracture of interest by requiring a tracer-free zone prior to sampling. Sampling procedures are described conceptually for nine bedrock wells with varying flow conditions containing one, two, or three transmissive inflowing fractures. The method was demonstrated in two crystalline bedrock wells containing one and two transmissive inflowing fractures.

  17. Seasonal variations of dissolved and particulate copper species in estuarine waters

    Science.gov (United States)

    Waeles, Matthieu; Riso, Ricardo D.; Le Corre, Pierre

    2005-01-01

    This one-year survey conducted in the macrotidal estuary of Penzé (Brittany, Western part of the Channel, France) was aimed at examining the variations of the various dissolved and particulate copper species. Ten field stations along the whole freshwater-seawater mixing zone were sampled each month. Different biogeochemical parameters (SPM, chl- a, pH and DOC) were also measured. The levels in total dissolved and total particulate copper ranged from 1.8 to 9.5 nM and from 5 to 98 μg g -1, respectively; such amounts are indicative of a pollution-free system. Extractable C 18 copper (non-polar hydrophobic organic copper species), in winter and spring, accounted for 30-40% of the total dissolved copper. In summer, this contribution rapidly rose to 60% in the salinity range 20-30; over the same period of time, total particulate copper decreased. The change in dissolved copper speciation and the lowering of particulate copper concentrations were attributed to the release of strong organic ligands by phytoplankton. Our field data evidenced a highly variable behaviour for the various copper species over the seasonal cycle, and then led us to identify the following mechanisms: (i) metal desorption from organic river-flown particles (winter and spring), (ii) metal desorption from resuspended sediment in the upstream section (summer), (iii) competition between particles, non-extractable C 18 organic ligands and phytoplankton-released extractable C 18 organic ligands to complex copper in the downstream section (summer), and (iv) removal of non-extractable C 18 organic copper by adsorption (autumn). Dissolved copper species fluxes were assessed: most of metal inputs to the estuary (60-74%) corresponded to non-extractable C 18 organic copper. Winter and spring metal output fluxes were mainly constituted of non-extractable C 18 organic complexes; on the other hand, extractable C 18 organic complexes were predominant in summer and autumn output fluxes.

  18. Vertical distribution and temporal dynamics of dissolved (137)Cs concentrations in soil water after the Fukushima Dai-ichi Nuclear Power Plant accident.

    Science.gov (United States)

    Iwagami, Sho; Onda, Yuichi; Tsujimura, Maki; Hada, Manami; Pun, Ishwar

    2017-11-01

    Radiocesium ((137)Cs) migration from headwater forested areas to downstream rivers has been investigated in many studies since the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident, which was triggered by a catastrophic earthquake and tsunami on 11 March 2011. The accident resulted in the release of a huge amount of radioactivity and its subsequent deposition in the environment. A large part of the radiocesium released has been shown to remain in the forest. The dissolved (137)Cs concentration and its temporal dynamics in river water, stream water, and groundwater have been reported, but reports of dissolved (137)Cs concentration in soil water remain sparse. In this study, soil water was sampled, and the dissolved (137)Cs concentrations were measured at five locations with different land-use types (mature/young cedar forest, broadleaf forest, meadow land, and pasture land) in Yamakiya District, located 35 km northwest of FDNPP from July 2011 to October 2012. Soil water samples were collected by suction lysimeters installed at three different depths at each site. Dissolved (137)Cs concentrations were analyzed using a germanium gamma ray detector. The dissolved (137)Cs concentrations in soil water were high, with a maximum value of 2.5 Bq/L in July 2011, and declined to less than 0.32 Bq/L by 2012. The declining trend of dissolved (137)Cs concentrations in soil water was fitted to a two-component exponential model. The rate of decline in dissolved (137)Cs concentrations in soil water (k1) showed a good correlation with the radiocesium interception potential (RIP) of topsoil (0-5 cm) at the same site. Accounting for the difference of (137)Cs deposition density, we found that normalized dissolved (137)Cs concentrations of soil water in forest (mature/young cedar forest and broadleaf forest) were higher than those in grassland (meadow land and pasture land). Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Inputs of iron, manganese and aluminium to surface waters of the Northeast Atlantic Ocean and the European continental shelf

    NARCIS (Netherlands)

    Jong, Jeroen T.M. de; Boyé, Marie; Gelado-Caballero, Maria D.; Timmermans, Klaas R.; Veldhuis, Marcel J.W.; Nolting, Rob F.; Berg, Constant M.G. van den; Baar, Hein J.W. de

    2007-01-01

    Dissolved Fe, Mn and Al concentrations (dFe, dMn and dAl hereafter) in surface waters and the water column of the Northeast Atlantic and the European continental shelf are reported. Following an episode of enhanced Saharan dust inputs over the Northeast Atlantic Ocean prior and during the cruise in

  20. 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

  1. Bench-Scale and Pilot-Scale Treatment Technologies for the Removal of Total Dissolved Solids from Coal Mine Water: A Review

    Science.gov (United States)

    Coal mine water (CMW) is typically treated to remove suspended solids, acidity, and soluble metals, but high concentrations of total dissolved solids (TDS) have been reported to impact the environment at several CMW discharge points. Consequently, various states have establishe...

  2. Dissolved and Particulate lipids in the Arabian Sea off Bombay coast

    Digital Repository Service at National Institute of Oceanography (India)

    Nandakumar, K.; Bhosle, N.B.; Wagh, A.B.

    Concentrations of dissolved lipid ranged from 20-140 mu g.l-1 in the surface and 30-150 mu g.l in near bottom waters while particulates lipid varied from 6-109 and 29-133 mu g.l-1 respectively in surface and bottom waters. Dissolved lipid...

  3. 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…

  4. 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

  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. Hydrology of the Poverty Bay flats aquifers, New Zealand: recharge mechanisms, evolution of the isotopic composition of dissolved inorganic carbon, and ground-water ages

    Science.gov (United States)

    Taylor, C. B.

    1994-06-01

    With the exception of water-bearing remnants of earlier fluvial gravels overlying basement, the sediments of the Poverty Bay flats have accumulated during the postglacial period of the past 14 000 years, and have been tilted and deformed by recent tectonism. A sequence of gravel aquifers, separated by poorly permeable silt layers, lies between surface and basement, which is at depths varying between 50 and 200 m. A shallow sand/silt aquifer is situated near the coast. This study applies evidence of chemical and isotopic properties of river and ground water to clarify the recharge mechanisms, chemical evolution and age of the ground water in the aquifers. Particular attention is paid to the evolution of dissolved inorganic carbon content, applying carbon-14 data measured by accelerator mass spectrometry. Most of the ground water is recharged from the Waipaoa River, which flows across the flats and discharges into Poverty Bay. The two deepest aquifers (Matokitoki and Makauri) are both tritium-free; the deeper Matokitoki Gravels yield water of age about 4300 years since recharge (possibly up to 1300 years greater), but the Makauri water is no older than 100-200 years, discharging slowly through overlying aquitards near the limit of closest approach to the present coast.

  7. The dependence on temperature and salinity of dissolved

    NARCIS (Netherlands)

    Bakker, Dorothee C.E.; Baar, Hein J.W. de; Jong, Edwin de

    1999-01-01

    Recurring latitudinal patterns of the dissolved inorganic carbon (DIC) content and the fugacity of CO2 (fCO2) were observed in East Atlantic surface waters with strong gradients at hydrographic fronts. The dissolved inorganic carbon chemistry clearly displayed the effects of oceanic circulation and

  8. Halogens in pore water of peat bogs – the role of peat decomposition and dissolved organic matter

    Directory of Open Access Journals (Sweden)

    H. Biester

    2006-01-01

    Full Text Available Halogens are strongly enriched in peat and peatlands and such they are one of their largest active terrestrial reservoir. The enrichment of halogens in peat is mainly attributed to the formation of organohalogens and climatically controlled humification processes. However, little is known about release of halogens from the peat substrate and the distribution of halogens in the peat pore water. In this study we have investigated the distribution of chlorine, bromine and iodine in pore water of three pristine peat bogs located in the Magellanic Moorlands, southern Chile. Peat pore waters were collected using a sipping technique, which allows in situ sampling down to a depth greater than 6m. Halogens and halogen species in pore water were determined by ion-chromatography (IC (chlorine and IC-ICP-MS (bromine and iodine. Results show that halogen concentrations in pore water are 15–30 times higher than in rainwater. Mean concentrations of chlorine, bromine and iodine in pore water were 7–15 mg l−1, 56–123 μg l−1, and 10–20 μg l−1, which correspond to mean proportions of 10–15%, 1–2.3% and 0.5–2.2% of total concentrations in peat, respectively. Organobromine and organoiodine were the predominant species in pore waters, whereas chlorine in pore water was mostly chloride. Advection and diffusion of halogens were found to be generally low and halogen concentrations appear to reflect release from the peat substrate. Release of bromine and iodine from peat depend on the degree of peat degradation, whereas this relationship is weak for chlorine. Relatively higher release of bromine and iodine was observed in less degraded peat sections, where the release of dissolved organic carbon (DOC was also the most intensive. It has been concluded that the release of halogenated dissolved organic matter (DOM is the predominant mechanism of iodine and bromine release from peat.

  9. Why are the Wetland and Surface Waters Sometimes Colored in the Croton Watershed (New York)?

    Science.gov (United States)

    Siegel, D. I.; Otz, M.; Otz, I.; McKenzie, J. M.; Hassett, J.; Bartos, J.; Tedorov, S.; Flusche, M. A.; Lesniak, K. A.; Tasillo, J.; Cuomo, D.

    2001-05-01

    The Croton Reservoir that provides water to New York City periodically has color problems in late fall. Consequently, a synoptic sampling of 92 streams draining wetlands in the watershed was done to determine whether water color is related to dissolved organic carbon, iron and manganese concentrations. In addition, major solute concentrations were measured to evaluate overall surface-water quality. Gelbstoff color (at 440nm wavelength) and platinum-cobalt color are well correlated. These measures of color also correlate to dissolved organic carbon and dissolved iron concentrations. Proportions of sodium and chloride in surface waters are identical to that of road salt. The tight covariance between Na and Cl reflects simple dilution. A plot of chloride and nitrate concentrations also shows a direct relationship, but with substantial scatter. This scatter probably reflects biochemical processing of nitrate and different amounts of nitrate and salt contributed to subwatersheds at different scales. The Croton watershed is underlain by metasedimentary and crystalline rocks, and minor marble overlain by thin glacial drift. Concentrations of Ca and Mg are greater than that predicted by alkalinity equivalence, based on simple dissolution of carbonate minerals by carbonic acid. These greater base cation concentrations supports the hypothesis that silicate minerals provide most of the base cations in the watershed, except for the sodium released by dissolving road salt.

  10. Particulate products and new polymers for a more efficient removal of dissolved organic matter in drinking water resources.

    Science.gov (United States)

    Treguer, R; Couvert, A; Wolbert, D; Suty, H; Randon, G

    2007-08-01

    More restricting legislation on dissolved organic carbon (DOC), especially when applied to waters with high DOC contents and low turbidity, urges the drinking water industry to improve the removal of dissolved organic matter (DOM). Jar tests were carried out on sand-filtered water (SFW) and raw water (RW), with respectively 50 different particulate compounds and different cationic polymers. Analytical measurements of DOC and UV absorbance at 254 nm, as well as a characterisation by size exclusion chromatography (SEC), were performed in order to determine the efficiency of the process. Experiments on SFW showed that activated carbon was the only compound able to remove efficiently the residual DOC remaining after conventional treatments (up to 40% of reduction). Other trials on RW using mixes of ferric chloride (FeCl3) and cationic polymers (polyamines and polyDADMAC) pointed out that the molecular mass and the reticulation ratios have a significant influence on the efficiency of the treatment. Finally, the addition of activated carbons to the previous reagents significantly improved the observed removal efficiencies by similar amounts.

  11. Speciation of rare earth elements in natural terrestrial waters: assessing the role of dissolved organic matter from the modeling approach

    Science.gov (United States)

    Tang, Jianwu; Johannesson, Karen H.

    2003-07-01

    Humic Ion-Binding Model V, which focuses on metal complexation with humic and fulvic acids, was modified to assess the role of dissolved natural organic matter in the speciation of rare earth elements (REEs) in natural terrestrial waters. Intrinsic equilibrium constants for cation-proton exchange with humic substances (i.e., p KMHA for type A sites, consisting mainly of carboxylic acids), required by the model for each REE, were initially estimated using linear free-energy relationships between the first hydrolysis constants and stability constants for REE metal complexation with lactic and acetic acid. p KMHA values were further refined by comparison of calculated Model V "fits" to published data sets describing complexation of Eu, Tb, and Dy with humic substances. A subroutine that allows for the simultaneous evaluation of REE complexation with inorganic ligands (e.g., Cl -, F -, OH -, SO 42-, CO 32-, PO 43-), incorporating recently determined stability constants for REE complexes with these ligands, was also linked to Model V. Humic Ion-Binding Model V's ability to predict REE speciation with natural organic matter in natural waters was evaluated by comparing model results to "speciation" data determined previously with ultrafiltration techniques (i.e., organic acid-rich waters of the Nsimi-Zoetele catchment, Cameroon; dilute, circumneutral-pH waters of the Tamagawa River, Japan, and the Kalix River, northern Sweden). The model predictions compare well with the ultrafiltration studies, especially for the heavy REEs in circumneutral-pH river waters. Subsequent application of the model to world average river water predicts that organic matter complexes are the dominant form of dissolved REEs in bulk river waters draining the continents. Holding major solute, minor solute, and REE concentrations of world average river water constant while varying pH, the model suggests that organic matter complexes would dominate La, Eu, and Lu speciation within the pH ranges of 5

  12. 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,...

  13. 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.

  14. 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.

  15. 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...

  16. 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...

  17. 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...

  18. 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...

  19. Comparing molecular composition of dissolved organic matter in soil and stream water: Influence of land use and chemical characteristics.

    Science.gov (United States)

    Seifert, Anne-Gret; Roth, Vanessa-Nina; Dittmar, Thorsten; Gleixner, Gerd; Breuer, Lutz; Houska, Tobias; Marxsen, Jürgen

    2016-11-15

    Electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) was used to examine the molecular composition of dissolved organic matter (DOM) from soils under different land use regimes and how the DOM composition in the catchment is reflected in adjacent streams. The study was carried out in a small area of the Schwingbach catchment, an anthropogenic-influenced landscape in central Germany. We investigated 30 different soil water samples from 4 sites and different depths (managed meadow (0-5cm, 40-50cm), deciduous forest (0-5cm), mixed-coniferous forest (0-5cm) and agricultural land (0-5cm, 40-50cm)) and 8 stream samples. 6194 molecular formulae and their magnitude-weighted parameters ((O/C)w, (H/C)w, (N/C)w, (AI-mod)w, (DBE/C)w, (DBE/O)w, (DBE-O)w, (C#)w, (MW)w) were used to describe the molecular composition of the samples. The samples can be roughly divided in three groups. Group 1 contains samples from managed meadow 40-50cm and stream water, which are characterized by high saturation compared to samples from group 2 including agricultural samples and samples from the surface meadow (0-5cm), which held more nitrogen containing and aromatic compounds. Samples from both forested sites (group 3) are characterized by higher molecular weight and O/C ratio. Environmental parameters vary between sites and among these parameters pH and nitrate significantly affect chemical composition of DOM. Results indicate that most DOM in streams is of terrestrial origin. However, 120 molecular formulae were detected only in streams and not in any of the soil samples. These compounds share molecular formulae with peptides, unsaturated aliphatics and saturated FA-CHO/FA-CHOX. Compounds only found in soil samples are much more aromatic, have more double bonds and a much lower H/C ratio but higher oxygen content, which indicates the availability of fresh plant material and less microbial processed material compared to stream samples. Copyright

  20. 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

  1. Effect of dissolved gases in water on acoustic cavitation and bubble growth rate in 0.83 MHz megasonic of interest to wafer cleaning.

    Science.gov (United States)

    Kang, Bong-Kyun; Kim, Min-Su; Park, Jin-Goo

    2014-07-01

    Changes in the cavitation intensity of gases dissolved in water, including H2, N2, and Ar, have been established in studies of acoustic bubble growth rates under ultrasonic fields. Variations in the acoustic properties of dissolved gases in water affect the cavitation intensity at a high frequency (0.83 MHz) due to changes in the rectified diffusion and bubble coalescence rate. It has been proposed that acoustic bubble growth rates rapidly increase when water contains a gas, such as hydrogen faster single bubble growth due to rectified diffusion, and a higher rate of coalescence under Bjerknes forces. The change of acoustic bubble growth rate in rectified diffusion has an effect on the damping constant and diffusivity of gas at the acoustic bubble and liquid interface. It has been suggested that the coalescence reaction of bubbles under Bjerknes forces is a reaction determined by the compressibility and density of dissolved gas in water associated with sound velocity and density in acoustic bubbles. High acoustic bubble growth rates also contribute to enhanced cavitation effects in terms of dissolved gas in water. On the other hand, when Ar gas dissolves into water under ultrasound field, cavitation behavior was reduced remarkably due to its lower acoustic bubble growth rate. It is shown that change of cavitation intensity in various dissolved gases were verified through cleaning experiments in the single type of cleaning tool such as particle removal and pattern damage based on numerically calculated acoustic bubble growth rates. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. 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.

  3. Chemical characteristics of dissolved organic matter (DOM) in relation to heavy metal concentrations in soil water from boreal peatlands after clear-cut harvesting

    Science.gov (United States)

    Kiikkilä, O.; Nieminen, T.; Starr, M.; Ukonmaanaho, L.

    2012-04-01

    Boreal peatlands form an important terrestrial carbon reserve and are a major source of dissolved organic matter (DOM) to surface waters, particularly when disturbed through forestry practices such as draining or timber harvesting. Heavy metals show a strong affinity to organic matter and so, along with DOM, heavy metals can be mobilized and transported from the soil to surface waters and sediments where they may become toxic to aquatic organisms and pass up the food chain. The complexation of heavy metals with DOM can be expected to be related and determined by the chemical characteristics of DOM and oxidation/reducing conditions in the peat. We extracted interstitial water from peat samples and determined the concentrations of dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and Al, Cu, Zn and Fe in various fractions of DOM isolated by adsorption properties (XAD-8 fractionation) and molecular-weight (ultrafiltration). The peat samples were taken from 0-30 and 30-50 cm depth in drained peatland catchments two years after whole-tree or stem-only clear-cut harvesting (Scots pine or Norway spruce) had been carried out. The samples from the upper layer had been subject to alternating saturation/aeration conditions while the deeper layer had been continuously under the water table. The fractionation of DOC and DON according to both adsorption properties and molecular-weight fractions clearly differed between the upper and lower peat layers. While the hydrophobic acid fraction contained proportionally more DOC and DON than the hydrophilic acid fraction in the upper peat layer the results were vice versa in the lower peat layer. High-molecular-weight compounds (> 100 kDa) were proportionally more abundant in the upper and low-molecular-weight compounds (< 1 kDa) in the lower peat layer. These differences are assumed to reflect differences in the aerobic/ anaerobic conditions and degree of decomposition between the two layers. The concentrations of Zn, Al

  4. 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.

  5. Spatio-temporal distribution of cell-bound and dissolved geosmin in Wahnbach Reservoir: Causes and potential odour nuisances in raw water.

    Science.gov (United States)

    Jähnichen, Sabine; Jäschke, Kathrin; Wieland, Falk; Packroff, Gabriele; Benndorf, Jürgen

    2011-10-15

    In many lakes and reservoirs, problems caused by off-flavours are known to be particularly associated with the occurrence of planktonic and benthic cyanobacteria. Frequently observed objectionable taste and odorous products of cyanobacteria are geosmin and 2-methylisoborneol. Investigations focused on the littoral zone of Wahnbach Reservoir (Germany) revealed that benthic cyanobacteria were present in this oligotrophic drinking water reservoir. Benthic cyanobacteria were found in the depth horizon between 1.75 m and 11 m, particularly on south-exposed slopes. This spatial distribution indicates a possible key role of the underwater light climate. Moreover, cell-bound and dissolved geosmin were detected in corresponding littoral samples. Both fractions were subjected to spatial and primarily temporal variations with maximum concentrations at the end of summer. However, a substantial lowering of the water level caused a diminution of cyanobacterial growth. Due to the drawdown of the water level concentrations of cell-bound geosmin and pigments (as a proxy of cyanobacterial biomass) were remarkably reduced, and dissolved geosmin was never detected during this phase. Except for the influence of water level fluctuation no other abiotic variables had a significant influence on pigment and geosmin concentrations. From geosmin concentrations detected in the littoral zone, the probability of serious episodes of odour events in the raw water of the Wahnbach Reservoir was estimated. Hence, the probability that the raw water was affected by geosmin was minor, which was supported by routine flavour profiles. Nevertheless, the study shows that odorous episodes caused by benthic cyanobacteria are likely to develop even in an oligotrophic lake or reservoir when these cyanobacteria, and consequently odorous production, proliferate. In principle, such a proliferation cannot be excluded as nutrients are available from the sediment pore water, and underwater light at the sediment

  6. 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

  7. 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

  8. Tracking changes in the optical properties and molecular composition of dissolved organic matter during drinking water production.

    Science.gov (United States)

    Lavonen, E E; Kothawala, D N; Tranvik, L J; Gonsior, M; Schmitt-Kopplin, P; Köhler, S J

    2015-11-15

    Absorbance, 3D fluorescence and ultrahigh resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FT-ICR-MS) were used to explain patterns in the removal of chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) at the molecular level during drinking water production at four large drinking water treatment plants in Sweden. When dissolved organic carbon (DOC) removal was low, shifts in the dissolved organic matter (DOM) composition could not be detected with commonly used DOC-normalized parameters (e.g. specific UV254 absorbance - SUVA), but was clearly observed by using differential absorbance and fluorescence or ESI-FT-ICR-MS. In addition, we took a novel approach by identifying how optical parameters were correlated to the elemental composition of DOM by using rank correlation to connect optical properties to chemical formulas assigned to mass peaks from FT-ICR-MS analyses. Coagulation treatment selectively removed FDOM at longer emission wavelengths (450-600 nm), which significantly correlated with chemical formulas containing oxidized carbon (average carbon oxidation state ≥ 0), low hydrogen to carbon ratios (H/C: average ± SD = 0.83 ± 0.13), and abundant oxygen-containing functional groups (O/C = 0.62 ± 0.10). Slow sand filtration was less efficient in removing DOM, yet selectively targeted FDOM at shorter emission wavelengths (between 300 and 450 nm), which commonly represents algal rather than terrestrial sources. This shorter wavelength FDOM correlated with chemical formulas containing reduced carbon (average carbon oxidation state ≤ 0), with relatively few carbon-carbon double bonds (H/C = 1.32 ± 0.16) and less oxygen per carbon (O/C = 0.43 ± 0.10) than those removed during coagulation. By coupling optical approaches with FT-ICR-MS to characterize DOM, we were for the first time able to confirm the molecular composition of absorbing and fluorescing DOM selectively targeted during drinking

  9. Isotopic analysis of dissolved organic carbon in produced water brines by wet chemical oxidation and cavity ring-down spectroscopy

    Science.gov (United States)

    Thomas, Randal; Conaway, Christopher; Saad, Nabil; Kharaka, Yousif

    2013-04-01

    Identification of fluid migration and escape from intentionally altered subsurface geologic systems, such as in hydraulic fracturing, enhanced oil recovery, and carbon sequestration activities, is an important issue for environmental regulators based on the traction that the "fracking" process is gathering across the United States. Given diverse injected fluid compositions and the potential for toxic or regulated compounds to be released, one of the most important steps in the process is accurately identifying evidence of injected fluid escape during and after injection processes. An important tool in identifying differences between the natural groundwater and injected fluid is the isotopic composition of dissolved constituents including inorganic components such as Sr and carbon isotopes of the dissolved organic compounds. Since biological processes in the mesothermal subsurface can rapidly alter the organic composition of a fluid, stable carbon isotopes of the dissolved organic compounds (DOC) are an effective means to identify differences in the origin of two fluids, especially when coupled with inorganic compound analyses. The burgeoning field of cavity ring-down spectroscopy (CRDS) for isotopic analysis presents an opportunity to obtain rapid, reliable and cost-effective isotopic measurements of DOC in potentially affected groundwater for the identification of leakage or the improvement of hydrogeochemical pathway models. Here we adapt the use of the novel hyphenated TOC-CRDS carbon isotope analyzer for the analysis of DOC in produced water by wet oxidation and describe the methods to evaluate performance and obtain useful information at higher salinities. Our methods are applied to a specific field example in a CO2-enhanced EOR field in Cranfield, Mississippi (USA) as a means to demonstrate the ability to distinguish natural and injected DOC using the stable isotopic composition of the dissolved organic carbon when employing the novel TOC-CRDS instrumentation

  10. Efficiency Research on Meat Industry Waste Water Treatment Applying the Method of Dissolved Air Flotation

    OpenAIRE

    Valentinas Gerasimovas; Robertas Urbanavičius

    2012-01-01

    To protect environment from industrial pollution, strict requirements for waste water treatment are imposed. The purpose of research is to establish an optimal ratio of saturated liquid and meat industry waste water. Research included JCC “Traidenis” waste water treatment system installed in JSC “BHJ Baltic”. Investigations into treated waste water indicated that an optimal ratio of waste water and saturated liquid was 2/1 under duration time of 8 minutes. Efficient waste water treatment made...

  11. Dissolved and particulate metals in water from Sonora Coast: a pristine zone of Gulf of California: metals in water from Sonora Coast.

    Science.gov (United States)

    García-Rico, Leticia; Tejeda-Valenzuela, Lourdes; Jara-Marini, Martín E; Gómez-Álvarez, Agustín

    2011-05-01

    The purpose of this study was to investigate the distribution of metals (Cd, Pb, Hg, Cu, Fe, Mn, and Zn) in dissolved and particulate fractions in seawater from Bacochibampo Bay, Northern part of Mexico. Water samples were collected from November 2004 to October 2005. Metal analysis was done by graphite furnace atomic absorption spectroscopy. Results indicated highest concentrations of dissolved Cd and Zn in the sites localized at the mouth and center of the bay. During summer and spring, the highest levels of Cd, Mn, and Fe were detected, Zn in fall, and Pb and Cu in winter and spring. Mercury was the only metal that was not found in this fraction. In particulate fraction, Fe, Hg, and Mn were the most abundant elements in all the sampling sites, followed by Zn, Cu, Pb, and Cd. The highest levels of the majority of the metals were observed in the coastline, suggesting a continental and/or urban source for these chemicals. The highest level of Cd was detected during the summer and the rest of the metals in the fall. Statistically significant correlations were observed between dissolved and particulate forms of Pb:Mn, Cu:Fe, and Cu:Mn. The mean partition coefficient values were as follows: Fe>Mn>Cu>Pb>Cd>Zn. All dissolved metal concentrations found, except Pb, were lower than EPA-recommended water quality values. The levels of dissolved metals in this study reveal low bioavailability and toxic potential. However, further toxicological and sediment chemistry studies in this area are needed for a full risk assessment.

  12. What Happened when a Superhydrophobic Surface was Immersed in Water? A Study by Optical Transmission Microscopy

    DEFF Research Database (Denmark)

    Søgaard, Emil; Andersen, Nis Korsgaard; Smistrup, Kristian

    2014-01-01

    , the wetting transitions had a stochastic nature, which may result from the diffusion of dissolved gas molecules in the water between neighboring cavities. Further, we compared the contact angle properties of two polymeric materials (COC and PP) with moderate hydrophobicity. We attributed the different water...... repellent properties of the two materials to a difference in the wetting of their nanostructures. The experimental observations indicate that both the diffusion of gas molecules in water, and the geometry of nanostructures influence the sustainability of superhydrophobicity of surfaces under water...

  13. Equilibrator-based measurements of dissolved nitrous oxide in the surface ocean using an integrated cavity output laser absorption spectrometer

    Science.gov (United States)

    Grefe, I.; Kaiser, J.

    2014-06-01

    Dissolved nitrous oxide (N2O) concentrations are usually determined by gas chromatography (GC). Here we present laboratory tests and initial field measurements using a novel setup comprising a commercially available laser-based analyser for N2O, carbon monoxide and water vapour coupled to a glass-bed equilibrator. This approach is less labour-intensive and provides higher temporal and spatial resolution than the conventional GC technique. The standard deviation of continuous equilibrator or atmospheric air measurements was 0.2 nmol mol-1 (averaged over 5 min). The short-term repeatability for reference gas measurements within 1 h of each other was 0.2 nmol mol-1 or better. Another indicator of the long-term stability of the analyser is the standard deviation of the calibrated N2O mole fraction in marine air, which was between 0.5 and 0.7 nmol mol-1. The equilibrator measurements were compared with purge-and-trap gas chromatography-mass spectrometry (GC-MS) analyses of N2O concentrations in discrete samples from the Southern Ocean and showed agreement to within the 2% measurement uncertainty of the GC-MS method. The equilibrator response time to concentration changes in water was from 142 to 203 s, depending on the headspace flow rate. The system was tested at sea during a north-to-south transect of the Atlantic Ocean. While the subtropical gyres were slightly undersaturated, the equatorial region was a source of nitrous oxide to the atmosphere, confirming previous findings (Forster et al., 2009). The ability to measure at high temporal and spatial resolution revealed submesoscale variability in dissolved N2O concentrations. Mean sea-to-air fluxes in the tropical and subtropical Atlantic ranged between -1.6 and 0.11 μmol m-2 d-1 and confirm that the subtropical Atlantic is not an important source region for N2O to the atmosphere, compared to global average fluxes of 0.6-2.4 μmol m-2 d-1. The system can be easily modified for autonomous operation on voluntary

  14. Biodegradability and Molecular Composition of Dissolved Organic Nitrogen in Urban Stormwater Runoff and Outflow Water from a Stormwater Retention Pond.

    Science.gov (United States)

    Lusk, Mary G; Toor, Gurpal S

    2016-04-01

    Dissolved organic nitrogen (DON) can be a significant part of the reactive N in aquatic ecosystems and can accelerate eutrophication and harmful algal blooms. A bioassay method was coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) to determine the biodegradability and molecular composition of DON in the urban stormwater runoff and outflow water from an urban stormwater retention pond. The biodegradability of DON increased from 10% in the stormwater runoff to 40% in the pond outflow water and DON was less aromatic and had lower overall molecular weight in the pond outflow water than in the stormwater runoff. More than 1227 N-bearing organic formulas were identified with FT-ICR-MS in the stormwater runoff and pond outflow water, which were only 13% different in runoff and outflow water. These molecular formulas represented a wide range of biomolecules such as lipids, proteins, amino sugars, lignins, and tannins in DON from runoff and pond outflow water. This work implies that the urban infrastructure (i.e., stormwater retention ponds) has the potential to influence biogeochemical processes in downstream water bodies because retention ponds are often a junction between the natural and the built environment.

  15. Removal of dissolved organic carbon by aquifer material: Correlations between column parameters, sorption isotherms and octanol-water partition coefficient.

    Science.gov (United States)

    Pradhan, Snigdhendubala; Boernick, Hilmar; Kumar, Pradeep; Mehrotra, Indu

    2016-07-15

    The correlation between octanol-water partition coefficient (KOW) and the transport of aqueous samples containing single organic compound is well documented. The concept of the KOW of river water containing the mixture of organics was evolved by Pradhan et al. (2015). The present study aims at determining the KOW and sorption parameters of synthetic aqueous samples and river water to finding out the correlation, if any. The laboratory scale columns packed with aquifer materials were fed with synthetic and river water samples. Under the operating conditions, the compounds in the samples did not separate, and all the samples that contain more than one organic compound yielded a single breakthrough curve. Breakthrough curves simulated from sorption isotherms were compared with those from the column runs. The sorption parameters such as retardation factor (Rf), height of mass transfer zone (HMTZ), rate of mass transfer zone (RMTZ), breakpoint column capacity (qb) and maximum column capacity (qx) estimated from column runs, sorption isotherms and models developed by Yoon-Nelson, Bohart-Adam and Thomas were in agreement. The empirical correlations were found between the KOW and sorption parameters. The transport of the organics measured as dissolved organic carbon (DOC) through the aquifer can be predicted from the KOW of the river water and other water samples. The novelty of the study is to measure KOW and to envisage the fate of the DOC of the river water, particularly during riverbank filtration. Statistical analysis of the results revealed a fair agreement between the observed and computed values.

  16. 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.

  17. Characterization of water quality and simulation of temperature, nutrients, biochemical oxygen demand, and dissolved oxygen in the Wateree River, South Carolina, 1996-98

    Science.gov (United States)

    Feaster, Toby D.; Conrads, Paul A.

    2000-01-01

    In May 1996, the U.S. Geological Survey entered into a cooperative agreement with the Kershaw County Water and Sewer Authority to characterize and simulate the water quality in the Wateree River, South Carolina. Longitudinal profiling of dissolved-oxygen concentrations during the spring and summer of 1996 revealed dissolved-oxygen minimums occurring upstream from the point-source discharges. The mean dissolved-oxygen decrease upstream from the effluent discharges was 2.0 milligrams per liter, and the decrease downstream from the effluent discharges was 0.2 milligram per liter. Several theories were investigated to obtain an improved understanding of the dissolved-oxygen dynamics in the upper Wateree River. Data suggest that the dissolved-oxygen concentration decrease is associated with elevated levels of oxygen-consuming nutrients and metals that are flowing into the Wateree River from Lake Wateree. Analysis of long-term streamflow and water-quality data collected at two U.S. Geological Survey gaging stations suggests that no strong correlation exists between streamflow and dissolved-oxygen concentrations in the Wateree River. However, a strong negative correlation does exist between dissolved-oxygen concentrations and water temperature. Analysis of data from six South Carolina Department of Health and Environmental Control monitoring stations for 1980.95 revealed decreasing trends in ammonia nitrogen at all stations where data were available and decreasing trends in 5-day biochemical oxygen demand at three river stations. The influence of various hydrologic and point-source loading conditions on dissolved-oxygen concentrations in the Wateree River were determined by using results from water-quality simulations by the Branched Lagrangian Transport Model. The effects of five tributaries and four point-source discharges were included in the model. Data collected during two synoptic water-quality samplings on June 23.25 and August 11.13, 1997, were used to calibrate

  18. 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.

  19. Linking the mobilization of dissolved organic matter in catchments and its removal in drinking water treatment to its molecular characteristics.

    Science.gov (United States)

    Raeke, Julia; Lechtenfeld, Oliver J; Tittel, Jörg; Oosterwoud, Marieke R; Bornmann, Katrin; Reemtsma, Thorsten

    2017-04-15

    Drinking water reservoirs in the Northern Hemisphere are largely affected by the decadal-long increase in riverine dissolved organic carbon (DOC) concentrations. The removal of DOC in drinking water treatment is costly and predictions are needed to link DOC removal efficiency to its mobilization in catchments, both of which are determined by the molecular composition. To study the effect of hydrological events and land use on the molecular characteristics of dissolved organic matter (DOM), 36 samples from three different catchment areas in the German low mountain ranges, with DOC concentrations ranging from 3 to 32 mg L(-1), were examined. Additionally, nine pairs of samples from downstream drinking water reservoirs were analyzed before and after flocculation. The molecular composition and the age of DOM were analyzed using ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) and radiocarbon ((14)C) analysis. At elevated discharge in a forested catchment comparatively younger, more oxygenated and unsaturated molecules of higher molecular weight were preferentially mobilized, likely linked to the reductive mobilization of iron. DOM with highly similar molecular characteristics (O/C ratio > 0.5, m/z > 500) could also be efficiently removed through flocculation in drinking water treatment. The proportion of DOM removed through flocculation ranged between 43% and 73% of DOC and was highest at elevated discharge. In catchment areas with a higher percentage of grassland and agriculture a higher proportion of DOM molecules containing sulfur and nitrogen was detected, which in turn could be less efficiently flocculated. Altogether, it was shown that DOM that is released during large hydrological events can be efficiently flocculated again, suggesting a reversal of similar chemical mechanisms in both processes. Since the occurrence of heavy rainfall events is predicted to increase in the future, event-driven mobilization of DOC

  20. Analysis of minerals containing dissolved traces of the fluid phase components water and carbon dioxide

    Science.gov (United States)

    Freund, Friedemann

    1991-01-01

    Substantial progress has been made towards a better understanding of the dissolution of common gas/fluid phase components, notably H2O and CO2, in minerals. It has been shown that the dissolution mechanisms are significantly more complex than currently believed. By judiciously combining various solid state analytical techniques, convincing evidence was obtained that traces of dissolved gas/fluid phase components undergo, at least in part, a redox conversion by which they split into reduced H2 and and reduced C on one hand and oxidized oxygen, O(-), on the other. Analysis for 2 and C as well as for any organic molecules which may form during the process of co-segregation are still impeded by the omnipresent danger of extraneous contamination. However, the presence of O(-), an unusual oxidized form of oxygen, has been proven beyond a reasonable doubt. The presence of O(-) testifies to the fact that a redox reaction must have taken place in the solid state involving the dissolved traces of gas/fluid phase components. Detailed information on the techniques used and the results obtained are given.

  1. Ground water flow in a desert basin: challenges of simulating transport of dissolved chromium.

    Science.gov (United States)

    Andrews, Charles B; Neville, Christopher J

    2003-01-01

    A large chromium plume that evolved from chromium releases in a valley near the Mojave River was studied to understand the processes controlling fate and migration of chromium in ground water and used as a tracer to study the dynamics of a basin and range ground water system. The valley that was studied is naturally arid with high evapotranspiration such that essentially no precipitation infiltrates to the water table. The dominant natural hydrogeologic processes are recharge to the ground water system from the Mojave River during the infrequent episodes when there is flow in the river, and ground water flow toward a playa lake where the ground water evaporates. Agricultural pumping in the valley from the mid-1930s to the 1970s significantly altered ground water flow conditions by decreasing water levels in the valley by more than 20 m. This pumping declined significantly as a result of dewatering of the aquifer, and water levels have since recovered modestly. The ground water system was modeled using MODFLOW, and chromium transport was simulated using MT3D. Several innovative modifications were made to these modeling programs to simulate important processes in this ground water system. Modifications to MODFLOW include developing a new well package that estimates pumping rates from irrigation wells at each time step based on available drawdown. MT3D was modified to account for mass trapped above the water table when the water table declines beneath nonirrigated areas and to redistribute mass to the system when water levels rise.

  2. Assessment of historical surface-water quality data in southwestern Colorado, 1990-2005

    Science.gov (United States)

    Miller, Lisa D.; Schaffrath, Keelin R.; Linard, Joshua I.

    2013-01-01

    The spatial and temporal distribution of selected physical and chemical surface-water-quality characteristics were analyzed at stream sites throughout the Dolores and San Juan River Basins in southwestern Colorado using historical data collected from 1990 through 2005 by various local, State, Tribal, and Federal agencies. Overall, streams throughout the study area were well oxygenated. Values of pH generally were near neutral to slightly alkaline throughout most of the study area with the exception of the upper Animas River Basin near Silverton where acidic conditions existed at some sites because of hydrothermal alteration and(or) historical mining. The highest concentrations of dissolved aluminum, total recoverable iron, dissolved lead, and dissolved zinc were measured at sites located in the upper Animas River Basin. Thirty-two sites throughout the study area had at least one measured concentration of total mercury that exceeded the State chronic aquatic-life criterion of 0.01 μg/L. Concentrations of dissolved selenium at some sites exceeded the State chronic water-quality standard of 4.6 μg/L. Total ammonia, nitrate, nitrite, and total phosphorus concentrations generally were low throughout the study area. Overall, results from the trend analyses indicated improvement in water-quality conditions as a result of operation of the Paradox Valley Unit in the Dolores River Basin and irrigation and water-delivery system improvements made in the McElmo Creek Basin (Lower San Juan River Basin) and Mancos River Valley (Upper San Juan River Basin).

  3. Geochemical characterization of surface water and spring water in SE Kashmir Valley, western Himalaya: Implications to water–rock interaction

    Indian Academy of Sciences (India)

    Gh Jeelani; Nadeem A Bhat; K Shivanna; M Y Bhat

    2011-10-01

    Water samples from precipitation, glacier melt, snow melt, glacial lake, streams and karst springs were collected across SE of Kashmir Valley, to understand the hydrogeochemical processes governing the evolution of the water in a natural and non-industrial area of western Himalayas. The time series data on solute chemistry suggest that the hydrochemical processes controlling the chemistry of spring waters is more complex than the surface water. This is attributed to more time available for infiltrating water to interact with the diverse host lithology. Total dissolved solids (TDS), in general, increases with decrease in altitude. However, high TDS of some streams at higher altitudes and low TDS of some springs at lower altitudes indicated contribution of high TDS waters from glacial lakes and low TDS waters from streams, respectively. The results show that some karst springs are recharged by surface water; Achabalnag by the Bringi stream and Andernag and Martandnag by the Liddar stream. Calcite dissolution, dedolomitization and silicate weathering were found to be the main processes controlling the chemistry of the spring waters and calcite dissolution as the dominant process in controlling the chemistry of the surface waters. The spring waters were undersaturated with respect to calcite and dolomite in most of the seasons except in November, which is attributed to the replenishment of the CO2 by recharging waters during most of the seasons.

  4. 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.

  5. 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.

  6. The influence of dissolved Si on Ni precipitate formation at the kaolinite water interface: Kinetics, DRS and EXAFS analysis.

    Science.gov (United States)

    Tan, Xiaoli; Liu, Ge; Mei, Huiyang; Fang, Ming; Ren, Xuemei; Chen, Changlun

    2017-04-01

    Unraveling the formation process of Ni precipitates at molecular scale is important for understanding the fate and mobility of Ni species in the real environment. Dissolved Si presents in the natural environment ubiquitously, which can alter Ni sorption as well as incorporation into neoformed precipitates. Batch experiments show that the dissolved Si leads to a rapid increase in the Ni sorption rate and interferes with the formation of Ni precipitates. The results of diffuse reflectance spectroscopy (DRS) and extended X-ray absorption fine structure (EXAFS) spectroscopy analyses suggest that the nucleation of a (Ni,Al) phyllosilicate phase involves a kaolinite-like local structure. Then, the substantial presence of Si affects the initial formation of Ni precipitate nucleation and the resulting crystal growth. Dioctahedral kaolinite may act as a nucleating surface for the heterogeneous formation of trioctahedral (Ni,Al) phyllosilicates under environmentally relevant conditions. This study provides experimental evidence on nucleation and epitaxial growth processes of Ni precipitate on kaolinite and provides insight on the relationship between substrates and precipitation, which is crucial for understanding the physicochemical behavior of Ni on mineral surfaces.

  7. Hydrogeochemical analysis and evaluation of surface water quality of Pratapgarh district, Uttar Pradesh, India

    Science.gov (United States)

    Tiwari, Ashwani Kumar; Singh, Abhay Kumar; Singh, Amit Kumar; Singh, M. P.

    2017-07-01

    The hydrogeochemical study of surface water in Pratapgarh district has been carried out to assess the major ion chemistry and water quality for drinking and domestic purposes. For this purpose, twenty-five surface water samples were collected from river, ponds and canals and analysed for pH, electrical conductivity, total dissolved solids (TDS), turbidity, hardness, major cations (Ca2+, Mg2+, Na+ and K+), major anions (HCO3 -, F-, Cl-, NO3 -, SO4 2-) and dissolved silica concentration. The analytical results show mildly acidic to alkaline nature of surface water resources of Pratapgarh district. HCO3 - and Cl- are the dominant anions, while cation chemistry is dominated by Na+ and Ca2+. The statistical analysis and data plotted on the Piper diagram reveals that the surface water chemistry is mainly controlled by rock weathering with secondary contributions from agriculture and anthropogenic sources. Ca2+-Mg2+-HCO3 -, Ca2+-Mg2+-Cl- and Na+-HCO3 --Cl- are the dominant hydrogeochemical facies in the surface water of the area. For quality assessment, values of analysed parameters were compared with Indian and WHO water quality standards, which shows that the concentrations of TDS, F-, NO3 -, Na+, Mg2+ and total hardness are exceeding the desirable limits in some water samples. Water Quality Index (WQI) is one of the most effective tools to communicate information on the quality of any water body. The computed WQI values of Pratapgarh district surface water range from 28 to 198 with an average value of 82, and more than half of the study area is under excellent to good category.

  8. Geochemistry of dissolved trace elements and heavy metals in the Dan River Drainage (China): distribution, sources, and water quality assessment.

    Science.gov (United States)

    Meng, Qingpeng; Zhang, Jing; Zhang, Zhaoyu; Wu, Tairan

    2016-04-01

    Dissolved trace elements and heavy metals in the Dan River drainage basin, which is the drinking water source area of South-to-North Water Transfer Project (China), affect large numbers of people and should therefore be carefully monitored. To investigate the distribution, sources, and quality of river water, this study integrating catchment geology and multivariate statistical techniques was carried out in the Dan River drainage from 99 river water samples collected in 2013. The distribution of trace metal concentrations in the Dan River drainage was similar to that in the Danjiangkou Reservoir, indicating that the reservoir was significantly affected by the Dan River drainage. Moreover, our results suggested that As, Sb, Cd, Mn, and Ni were the major pollutants. We revealed extremely high concentrations of As and Sb in the Laoguan River, Cd in the Qingyou River, Mn, Ni, and Cd in the Yinhua River, As and Sb in the Laojun River, and Sb in the Dan River. According to the water quality index, water in the Dan River drainage was suitable for drinking; however, an exposure risk assessment model suggests that As and Sb in the Laojun and Laoguan rivers could pose a high risk to humans in terms of adverse health and potential non-carcinogenic effects.

  9. Water uptake and growth of cucumber plants (Cucumis sativus L.) under control of dissolved O2 concentration in hydroponics.

    Science.gov (United States)

    Yoshida, S; Kitano, M; Eguchi, H

    1996-12-01

    Dissolved O2 concentration ([O2]) in nutrient solution was controlled at 0.01, 0.10 and 0.20 mM with accuracy of +/- 0.005 mM in a newly developed hydroponic system, and the effects of [O2] on water uptake and growth of cucumber plants (Cucumis sativus L.) were analyzed. For evaluating water uptake rate under the control of [O2], water flux at the stem base was measured on-line with +/-5% in accuracy, 1 mg s-1 in resolution and 1 min in time constant by heat flux control (HFC) method. Water uptake rate was drastically increased by lighting to the plant at each [O2], and water uptake per day was depressed in proportion to decrease in [O2]. In the plants grown for 10 days, leaf area, fresh weight and dry weight of leaves decreased at lower [O2], while stem length and number of leaves were scarcely affected. These facts suggest that membrane permeability of root cells reduces at lower [O2] through respiration-dependent processes, and growth is inhibited through leaf turgor loss caused by the depressed water uptake of roots in O2-deficient nutrient solution in hydroponics.

  10. 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

  11. Research on the influence of ozone dissolved in the fuel-water emulsion on the parameters of the CI engine

    Science.gov (United States)

    Wojs, M. K.; Orliński, P.; Kamela, W.; Kruczyński, P.

    2016-09-01

    The article presents the results of empirical research on the impact of ozone dissolved in fuel-water emulsion on combustion process and concentration of toxic substances in CI engine. The effect of ozone presence in the emulsion and its influence on main engine characteristics (power, torque, fuel consumption) and selected parameters that characterize combustion process (levels of pressures and temperatures in combustion chamber, period of combustion delay, heat release rate, fuel burnt rate) is shown. The change in concentration of toxic components in exhausts gases when engine is fueled with ozonized emulsion was also identified. The empirical research and their analysis showed significant differences in the combustion process when fuel-water emulsion containing ozone was used. These differences include: increased power and efficiency of the engine that are accompanied by reduction in time of combustion delay and beneficial effects of ozone on HC, PM, CO and NOX emissions.

  12. Long-term Effects of Hydrologic Manipulations on Pore Water Dissolved Organic Carbon in an Alaskan Rich Fen

    Science.gov (United States)

    Rupp, D.; Kane, E. S.; Keller, J.; Turetsky, M. R.; Meingast, K. M.

    2016-12-01

    Boreal peatlands are experiencing rapid changes due to temperature and precipitation regime shifts in northern latitudes. In areas near Fairbanks, Alaska, thawing permafrost due to climatic changes alters peatland hydrology and thus the biogeochemical cycles within. Pore water chemistry reflects the biological and chemical processes occurring in boreal wetlands. The characterization of dissolved organic carbon (DOC) within pore water offers clues into the nature of microbially-driven biogeochemical shifts due to changing hydrology. There is mounting evidence that organic substances play an important role in oxidation-reduction (redox) reactivity of peat at northern latitudes, which is closely linked to carbon cycling. However, the redox dynamics of DOC are complex and have not been examined in depth in boreal peatlands. Here, we examine changes in organic substances and their influences on redox activity at the Alaska Peatland Experiment (APEX) site near Fairbanks, Alaska, where water table manipulation treatments have been in place since 2005 (control, raised water table, and lowered water table). With time, the altered hydrology has led to a shift in the plant community to favor sedge species in the raised water table treatment and more shrubs and non-aerenchymous plants in the lowered water table treatment. The litter from different plant functional types alters the character of the dissolved organic carbon, with more recalcitrant material containing lignin in the lowered water table plot due to the greater abundance of shrubs. A greater fraction of labile DOC in the raised treatment plot likely results from more easily decomposed sedge litter, root exudates at depth, and more frequently waterlogged conditions, which are antagonistic to aerobic microbial decomposition. We hypothesize that a greater fraction of phenolic carbon compounds supports higher redox activity. However, we note that not all "phenolic" compounds, as assayed by spectrophotometry, have the

  13. [Impact of Rocky Desertification Treatment on Underground Water Chemistry and Dissolved Inorganic Carbon Isotope in Karst Areas].

    Science.gov (United States)

    Xiao, Shi-zhen; Xiong, Kang-ning; Lan, Jia-cheng; Zhang, Hui; Yang, Long

    2015-05-01

    Five springs representing different land-use types and different karst rocky desertification treatment models were chosen at the Huajiang Karst Rocky Desertification Treatment Demonstration Site in Guanling-Zhenfeng Counties in Guizhou, to analyze the features of underground water chemistry and dissolved inorganic carbon isotopes (δ13C(DIC)) and reveal the effect of rocky desertification treatment on karstification and water quality. It was found that, the underground water type of the research area was HCO3-Ca; the water quality of the springs which were relatively less affected by human activities including Shuijingwan Spring (SJW) , Gebei Spring (GB), and Maojiawan Spring (MJW) was better than those relatively more affected by human activities including Diaojing Spring (DJ) and Tanjiazhai Spring (TJZ) , the main ion concentrations and electrical conductivity of which were higher; pH, SIc and pCO2 were sensitive to land-use types and rocky desertification treatment, which could be shown by the higher pH and SIc and lower pCO2 in MJW than those in the other four springs; (Ca(2+) + Mg2+)/HCO(3-) of SJW, MJW and GB were nearly 1:1, dominated by carbonate rock weathering by carbon acid, while the (Ca(2+) + Mg2+) of DJ and TJZ was much higher than HCO3-, suggesting that sulfate and nitrate might also dissolve carbonate rock because of the agricultural activities; δ13C(DIC) was lighter in wet season because of the higher biological activities; the average δ13C(DIC) was in the order of DJ (-12.79 per thousand) < SJW (-12.48 per thousand) < GB (-10.76 per thousand)) < MJW (-10.30 per thousand) < TJZ (-6.70 per thousand), which demonstrated that δ13C(DIC) would be heavier after rocky desertification and lighter after the rocky desertification are treated and controlled.

  14. On-line technique for preparingand measuring stable carbon isotopeof total dissolved inorganic carbonin water samples ( d13CTDIC

    Directory of Open Access Journals (Sweden)

    S. Inguaggiato

    2005-06-01

    Full Text Available A fast and completely automated procedure is proposed for the preparation and determination of d13C of total inorganic carbon dissolved in water ( d13CTDIC. This method is based on the acidification of water samples transforming the whole dissolved inorganic carbon species into CO2. Water samples are directly injected by syringe into 5.9 ml vials with screw caps which have a pierciable rubber septum. An Analytical Precision «Carbonate Prep System» was used both to flush pure helium into the vials and to automatically dispense a fixed amount of H3PO4. Full-equilibrium conditions between produced CO2 and water are reached at a temperature of 70°C (± 0.1°C in less than 24 h. Carbon isotope ratios (13C/ 12C were measured on an AP 2003 continuous flow mass spectrometer, connected on-line with the injection system. The precision and reproducibility of the proposed method was tested both on aqueous standard solutions prepared using Na2CO3 with d13C=-10.78 per mil versus PDB (1 s= 0.08, n = 11, and at five different concentrations (2, 3, 4, 5 and 20 mmol/l and on more than thirty natural samples. Mean d13CTDIC on standard solution samples is ?10.89 < per mil versus PDB (1 s= 0.18, n = 50, thus revealing both a good analytical precision and reproducibility. A comparison between average d13CTDIC values on a quadruplicate set of natural samples and those obtained following the chemical and physical stripping method highlights a good agreement between the two analytical methods.

  15. Avaliação da influência de sulfetos solúveis na complexação do cobre em águas superficiais empregando métodos voltamétricos Influence of dissolved sulfides on copper complexation in surface waters using voltammetric methods

    Directory of Open Access Journals (Sweden)

    Elizabeth W. O. Scheffer

    2010-01-01

    Full Text Available In this work a sulfide quantification protocol using voltammetric methods was developed to evaluate the effect of dissolved sulfides on copper complexation. On the basis of pH, sulfide release from the dissociation of specific metal sulfide complexes can be electrochemically measured and then removed (as H2S by a N2 purge. Cathodic stripping square wave voltammetry (CSSWV was conducted to quantify Cu sulfides complexes which dissociate at pH < 5.0 during the process of acid titration.

  16. 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...

  17. Dissolved inorganic nitrogen pools and surface flux under different brackish marsh vegetation types, common reed (Phragmites australis) and salt hay (Spartina patens)

    Science.gov (United States)

    Windham-Myers, L.

    2005-01-01

    The current expansion of Phragmites australis into the high marsh shortgrass (Spartina patens, Distichlis spicata) communities of eastern U.S. salt marshes provided an opportunity to identify the influence of vegetation types on pools and fluxes of dissolved inorganic nitrogen (DIN). Two brackish tidal marshes of the National Estuarine Research Reserve system were examined, Piermont Marsh of the Hudson River NERR in New York and Hog Island in the Jacques Coustaeu NERR of New Jersey. Pools of DIN in porewater and rates of DIN surface flux were compared in replicated pairs of recently-expanded P. australis and neighboring S. patens-dominated patches on the high marsh surface. Both marshes generally imported nitrate (NO3-) and exported ammonium (NH4+), such that overall DIN was exported. No differences in surface exchange of NO3- or NH4+ were observed between vegetation types. Depth-averaged porewater NH4+ concentrations over the entire growing season were 56% lower under P. australis than under S. patens (average 1.4 vs. 3.2 mg NH4+ L-1) with the most profound differences in November. Porewater profiles showed an accumulation of NH4+ at depth in S. patens and constant low concentrations in P. australis from the soil surface to 50 cm depth, with no significant differences in porewater salinity. Despite these profound differences in porewater, NH 4+ diffusion from soils of P. australis and S. patens were not measurably different, were similar to other published rates, and were well below estimated rates based on passive diffusion alone. Rapid adsorption and uptake by litter and microbes in surface soils of both communities may buffer NH4+ loss to flooding tides in both communities, thereby reducing the impact of P. australis invasion on NH4+ flux to flooding waters. ?? Springer 2005.

  18. 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.

  19. 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....

  20. Nitrogen patterns in subsurface waters of the Yzeron stream: effect of combined sewer overflows and subsurface-surface water mixing.

    Science.gov (United States)

    Aucour, A M; Bariac, T; Breil, P; Namour, P; Schmitt, L; Gnouma, R; Zuddas, P

    2013-01-01

    Urbanization subjects streams to increased nitrogen loads. Therefore studying nitrogen forms at the interface between urban stream and groundwater is important for water resource management. In this study we report results on water δ(18)O and nitrogen forms in subsurface waters of a stream (Yzeron, France). The sites studied were located upstream and downstream of combined sewer overflows (CSO) in a rural area and a periurban area, respectively. Water δ(18)O allowed us to follow the mixing of subsurface water with surface water. Dissolved organic nitrogen and organic carbon of fine sediment increased by 20-30% between rural and periurban subsurface waters in the cold season, under high flow. The highest nitrate levels were observed in rural subsurface waters in the cold season. The lowest nitrate levels were found in periurban subsurface waters in the warm season, under low flow. They corresponded to slow exchange of subsurface waters with channel water. Thus reduced exchange between surface and subsurface waters and organic-matter-rich input seemed to favor nitrate reduction in the downstream, periurban, subsurface waters impacted by CSO.

  1. Methane bioattenuation and implications for explosion risk reduction along the groundwater to soil surface pathway above a plume of dissolved ethanol.

    Science.gov (United States)

    Ma, Jie; Rixey, William G; DeVaull, George E; Stafford, Brent P; Alvarez, Pedro J J

    2012-06-05

    Fuel ethanol releases can stimulate methanogenesis in impacted aquifers, which could pose an explosion risk if methane migrates into enclosed spaces where ignitable conditions exist. To assess this potential risk, a flux chamber was emplaced on a pilot-scale aquifer exposed to continuous release (21 months) of an ethanol solution (10% v:v) that was introduced 22.5 cm below the water table. Despite methane concentrations within the ethanol plume reaching saturated levels (20-23 mg/L), the maximum methane concentration reaching the chamber (21 ppm(v)) was far below the lower explosion limit in air (50,000 ppm(v)). The low concentrations of methane observed in the chamber are attributed to methanotrophic activity, which was highest in the capillary fringe. This was indicated by methane degradation assays in microcosms prepared with soil samples from different depths, as well as by PCR measurements of pmoA, which is a widely used functional gene biomarker for methanotrophs. Simulations with the analytical vapor intrusion model "Biovapor" corroborated the low explosion risk associated with ethanol fuel releases under more generic conditions. Model simulations also indicated that depending on site-specific conditions, methane oxidation in the unsaturated zone could deplete the available oxygen and hinder aerobic benzene biodegradation, thus increasing benzene vapor intrusion potential. Overall, this study shows the importance of methanotrophic activity near the water table to attenuate methane generated from dissolved ethanol plumes and reduce its potential to migrate and accumulate at the surface.

  2. First flush of dissolved compounds

    DEFF Research Database (Denmark)

    Krebs, P.; Holzer, P.; Huisman, J.L.

    1999-01-01

    In a crude conceptual approach it is commonly assumed that in a combined sewer system the concentration of dissolved compounds is diluted by an increasing flow rate due to rainwater inflow. However, theory of hydraulics suggests that these compounds are influenced by hydrodynamic effects....... It is known that since the wave celerity is higher than the flow velocity of the water, the increase of flow rate induced through rain runoff is recognised earlier at a certain downstream section of the combined sewer than the concentration increase of typical rain-water compounds originating from surface...... wash-off. This description implies that the wave front is formed from the fluid that was present in the sewer before the Bow rare increased, that is the sewage! By means of measurements and numerical simulations, it is shown that this effect may cause a significant impact of dissolved compounds...

  3. 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.

  4. Oxidation-state distribution of plutonium in surface and subsurface waters at Thule, northwest Greenland

    DEFF Research Database (Denmark)

    McMahon, C.A.; Vintró, L.L.; Mitchell, P.I.

    2000-01-01

    chemical form) is present as fully dissolved species. Most of this plutonium would seem to be of weapons fallout origin, as the mean Pu-238/Pu-239,Pu-240 activity ratio in the water column (dissolved phase) at Thule (0.06 +/- 0.02; n = 10) is similar to the global fallout ratio at this latitude......The speciation of plutonium in Arctic waters sampled on the northwest Greenland shelf in August 1997 is discussed in this paper. Specifically, we report the results of analyses carried out on seawater sampled (a) close to the Thule air base where, in 1968, a US military aircraft carrying four......(V, VI) (mean, 68 +/- 6%; n = 6), with little if any distinction apparent between surface and bottom waters. Further, the oxidation state distribution at stations close to the accident site is similar to that measured at Upernavik, remote from this site. It is also similar to the distribution observed...

  5. Atmospheric fluxes of organic matter to the Mediterranean Sea: contribution to the elemental C: N: P ratios of surface dissolved organic matter

    Science.gov (United States)

    Djaoudi, Kahina; Barani, Aude; Hélias-Nunige, Sandra; Van Wambeke, France; Pulido-Villena, Elvira

    2016-04-01

    It has become increasingly apparent that atmospheric transport plays an important role in the supply of macro- and micro-nutrients to the surface ocean. This atmospheric input is especially important in oligotrophic regions where the vertical supply from the subsurface is low particularly during the stratification period. Compared to its inorganic counterpart, the organic fraction of atmospheric deposition and its impact on surface ocean biogeochemistry has been poorly explored. In the ocean, carbon export to depth (and therefore, its long term storage with presumed consequences on climate) occurs both through particle sedimentation and through the transfer of dissolved organic matter (DOM) via diffusion or convection. DOM export from the surface ocean represents up to 50% of total organic carbon flux to the deep ocean in oligotrophic regions such as the Mediterranean Sea. The efficiency of this C export pathway depends, among others, on the elemental C: N: P ratios of surface DOM which might be affected by the relative contribution of microbial processes and allochthonous sources. This work reports a one-year time-series (April 2015-April 2016) of simultaneous measurements of (1) total (dry + wet) atmospheric fluxes of organic carbon, organic nitrogen, and organic phosphorus and (2) concentration of dissolved organic carbon, dissolved organic nitrogen, and dissolved organic phosphate at the surface layer (0-200 m) in the NW Mediterranean Sea. Atmospheric and oceanic surveys were conducted at the Frioul and ANTARES sites, respectively, operated by the long-term observation network MOOSE (Mediterranean Oceanic Observation System for the Environment).

  6. Effect of the spatiotemporal variability of rainfall inputs in water quality integrated catchment modelling for dissolved oxygen concentrations

    Science.gov (United States)

    Moreno Ródenas, Antonio Manuel; Cecinati, Francesca; ten Veldhuis, Marie-Claire; Langeveld, Jeroen; Clemens, Francois

    2016-04-01

    Maintaining water quality standards in highly urbanised hydrological catchments is a worldwide challenge. Water management authorities struggle to cope with changing climate and an increase in pollution pressures. Water quality modelling has been used as a decision support tool for investment and regulatory developments. This approach led to the development of integrated catchment models (ICM), which account for the link between the urban/rural hydrology and the in-river pollutant dynamics. In the modelled system, rainfall triggers the drainage systems of urban areas scattered along a river. When flow exceeds the sewer infrastructure capacity, untreated wastewater enters the natural system by combined sewer overflows. This results in a degradation of the river water quality, depending on the magnitude of the emission and river conditions. Thus, being capable of representing these dynamics in the modelling process is key for a correct assessment of the water quality. In many urbanised hydrological systems the distances between draining sewer infrastructures go beyond the de-correlation length of rainfall processes, especially, for convective summer storms. Hence, spatial and temporal scales of selected rainfall inputs are expected to affect water quality dynamics. The objective of this work is to evaluate how the use of rainfall data from different sources and with different space-time characteristics affects modelled output concentrations of dissolved oxygen in a simplified ICM. The study area is located at the Dommel, a relatively small and sensitive river flowing through the city of Eindhoven (The Netherlands). This river stretch receives the discharge of the 750,000 p.e. WWTP of Eindhoven and from over 200 combined sewer overflows scattered along its length. A pseudo-distributed water quality model has been developed in WEST (mikedhi.com); this is a lumped-physically based model that accounts for urban drainage processes, WWTP and river dynamics for several

  7. Isotope fractionation between dissolved and suspended particulate Fe in the oxic and anoxic water column of the Baltic Sea

    Directory of Open Access Journals (Sweden)

    M. Staubwasser

    2013-01-01

    Full Text Available Fe isotope ratios and concentrations of dissolved Fe (Fedis, < 0.45 μm and of suspended particulate Fe (FeSPM were analyzed from a depth profile through the anoxic Eastern Gotland Basin water column, Baltic Sea. Results show a sharp gradient in δ56Fedis across the ferruginous layer with δ56Fedis = −0.4‰ in the euxinic deep basin and δ56Fedis = +0.3‰ in the oxic upper water column. The isotopic gradient overlaps with a strong concentration gradient of Fedis, a concentration maximum in FeSPM and lower δ56FeSPM values than δ56Fedis. These features indicate preferential loss of light Fe isotopes from solution to suspended iron-oxyhydroxides (FeIOH during typical oxidative precipitation across the redox interface. The sign of the overall fractionation, Δ56FeIOH-Fe(II(aq < 0‰, is in contrast to similar, mostly non-marine redox environments, where Δ56FeIOH-Fe(II(aq > 0‰. The difference appears to be the result of isotope exchange dominated by reaction kinetics in the marine water column, rather than equilibrium fractionation generally inferred for oxidative Fe precipitation elsewhere. High residual δ56Fedis immediately above the oxic–ferruginous interface and throughout the oxic water column suggests that any potential dissolved Fe export from marine reducing waters into the oxic open water column is enriched in the heavy isotopes. In the deep, mildly euxinic water column above the level of Fe sulfide saturation, a decreasing δ56FeSPM trend with depth and a generally low δ56Fedis are comparable to trends generally observed in marine anoxic sediment profiles where microbial reductive Fe dissolution occurs. The isotope composition of the redox-cycled Fe

  8. Behavior of Aluminum Based Coagulants in Treatment of Surface Water–Assessment of Chemical and Microbiological Properties of Treated Water

    Directory of Open Access Journals (Sweden)

    Spînu (Gologan Daniela

    2014-03-01

    Full Text Available Pre-polymerized inorganic aluminum coagulants have high efficiency in reducing turbidity, total, dissolved, biodegradable organic carbon and microbiological content of surface waters used for drinking, while obtaining low concentrations of residual aluminum after the coagulation phase. Correlation between turbidity raw water and coagulant dose is logarithmic being influenced by temperature and organic content of surface waters. The coagulant’s effect on the organic content of the raw water is closely related to the microbiological concentration and can thus determine the mathematical correlations between the two types of parameters after the coagulation-flocculation stage that can be used to assess the water biostability coagulant action.

  9. Influence of geology on arsenic concentrations in ground and surface water in central Lesvos, Greece.

    Science.gov (United States)

    Aloupi, Maria; Angelidis, Michael O; Gavriil, Apostolos M; Koulousaris, Michael; Varnavas, Soterios P

    2009-04-01

    The occurrence of As was studied in groundwater used for human consumption and irrigation, in stream water and sediments and in water from thermal springs in the drainage basin of Kalloni Gulf, island of Lesvos, Greece, in order to investigate the potential influence of the geothermal field of Polichnitos-Lisvori on the ground and surface water systems of the area. Total dissolved As varied in the range geology exerts a determinant influence on As geochemical behaviour. On the other hand, the geothermal activity manifested in the area of Polichnitos-Lisvori does not affect the presence of As in groundwater and streams.

  10. Physico-chemical characterization of surface waters of the west coast of Algeria: Bay of Mostaganem and Cheliff estuary

    OpenAIRE

    Fatima Kies; Ahmed Kerkouf

    2014-01-01

    A follow-up in 2013 of the indicators of pollution (temperature, hydrogen potential, salinity, dissolved oxygen, ammonium, nitrites, nitrates, orthophosphates, ortho silicates, biological oxygen demand, chemical oxygen demand, suspended solids) in surface water was performed, in order to estimate the physicochemical quality of the west coast of Algeria. The results obtained revealed the existence of a water contamination by domestic and industrial waste water conveyed to the north by the Chel...

  11. 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.

  12. Source water controls on the character and origin of dissolved organic matter in streams of the Yukon River basin, Alaska

    Science.gov (United States)

    O'Donnell, Jonathan A.; Aiken, George R.; Kane, Evan S.; Jones, Jeremy B.

    2010-01-01

    Climate warming and permafrost degradation at high latitudes will likely impact watershed hydrology, and consequently, alter the concentration and character of dissolved organic carbon (DOC) in northern rivers. We examined seasonal variation of DOC chemistry in 16 streams of the Yukon River basin, Alaska. Our primary objective was to evaluate the relationship between source water (shallow versus deep groundwater flow paths) and DOC chemical composition. Using base cation chemistry and principal component analysis, we observed high contributions of deep groundwater to glacial and clearwater streams, whereas blackwater streams received larger contributions from shallow groundwater sources. DOC concentration and specific ultraviolet absorbance peaked during spring snowmelt in all streams, and were consistently higher in blackwater streams than in glacial and clearwater streams. The hydrophobic acid fraction of DOC dominated across all streams and seasons, comprising between 35% and 56% of total DOC. The hydrophilic acid fraction of DOC was more prominent in glacial (23% ± 3%) and clearwater streams (19% ± 1%) than in blackwater streams (16% ± 1%), and was enriched during winter base flow (29% ± 1%) relative to snowmelt and summer base flow. We observed that an increase in the contribution of deep groundwater to streamflow resulted in decreased DOC concentration, aromaticity, and DOC-to-dissolved organic nitrogen ratio, and an increase in the proportion of hydrophilic acids relative to hydrophobic acids. Our findings suggest that future permafrost degradation and higher contributions of groundwater to streamflow may result in a higher fraction of labile DOM in streams of the Yukon basin.

  13. Occurrence and dominance of Cylindrospermopsis raciborskii and dissolved cylindrospermopsin in urban reservoirs used for drinking water supply, South China.

    Science.gov (United States)

    Lei, Lamei; Peng, Liang; Huang, Xianghui; Han, Bo-Ping

    2014-05-01

    The tropical cyanobacterium Cylindrospermopsis raciborskii is of particular concern for its invasive characteristics and production of the toxin cylindrospermopsin (CYN). The present study represents the first attempt to determine the distribution of C. raciborskii and CYN in tropical China. The presence of C. raciborskii and CYN, as well as the composition of phytoplankton, was determined from a total of 86 samples from 25 urban reservoirs for drinking water supply in Dongguan City of South China. The presence of C. raciborskii was observed in 21 of the 25 reservoirs and confirmed that this species has been widely distributed in the investigated reservoirs. C. raciborskii accounted for between 0.1 and 90.3 % of the total phytoplankton biomass and contributed to the majority of the phytoplankton in some reservoirs such as Tangkengbian and Xiagongyan. Its biomass was negatively correlated with NO3 (-)-N concentration and Secchi depth. Dissolved CYN was detected in more than one-half of the reservoirs with concentrations up to 8.25 μg L(-1), and it positively correlated with C. raciborskii biomass. Dissolved microcystins (MCs) were detected in 12 of the 25 reservoirs with a maximum concentration 1.99 μg L(-1). Our data strongly suggest that C. raciborskii and CYN could be important health hazards in urban reservoirs of South China and that more data are needed for further assessment.

  14. Quality of surface-water supplies in the Triangle Area of North Carolina, water years 2012–13

    Science.gov (United States)

    Pfeifle, C.A.; Cain, J.L.; Rasmussen, R.B.

    2016-09-07

    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 local 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 2011 through September 2012 (water year 2012) and October 2012 through September 2013 (water year 2013). Major findings for this period include:Annual precipitation was approximately 2 percent above the long-term mean (average) annual precipitation in 2012 and approximately 3 percent below the long-term mean in 2013.In water year 2012, streamflow was generally below the long-term mean during most of the period for the 10 project streamflow gaging stations. Streamflow was near or above the long-term mean at the same streamflow gaging stations during the 2013 water year.More than 7,000 individual measurements of water quality were made at a total of 17 sites—6 in the Neuse River Basin and 11 in the Cape Fear River Basin. Forty-three water-quality properties or constituents were measured; State water-quality standards exist for 23 of these.All observations met State water-quality standards for pH, temperature, 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, turbidity, chlorophyll a, copper, iron, manganese, mercury, silver, and zinc. Exceedances occurred at all 17 sites.Stream samples collected during storm events contained elevated concentrations of 19 water-quality constituents relative to non-storm events.

  15. 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

  16. Effects of sulfate deposition on pore water dissolved organic carbon, nutrients, and microbial enzyme activities in a northern peatland

    Science.gov (United States)

    Export of dissolved organic carbon from lakes and streams has increased throughout Europe and North America over the past several decades. One possible cause is altered deposition chemistry; specifically, decreasing sulfate inputs leading to changes in ionic strength and dissolve...

  17. Effects of sulfate deposition on pore water dissolved organic carbon, nutrients, and microbial enzyme activities in a northern peatland

    Science.gov (United States)

    Export of dissolved organic carbon from lakes and streams has increased throughout Europe and North America over the past several decades. One possible cause is altered deposition chemistry; specifically, decreasing sulfate inputs leading to changes in ionic strength and dissolve...

  18. Applying Spectral Unmixing to Determine Surface Water Parameters in a Mining Environment

    Directory of Open Access Journals (Sweden)

    Veronika Kopačková

    2014-11-01

    Full Text Available Compared to natural waters, mine waters represent an extreme water type that is frequently heavily polluted. Although they have been traditionally monitored by in situ measurements of point samples taken at regular intervals, the emergence of a new generation of multispectral and hyperspectral (HS sensors means that image spectroscopy has the potential to become a modern method for monitoring polluted surface waters. This paper describes an approach employing linear Spectral Unmixing (LSU for analysis of hyperspectral image data to map the relative abundances of mine water components (dissolved Fe—Fediss, dissolved organic carbon—DOC, undissolved particles. The ground truth data (8 monitored ponds were used to validate the results of spectral mapping. The same approach applied to HS data was tested using the image data resampled to WorldView2 (WV2 spectral resolution. A key aspect of the image data processing was to define the proper pure image end members for the fundamental water types. The highest correlations detected between the studied water parameters and the fractional images using the HyMap and the resampled WV2 data, respectively, were: dissolved Fe (R2 = 0.74 and R2vw2 = 0.6, undissolved particles (R2 = 0.57 and R2vw2 = 0.49 and DOC (R2 = 0.42 and R2vw2 < 0.40. These fractional images were further classified to create semi-quantitative maps. In conclusion, the classification still benefited from the higher spectral resolution of the HyMap data; however the WV2 reflectance data can be suitable for mapping specific inherent optical properties (SIOPs, which significantly differ from one another from an optical point of view (e.g., mineral suspension, dissolved Fe and phytoplankton, but it seems difficult to differentiate among diverse suspension particles, especially when the waters have more complex properties (e.g., mineral particles, DOC together with tripton or other particles, etc..

  19. Estimation of colored dissolved organic matter and salinity fields in case 2 waters using SeaWiFS: Examples from Florida Bay and Florida Shelf

    Indian Academy of Sciences (India)

    E J D'Sa; C Hu; F E Muller-Karger; K L Carder

    2002-09-01

    Estimates of water quality variables such as chlorophyll concentration (Chl), colored dissolved organic matter (CDOM), or salinity from satellite sensors are of great interest to resource managers monitoring coastal regions such as the Florida Bay and the Florida Shelf. However, accurate stimates of these variables using standard ocean color algorithms have been di#cult due to the complex nature of the light field in these environments. In this study, we process SeaWiFS satellite data using two recently developed algorithms; one for atmospheric correction and the other a semi-analytic bio-optical algorithm and compare the results with standard SeaWiFS algorithms. Overall, the two algorithms produced more realistic estimates of Chl and CDOM distributions in Florida Shelf and Bay waters. Estimates of surface salinity were obtained from the CDOM absorption field assuming a conservative mixing behavior of these waters. A comparison of SeaWiFS-derived Chl and CDOM absorption with field measurements in the Florida Bay indicated that although well correlated, CDOM was underestimated, while Chl was overestimated. Bottom reflectance appeared to affect these estimates at the shallow central Bay stations during the winter. These results demonstrate the need for new bio-optical algorithms or tuning of the parameters used in the bio-optical algorithm for local conditions encountered in the Bay.

  20. Selected elements in surface waters of Antarctica and their relations with the natural environment

    Directory of Open Access Journals (Sweden)

    Arkadiusz Nędzarek

    2014-03-01

    Full Text Available The aim of the study was to specify the concentration of selected chemical elements in surface waters of King George Island, off the western coast of the Antarctic Peninsula. The research encompassed six streams, a lake and an artificial water reservoir located on the western coast of Admiralty Bay. Measured hydrochemical parameters included pH, conductivity, total dissolved solids (TDS, and total and dissolved forms elements such as Al, Co, Ni, Cu, Zn, Cd, Pb, Mn, Fe, As and Se. The values of pH, conductivity and TDS had the following ranges: 6.09–8.21, 6.0–875 µS cm−1 and 7.0–975 mg/L, respectively, and were typical for surface waters of Antarctica. Wide disparities were discovered regarding concentrations of the investigated elements, ranging from <0.01 µg/L for Cd to 510 µg/L for Fe, and differing from one water body to another. The investigated elements are discussed with reference to environmental conditions and anthropogenic factors. Concentrations of total and dissolved forms of elements are considered in connection with the composition of soil in their surroundings and with atmospheric deposition, mostly such as that took place locally. The increased levels of Pb and Zn concentrations in the immediate proximity of a research station suggested anthropogenic contamination.

  1. 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...

  2. 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.

  3. Tracing dissolved organic carbon and trihalomethane formation potential between source water and finished drinking water at a lowland and an upland UK catchment.

    Science.gov (United States)

    Brooks, Emma; Freeman, Christopher; Gough, Rachel; Holliman, Peter J

    2015-12-15

    Rising dissolved organic carbon (DOC) concentrations in many upland UK catchments represents a challenge for drinking water companies, in particular due to the role of DOC as a precursor in the formation of trihalomethanes (THMs). Whereas traditionally, the response of drinking water companies has been focussed on treatment processes, increasingly, efforts have been made to better understanding the role of land use and catchment processes in affecting drinking water quality. In this study, water quality, including DOC and THM formation potential (THMFP) was assessed between the water source and finished drinking water at an upland and a lowland catchment. Surprisingly, the lowland catchment showed much higher reservoir DOC concentrations apparently due to the influence of a fen within the catchment from where a major reservoir inflow stream originated. Seasonal variations in water quality were observed, driving changes in THMFP. However, the reservoirs in both catchments appeared to dampen these temporal fluctuations. Treatment process applied in the 2 catchments were adapted to reservoir water quality with much higher DOC and THMFP removal rates observed at the lowland water treatment works where coagulation-flocculation was applied. However, selectivity during this DOC removal stage also appeared to increase the proportion of brominated THMs produced. Copyright © 2015. Published by Elsevier B.V.

  4. 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

  5. Trend Impact Analysis of Dissolved Nutrients Released From Soil on Water Quality in Qinglongshan Reservoir%青龙山水库土壤养分对水库水质的影响研究

    Institute of Scientific and Technical Information of China (English)

    李鱼; 王国平

    2000-01-01

    During the storage of water and the initial running of a reservoir, part of the dissolved nutrients released from the soil in water will effect water quality. Taking Qinglongshan Reservoir as an example , estimating the value of the contribution of dissolved nutrients to the water q uality and analyzing the trend or level of the dissolved nutrients effecting on the water quality under the soil nutrient inquiring, the soil nutrient monitorin g, and the dissolving experiment of nutrients released from soil, also accord ing to the capacity curve of Qinglongshan Reservoir.

  6. Rapid accretion of dissolved organic carbon in the Springs of Florida: the most organic-poor natural waters

    Directory of Open Access Journals (Sweden)

    C. M. Duarte

    2010-07-01

    Full Text Available The concentration of dissolved organic carbon (DOC in groundwater emanating as spring discharge at several locations in Florida, USA, and the net rate of DOC increase in the downstream receiving waters were measured as part of a larger investigation of carbon dynamics in flowing waters. Springs with high discharge (>2.8 m3 s−1 were found to be the most organic-poor natural waters yet reported (13 ±1.6 μmol C L−1, while springs with lesser discharge exhibited somewhat higher DOC concentrations (values ranging from 30 to 77 μmol C L−1. DOC concentrations increased rapidly downstream from the point of spring discharge, with the calculated net areal input rate of DOC ranging from 0.04 to 1.64 mol C m−2 d−1 across springs. Rates of DOC increase were generally greater in those springs with high discharge rates. These input rates compare favorably with values reported for gross primary production in these macrophyte-dominated spring systems, assuming that 17% of macrophyte primary production is lost, on average, as DOC. The measures reported here are possible only because of the remarkably low DOC levels in the up-surging groundwaters and the short residency times of the water in the spring-runs themselves.

  7. Molecular characterization of low molecular weight dissolved organic matter in water reclamation processes using Orbitrap mass spectrometry.

    Science.gov (United States)

    Phungsai, Phanwatt; Kurisu, Futoshi; Kasuga, Ikuro; Furumai, Hiroaki

    2016-09-01

    Reclaimed water has recently become an important water source for urban use, but the composition of dissolved organic matter (DOM) in reclaimed water has rarely been characterized at the compound level because of its complexity. In this study, the transformation and changes in composition of low molecular weight DOM in water reclamation processes, where secondary effluent of the municipal wastewater treatment plant was further treated by biofiltration, ozonation and chlorination, were investigated by "unknown" screening analysis using Orbitrap mass spectrometry (Orbitrap MS). The intense ions were detected over an m/z range from 100 to 450. In total, 2412 formulae with various heteroatoms were assigned, and formulae with carbon (C), hydrogen (H) and oxygen (O) only and C, H, O and sulfur (S) were the most abundant species. During biofiltration, CHO-only compounds with relatively high hydrogen to carbon (H/C) ratio or with saturated structure were preferentially removed, while CHOS compounds were mostly removed. Ozonation induced the greatest changes in DOM composition. CHOS compounds were mostly decreased after ozonation while ozone selectively removed CHO compounds with relatively unsaturated structure and produced compounds that were more saturated and with a higher degree of oxidation. After chlorination, 168 chlorine-containing formulae, chlorinated disinfection by-products (DBPs), were additionally detected. Candidate DBP precursors were determined by tracking chlorinated DBPs formed via electrophilic substitution, half of which were generated during the ozonation.

  8. Partial pressure (or fugacity) of carbon dioxide, dissolved inorganic carbon, pH, alkalinity, temperature, salinity and other variables collected from Surface underway observations using Carbon dioxide (CO2) gas analyzer, Shower head chamber equilibrator for autonomous carbon dioxide (CO2) measurement and other instruments from WEATHERBIRD II in the Coastal Waters of Florida and Gulf of Mexico from 2008-08-11 to 2011-06-30 (NCEI Accession 0144622)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — NCEI Accession 0144622 includes Surface underway data collected from WEATHERBIRD II in the Coastal Waters of Florida and Gulf of Mexico from 2008-08-11 to...

  9. Inflow rate-driven changes in the composition and dynamics of chromophoric dissolved organic matter in a large drinking water lake.

    Science.gov (United States)

    Zhou, Yongqiang; Zhang, Yunlin; Jeppesen, Erik; Murphy, Kathleen R; Shi, Kun; Liu, Mingliang; Liu, Xiaohan; Zhu, Guangwei

    2016-09-01

    Drinking water lakes are threatened globally and therefore in need of protection. To date, few studies have been carried out to investigate how the composition and dynamics of chromophoric dissolved organic matter (CDOM) in drinking water lakes are influenced by inflow rate. Such CDOM can lead to unpleasant taste and odor of the water and produce undesirable disinfection byproducts during drinking water treatment. We studied the drinking water Lake Qiandao, China, and found that the concentrations of suspended particulate matter (SPM) in the lake increased significantly with inflow rate (p water safety and requires higher removal efficiency of CDOM during drinking water treatment processes.

  10. A comparative study of the triple oxygen analyses of dissolved oxygen in a fresh water system (Feitsui reservoir) and South China Sea at SEATS station

    Science.gov (United States)

    Jurikova, H.; Guha, T.; Liang, M. C.

    2014-12-01

    We report the first insight into the stable isotopic composition of dissolved O2 from the Feitsui Reservoir, which supplies drinking water for millions of people living in Taipei, Taiwan. In addition, first observations on 17Δ from a cruise to South China Sea (the long-term station SEATS) in 2013 were also included for comparison. A regular sampling effort for collection of water samples from the Feitsui Reservoir was initiated in May 2014. The 17Δ of dissolved O2 from water samples was assessed to examine its spatial variations, variability over time and to estimate the gross oxygen production rates (GOP). Primary productivity estimated from the dissolved O2 will be compared to that from 14C. Results and implications will be presented and discussed.

  11. 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).

  12. 矿山湿地表层水中颗粒态和溶解态Pb,Cr影响因子分析及环境风险评价%On Environmental Risk Assessment and Factors Influencing for Dissolved and Particulate Pb,Cr in Surface Water of Mine Wetland

    Institute of Scientific and Technical Information of China (English)

    王化杰; 赵淑云; 任理想; 李刚

    2014-01-01

    通过1年的监测分析,结果表明,矿山湿地表层水中颗粒态 Pb(SPb)、溶解态 Pb(DPb)、颗粒态 Cr(SCr)和溶解态 Cr(DCr)含量空间差异显著.其中 MW-1中溶解态、颗粒态 Pb 含量分别为:0.44μg/L和1.12μg/L,溶解态、颗粒态 Cr含量分别为:1.40μg/L和1.96μg/L;MW-2中溶解态、颗粒态 Pb 含量分别为:0.89μg/L和2.24μg/L ,溶解态、颗粒态C r含量分别为:3.51μg/L和4.91μg/L;且均以颗粒态为主;矿山湿地表层水中颗粒态Pb,Cr季节性变化显著(p0.05);溶解态Pb含量冬季最高,夏季最低,颗粒态 Pb含量夏季最高,秋季最小.溶解态 Cr冬季最低,颗粒态 Cr夏季最高.主成分分析表明,前2个主成分累计解释了总因子的55.575%,82.824%,其主要受人类活动污染和自然地球化学因素共同影响.聚类分析表明,各元素可归为三类:其中,pH,DO,BOD5,COD和 TSS为一类;DCr,SCr,SPb,TN 和 DPb 为一类;TP单独为一类.采用单因子指数法评价分析,矿山湿地表层水中各水期溶解态铅、铬均未污染;同一水期MW-2的溶解态Pb,Cr的P值均大于MW-1.应用健康风险评价表明,鱼肉中铅、铬食入途径所产生的个人健康危害年风险均低于国际辐射防护委员会(ICRP)推荐的最大可接受水平5×10-5 a-1,不会对暴露人群构成危害.%Surface water samples have been collected from two mine wetland.The results indicate that the charac-teristics of heavy metal species in spatially cause significant differences (p0.05)on DPb and DCr.The average concentrations of DPb and SPb are higher in winter than in summer,higher in summer than in fall respectively.The minimum of DCr average concentrations is in winter.The maximum of SCr average concentrations is in summer.Principal Compo-nent Analysis (PCA)reveals that the cumulative rates of the top two principal components are 55.575%and 82.824%,indicating that the two main sources of heavy metals are human activities and natural geo

  13. Risk assessment of dissolved trace metals in drinking water of Karachi, Pakistan.

    Science.gov (United States)

    Karim, Zahida

    2011-06-01

    Health risk caused by the exposure to trace metals in water through different exposure pathways was investigated. Graphite furnace atomic absorption spectrometry was used for the determination of trace metals (nickel, copper, chromium, lead, cobalt, manganese and iron) in drinking water samples. The concentration of metals was compared with the world health organization (WHO) drinking water quality guideline values. Risk of metals on human health was evaluated using Hazard Quotient (HQ). Hazard quotients of all metals through oral ingestion and dermal absorption are found in the range of 1.11 × 10⁻² to 1.35 × 10⁻¹ and 8.52 × 10⁻⁵ to 9.75 × 10⁻², respectively. The results of the present study reflect the unlikely potential for adverse health effects to the inhabitants of Karachi due to the oral ingestion and dermal absorption of water containing these metals.

  14. Determination of dissolved boron in fresh, estuarine, and geothermal waters by d.c. argon-plasma emission spectrometry

    Science.gov (United States)

    Ball, J.W.; Thompson, J.M.; Jenne, E.A.

    1978-01-01

    A d.c. argon-plasma emission spectrometer is used to determine dissolved boron in natural (fresh and estuarine) water samples. Concentrations ranged from 0.02 to 250 mg l-1. The emission-concentration function is linear from 0.02 to 1000 mg l-1. Achievement of a relative standard deviation of ??? 3% requires frequent restandardization to offset sensitivity changes. Dilution may be necessary to overcome high and variable electron density caused by differences in alkali-metal content and to avoid quenching of the plasma by high solute concentrations of sodium and other easily ionized elements. The proposed method was tested against a reference method and found to be more sensitive, equally or more precise and accurate, less subject to interferences, with a wider linear analytical range than the carmine method. Analyses of standard reference samples yielded results in all cases within one standard deviation of the means. ?? 1978.

  15. Molecular size-dependent abundance and composition of dissolved organic matter in river, lake and sea waters.

    Science.gov (United States)

    Xu, Huacheng; Guo, Laodong

    2017-06-15

    Dissolved organic matter (DOM) is ubiquitous in natural waters. The ecological role and environmental fate of DOM are highly related to the chemical composition and size distribution. To evaluate size-dependent DOM quantity and quality, water samples were collected from river, lake, and coastal marine environments and size fractionated through a series of micro- and ultra-filtrations with different membranes having different pore-sizes/cutoffs, including 0.7, 0.4, and 0.2 μm and 100, 10, 3, and 1 kDa. Abundance of dissolved organic carbon, total carbohydrates, chromophoric and fluorescent components in the filtrates decreased consistently with decreasing filter/membrane cutoffs, but with a rapid decline when the filter cutoff reached 3 kDa, showing an evident size-dependent DOM abundance and composition. About 70% of carbohydrates and 90% of humic- and protein-like components were measured in the properties of DOM, such as specific ultraviolet absorbance, spectral slope, and biological and humification indices also varied significantly with membrane cutoffs. In addition, different ultrafiltration membranes with the same manufacture-rated cutoff also gave rise to different DOM retention efficiencies and thus different colloidal abundances and size spectra. Thus, the size-dependent DOM properties were related to both sample types and membranes used. Our results here provide not only baseline data for filter pore-size selection when exploring DOM ecological and environmental roles, but also new insights into better understanding the physical definition of DOM and its size continuum in quantity and quality in aquatic environments. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. 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

  17. Dissolved organic nitrogen transformation in river water: Effects of suspended sediment and organic nitrogen concentration

    Science.gov (United States)

    Xia, Xinghui; Liu, Ting; Yang, Zhifeng; Zhang, Xueqing; Yu, Zhongbo

    2013-03-01

    SummaryHigh suspended sediment (SPS) concentration exists in many Asian rivers. In addition, human activities and climate change can change river runoff, leading to the variation of SPS and pollutant concentrations. In this research, the effects of SPS and dissolved organic nitrogen (DON) concentration on DON transformation in river systems were studied through simulation experiments with samples collected from the Yellow River which is famous for its high SPS concentration. The results indicated that high DON concentration resulted in a longer retention time of NH4+-N and NO2--N in the system due to the inhibition effect of ammonia on nitrification. The re-suspension of sediment accelerated DON transformation, and both the ammonification and nitrification rates increased with SPS concentration. The ammonification rate constants obtained from the first-order kinetics were 0.286, 0.332, 0.538 day-1; the nitrification rate constants obtained from the Logistic model were 0.0018, 0.0038, 0.005 day-1 μmol-1 L-1 for the systems with SPS concentration of 0, 5, 10 g L-1, respectively. Bacteria tended to attach onto SPS, and the specific growth rate in the systems with SPS was approximately two orders of magnitude higher than that without SPS in the first 3 days of cultivation, which resulted in an increase of DON transformation rate with SPS concentration. This study implied that DON transformation rate may be lower in the dry season than that in the wet season, and nitrogen transformation will be affected by the variation of river runoff and SPS concentration.

  18. Differential effects of dissolved organic carbon upon re-entrainment and surface properties of groundwater bacteria and bacteria-sized microspheres during transport through a contaminated, sandy aquifer

    Science.gov (United States)

    Harvey, R.W.; Metge, D.W.; Mohanram, A.; Gao, X.; Chorover, J.

    2011-01-01

    Injection-and-recovery studies involving a contaminated, sandy aquifer (Cape Cod, Massachusetts) were conducted to assess the relative susceptibility for in situ re-entrainment of attached groundwater bacteria (Pseudomonas stuzeri ML2, and uncultured, native bacteria) and carboxylate-modified microspheres (0.2 and 1.0 ??m diameters). Different patterns of re-entrainment were evident for the two colloids in response to subsequent injections of groundwater (hydrodynamic perturbation), deionized water (ionic strength alteration), 77 ??M linear alkylbenzene sulfonates (LAS, anionic surfactant), and 76 ??M Tween 80 (polyoxyethylene sorbitan monooleate, a very hydrophobic nonionic surfactant). An injection of deionized water was more effective in causing detachment of micrsopheres than were either of the surfactants, consistent with the more electrostatic nature of microsphere's attachment, their extreme hydrophilicity (hydrophilicity index, HI, of 0.99), and negative charge (zeta potentials, ??, of -44 to -49 mv). In contrast, Tween 80 was considerably more effective in re-entraining the more-hydrophobic native bacteria. Both the hydrophilicities and zeta potentials of the native bacteria were highly sensitive to and linearly correlated with levels of groundwater dissolved organic carbon (DOC), which varied modestly from 0.6 to 1.3 mg L-1. The most hydrophilic (0.52 HI) and negatively charged (?? -38.1 mv) indigenous bacteria were associated with the lowest DOC. FTIR spectra indicated the latter community had the highest average density of surface carboxyl groups. In contrast, differences in groundwater (DOC) had no measurable effect on hydrophilicity of the bacteria-sized microspheres and only a minor effect on their ??. These findings suggest that microspheres may not be very good surrogates for bacteria in field-scale transport studies and that adaptive (biological) changes in bacterial surface characteristics may need to be considered where there is longer

  19. Role of dissolved organic carbon upon re-entrainment and surface properties of aquifer bacteria and bacteria-sized microspheres during subsurface transport (Invited)

    Science.gov (United States)

    Harvey, R. W.; Metge, D. W.; Mohanram, A.; Gao, X.; Chorover, J.

    2010-12-01

    Susceptibilities for in-situ re-entrainment of attached 0.2 and 1.0 μm (diameter) microspheres and groundwater bacteria (Pseudomonas stuzeri and uncultured, native bacteria) were assessed during transport studies involving an organically contaminated, sandy aquifer in Cape Cod, MA. Aquifer sediments between pairs of injection and sampling wells were initially loaded with fluorescently labeled, carboxylated microspheres and bacteria that had been stained with the DNA-specific fluorochrome 4',6-diamidino-2-phenylindole. In response to subsequent hydrodynamic perturbations and injections of deionized water (ionic strength reduction), anionic surfactants (77 μM linear alkylbenzene sulfonates, LAS) and non-ionic surfactant (76 μM polyoxyethylene sorbitan monooleate, Tween 80), differing patterns of re-entrainment were evident for the two colloids. Injections of anionic surfactant and deionized water were the most efficient in causing detachment of the highly hydrophilic and negatively charged microspheres, but largely ineffective in causing re-entrainment of bacteria. In contrast, the nonionic surfactant was highly effective in re-entraining bacteria, but not microspheres. The hydrophobicities and zeta potentials of the indigenous bacteria were highly sensitive to modest concentration changes (0.6 to 1.3 mg L-1) in groundwater dissolved organic carbon (DOC), whereas the microspheres were largely unaffected. The most hydrophilic and negatively charged bacterial community was isolated from groundwater having the lowest DOC. FTIR spectra indicated that the community from the lowest DOC groundwater also had the highest average density of surface carboxyl groups. This indicates that DOC may have a biological effect on native bacteria resulting in changes to surface structures or changes in the makeup of the bacterial community.

  20. Importance of Ekman transport and gyre circulation change on seasonal variation of surface dissolved iron in the western subarctic North Pacific

    Science.gov (United States)

    Nakanowatari, Takuya; Nakamura, Tomohiro; Uchimoto, Keisuke; Nishioka, Jun; Mitsudera, Humio; Wakatsuchi, Masaaki

    2017-05-01

    Iron (Fe) is an essential nutrient for marine phytoplankton and it constitutes an important element in the marine carbon cycle in the ocean. This study examined the mechanisms controlling seasonal variation of dissolved Fe (dFe) in the western subarctic North Pacific (WSNP), using an ocean general circulation model coupled with a simple biogeochemical model incorporating a dFe cycle fed by two major sources (atmospheric dust and continental shelf sediment). The model reproduced the seasonal cycle of observed concentrations of dFe and macronutrients at the surface in the Oyashio region with maxima in winter (February-March) and minima in summer (July-September), although the simulated seasonal amplitudes are a half of the observed values. Analysis of the mixed-layer dFe budget indicated that both local vertical entrainment and lateral advection are primary contributors to the wintertime increase in dFe concentration. In early winter, strengthened northwesterly winds excite southward Ekman transport and Ekman upwelling over the western subarctic gyre, transporting dFe-rich water southward. In mid to late winter, the southward western boundary current of the subarctic gyre and the outflow from the Sea of Okhotsk also bring dFe-rich water to the Oyashio region. The contribution of atmospheric dust to the dFe budget is several times smaller than these ocean transport processes in winter. These results suggest that the westerly wind-induced Ekman transport and gyre circulation systematically influence the seasonal cycle of WSNP surface dFe concentration.

  1. 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

    once in 2006 and once in 2007 at Moenkopi School Spring. Flow decreased by 18.9 percent at Moenkopi School Spring. During the period of record, flow fluctuated, and a decreasing trend was apparent. Continuous records of surface-water discharge in the Black Mesa area have been collected from streamflow gages at the following sites: Moenkopi Wash at Moenkopi (1976 to 2006), Dinnebito Wash near Sand Springs (1993 to 2006), Polacca Wash near Second Mesa (1994 to 2006), and Pasture Canyon Springs (August 2004 to December 2006). Median flows during November, December, January, and February of each water year were used as an index of the amount of ground-water discharge to the above named sites. For the period of record at each streamflow-gaging station, the median winter flows have generally remained even, showing neither a significant increase nor decrease in flows. There is not a long enough period of record for Pasture Canyon Spring for a trend to be apparent. In 2007, water samples were collected from 1 well and 1 spring in the Black Mesa area and were analyzed for selected chemical constituents. Concentrations of dissolved solids, chloride, and sulfate have varied at Peabody well 5 for the period of record, and there is an apparent increasing trend. Dissolved-solids, chloride, and sulfate concentrations increased at Moenkopi School Spring during the more than 12 years of record.

  2. Relations of surface-water quality to streamflow in the Raritan River basin, New Jersey, water years 1976-93

    Science.gov (United States)

    Buxton, Debra E.; Hunchak-Kariouk, Kathryn; Hickman, R. Edward

    1999-01-01

    Relations of water quality to streamflow were determined for 18 water-quality constituents at 21 surface-water stations within the drainage area of the Raritan River Basin for water years 1976-93. Surface-water-quality and streamflow data were evaluated for trends (through time) in constituent concentrations during high and low flows, and relations between constituent concentration and streamflow, and between constituent load and streamflow, were determined. Median concentrations were calculated for the entire period of study (water years 1976-93) and for the last 5 years of the period of study (water years 1989-93) to determine whether any large variation in concentration exists between the two periods. Medians also were used to determine the seasonal Kendall’s tau statistic, which was then used to evaluate trends in concentrations during high and low flows. Trends in constituent concentrations during high and low flows were evaluated to determine whether the distribution of the observations changes through time for intermittent (nonpoint storm runoff) or constant (point sources and ground water) sources, respectively. Highand low-flow trends in concentrations were determined for some constituents at 13 of the 21 water-quality stations; 8 stations have insufficient data to determine trends. Seasonal effects on the relations of concentration to streamflow are evident for 16 of the 18 constituents. Negative slopes of relations of concentration to streamflow, which indicate a decrease in concentration at high flows, predominate over positive slopes because of the dilution of instream concentrations by storm runoff. The slopes of the regression lines of load to streamflow were determined in order to show the relative contributions to the instream load from constant (point sources and ground water) and intermittent sources (storm runoff). Greater slope values indicate larger contributions from storm runoff to instream load, which most likely indicate an increased

  3. 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

  4. 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

  5. Hydrogeologic controls of surface-water chemistry in the Adirondack region of New York State

    Science.gov (United States)

    Peters, N.E.; Driscoll, C.T.

    1987-01-01

    Relationships between surface-water discharge, water chemistry, and watershed geology were investigated to evaluate factors affecting the sensitivity of drainage waters in the Adirondack region of New York to acidification by atmospheric deposition. Instantaneous discharge per unit area was derived from relationships between flow and staff-gage readings at 10 drainage basins throughout the region. The average chemical composition of the waters was assessed from monthly samples collected from July 1982 through July 1984. The ratio of flow at the 50-percent exceedence level to the flow at the 95-percent exceedence level of flow duration was negatively correlated with mean values of alkalinity or acid-neutralizing capacity (ANC), sum of basic cations (SBC), and dissolved silica, for basins containing predominantly aluminosilicate minerals and little or no carbonate-bearing minerals. Low ratios are indicative of systems in which flow is predominately derived from surface- and ground-water storage, whereas high ratios are characteristic of watersheds with variable flow that is largely derived from surface runoff. In an evaluation of two representative surface-water sites, concentrations of ANC, SBC, and dissolved silica, derived primarily from soil mineral weathering reactions. decreased with increasing flow. Furthermore, the ANC was highest at low flow when the percentage of streamflow derived from ground water was maximum. As flow increased, the ANC decreased because the contribution of dilute surface runoff and lateral flow through the shallow acidic soil horizons to total flow increased. Basins having relatively high ground-water contributions to total flow, in general, have large deposits of thick till or stratified drift. A major factor controlling the sensitivity of these streams and lakes to acidification is the relative contribution of ground water to total discharge. ?? 1987 Martinus Nijhoff/Dr W. Junk Publishers.

  6. Temporal changes in dissolved (137)Cs concentrations in groundwater and stream water in Fukushima after the Fukushima Dai-ichi Nuclear Power Plant accident.

    Science.gov (United States)

    Iwagami, Sho; Tsujimura, Maki; Onda, Yuichi; Nishino, Masataka; Konuma, Ryohei; Abe, Yutaka; Hada, Manami; Pun, Ishwar; Sakaguchi, Aya; Kondo, Hiroaki; Yamamoto, Masayoshi; Miyata, Yoshiki; Igarashi, Yasuhito

    2017-01-01

    The concentration of dissolved (137)Cs in groundwater and stream water in the headwater catchments in Yamakiya district, located ∼35 km north west of Fukushima Dai-ichi Nuclear Power Plant (FDNPP), was monitored from June 2011 to July 2013, after the earthquake and tsunami disaster. Groundwater and stream water were sampled at intervals of approximately 2 months at each site. Intensive sampling was also conducted during rainstorm events. Compared with previous data from the Chernobyl NPP accident, the concentration of dissolved (137)Cs in stream water was low. In the Iboishi-yama catchment, a trend was observed for the concentration of dissolved (137)Cs in stream water to decline, which could be divided into two phases by October 2011 (a fast flush of activity as a result of rapid washoff and a slow decline as a result of soil fixation and redistribution processes). The highest (137)Cs concentration recorded at Iboishi-yama was 1.2 Bq/L on August 6, 2011, which then declined to 0.021-0.049 Bq/L during 2013 (in stream water under normal water-flow conditions). During the rainfall events, the concentration of dissolved (137)Cs in stream water increased temporarily. The concentration of dissolved (137)Cs in groundwater at a depth of 30 m at Iboishi-yama displayed a decreasing trend from 2011 to 2013, with a range from 0.039 Bq/L to 0.0025 Bq/L. The effective half-lives of stream water in the initial fast flush and secondary phases were 0.10-0.21 and 0.69-1.5 y, respectively in the three catchments. The effective half-life of groundwater was 0.46-0.58 y at Koutaishi-yama and 0.50-3.3 y at Iboishi-yama. The trend for the concentration of dissolved (137)Cs to decline in groundwater and stream water was similar throughout 2012-2013, and the concentrations recorded in deeper groundwater were closer to those in stream water. The declining trend of dissolved (137)Cs concentrations in stream water was similar to that of the loss of canopy (137)Cs by throughfall, as

  7. Polybrominated diphenyl ethers in dissolved and suspended phases of seawater and in surface sediment from Jiaozhou Bay, North China.

    Science.gov (United States)

    Ju, Ting; Ge, Wei; Jiang, Tao; Chai, Chao

    2016-07-01

    The concentration and distribution of polybrominated diphenyl ethers (PBDEs) in the dissolved phase (DP) and suspended particulate matter (SPM) of seawater and in surface sediment obtained from Jiaozhou Bay (JZB) were determined. The potential sources of these compounds were evaluated. The total concentrations of 14 PBDEs (∑14PBDE) in DP and SPM were 0.09-1.35 and 1.17-5.45ng/L, respectively, indicating that the PBDE congeners are predominantly partitioned into the SPM fraction. The ∑14PBDE concentrations in sediment ranged from 2.18ng/g to 10.59ng/g with a mean value of 6.59ng/g. BDE-209 was dominant among 14 PBDE congeners, and BDE-47 was another abundant congener in the SPM and sediment samples. The PBDE concentration in SPM showed a significantly positive correlation with chlorophyll a level (r(2)=0.496, pparametric multidimensional scaling ordination showed that BDE-209 and BDE-47 are the important products discriminating PBDE contamination. This result is associated with industrial waste discharge from urban areas and with heavy ship traffic, indicating that DecaBDE and PentaBDE products are the potential sources of PBDEs. PBDE concentrations were lower in the sediment in JZB than in other coastal areas in South China, although the PBDE concentrations in DP were higher than those in some coastal areas worldwide. Moreover, the PBDE concentrations in DP and sediment increased in the last decade.

  8. Microbial and geochemical investigations of dissolved organic carbon and microbial ecology of native waters from the Biscayne and Upper Floridan Aquifers

    Science.gov (United States)

    Lisle, John T.; Harvey, Ron W.; Aiken, George R.; Metge, David W.

    2010-01-01

    Groundwater resources in the United States are under ever-increasing demands for potable, irrigation, and recreational uses. Additionally, aquifer systems are being used or targeted for use as storage areas for treated surface waters and (or) groundwaters via injection (for example, aquifer storage and recovery). To date, the influence that the nutrients, including carbon, in the injected water have on native microbial communities and the biogeochemistry in the subsurface zones used for storage of the injectate has not been determined. In this report, we describe a series of experiments that establishes a baseline dataset for the quantity and quality of organic and inorganic carbon and nutrients in the Biscayne Aquifer (BA) and Upper Floridan Aquifer (UFA) in south Florida. The most significant differences between the BA (26 meters below surface) and UFA (366 meters below surface) are the average specific conductance (0.552 and 6.12 microsiemens per centimeter, respectively), dissolved oxygen (1.6 and 0 milligrams per liter, respectively), and oxidation-reduction potential (40.3 and -358 millivolts, respectively). The dissolved organic carbon from the BA is characterized by carbon originating from terrestrial sources and microbial activities, while the UFA has a distinctive microbial signature. Acetate and lactate are the dominant carbon constituents in both aquifers. Additionally, components of the dissolved organic carbon from the UFA have a total trihalomethane-formation potential that is approximately threefold greater than the maximum contaminat level of 80 micrograms per liter established by the U.S. Environmental Protection Agency. The average native bacterial abundances in the aquifers are similar with 4.69x10^4 cells per milliliter in the BA and 1.33x10^4 cells per milliliter in the UFA. The average bacteriophage abundances are also similar with 1.15x10^5 virus-like particles in the BA and 1.92x10^5 virus-like particles in the UFA. Interestingly, ciliated

  9. Extreme learning machines: a new approach for modeling dissolved oxygen (DO) concentration with and without water quality variables as predictors.

    Science.gov (United States)

    Heddam, Salim; Kisi, Ozgur

    2017-07-01

    In this paper, several extreme learning machine (ELM) models, including standard extreme learning machine with sigmoid activation function (S-ELM), extreme learning machine with radial basis activation function (R-ELM), online sequential extreme learning machine (OS-ELM), and optimally pruned extreme learning machine (OP-ELM), are newly applied for predicting dissolved oxygen concentration with and without water quality variables as predictors. Firstly, using data from eight United States Geological Survey (USGS) stations located in different rivers basins, USA, the S-ELM, R-ELM, OS-ELM, and OP-ELM were compared against the measured dissolved oxygen (DO) using four water quality variables, water temperature, specific conductance, turbidity, and pH, as predictors. For each station, we used data measured at an hourly time step for a period of 4 years. The dataset was divided into a training set (70%) and a validation set (30%). We selected several combinations of the water quality variables as inputs for each ELM model and six different scenarios were compared. Secondly, an attempt was made to predict DO concentration without water quality variables. To achieve this goal, we used the year numbers, 2008, 2009, etc., month numbers from (1) to (12), day numbers from (1) to (31) and hour numbers from (00:00) to (24:00) as predictors. Thirdly, the best ELM models were trained using validation dataset and tested with the training dataset. The performances of the four ELM models were evaluated using four statistical indices: the coefficient of correlation (R), the Nash-Sutcliffe efficiency (NSE), the root mean squared error (RMSE), and the mean absolute error (MAE). Results obtained from the eight stations indicated that: (i) the best results were obtained by the S-ELM, R-ELM, OS-ELM, and OP-ELM models having four water quality variables as predictors; (ii) out of eight stations, the OP-ELM performed better than the other three ELM models at seven stations while the R

  10. Effect of total dissolved gas supersaturated water on early life of David’s schizothoracin (Schizothorax davidi)*

    Science.gov (United States)

    Liang, Rui-feng; Li, Bo; Li, Ke-feng; Tuo, You-cai

    2013-01-01

    The effect of total dissolved gas (TDG) supersaturation on fish living downstream of dams is one of the main ecological risks of high dam construction. A strategy for mitigating the negative effects is needed urgently since many high dams are under construction in the upper reaches of the Yangtze River in China. Experiments on the hatching process of David’s schizothoracin were carried out and the results show that the hatching rate decreased with increasing TDG levels, and that most eggs hatched within a very short time in the higher TDG saturation groups. By using a stereomicroscope, damages to the head, yolk sac, body, anus, etc. were found in larvae which hatched in TDG supersaturated water. Results show that the lesion rate increased with increasing TDG levels. Furthermore, 7-d-old David’s schizothoracin were exposed to TDG supersaturated water levels of 100%, 105%, 110%, 115%, 120%, 125%, 130%, 135%, and 140% for testing their tolerance to TDG supersaturation. We found that the median lethal concentrations (LC50) for 13, 14, 20, 35, 52, 73, and 96 h exposure were 138%, 138%, 134%, 130%, 129%, 128%, and 126%, respectively. The median lethal times (LT50) were 7.49, 11.04, 19.25, and 35.38 h for exposure to water with TDG levels of 145%, 140%, 135%, and 130%, respectively. PMID:23825149

  11. Predicting Copper Speciation in Estuarine Waters-Is Dissolved Organic Carbon a Good Proxy for the Presence of Organic Ligands?

    Science.gov (United States)

    Pearson, Holly B C; Comber, Sean D W; Braungardt, Charlotte; Worsfold, Paul J

    2017-02-21

    A new generation of speciation-based aquatic environmental quality standards (EQS) for metals have been developed using models to predict the free metal ion concentration, the most ecologically relevant form, to set site-specific values. Some countries such as the U.K. have moved toward this approach by setting a new estuarine and marine water EQS for copper, based on an empirical relationship between copper toxicity to mussels (Mytilus sp.) and ambient dissolved organic carbon (DOC) concentrations. This assumes an inverse relationship between DOC and free copper ion concentration owing to complexation by predominantly organic ligands. At low DOC concentrations, the new EQS is more stringent, but above 162 μM DOC it is higher than the previous value. However, the relationship between DOC and copper speciation is poorly defined in estuarine waters. This research discusses the influence of DOC from different sources on copper speciation in estuaries and concludes that DOC is not necessarily an accurate predictor of copper speciation. Nevertheless, the determination of ligand strength and concentrations by Competitive Ligand Exchange Adsorptive Cathodic Stripping Voltammetry enabled the prediction of the free metal ion concentration within an order of magnitude for estuarine waters by using a readily available metal speciation model (Visual MINTEQ).

  12. Gold-coated silica as a preconcentration phase for the determination of total dissolved mercury in natural waters using atomic fluorescence spectrometry.

    Science.gov (United States)

    Leopold, Kerstin; Foulkes, Michael; Worsfold, Paul J

    2009-05-01

    A novel solid-phase preconcentration method is reported, using in-house gold-coated silica adsorbent packed in a microcolumn, for the determination of dissolved mercury in natural waters by atomic fluorescence spectrometry (AFS). The adsorbent was prepared by chemical reduction of a Au(III) solution with hydroxylamine in the presence of suspended silica particles. The resulting Au nanoparticles on the silica surface were highly efficient for adsorbing different mercury species from acidified waters without additional reagents. The acidified aqueous samples were passed over the microcolumn, either incorporated in a fully automated flow injection (FI) system directly coupled to the AFS or as part of a portable FI system for in situ preconcentration. After rinsing and drying of the column, Hg(0) was released by heating and directed to the AFS cell for quantification. The method offers significant advantages because no reagents are needed for species conversion, preconcentration, sample storage, or desorption and therefore the risk of contamination is minimized and blank values are lowered. This results in a low detection limit of 180 pg L(-1) using a sample volume of only 7 mL and good reproducibility, with relative standard deviations 90% in spiked river waters (spiked [Hg] = 0, 1, 5, 10 ng L(-1)), and the experimental value for the certified reference material ORMS-4 (elevated mercury in river water) was 22.3 +/- 2.6 ng Hg L(-1) which was in good agreement with the certified value of 22.0 +/- 1.6 ng Hg L(-1) (recovery = 101%). The method was successfully applied to seven different natural waters and wastewaters ([Hg] 0.5-4.6 ng L(-1)) from south west England.

  13. Removal of dissolved VOCs from water with an air stripper/membrane vapor separation system

    NARCIS (Netherlands)

    Wijmans, J.G.; Kamaruddin, H.D.; Segelke, S.V.; Wessling, Matthias; Baker, R.W.

    1997-01-01

    Treatment of water contaminated with volatile organic compounds (VOCs) is a major problem for the United States chemical industry. Currently, VOCs are removed from moderately contaminated wastewater streams by processes such as steam stripping and from dilute wastewaters by air stripping combined wi

  14. 40 CFR 795.70 - Indirect photolysis screening test: Sunlight photolysis in waters containing dissolved humic...

    Science.gov (United States)

    2010-07-01

    ... mobile phase is 2 percent acetic acid, 50 percent acetonitrile and 48 percent water (2 mL/min flow rate... of sunlight actinometers.” Environmental Science and Technology, 6:815. (1982). (6) Haag H.R., Hoigne... Science and Technology, 11:359. (1977). (20) Zepp, R.G., Wolfe N.L., Baughman G.L., Hollis R.C....

  15. Bromination of Marine Dissolved Organic Matter following Full Scale Electrochemical Ballast Water Disinfection.

    Science.gov (United States)

    Gonsior, Michael; Mitchelmore, Carys; Heyes, Andrew; Harir, Mourad; Richardson, Susan D; Petty, William Tyler; Wright, David A; Schmitt-Kopplin, Philippe

    2015-08-01

    An extensively diverse array of brominated disinfection byproducts (DBPs) were generated following electrochemical disinfection of natural coastal/estuarine water, which is one of the main treatment methods currently under consideration for ballast water treatment. Ultra-high-resolution mass spectrometry revealed 462 distinct brominated DBPs at a relative abundance in the mass spectra of more than 1%. A brominated DBP with a relative abundance of almost 22% was identified as 2,2,4-tribromo-5-hydroxy-4-cyclopentene-1,3-dione, which is an analogue to several previously described 2,2,4-trihalo-5-hydroxy-4-cyclopentene-1,3-diones in drinking water. Several other brominated molecular formulas matched those of other known brominated DBPs, such as dibromomethane, which could be generated by decarboxylation of dibromoacetic acid during ionization, dibromophenol, dibromopropanoic acid, dibromobutanoic acid, bromohydroxybenzoic acid, bromophenylacetic acid, bromooxopentenoic acid, and dibromopentenedioic acid. Via comparison to previously described chlorine-containing analogues, bromophenylacetic acid, dibromooxopentenoic acid, and dibromopentenedioic acid were also identified. A novel compound at a 4% relative abundance was identified as tribromoethenesulfonate. This compound has not been previously described as a DBP, and its core structure of tribromoethene has been demonstrated to show toxicological implications. Here we show that electrochemical disinfection, suggested as a candidate for successful ballast water treatment, caused considerable production of some previously characterized DBPs in addition to novel brominated DBPs, although several hundred compounds remain structurally uncharacterized. Our results clearly demonstrate that electrochemical and potentially direct chlorination of ballast water in estuarine and marine systems should be approached with caution and the concentrations, fate, and toxicity of DBP need to be further characterized.

  16. 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

  17. Spectroscopic measurements of the surface waters for evaluating the fresh-water transport to marine environments in the Southern Baltic

    Science.gov (United States)

    Drozdowska, Violetta; Markuszewski, Piotr; Kowalczyk, Jakub; Makuch, Przemysław; Pakszyc, Paulina; Strzałkowska, Agata; Piskozub, Jacek; Petelski, Tomasz; Zieliński, Tymon; Gutowska, Dorota

    2014-05-01

    To asses concentration and spatial distribution of surface-active molecules (surfactants) the spectrophotometric and spectrofluorometric measurements of water samples taken from a surface film and a depth 0.5 m were carried out during three cruises of r/v Oceania in Springs' 2010-2011 and Autumn' 2012. Measurements were conducted along the transects from the river outlets to the open waters of the Southern Baltic Sea. Surfactants consist of polar molecules of marine dissolved organic matter and are chemically not entirely classified. However, fractions of dissolved organic matter having chromophores or fluorophores (CDOM or FDOM) are recognized through their specific absorption and fluorescence spectra. The sea surface is a layer of transition between the atmosphere and the sea, where there is a variety of biological, physical and chemical processes which contribute to the accumulation and exchange of surfactants, the chemical species concentrated in the surface layer (surface active agents). The main source of marine surfactants are remains of phytoplankton and its degradation products, created by bacterial activity, and as a result of condensation of molecules of low molecular weight to form of surface-active macromolecules. The presence of surfactants in the surface layers can significantly affect the access of solar energy into the sea as well as the air-sea interaction processes. The main objective of the research was to investigate the luminescent properties of surfactants, sampled in different regions of the Southern Baltic, and to find the differences between a surface film and a subsurface layer (of 50 cm). The next aim was to combine the differences in optical properties with the different dynamics for various river outlets. The results of spectrophotometric studies show the differences in the intensity of spectral bands, particularly between coastal (estuaries) and the open sea zones. Also, analysis of the spectra shows differences between areas of the

  18. Radiochemical analyses of surface water from U.S. Geological Survey hydrologic bench-mark stations

    Science.gov (United States)

    Janzer, V.J.; Saindon, L.G.

    1972-01-01

    The U.S. Geological Survey's program for collecting and analyzing surface-water samples for radiochemical constituents at hydrologic bench-mark stations is described. Analytical methods used during the study are described briefly and data obtained from 55 of the network stations in the United States during the period from 1967 to 1971 are given in tabular form.Concentration values are reported for dissolved uranium, radium, gross alpha and gross beta radioactivity. Values are also given for suspended gross alpha radioactivity in terms of natural uranium. Suspended gross beta radioactivity is expressed both as the equilibrium mixture of strontium-90/yttrium-90 and as cesium-137.Other physical parameters reported which describe the samples include the concentrations of dissolved and suspended solids, the water temperature and stream discharge at the time of the sample collection.

  19. Chemical characteristics of fulvic acids from Arctic surface waters: Microbial contributions and photochemical transformations

    Science.gov (United States)

    Cory, Rose M.; McKnight, Diane M.; Chin, Yu-Ping; Miller, Penney; Jaros, Chris L.

    2007-12-01

    Dissolved organic matter (DOM) originating from the extensive Arctic tundra is an important source of organic material to the Arctic Ocean. Chemical characteristics of whole water dissolved organic matter (DOM) and the fulvic acid fraction of DOM were studied from nine surface waters in the Arctic region of Alaska to gain insight into the extent of microbial and photochemical transformation of this DOM. All the fulvic acids had a strong terrestrial/higher plant signature, with uniformly depleted δ13C values of -28‰, and low fluorescence indices around 1.3. Several of the measured chemical characteristics of the Arctic fulvic acids were related to water residence time, a measure of environmental exposure to sunlight and microbial activity. For example, fulvic acids from Arctic streams had higher aromatic contents, higher specific absorbance values, lower nitrogen content, lower amino acid-like fluorescence and were more depleted in δ15N relative to fulvic acids isolated from lake and coastal surface waters. The differences in the nitrogen signature between the lake and coastal fulvic acids compared to the stream fulvic acids indicated that microbial contributions to the fulvic acid pool increased with increasing water residence time. The photo-lability of the fulvic acids was positively correlated with water residence time, suggesting that the fulvic acids isolated from source waters with larger water residence times (i.e., lakes and coastal waters) have experienced greater photochemical degradation than the stream fulvic acids. In addition, many of the initial differences in fulvic acid chemical characteristics across the gradient of water residence times were consistent with changes observed in fulvic acid photolysis experiments. Taken together, results from this study suggest that photochemical processes predominantly control the chemical character of fulvic acids in Arctic surface waters. Our findings show that hydrologic transport in addition to

  20. 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.

  1. Short-term dissolved organic carbon dynamics reflect water management and precipitation patterns in a subtropical estuary

    Directory of Open Access Journals (Sweden)

    Peter Regier

    2016-12-01

    Full Text Available Estuaries significantly impact the global carbon cycle by regulating the exchange of organic matter, primarily in the form of dissolved organic carbon (DOC, between terrestrial and marine carbon pools. Estuarine DOC dynamics are complex as tides and other hydrological and climatic drivers can affect carbon fluxes on short and long time scales. While estuarine and coastal DOC dynamics have been well studied, variations on short time scales are less well constrained. Recent advancements in sonde technology enable autonomous in situ collection of high frequency DOC data using fluorescent dissolved organic matter (fDOM as a proxy, dramatically improving our capacity to characterize rapid changes in DOC, even in remote ecosystems. This study utilizes high-frequency fDOM measurements to untangle rapid and complex hydrologic drivers of DOC in the Shark River estuary, the main drainage of Everglades National Park, Florida. Non-conservative mixing of fDOM along the salinity gradient suggested mangrove inputs accounted for 6% of the total DOC pool. Average changes in fDOM concentrations through individual tidal cycles ranged from less than 10% to greater than 50% and multi-day trends greater than 100% change in fDOM concentration were observed. Salinity and water level both inversely correlated to fDOM at sub-hourly and daily resolutions, while freshwater controls via precipitation and water management were observed at diel to monthly time-scales. In particular, the role of water management in rapidly shifting estuarine salinity gradients and DOC export regimes at sub-weekly time-scales was evident. Additionally, sub-hourly spikes in ebb-tide fDOM indicated rapid exchange of DOC between mangrove sediments and the river channel. DOC fluxes calculated from high-resolution fDOM measurements were compared to monthly DOC measurements with high-resolution fluxes considerably improving accuracy of fluxes (thereby constraining carbon budgets. This study provides

  2. Modeling the improvement of ultrafiltration membrane mass transfer when using biofiltration pretreatment in surface water applications.

    Science.gov (United States)

    Netcher, Andrea C; Duranceau, Steven J

    2016-03-01

    In surface water treatment, ultrafiltration (UF) membranes are widely used because of their ability to supply safe drinking water. Although UF membranes produce high-quality water, their efficiency is limited by fouling. Improving UF filtrate productivity is economically desirable and has been attempted by incorporating sustainable biofiltration processes as pretreatment to UF with varying success. The availability of models that can be applied to describe the effectiveness of biofiltration on membrane mass transfer are lacking. In this work, UF water productivity was empirically modeled as a function of biofilter feed water quality using either a quadratic or Gaussian relationship. UF membrane mass transfer variability was found to be governed by the dimensionless mass ratio between the alkalinity (ALK) and dissolved organic carbon (DOC). UF membrane productivity was optimized when the biofilter feed water ALK to DOC ratio fell between 10 and 14. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. A statistical assessment of the impact of land uses on surface water quality indexes.

    Science.gov (United States)

    Seeboonruang, Uma

    2012-06-30

    The release of wastewater from various land uses is threatening the quality of surface water. Different land uses pose varying degrees of danger to water resources. The hazardous extent of each activity depends on the amount and characteristics of the wastewater. The concept of the contamination potential index (CPI) of an activity is introduced and applied here. The index depends on the quantity of wastewater from a single source and on various chemicals in the waste whose concentrations are above allowable standards. The CPI concept and the land use impact assessment are applied to the surface water conditions in Nakhon Nayok Province in the central region of Thailand. The land uses considered in this study are residential area, industrial zone, in-season and off-season rice farming, and swine and poultry livestock. Multiple linear regression analysis determines the impact of the CPIs of these land uses on certain water quality characteristics, i.e., total dissolved solids, electrical conductivity, phosphate, and chloride concentrations, using CPIs and previous water quality measurements. The models are further verified according to the current CPIs and measured concentrations. The results of the backward and forward modeling show that the land uses that affect water quality are off-season rice farming, raising poultry, and residential activity. They demonstrate that total dissolved solids and conductivity are reasonable parameters to apply in the land use assessment.

  4. Treatability of South African surface waters by activated carbon

    African Journals Online (AJOL)

    This suggests that GAC usage rate is not only a function of the initial UV absorbance but also ... and dissolved organic carbon (DOC) data suggested that for some waters UV254 ..... analysis was done with the UV254 absorbance value, as this.

  5. Dissolved oxygen - A target indicator in determining use of the Gulf of Kachchh waters

    Digital Repository Service at National Institute of Oceanography (India)

    Desa, E.; Zingde, M.D.; Vethamony, P.; Babu, M.T.; DeSousa, S.N.; Verlecar, X.N.

    in this zone under controlled conditions only. Thus, it is neces- sary to estimate the BOD load of the effluent of the pro- posed industry and the resultant minimum DO levels attainable in the receiving water body for planning pur- poses. This approach... at three select loca- tions, DO reduces from 5.1mgl C01 to 3.1, 5.0 and 3.8mgl C01 , respectively, indicating a strong sensitivity to effluent load. Based on the This paper deals with (i) availability of DO in the GoK, (ii) role of BOD in controlling DO...

  6. Fluorescence spectroscopy and parallel factor analysis as a dissolved organic monitoring tool to assess treatment performance in drinking water trains.

    Science.gov (United States)

    Vera, M; Cruz, S; Boleda, M R; Mesa, J; Martín-Alonso, J; Casas, S; Gibert, O; Cortina, J L

    2017-04-15

    Fluorescence excitation emission matrix (FEEM) spectroscopy was used to evaluate its applicability as a tool to track dissolved organic matter (DOM) in a drinking water treatment plant (DWTP) that incorporates a conventional line (consisting in ozonation and GAC filtration) and a membrane-based line (consisting in ultrafiltration, reverse osmosis and mineralization) working in parallel. Seven sampling points within the different process stages were characterized monthly during 2014. A global Parallel Factor Analysis (PARAFAC) was used to pull out underlying organic fractions from the fluorescence spectra. Accordingly a five components model was selected to describe the system and the pros and cons of the model were discussed by analysis of the residuals. Among the five fluorescent components, those associated to humic-like matter (C1, C3 and C4) showed a similar season variability in the river water feeding the DWTP (which resembled that of UV254 and TOC), whereas the two components associated to protein-like matter (C2 and C5) exhibited a different behavior. The maximum fluorescence intensity values (Fmax) were used to quantify DOM removals across the plant. Compared to the conventional line, water from the UF/RO membrane-based line showed between 6 and 14 times lower fluorescence intensity signal for the humic-like components and between 1 and 3 for the protein-like components as compared to the conventional line. The differences in DOM composition due to seasonal variations and along the treatment trains point out the suitability of using fluorescence measurements over other parameters such as UV254 as a monitoring tool to help optimize operation conditions of each treatment stage and improve produced water quality in a DWTP.

  7. Bacterial production and their role in the removal of dissolved organic matter from tributaries of drinking water reservoirs.

    Science.gov (United States)

    Kamjunke, Norbert; Oosterwoud, Marieke R; Herzsprung, Peter; Tittel, Jörg

    2016-04-01

    Enhanced concentrations of dissolved organic matter (DOM) in freshwaters are an increasing problem in drinking water reservoirs. In this study we investigated bacterial DOM degradation rates in the tributaries of the reservoirs and tested the hypotheses that (1) DOM degradation is high enough to decrease DOM loads to reservoirs considerably, (2) DOM degradation is affected by stream hydrology, and (3) phosphorus addition may stimulate bacterial DOM degradation. Bacterial biomass production, which was used as a measure of DOM degradation, was highest in summer, and was usually lower at upstream than at downstream sites. An important proportion of bacterial production was realized in epilithic biofilms. Production of planktonic and biofilm bacteria was related to water temperature. Planktonic production weakly correlated to DOM quality and to total phosphorus concentration. Addition of soluble reactive phosphorus did not stimulate bacterial DOM degradation. Overall, DOM was considerably degraded in summer at low discharge levels, whereas degradation was negligible during flood events (when DOM load in reservoirs was high). The ratio of DOM degradation to total DOM release was negatively related to discharge. On annual average, only 0.6-12% of total DOM released by the catchments was degraded within the tributaries.

  8. Speciative determination of total V and dissolved inorganic vanadium species in environmental waters by catalytic–kinetic spectrophotometric method

    Directory of Open Access Journals (Sweden)

    Ramazan Gürkan

    2017-02-01

    Full Text Available A kinetic determination of V(V as a catalyst was spectrophotometrically performed by using the indicator reaction of Gallamine blue (GB+ and bromate at pH 2.0. The reaction was followed by measuring absorbance change for a fixed-time of 3 min at 537 nm. The variables such as reagent concentration, pH, buffer concentration, ionic strength and temperature were optimized to improve the selectivity and sensitivity. Under the optimized conditions, the determination of V(V was performed in the range 1–100 μg L−1 with limits of detection and quantification of 0.31 and 0.94 μg L−1. The developed kinetic method is sufficiently sensitive, selective and simple. It was successfully applied to the speciative determination of total V and inorganic dissolved vanadium species, V(V and V(IV in environmental water samples. The oxidizing property of permanganate is used to differentiate between V(IV and V(V species. The V(IV content was found by subtracting the V(V content from those of total V. The recovery is above 95% for V(V spiked samples. Additionally, the accuracy was validated by analysis of a certified water sample, CRM TMDA-53.3, and the results were in good agreement with the certified value.

  9. Impact of forest harvesting on water quality and fluorescence characteristics of dissolved organic matter in Eastern Canadian Boreal Shield lakes

    Directory of Open Access Journals (Sweden)

    P. Glaz

    2015-06-01

    Full Text Available Forestry activities in the Canadian Boreal region have increased in the last decades, raising concerns about their potential impact on aquatic ecosystems. Water quality and fluorescence characteristics of dissolved organic matter (DOM were measured over a three-year period in eight Eastern Boreal Shield lakes: four lakes were studied before, one and two years after forest harvesting (perturbed lakes and compared with four undisturbed reference lakes (unperturbed lakes sampled at the same time. ANOVAs showed a significant increase in total phosphorus (TP in perturbed lakes when the three sampling dates were considered and in DOC concentrations when considering one year before and one year after the perturbation only. At one year post-clear cutting DOC concentrations were about 15 % greater in the perturbed lakes at ~15 mg C L−1 compared to 12.5 mg C L−1 in the unperturbed lakes. In contrast, absorbance and fluorescence measurements showed that all metrics remained within narrow ranges compared to the range observed in natural waters, indicating that forest harvesting did not affect the nature of DOM characterised with spectroscopic techniques. Multivariate statistical analysis showed lakes to be significantly different one year after the perturbation. These results confirm an impact of forestry activities one year after the perturbation. However, this effect seems to be mitigated two years after, indicating that the system shows high resilience and may be able to return to its original condition.

  10. 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...

  11. River stage influences on uranium transport in a hydrologically dynamic groundwater-surface water transition zone: U TRANSPORT IN A GROUNDWATER-SURFACE WATER TRANSITION ZONE

    Energy Technology Data Exchange (ETDEWEB)

    Zachara, John M. [Pacific Northwest National Laboratory, Richland Washington USA; Chen, Xingyuan [Pacific Northwest National Laboratory, Richland Washington USA; Murray, Chris [Pacific Northwest National Laboratory, Richland Washington USA; Hammond, Glenn [Sandia National Laboratories, Albuquerque New Mexico USA

    2016-03-01

    A tightly spaced well-field within a groundwater uranium (U) plume in the groundwater-surface water transition zone was monitored for a three year period for groundwater elevation and dissolved solutes. The plume discharges to the Columbia River, which displays a dramatic spring stage surge resulting from mountain snowmelt. Groundwater exhibits a low hydrologic gradient and chemical differences with river water. River water intrudes the site in spring. Specific aims were to assess the impacts of river intrusion on dissolved uranium (Uaq), specific conductance (SpC), and other solutes, and to discriminate between transport, geochemical, and source term heterogeneity effects. Time series trends for Uaq and SpC were complex and displayed large temporal well-to well variability as a result of water table elevation fluctuations, river water intrusion, and changes in groundwater flow directions. The wells were clustered into subsets exhibiting common temporal behaviors resulting from the intrusion dynamics of river water and the location of source terms. Concentration hot spots were observed in groundwater that varied in location with increasing water table elevation. Heuristic reactive transport modeling with PFLOTRAN demonstrated that mobilized U was transported between wells and source terms in complex trajectories, and was diluted as river water entered and exited the groundwater system. While uranium time-series concentration trends varied significantly from year to year as a result of climate-caused differences in the spring hydrograph, common and partly predictable response patterns were observed that were driven by water table elevation, and the extent and duration of the river water intrusion event.

  12. Distribution of dissolved and labile particulate trace metals in the overlying bottom water in the Vistula River plume (southern Baltic Sea)

    NARCIS (Netherlands)

    Sokolowski, A.; Wolowicz, M.; Hummel, H.

    2001-01-01

    Overlying bottom water samples were collected in the Vistula River plume, southern Baltic Sea, (Poland) and analysed for dissolved and labile particulate (1 M HCl extractable) Cu, Pb, Zn, Mn, Fe and Ni, hydrological parameters being measured simultaneously. Particulate organic matter (POM), chloroph

  13. Distribution of dissolved and labile particulate trace metals in the overlying bottom water in the Vistula River plume (southern Baltic Sea)

    NARCIS (Netherlands)

    Sokolowski, A.; Wolowicz, M.; Hummel, H.

    2001-01-01

    Overlying bottom water samples were collected in the Vistula River plume, southern Baltic Sea, (Poland) and analysed for dissolved and labile particulate (1 M HCl extractable) Cu, Pb, Zn, Mn, Fe and Ni, hydrological parameters being measured simultaneously. Particulate organic matter (POM),

  14. Development of a UV Miniaturised Fourier Transform Spectrometer (MicroFTS) for the Detection of Dissolved Organic Carbon in Water

    Science.gov (United States)

    Scholefield, Paul; Mortimer, Hugh; Hussain, Ali; Tipping, Ed; Monteith, Don; Adams, Jessica

    2015-04-01

    Within the UK and overseas, there are increasing scientific and water industry needs to acquire spatially and temporally intensive measurements of levels and molecular character of dissolved organic carbon (DOC) in the aquatic environment. The need is particularly acute in upland catchments that are often crucial for drinking water supply, and where DOC concentrations are high and have been increasing in recent years. Spectrometer-based systems currently on the market for this purpose are heavy, cumbersome, have a large power requirement, not sensitive in low light conditions, measure absorbance at single wavelengths, require frequent recalibration by trained operators and provide data based on hidden algorithms that limit interpretation of the resulting data. We have developed a new smaller, lighter, and self-calibrating instrument, combining novel miniaturisation of Fourier Transform Spectrometry, and a new scientifically peer-reviewed (and published) approach to assessing DOC concentrations in water. The portable sensor system uses a xenon flash lamp, where the light pulse is collimated and focused into one input of a bifurcated fibre dip probe. At the fibre tip, light is collimated and reflected in the water sample region over a total path length of 5mm. Shorter wavelengths (near the UV) are absorbed due to water containing DOC concentration. Light from the output end of the bifurcated fibre is collimated and coupled to the micro Fourier Transform Spectrometer. Within the interferometer, a broadband beam splitter and two concave mirrors are used to create an optical path difference between the beams. A UV sensitive detector is placed at the focus point of the generated interferogram. The interferogram is recorded and a Fourier Transform is applied to retrieve the spectral data. An absorbance of the DOC is measured and when a ratio is taken between the water sample containing DOC and DI water. Both detector and flash-lamp are triggered by an on-board dual

  15. 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

  16. Effects of overlying water aeration on phosphorus fractions and alkaline phosphatase activity in surface sediment

    Institute of Scientific and Technical Information of China (English)

    Jianjun Chen; Shaoyong Lu; Yikun Zhao; Wei Wang; Minsheng Huang

    2011-01-01

    Microbial activity may influence phosphorus (P) deposit and release at the water sediment interface.The properties of DO (dissolved oxygen), pH, P fractions (TP, Ca-P, Fe-P, OP, IP), and APA (alkaline phosphatase activity) at the water sediment interface were measured to investigate microbial activity variations in surface sediment under conditions of two-month intermittent aeration in overlying water.Results showed that DO and TP of overlying water increased rapidly in the first week and then decreased gradually after 15 day of intermittent aeration.Microorganism metabolism in surface sediment increased pH and decreased DO and TP in the overlying water.After two-month intermittent aeration, APA and OP from surface sediment (0-2 crm) were both significantly higher than those from bottom sediment (6-8 cm) (p < 0.05), and surface sediment Fe-P was transferred to OP during the course of microorganism reproduction on the surface sediment.These results suggest that microbial activity and microorganism biomass from the surface sediment were higher than those from bottom sediment afar two-month intermittent aeration in the overlying water.

  17. Polycyclic Musks in the Air and Water of the Lower Great Lakes: Spatial Distribution and Volatilization from Surface Waters.

    Science.gov (United States)

    McDonough, Carrie A; Helm, Paul A; Muir, Derek; Puggioni, Gavino; Lohmann, Rainer

    2016-11-01

    Polycyclic musks (PCMs) are synthetic fragrance compounds used in personal care products and household cleaners. Previous studies have indicated that PCMs are introduced to aquatic environments via wastewater and river discharge. Polyethylene passive samplers (PEs) were deployed in air and water during winter 2011 and summer 2012 to investigate the role of population centers as sources of these contaminants to the Great Lakes and determine whether the lakes were acting as sources of PCMs via volatilization. Average gaseous Σ5PCM ranged from below detection limits (Lake Erie in Toledo. Average dissolved Σ5PCM ranged from Lake Ontario near the mouth of the Oswego River. Significant correlations were observed between population density and Σ5PCM in both air and water, with strongest correlations within a 25 and 40 km radius, respectively. At sites where HHCB was detected it was generally volatilizing, while the direction of AHTN air-water exchange was variable. Volatilization fluxes of HHCB ranged from 11 ± 6 to 341 ± 127 ng/m(2)/day, while air-water exchange fluxes of AHTN ranged from -3 ± 2 to 28 ± 10 ng/m(2)/day. Extrapolation of average air-water exchange flux values over the surface area of the lakes' coastal boundary zone suggested volatilization may be responsible for the loss of 64-213 kg/year of dissolved Σ5PCM from the lakes.

  18. Effects of bottom water dissolved oxygen variability on copper and lead fractionation in the sediments across the oxygen minimum zone, western continental margin of India.

    Science.gov (United States)

    Chakraborty, Parthasarathi; Chakraborty, Sucharita; Jayachandran, Saranya; Madan, Ritu; Sarkar, Arindam; Linsy, P; Nath, B Nagender

    2016-10-01

    This study describes the effect of varying bottom-water oxygen concentration on geochemical fractionation (operational speciation) of Cu and Pb in the underneath sediments across the oxygen minimum zone (Arabian Sea) in the west coast of India. Both, Cu and Pb were redistributed among the different binding phases of the sediments with changing dissolved oxygen level (from oxic to hypoxic and close to suboxic) in the bottom water. The average lability of Cu-sediment complexes gradually decreased (i.e., stability increased) with the decreasing dissolved oxygen concentrations of the bottom water. Decreasing bottom-water oxygen concentration increased Cu association with sedimentary organic matter. However, Pb association with Fe/Mn-oxyhydroxide phases in the sediments gradually decreased with the decreasing dissolved oxygen concentration of the overlying bottom water (due to dissolution of Fe/Mn oxyhydroxide phase). The lability of Pb-sediment complexes increased with the decreasing bottom-water oxygen concentration. This study suggests that bottom-water oxygen concentration is one of the key factors governing stability and lability of Cu and Pb complexes in the underneath sediment. Sedimentary organic matter and Fe/Mn oxyhydroxide binding phases were the major hosting phases for Cu and Pb respectively in the study area. Increasing lability of Pb-complexes in bottom sediments may lead to positive benthic fluxes of Pb at low oxygen environment. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Hydration in Lipid Monolayers: Correlation of Water Activity and Surface Pressure.

    Science.gov (United States)

    Disalvo, E Anibal; Hollmann, Axel; Martini, M Florencia

    2015-01-01

    In order to give a physical meaning to each region of the membrane we define the interphase as the region in a lipid membrane corresponding to the polar head groups imbibed in water with net different properties than the hydrocarbon region and the water phase. The interphase region is analyzed under the scope of thermodynamics of surface and solutions based on the definition of Defay-Prigogine of an interphase and the derivation that it has in the understanding of membrane processeses in the context of biological response. In the view of this approach, the complete monolayer is considered as the lipid layer one molecule thick plus the bidimensional solution of the polar head groups inherent to it (the interphase region). Surface water activity appears as a common factor for the interaction of several aqueous soluble and surface active proteins with lipid membranes of different composition. Protein perturbation can be measured by changes in the surface pressure of lipid monolayers at different initial water surface activities. As predicted by solution chemistry, the increase of surface pressure is independent of the particle nature that dissolves. Therefore, membranes give a similar response in terms of the determined surface states given by water activity independent of the protein or peptide.

  20. Dissolved organic nitrogen measurement using dialysis pretreatment.

    Science.gov (United States)

    Lee, Wontae; Westerhoff, Paul

    2005-02-01

    Dissolved organic nitrogen (DON) is important for ecological and engineering researches. Quantification of low DON concentrations in waters with elevated dissolved inorganic nitrogen (DIN) using existing methods is inaccurate. In this study, a dialysis-based pretreatment technique was optimized and adopted to reduce the interference from DIN to the quantification of DON in natural water. A cellulose ester dialysis tube (nominal molecular weight cutoff = 100 Da) was used in batch and continuous-flow dialysis steps with model compounds, natural organic matter isolates, and bulk waters to develop a dialysis pretreatment approach that selectively reduces DIN from solutions containing DON. By reducing DIN concentrations, propagation of analytical variance in total dissolved nitrogen (TDN) and DIN species concentrations allows more accurate determination of DON (DON = TDN - NO3 - NO2- - NH3/NH4+). Dialysis for 24 h against continuously flowing distilled water reduced DIN species by 70%. With dialysis pretreatment, DON recoveries of more than 95% were obtained for surface water and finished drinking water, but wastewater experienced a slight loss (approximately 10%) of DON possibly due to the adsorption of organics onto the dialysis membrane, permeation of low molecular weight fractions, or biodegradation. Dialysis experiments using surface water spiked with different DIN/TDN ratios concluded that dialysis pretreatment leads to more accurate DON determination than no dialysis when DIN/TDN ratios exceed 0.6 mg of N/mg of N.