Science.gov

Sample records for additional carbon sources

  1. RAINFALL AND RUNOFF AS A SOURCE OF ORGANIC CARBON ADDITIONS TO BAYOU TEXAR, FLORIDA

    EPA Science Inventory

    Rainfall and Runoff as a Source of Organic Carbon Additions to Bayou Texar, Florida (Abstract). To be presented at the16th Biennial Conference of the Estuarine Research Foundation, ERF 2001: An Estuarine Odyssey, 4-8 November 2001, St. Pete Beach, FL. 1 p. (ERL,GB R852).

    T...

  2. Modeling the Effect of External Carbon Source Addition under Different Electron Acceptor Conditions in Biological Nutrient Removal Activated Sludge Systems.

    PubMed

    Hu, Xiang; Wisniewski, Kamil; Czerwionka, Krzysztof; Zhou, Qi; Xie, Li; Makinia, Jacek

    2016-02-16

    The aim of this study was to expand the International Water Association Activated Sludge Model No. 2d (ASM2d) to predict the aerobic/anoxic behavior of polyphosphate accumulating organisms (PAOs) and "ordinary" heterotrophs in the presence of different external carbon sources and electron acceptors. The following new aspects were considered: (1) a new type of the readily biodegradable substrate, not available for the anaerobic activity of PAOs, (2) nitrite as an electron acceptor, and (3) acclimation of "ordinary" heterotrophs to the new external substrate via enzyme synthesis. The expanded model incorporated 30 new or modified process rate equations. The model was evaluated against data from several, especially designed laboratory experiments which focused on the combined effects of different types of external carbon sources (acetate, ethanol and fusel oil) and electron acceptors (dissolved oxygen, nitrate and nitrite) on the behavior of PAOs and "ordinary" heterotrophs. With the proposed expansions, it was possible to improve some deficiencies of the ASM2d in predicting the behavior of biological nutrient removal (BNR) systems with the addition of external carbon sources, including the effect of acclimation to the new carbon source. PMID:26783836

  3. Effect of cycle time on fungal morphology, broth rheology, and recombinant enzyme productivity during pulsed addition of limiting carbon source.

    PubMed

    Bhargava, Swapnil; Wenger, Kevin S; Rane, Kishore; Rising, Vanessa; Marten, Mark R

    2005-03-01

    For many years, high broth viscosity has remained a key challenge in large-scale filamentous fungal fermentations. In previous studies, we showed that broth viscosity could be reduced by pulsed addition of limiting carbon during fed-batch fermentation. The objective in this study was to determine how changing the frequency of pulsed substrate addition affects fungal morphology, broth rheology, and recombinant enzyme productivity. To accomplish this, a series of duplicate fed-batch fermentations were performed in 20-L fermentors with a recombinant glucoamylase producing strain of Aspergillus oryzae. The total cycle time for substrate pulsing was varied over a wide range (30-2,700 s), with substrate added only during the first 30% of each cycle. As a control, a fermentation was conducted with continuous substrate feeding, and in all fermentations the same total amount of substrate was added. Results show that the total biomass concentration remained relatively unaltered, while a substantial decrease in the mean projected area of fungal elements (i.e., average size) was observed with increasing cycle time. This led to reduced broth viscosity and increased oxygen uptake rate. However, high values of cycle time (i.e., 900-2,700 s) showed a significant increase in fungal conidia formation and significantly reduced recombinant enzyme productivity, suggesting that the fungi channeled substrate to storage compounds rather than to recombinant protein. In addition to explaining the effect of cycle time on fermentation performance, these results may aid in explaining the discrepancies observed on scale-up to larger fermentors. PMID:15643626

  4. Development of wide band gap p- a-SiOxCy:H using additional trimethylboron as carbon source gas

    NASA Astrophysics Data System (ADS)

    Kang, Dong-Won; Sichanugrist, Porponth; Janthong, Bancha; Khan, Muhammad Ajmal; Niikura, Chisato; Konagai, Makoto

    2016-07-01

    We report p-type a-SiOxCy:H thin films which were fabricated by introducing additional Trimethylboron (TMB, B(CH3)3) doping gas into conventional standard p-type a-SiOx:H films. The TMB addition into the condition of p-a-SiOx:H improved optical bandgap from 2.14 to 2.20 eV without deterioration of electrical conductivity, which is promising for p-type window layer of thin film solar cells. The suggested p-a-SiOxCy:H films were applied in amorphous silicon solar cells and we found an increase of quantum efficiency at short wavelength regions due to wide bandgap of the new p-layer, and thus efficiency improvement from 10.4 to 10.7% was demonstrated in a-Si:H solar cell by employing the p-a-SiOxCy:H film. In case of a-SiOx:H cell, high open circuit voltage of 1.01 V was confirmed by using the suggested the p-a-SiOxCy:H film as a window layer. This new p-layer can be highly promising as a wide bandgap window layer to improve the performance of thin film silicon solar cells. [Figure not available: see fulltext.

  5. Kilogram-scale production of SnO(2) yolk-shell powders by a spray-drying process using dextrin as carbon source and drying additive.

    PubMed

    Choi, Seung Ho; Kang, Yun Chan

    2014-05-01

    A simple and general method for the large-scale production of yolk-shell powders with various compositions by a spray-drying process is reported. Metal salt/dextrin composite powders with a spherical and dense structure were obtained by spray drying and transformed into yolk-shell powders by simple combustion in air. Dextrin plays a key role in the preparation of precursor powders for fabricating yolk-shell powders by spray drying. Droplets containing metal salts and dextrin show good drying characteristics even in a severe environment of high humidity. Sucrose, glucose, and polyvinylpyrrolidone are widely used as carbon sources in the preparation of metal oxide/carbon composite powders; however, they are not appropriate for large-scale spray-drying processes because of their caramelization properties and adherence to the surface of the spray dryer. SnO2 yolk-shell powders were studied as the first target material in the spray-drying process. Combustion of tin oxalate/dextrin composite powders at 600 °C in air produced single-shelled SnO2 yolk-shell powders with the configuration SnO2 @void@SnO2 . The SnO2 yolk-shell powders prepared by the simple spray-drying process showed superior electrochemical properties, even at high current densities. The discharge capacities of the SnO2 yolk-shell powders at a current density of 2000 mA g(-1) were 645 and 570 mA h g(-1) for the second and 100th cycles, respectively; the corresponding capacity retention measured for the second cycle was 88 %. PMID:24665070

  6. SOURCE ASSESSMENT: CARBON BLACK MANUFACTURE

    EPA Science Inventory

    The report summarizes the assessment of air emissions from the manufacture of carbon black, currently manufactured in the U.S. by two major processes: thermal and oil furnace. Sources of atmospheric emissions within oil furnace plants (about 90% of the 30 U.S. carbon black plants...

  7. Superconducting Properties of MgB2 with Addition of Other AlB2-type Diborides and Carbon Sources, Prepared Using High Energy Ball Milling and HIP

    NASA Astrophysics Data System (ADS)

    Rodrigues, Durval; Silva, Lucas B. S. da; Metzner, Vivian C. V.; Hellstrom, Eric E.

    In the present work it is described the production of MgB2 samples by using the mixture of MgB2 with other diborides, (TaB2, VB2, and AlB2) which have the same C32 hexagonal structure as the MgB2, and simultaneous addition with the diborides and SiC, that contribute with C, to replace B in the crystalline structure of the matrix. As an important result, the critical current density (Jc) was improved at low magnetic fields when just the diborides are added. However, when SiC is added simultaneously with the diborides, the result is the improvement of Jc at high fields. The critical temperature (Tc) was maintained high.

  8. Comparison of carbon onions and carbon blacks as conductive additives for carbon supercapacitors in organic electrolytes

    NASA Astrophysics Data System (ADS)

    Jäckel, N.; Weingarth, D.; Zeiger, M.; Aslan, M.; Grobelsek, I.; Presser, V.

    2014-12-01

    This study investigates carbon onions (∼400 m2 g-1) as a conductive additive for supercapacitor electrodes of activated carbon and compares their performance with carbon black with high or low internal surface area. We provide a study of the electrical conductivity and electrochemical behavior between 2.5 and 20 mass% addition of each of these three additives to activated carbon. Structural characterization shows that the density of the resulting film electrodes depends on the degree of agglomeration and the amount of additive. Addition of low surface area carbon black (∼80 m2 g-1) enhances the power handling of carbon electrodes but significantly lowers the specific capacitance even when adding small amounts of carbon black. A much lower decrease in specific capacitance is observed for carbon onions and the best values are seen for carbon black with a high surface area (∼1390 m2 g-1). The overall performance benefits from the addition of any of the studied additives only at either high scan rates and/or electrolytes with high ion mobility. Normalization to the volume shows a severe decrease in volumetric capacitance and only at high current densities nearing 10 A g-1 we can see an improvement of the electrode capacitance.

  9. Testing Carbon Sequestration in Soil Through the Addition of Gypsum

    NASA Astrophysics Data System (ADS)

    Han, Y.; Tokunaga, T. K.; Wan, J.; Conrad, M. E.; Salve, R.

    2011-12-01

    In order to help control adverse effects of increased atmospheric concentrations of CO2, effective methods for fixing carbon need to be developed. Given the large C inventories and fluxes associated with soils, it is important to identify cost- and energy-effective means for increasing long-term C retention within soil profiles. This study investigates the alternative strategy of increasing carbon retention in soils through accelerating calcite (CaCO3) precipitation and promoting soil organic carbon (SOC) complexation on mineral surfaces. With the addition of calcium ion to soils with pH > 8 often found in arid and semi-arid regions, the slow process of calcite precipitation may be accelerated. Calcium also promotes SOC binding onto mineral surfaces, diminishing leaching of SOC. Addition of flue gas desulfurization gypsum (FGDG) represents an inexpensive source of calcium to natural, slightly alkaline soil surfaces which might promote the fixation of CO2 as calcite and decrease leaching losses of organic carbon. To test this hypothesis, we prepared laboratory soil columns (7.5 cm in diameter and 85 cm in height) with and without calcium sulfate-amended layers. The distribution of carbon in the columns was monitored in gaseous, aqueous and solid phases over a period of several months to test the effect of adding calcium ions. In some columns, a relatively high fraction of 13C-labeled bicarbonate was injected to differentiate the newly precipitated calcite from the initial calcite present in the soil. The potential for more distinct calcite precipitation within the soil root zone will be investigated in vegetated soil columns. Through obtaining C mass balances in soil profiles, this study is quantifying the efficiency of gypsum amendments for mitigating C losses to the atmosphere.

  10. Effect of Carbon and Energy Source on Bacterial Chromate Reduction

    SciTech Connect

    Smith, William Aaron; Apel, William Arnold; Petersen, J. N.; Peyton, Brent Michael

    2002-07-01

    Studies were conducted to evaluate carbon and energy sources suitable to support hexavalent chromium (Cr(VI)) reduction by a bacterial consortium enriched from dichromate-contaminated aquifer sediments. The consortium was cultured under denitrifying conditions in a minimal, synthetic groundwater medium that was amended with various individual potential carbon and energy sources. The effects of these individual carbon and energy sources on Cr(VI) reduction and growth were measured. The consortium was found to readily reduce Cr(VI) with sucrose, acetate, L-asparagine, hydrogen plus carbon dioxide, ethanol, glycerol, glycolate, propylene glycol, or D-xylose as a carbon and energy source. Minimal Cr(VI) reduction was observed when the consortium was cultured with citrate, 2-ketoglutarate, L-lactate, pyruvate, succinate, or thiosulfate plus carbon dioxide as a carbon and energy source when compared with abiotic controls. The consortium grew on all of the above carbon and energy sources, with the highest cell densities reached using D-xylose and sucrose, demonstrating that the consortium is metabolically diverse and can reduce Cr(VI) using a variety of different carbon and energy sources. The results suggest that the potential exists for the enrichment of Cr(VI)-reducing microbial populations in situ by the addition of a sucrose-containing feedstock such as molasses, which is an economical and readily available carbon and energy source.

  11. Carbon additives for electrical double layer capacitor electrodes

    NASA Astrophysics Data System (ADS)

    Weingarth, D.; Cericola, D.; Mornaghini, F. C. F.; Hucke, T.; Kötz, R.

    2014-11-01

    Electrochemical double layer capacitors (EDLCs) are inherently high power devices when compared to rechargeable batteries. While capacitance and energy storage ability are mainly increased by optimizing the electrode active material or the electrolyte, the power capability could be improved by including conductive additives in the electrode formulations. This publication deals with the use of four different carbon additives - two carbon blacks and two graphites - in standard activated carbon based EDLC electrodes. The investigations include: (i) physical characterization of carbon powder mixtures such as surface area, press density, and electrical resistivity measurements, and (ii), electrochemical characterization via impedance spectroscopy and cyclic voltammetry of full cells made with electrodes containing 5 wt.% of carbon additive and compared to cells made with pure activated carbon electrodes in organic electrolyte. Improved cell performance was observed in both impedance and cyclic voltammetry responses. The results are discussed considering the main characteristics of the different carbon additives, and important considerations about electrode structure and processability are drawn.

  12. The Importance of Carbon Fiber to Polymer Additive Manufacturing

    SciTech Connect

    Love, Lonnie J; Kunc, Vlastimil; Rios, Orlando; Duty, Chad E; Post, Brian K; Blue, Craig A

    2014-01-01

    Additive manufacturing holds tremendous promise in terms of revolutionizing manufacturing. However, fundamental hurdles limit mass adoption of the technology. First, production rates are extremely low. Second, the physical size of parts is generally small, less than a cubic foot. Third, while there is much excitement about metal additive manufacturing, the major growth area is in polymer additive manufacturing systems. Unfortunately, the mechanical properties of the polymer parts are poor, limiting the potential for direct part replacement. To address this issue, we describe three benefits of blending carbon fiber with polymer additive manufacturing. First, development of carbon fiber reinforced polymers for additive manufacturing achieves specific strengths approaching aerospace quality aluminum. Second, carbon fiber radically changes the behavior of the material during deposition, enabling large scale, out-of-the-oven, high deposition rate manufacturing. Finally, carbon fiber technology and additive manufacturing complement each other. Merging the two manufacturing processes enables the construction of complex components that would not be possible otherwise.

  13. 46 CFR 151.50-40 - Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Additional requirements for carbon disulfide (carbon... Special Requirements § 151.50-40 Additional requirements for carbon disulfide (carbon bisulfide) and ethyl... waterways at the loading and unloading points. (f) The special requirements of § 151.50-41 for...

  14. 46 CFR 151.50-40 - Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Additional requirements for carbon disulfide (carbon... Special Requirements § 151.50-40 Additional requirements for carbon disulfide (carbon bisulfide) and ethyl... waterways at the loading and unloading points. (f) The special requirements of § 151.50-41 for...

  15. 46 CFR 151.50-40 - Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Additional requirements for carbon disulfide (carbon... Special Requirements § 151.50-40 Additional requirements for carbon disulfide (carbon bisulfide) and ethyl... waterways at the loading and unloading points. (f) The special requirements of § 151.50-41 for...

  16. 46 CFR 151.50-40 - Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Additional requirements for carbon disulfide (carbon... Special Requirements § 151.50-40 Additional requirements for carbon disulfide (carbon bisulfide) and ethyl... waterways at the loading and unloading points. (f) The special requirements of § 151.50-41 for...

  17. 46 CFR 151.50-40 - Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Additional requirements for carbon disulfide (carbon... Special Requirements § 151.50-40 Additional requirements for carbon disulfide (carbon bisulfide) and ethyl... waterways at the loading and unloading points. (f) The special requirements of § 151.50-41 for...

  18. Growth of graphene films from non-gaseous carbon sources

    DOEpatents

    Tour, James; Sun, Zhengzong; Yan, Zheng; Ruan, Gedeng; Peng, Zhiwei

    2015-08-04

    In various embodiments, the present disclosure provides methods of forming graphene films by: (1) depositing a non-gaseous carbon source onto a catalyst surface; (2) exposing the non-gaseous carbon source to at least one gas with a flow rate; and (3) initiating the conversion of the non-gaseous carbon source to the graphene film, where the thickness of the graphene film is controllable by the gas flow rate. Additional embodiments of the present disclosure pertain to graphene films made in accordance with the methods of the present disclosure.

  19. 17 CFR 38.801 - Additional sources for compliance.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 1 2013-04-01 2013-04-01 false Additional sources for compliance. 38.801 Section 38.801 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION DESIGNATED CONTRACT MARKETS Governance Fitness Standards § 38.801 Additional sources for...

  20. 17 CFR 38.258 - Additional sources for compliance.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 1 2013-04-01 2013-04-01 false Additional sources for compliance. 38.258 Section 38.258 Commodity and Securities Exchanges COMMODITY FUTURES TRADING COMMISSION DESIGNATED CONTRACT MARKETS Prevention of Market Disruption § 38.258 Additional sources for...

  1. Oxidative addition of carbon-carbon bonds to gold.

    PubMed

    Joost, Maximilian; Estévez, Laura; Miqueu, Karinne; Amgoune, Abderrahmane; Bourissou, Didier

    2015-04-20

    The oxidative addition of strained CC bonds (biphenylene, benzocyclobutenone) to DPCb (diphosphino-carborane) gold(I) complexes is reported. The resulting cationic organogold(III) complexes have been isolated and fully characterized. Experimental conditions can be adjusted to obtain selectively acyl gold(III) complexes resulting from oxidative addition of either the C(aryl)C(O) or C(alkyl)C(O) bond of benzocyclobutenone. DFT calculations provide mechanistic insight into this unprecedented transformation. PMID:25727203

  2. New Potential Sources for Black Onaping Carbon

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Becker, L.; Schultz, P. H.; Wolbach, W. S.

    1997-01-01

    One intriguing and important issue of the Sudbury Structure concerns the source of the relatively large amount of C in the Onaping Formation Black member. This dilemma was recently addressed, and the conclusion was reached that an impactor could not have delivered all of the requisite C. Becker et al. have suggested that much of the C came from the impactor and reported the presence of interstellar He "caged" inside some fullerenes that may have survived the impact. So, conceivably, the C inventory in the Sudbury Structure comes from both target and impactor materials, although the known target rocks have little C. We discuss here the possibility of two terrestrial sources for at least some of the C: (1) impact evaporation/dissociation of C from carbonate target rocks and (2) the presence of heretofore-unrecognized C-rich (up to 26 wt%) siliceous "shale," fragments, which are found in the upper, reworked Black member. Experimental: Hypervelocity impact of a 0.635-diameter Al projectile into dolomite at 5.03 km/s (performed at the Ames Research Center vertical gun range) produced a thin, black layer (= 0.05 mm thick) that partially lined the crater and coated impactor remnants. Scanning electronic microscope (SEM) imagery shows this layer to be spongelike on a submicron scale and Auger spectroscopic analyses yield: 33% C, 22% Mg, 19% 0, and 9% Al (from the projectile). Elemental mapping shows that all of the available 0 is combined with Ca and Mg, Al is not oxidized, and C is in elemental form. Dissociation efficiency of C from CO2 is estimated to be <10% of crater volume. Raman spectroscopy indicates that the C is highly disorganized graphite. Another impact experiment [4] also produced highly disordered graphite from a limestone target (reducing collector), in addition to small amounts of diamond/lonsdaleite/chaoite (oxidizing collector). These experiments confirm the reduction of C from carbonates in impact vapor plumes. Observational: SEM observations and

  3. Source of released carbon fibers

    NASA Technical Reports Server (NTRS)

    Bell, V. L.

    1979-01-01

    The potential for the release of carbon fibers from aircraft crashes/fires is addressed. Simulation of the conditions of aircraft crash fires in order to predict the quantities and forms of fibrous materials which might be released from civilian aircraft crashes/fires is considered. Figures are presented which describe some typical fiber release test activities together with some very preliminary results of those activities. The state of the art of carbon fiber release is summarized as well as some of the uncertainties concerning accidental fiber release.

  4. Improvement of cement concrete strength properties by carbon fiber additives

    NASA Astrophysics Data System (ADS)

    Nevsky, Andrey; Kudyakov, Konstantin; Danke, Ilia; Kudyakov, Aleksandr; Kudyakov, Vitaly

    2016-01-01

    The paper presents the results of studies of fiber-reinforced concrete with carbon fibers. The effectiveness of carbon fibers uniform distribution in the concrete was obtained as a result of its preliminary mechanical mixing in water solution with chemical additives. Additives are to be used in the concrete technology as modifiers at initial stage of concrete mix preparing. The technology of preparing of fiber-reinforced concrete mix with carbon fibers is developed. The superplasticizer is based on ether carboxylates as a separator for carbon fibers. The technology allows increasing of concrete compressive strength up to 43.4% and tensile strength up to 17.5% as well as improving stability of mechanical properties.

  5. A Fluorescent Source NDIR Carbon Monoxide Analyzer

    NASA Technical Reports Server (NTRS)

    Link, W. T.; McClatchie, E. A.; Watson, D. A.; Compher, A. B.

    1971-01-01

    This paper describes a new technique for measuring trace quantities of carbon monoxide by the nondispersive infrared (NDIR) methods. The technique uses the property of infrared fluorescence in a gas to generate a specific source of radiation which is an exact match of the absorption spectrum of the fundamental band of carbon monoxide. This results in an instrument with high sensitivity and specificity for CO. A novel method of referencing using an isotopic species of CO confers great stability on the instrument.

  6. Transition metal-catalyzed process for addition of amines to carbon-carbon double bonds

    DOEpatents

    Hartwig, John F.; Kawatsura, Motoi; Loeber, Oliver

    2002-01-01

    The present invention is directed to a process for addition of amines to carbon-carbon double bonds in a substrate, comprising: reacting an amine with a compound containing at least one carbon-carbon double bond in the presence a transition metal catalyst under reaction conditions effective to form a product having a covalent bond between the amine and a carbon atom of the former carbon-carbon double bond. The transition metal catalyst comprises a Group 8 metal and a ligand containing one or more 2-electron donor atoms. The present invention is also directed to enantioselective reactions of amine compounds with compounds containing carbon-carbon double bonds, and a calorimetric assay to evaluate potential catalysts in these reactions.

  7. New Potential Sources for Black Onaping Carbon

    NASA Technical Reports Server (NTRS)

    Bunch, T. E.; Becker, L.; Schultz, P. H.; Wolbach, W. S.

    1997-01-01

    One intriguing and important issue of the Sudbury Structure concerns the source of the relatively large amount of C in the Onaping Formation Black member. This dilemma was recently addressed, and the conclusion was reached that an impactor could not have delivered all of the requisite C. Becker et al. have suggested that much of the C came from the impactor and reported the presence of interstellar He "caged" inside some fullerenes that may have survived the impact. So, conceivably, the C inventory in the Sudbury Structure comes from both target and impactor materials, although the known target rocks have little C. We discuss here the possibility of two terrestrial sources for at least some of the C: (1) impact evaporation/dissociation of C from carbonate target rocks and (2) the presence of heretofore-unrecognized C-rich (up to 26 wt%) siliceous "shale," fragments, which are found in the upper, reworked Black member. Experimental: Hypervelocity impact of a 0.635-diameter Al projectile into dolomite at 5.03 km/s (performed at the Ames Research Center vertical gun range) produced a thin, black layer (= 0.05 mm thick) that partially lined the crater and coated impactor remnants. Scanning electronic microscope (SEM) imagery shows this layer to be spongelike on a submicron scale and Auger spectroscopic analyses yield: 33% C, 22% Mg, 19% 0, and 9% Al (from the projectile). Elemental mapping shows that all of the available 0 is combined with Ca and Mg, Al is not oxidized, and C is in elemental form. Dissociation efficiency of C from CO2 is estimated to be <10% of crater volume. Raman spectroscopy indicates that the C is highly disorganized graphite. Another impact experiment [4] also produced highly disordered graphite from a limestone target (reducing collector), in addition to small amounts of diamond/lonsdaleite/chaoite (oxidizing collector). These experiments confirm the reduction of C from carbonates in impact vapor plumes. Observational: SEM observations and

  8. Carbon source dependent promoters in yeasts

    PubMed Central

    2014-01-01

    Budding yeasts are important expression hosts for the production of recombinant proteins. The choice of the right promoter is a crucial point for efficient gene expression, as most regulations take place at the transcriptional level. A wide and constantly increasing range of inducible, derepressed and constitutive promoters have been applied for gene expression in yeasts in the past; their different behaviours were a reflection of the different needs of individual processes. Within this review we summarize the majority of the large available set of carbon source dependent promoters for protein expression in yeasts, either induced or derepressed by the particular carbon source provided. We examined the most common derepressed promoters for Saccharomyces cerevisiae and other yeasts, and described carbon source inducible promoters and promoters induced by non-sugar carbon sources. A special focus is given to promoters that are activated as soon as glucose is depleted, since such promoters can be very effective and offer an uncomplicated and scalable cultivation procedure. PMID:24401081

  9. Carbon source in the future chemical industries

    NASA Astrophysics Data System (ADS)

    Hofmann, Peter; Heinrich Krauch, Carl

    1982-11-01

    Rising crude oil prices favour the exploitation of hitherto unutilised energy carriers and the realisation of new technologies in all sectors where carbon is used. These changed economic constraints necessitate both savings in conventional petrochemistry and a change to oil-independent carbon sources in the chemical industry. While, in coal chemistry, the synthesis and process principles of petrochemistry — fragmentation of the raw material and subsequent buildup of molecular structures — can be maintained, the raw material structure largely remains unchanged in the chemistry of renewable raw materials. This lecture is to demonstrate the structural as well as the technological and energy criteria of the chemistry of alternative carbon sources, to forecast the chances of commercial realization and to discuss some promising fields of research and development.

  10. Production of polyhydroxyalkanoates (PHAs) with canola oil as carbon source.

    PubMed

    López-Cuellar, M R; Alba-Flores, J; Rodríguez, J N Gracida; Pérez-Guevara, F

    2011-01-01

    Wautersia eutropha was able to synthesize medium chain length polyhydroxyalkanoates (PHAs) when canola oil was used as carbon source. W. eutropha was cultivated using fructose and ammonium sulphate as carbon and nitrogen sources, respectively, for growth and inoculum development. The experiments were done in a laboratory scale bioreactor in three stages. Initially, the biomass was adapted in a batch culture. Secondly, a fed-batch was used to increase the cell dry weight and PHA concentration to 4.36 g L(-1) and 0.36 g L(-1), respectively. Finally, after the addition of canola oil as carbon source a final concentration of 18.27 g L(-1) PHA was obtained after 40 h of fermentation. With canola oil as carbon source, the polymer content of the cell dry matter was 90%. The polymer was purified from dried cells and analyzed by FTIR, NMR and DSC using PHB as reference. The polymer produced by W. eutropha from canola oil had four carbon monomers in the structure of the PHA and identified by 1H and 13C NMR analysis as 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 3-hydroxyoctanoate (3HO), and 3-hydroxydodecanoate (3HDD). PMID:20933541

  11. Geolocating Russian sources for Arctic black carbon

    NASA Astrophysics Data System (ADS)

    Cheng, Meng-Dawn

    2014-08-01

    To design and implement an effective emission control strategy for black carbon (BC), the locations and strength of BC sources must be identified. Lack of accurate source information from the Russian Federation has created difficulty for a range of research and policy activities in the Arctic because Russia occupies the largest landmass in the Arctic Circle. A project was initiated to resolve emission sources of BC in the Russian Federation by using the Potential Source Contribution Function (PSCF). It used atmospheric BC data from two Arctic sampling stations at Alert Nunavut, Canada, and Tiksi Bay, Russia. The geographical regions of BC emission sources in Russia were identified and summarized as follows: (1) a region surrounding Moscow, (2) regions in Eurasia stretching along the Ural Mountains from the White Sea to the Black Sea, and (3) a number of scattered areas from western Siberia to the Russian Far East. Particulate potassium ions, non-marine sulfate, and vanadium were used to assist in resolving the source types: forest fire/biomass burning, coal-fired power plant, and oil combustion. Correlating these maps with the BC map helped to resolve source regions of BC emissions and connect them to their corresponding source types. The results imply that a region south of Moscow and another north of the Ural Mountains could be significant BC sources, but none of the grid cells in these regions could be linked to forest fires, oil combustion, or coal-fired power plants based on these three markers.

  12. Carbon nanotube electron sources for electron microscopes

    SciTech Connect

    De Jonge, Niels

    2009-01-01

    Electron sources were made from individual multi-walled carbon nanotubes with closed caps and thoroughly cleaned surfaces. Nanotubes from both chemical vapor deposition growth and arc discharge growth were investigated. These emitters provide a highly stable emission current up to a threshold current of a few microamperes. At too large currents several processes take place such as splitting, breaking and cap closing. The emission process is field emission for a workfunction of 5 eV. The electron optical per-formance is highly beneficial for their use as high-brightness point sources in electron microscopes and advantageous with respect to state-of-the-art electron sources. The life-time is at least two years. We have tested the source successfully in a scanning electron microscope.

  13. Synthesis of barium and strontium carbonate crystals with unusual morphologies using an organic additive

    NASA Astrophysics Data System (ADS)

    Chen, Long; Jiang, Jizhong; Bao, Zuben; Pan, Jian; Xu, Weibing; Zhou, Lili; Wu, Zhigang; Chen, Xu

    2013-12-01

    In this paper, strontium carbonate (SrCO3) and barium carbonate (BaCO3) crystals were synthesized in the presence of an organic additive-hexamethylenetetramine (HMT) using two CO2 sources. Scanning electron microscopy and X-ray powder diffractometry were used to characterize the products. The results showed that the morphologies of orthorhombic strontianite SrCO3 transformed from branch-like to flower-like, and to capsicum-like at last, while the morphologies of BaCO3 change from fiber-like to branchlike, and to rod-like finally with an increase of the molar ratio HMT/Sr2+ and HMT/Ba2+ from 0.2 to 10 using ammonium carbonate as CO2 source. When using diethyl carbonate instead of ammonium carbonate as CO2 source, SrCO3 flowers aggregated by rods and BaCO3 shuttles were formed. The possible formation mechanisms of SrCO3 and BaCO3 crystals obtained in different conditions were also discussed.

  14. Photoautotrophic microorganisms as a carbon source for temperate soil invertebrates.

    PubMed

    Schmidt, Olaf; Dyckmans, Jens; Schrader, Stefan

    2016-01-01

    We tested experimentally if photoautotrophic microorganisms are a carbon source for invertebrates in temperate soils. We exposed forest or arable soils to a (13)CO2-enriched atmosphere and quantified (13)C assimilation by three common animal groups: earthworms (Oligochaeta), springtails (Hexapoda) and slugs (Gastropoda). Endogeic earthworms (Allolobophora chlorotica) and hemiedaphic springtails (Ceratophysella denticulata) were highly (13)C enriched when incubated under light, deriving up to 3.0 and 17.0%, respectively, of their body carbon from the microbial source in 7 days. Earthworms assimilated more (13)C in undisturbed soil than when the microbial material was mixed into the soil, presumably reflecting selective surface grazing. By contrast, neither adult nor newly hatched terrestrial slugs (Deroceras reticulatum) grazed on algal mats. Non-photosynthetic (13)CO2 fixation in the dark was negligible. We conclude from these preliminary laboratory experiments that, in addition to litter and root-derived carbon from vascular plants, photoautotrophic soil surface microorganisms (cyanobacteria, algae) may be an ecologically important carbon input route for temperate soil animals that are traditionally assigned to the decomposer channel in soil food web models and carbon cycling studies. PMID:26740559

  15. Double-walled carbon nanotubes synthesized using carbon black as the dot carbon source

    NASA Astrophysics Data System (ADS)

    Chen, Zhi-Gang; Li, Feng; Ren, Wen-Cai; Cong, Hongtao; Liu, Chang; Qing Lu, Gao; Cheng, Hui-Ming

    2006-07-01

    Double-walled carbon nanotubes (DWNTs) were synthesized used carbon black as the dot carbon source by a semi-continuous hydrogen arc discharge process. High-resolution transmission electron microscopy (HRTEM) observations revealed that most of the tubes were DWNTs with outer and inner diameters in the range of 2.67-4 nm and 1.96-3.21 nm, respectively. Most of the DWNTs were in a bundle form of about 10-30 nm in diameter with high purity (about 70%) from thermal gravimetric analysis (TGA), resonant laser Raman spectroscopy, scanning electron microscopy (SEM) and TEM characterizations. It was found that carbon black as the dot carbon source could be easy controlled to synthesize one type of nanotube. A simple process combining oxidation and acid treatment to purify the DWNT bundles was used without damaging the bundles. The structure of carbon black, as the key element for influencing purity, bundle formation and purification of DWNTs, is discussed.

  16. Improvement of capacitive performances of symmetric carbon/carbon supercapacitors by addition of nanostructured polypyrrole powder

    NASA Astrophysics Data System (ADS)

    Benhaddad, L.; Gamby, J.; Makhloufi, L.; Pailleret, A.; Pillier, F.; Takenouti, H.

    2016-03-01

    A nanostructured polypyrrole powder was synthesized in a previous work from the oxidation of pyrrole by a nanostructured MnO2 powder used simultaneously as an oxidizing agent and a sacrificial template in a redox heterogeneous mechanism. In this study, this original PPy powder was used as an active additive material with different ratio in carbon/carbon symmetrical supercapacitors whose performances were studied by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) using a Swagelok-type cell. From the EIS spectra, the complex capacitance was extracted using a model involving two Cole-Cole type complex capacitances linked in series. The specific capacitance values evaluated by EIS and cyclic voltammetry are in a good agreement between them. The results show that the addition of nanostructured polypyrrole powder improves significantly the specific capacitance of the carbon electrode and consequently the performances of carbon/carbon supercapacitors. The original and versatile synthesis method used to produce this polypyrrole powder appears to be attractive for large scale production of promising additives for electrode materials of supercapacitors.

  17. The Ultimate Electron Sources Using Millimeter Long Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Perea, N.; Rebollo, B.; Briones, J. A.; Morelos, A.; Hernandez, D.; Munoz, E.; Lopez-Urias, F.; Botello, A. R.; Charlier, J. C.; Meunier, V.; Hirata, G. A.; Maruyama, B.; Terrones, M.; Terrones, H.

    2012-02-01

    We are reporting the fabrication of a very efficient electron source using long and crystalline carbon nanotubes. These devices start to emit electrons at fields as low as 0.10 V/μm and reach threshold emission at 0.164 V/μm. In addition, these electron sources are very stable for long operation periods up to 200 hrs and can achieve peak current density of 2 Acm-2 at only 0.28 V/μm. To demonstrate intense electron beam generation, these devices were used to produce white light by cathodoluminescence. Finally, to rational the measured properties in open carbon nanotubes of different lengths we used density functional theory. The modeling establishes a clear correlation between length and field enhancement factor.

  18. Enhanced biological phosphorus removal with different carbon sources.

    PubMed

    Shen, Nan; Zhou, Yan

    2016-06-01

    Enhanced biological phosphorus removal (EBPR) process is one of the most economical and sustainable methods for phosphorus removal from wastewater. However, the performance of EBPR can be affected by available carbon sources types in the wastewater that may induce different functional microbial communities in the process. Glycogen accumulating organisms (GAOs) and polyphosphate accumulating organisms (PAOs) are commonly found by coexisting in the EBPR process. Predominance of GAO population may lead to EBPR failure due to the competition on carbon source with PAO without contributing phosphorus removal. Carbon sources indeed play an important role in alteration of PAOs and GAOs in EBPR processes. Various types of carbon sources have been investigated for EBPR performance. Certain carbon sources tend to enrich specific groups of GAOs and/or PAOs. This review summarizes the types of carbon sources applied in EBPR systems and highlights the roles of these carbon sources in PAO and GAO competition. Both single (e.g., acetate, propionate, glucose, ethanol, and amino acid) and complex carbon sources (e.g., yeast extract, peptone, and mixed carbon sources) are discussed in this review. Meanwhile, the environmental friendly and economical carbon sources that are derived from waste materials, such as crude glycerol and wasted sludge, are also discussed and compared. PMID:27087523

  19. Percolation model with an additional source of disorder.

    PubMed

    Kundu, Sumanta; Manna, S S

    2016-06-01

    The ranges of transmission of the mobiles in a mobile ad hoc network are not uniform in reality. They are affected by the temperature fluctuation in air, obstruction due to the solid objects, even the humidity difference in the environment, etc. How the varying range of transmission of the individual active elements affects the global connectivity in the network may be an important practical question to ask. Here a model of percolation phenomena, with an additional source of disorder, is introduced for a theoretical understanding of this problem. As in ordinary percolation, sites of a square lattice are occupied randomly with probability p. Each occupied site is then assigned a circular disk of random value R for its radius. A bond is defined to be occupied if and only if the radii R_{1} and R_{2} of the disks centered at the ends satisfy a certain predefined condition. In a very general formulation, one divides the R_{1}-R_{2} plane into two regions by an arbitrary closed curve. One defines a point within one region as representing an occupied bond; otherwise it is a vacant bond. The study of three different rules under this general formulation indicates that the percolation threshold always varies continuously. This threshold has two limiting values, one is p_{c}(sq), the percolation threshold for the ordinary site percolation on the square lattice, and the other is unity. The approach of the percolation threshold to its limiting values are characterized by two exponents. In a special case, all lattice sites are occupied by disks of random radii R∈{0,R_{0}} and a percolation transition is observed with R_{0} as the control variable, similar to the site occupation probability. PMID:27415234

  20. Percolation model with an additional source of disorder

    NASA Astrophysics Data System (ADS)

    Kundu, Sumanta; Manna, S. S.

    2016-06-01

    The ranges of transmission of the mobiles in a mobile ad hoc network are not uniform in reality. They are affected by the temperature fluctuation in air, obstruction due to the solid objects, even the humidity difference in the environment, etc. How the varying range of transmission of the individual active elements affects the global connectivity in the network may be an important practical question to ask. Here a model of percolation phenomena, with an additional source of disorder, is introduced for a theoretical understanding of this problem. As in ordinary percolation, sites of a square lattice are occupied randomly with probability p . Each occupied site is then assigned a circular disk of random value R for its radius. A bond is defined to be occupied if and only if the radii R1 and R2 of the disks centered at the ends satisfy a certain predefined condition. In a very general formulation, one divides the R1-R2 plane into two regions by an arbitrary closed curve. One defines a point within one region as representing an occupied bond; otherwise it is a vacant bond. The study of three different rules under this general formulation indicates that the percolation threshold always varies continuously. This threshold has two limiting values, one is pc(sq) , the percolation threshold for the ordinary site percolation on the square lattice, and the other is unity. The approach of the percolation threshold to its limiting values are characterized by two exponents. In a special case, all lattice sites are occupied by disks of random radii R ∈{0 ,R0} and a percolation transition is observed with R0 as the control variable, similar to the site occupation probability.

  1. Methane and carbon at equilibrium in source rocks

    PubMed Central

    2013-01-01

    Methane in source rocks may not exist exclusively as free gas. It could exist in equilibrium with carbon and higher hydrocarbons: CH4 + C < = > Hydrocarbon. Three lines of evidence support this possibility. 1) Shales ingest gas in amounts and selectivities consistent with gas-carbon equilibrium. There is a 50% increase in solid hydrocarbon mass when Fayetteville Shale is exposed to methane (450 psi) under moderate conditions (100°C): Rock-Eval S2 (mg g-1) 8.5 = > 12.5. All light hydrocarbons are ingested, but with high selectivity, consistent with competitive addition to receptor sites in a growing polymer. Mowry Shale ingests butane vigorously from argon, for example, but not from methane under the same conditions. 2) Production data for a well producing from Fayetteville Shale declines along the theoretical curve for withdrawing gas from higher hydrocarbons in equilibrium with carbon. 3) A new general gas-solid equilibrium model accounts for natural gas at thermodynamic equilibrium, and C6-C7 hydrocarbons constrained to invariant compositions. The results make a strong case for methane in equilibrium with carbon and higher hydrocarbons. If correct, the higher hydrocarbons in source rocks are gas reservoirs, raising the possibility of substantially more gas in shales than analytically apparent, and far more gas in shale deposits than currently recognized. PMID:24330266

  2. Examining the Role of Multiple Carbon Sources in Isoprene Synthesis in Plants Using Stable Isotope Techniques

    NASA Astrophysics Data System (ADS)

    Funk, J. L.; Mak, J. E.; Lerdau, M. T.

    2001-12-01

    The carbon source for phytogenc isoprene is an issue with important ramifications for both atmospheric and biological science because of its impact on the isotopic signature of isoprene and its oxidation products and because it lends insight into the function that isoprene serves within leaves. Although recently assimilated carbon is believed to be the primary carbon source for isoprene production in plants, variation in diurnal and seasonal isoprene fluxes that cannot be explained by temperature, light, and leaf development have led to the suggestion that alternative carbon sources may contribute. Stable isotopes of carbon can be used to identify changes in carbon partitioning into isoprene synthesis, and mixing models can assess the relative importance of each source. In preliminary studies, we document an additional 8-10 \\permil discrimination in isoprene emitted in the absence of photosynthesis. This change in signature suggests that the carbon source is switched from recently obtained photosynthate to a source more depleted in 13C. We propose that intermediates from carbohydrate degradation and/or re-fixation of CO2 from mitichondrial respiration and photorespiration can contribute to isoprene production. In addition, we expect alternative carbon sources to be most important when photosynthate is limiting (e.g. during water stress events). Photosynthesis, respiration, and isoprene emission measurements are used to calculate the isotopic signatures of the three potential carbon pools: photosynthate derived from ambient CO2, photosynthate derived from respired CO2, and carbohydrate-derived intermediates.

  3. Reassessing carbon sequestration in the North China Plain via addition of nitrogen.

    PubMed

    Dong, Wenxu; Duan, Yongmei; Wang, Yuying; Hu, Chunsheng

    2016-09-01

    Soil inorganic carbon (SIC) exerts a strong influence on the carbon (C) sequestered in response to nitrogen (N) additions in arid and semi-arid ecosystems, but limited information is available on in situ SIC storage and dissolution at the field level. This study determined the soil organic/inorganic carbon storage in the soil profile at 0-100cm depths and the concentration of dissolved inorganic carbon (DIC) in soil leachate in 4N application treatments (0, 200, 400, and 600kgNha(-1)yr(-)(1)) for 15years in the North China Plain. The objectives were to evaluate the effect of nitrogen fertilizer on total amount of carbon sequestration and the uptake of atmospheric CO2 in an agricultural system. Results showed that after 15years of N fertilizer application the SOC contents at depths of 0-100cm significantly increased, whereas the SIC contents significantly decreased at depths of 0-60cm. However, the actual measured loss of carbonate was far higher than the theoretical maximum values of dissolution via protons from nitrification. Furthermore, the amount of HCO3(-) and the HCO3(-)/(Ca(2+)+Mg(2+)) ratio in soil leachate were higher in the N application treatments than no fertilizer input (CK) for the 0-80cm depth. The result suggested that the dissolution of carbonate was mainly enhanced by soil carbonic acid, a process which can absorb soil or atmosphere CO2 and less influenced by protons through the nitrification which would release CO2. To accurately evaluate soil C sequestration under N input scenarios in semi-arid regions, future studies should include both changes in SIC storage as well as the fractions of dissolution with different sources of acids in soil profiles. PMID:27135576

  4. Source apportionment of PM10 mass and particulate carbon in the Kathmandu Valley, Nepal

    NASA Astrophysics Data System (ADS)

    Kim, Bong Mann; Park, Jin-Soo; Kim, Sang-Woo; Kim, Hyunjae; Jeon, Haeun; Cho, Chaeyoon; Kim, Ji-Hyoung; Hong, Seungkyu; Rupakheti, Maheswar; Panday, Arnico K.; Park, Rokjin J.; Hong, Jihyung; Yoon, Soon-Chang

    2015-12-01

    The Kathmandu Valley in Nepal is a bowl-shaped urban basin in the Himalayan foothills with a serious problem of fine particulate air pollution that impacts local health and impairs visibility. Particulate carbon concentrations have reached severe levels that threaten the health of 3.5 million local residents. Moreover, snow and ice on the Himalayan mountains are melting as a result of additional warming due to particulate carbon, especially high black carbon concentrations. To date, the sources of the Valley's particulate carbon and the impacts of different sources on particulate carbon concentrations are not well understood. Thus, before an effective control strategy can be developed, these particulate carbon sources must be identified and quantified. Our study has found that the four primary sources of particulate carbon in the Kathmandu Valley during winter are brick kilns, motor vehicles, fugitive soil dust, and biomass/garbage burning. Their source contributions are quantified using a recently developed new multivariate receptor model SMP. In contrast to other highly polluted areas such as China, secondary contribution is almost negligible in Kathmandu Valley. Brick kilns (40%), motor vehicles (37%) and biomass/garbage burning (22%) have been identified as the major sources of elemental carbon (black carbon) in the Kathmandu Valley during winter, while motor vehicles (47%), biomass/garbage burning (32%), and soil dust (13%) have been identified as the most important sources of organic carbon. Our research indicates that controlling emissions from motor vehicles, brick kilns, biomass/garbage burning, and soil dust is essential for the mitigation of the particulate carbon that threatens public health, impairs visibility, and influences climate warming within and downwind from the Kathmandu Valley. In addition, this paper suggests several useful particulate carbon mitigation methods that can be applied to Kathmandu Valley and other areas in South Asia with

  5. Acidification of East Siberian Arctic Shelf waters through addition of freshwater and terrestrial carbon

    NASA Astrophysics Data System (ADS)

    Semiletov, Igor; Pipko, Irina; Gustafsson, Örjan; Anderson, Leif G.; Sergienko, Valentin; Pugach, Svetlana; Dudarev, Oleg; Charkin, Alexander; Gukov, Alexander; Bröder, Lisa; Andersson, August; Spivak, Eduard; Shakhova, Natalia

    2016-05-01

    Ocean acidification affects marine ecosystems and carbon cycling, and is considered a direct effect of anthropogenic carbon dioxide uptake from the atmosphere. Accumulation of atmospheric CO2 in ocean surface waters is predicted to make the ocean twice as acidic by the end of this century. The Arctic Ocean is particularly sensitive to ocean acidification because more CO2 can dissolve in cold water. Here we present observations of the chemical and physical characteristics of East Siberian Arctic Shelf waters from 1999, 2000-2005, 2008 and 2011, and find extreme aragonite undersaturation that reflects acidity levels in excess of those projected in this region for 2100. Dissolved inorganic carbon isotopic data and Markov chain Monte Carlo simulations of water sources using salinity and δ18O data suggest that the persistent acidification is driven by the degradation of terrestrial organic matter and discharge of Arctic river water with elevated CO2 concentrations, rather than by uptake of atmospheric CO2. We suggest that East Siberian Arctic Shelf waters may become more acidic if thawing permafrost leads to enhanced terrestrial organic carbon inputs and if freshwater additions continue to increase, which may affect their efficiency as a source of CO2.

  6. Are Glaciers and Ice Sheets Carbon Sources or Carbon Sinks?

    NASA Astrophysics Data System (ADS)

    Graly, J. A.; Drever, J. I.; Humphrey, N. F.

    2014-12-01

    Subglacial waters typically contain considerable quantities of HCO3-. Where this HCO3- is coupled with Ca2+ and Mg2+, it will ultimately precipitate as (Ca, Mg)CO3 in the oceans. If the glacial HCO3- is derived from atmospheric CO2, this pathway represents a long-term CO2 sink. If the HCO3- is derived from carbonate minerals, precipitation is equal to dissolution and there is no net effect on the CO2 balance of the atmosphere. Only the weathering of Ca or Mg-bearing silicates can potentially draw CO2 out of the ocean/atmosphere system. Subglacial environments are potential habitats for a range of microbes that may generate CO2 from organic C. If the production of CO2 from organic sources exceeds the weathering of Ca and Mg from silicates, the subglacial environment is a long-term CO2 source. In order to determine whether ice bodies typically act as CO2 sources or sinks, we modeled the evolution of pH and alkalinity through a range of typical subglacial weathering reactions, considering both the case in which CO2 and O2 can openly exchange with the atmosphere and the case in which the subglacial environment is closed from atmospheric interaction. We find that in the closed system scenario, subglacial waters cannot reach atmospheric PCO2 levels under typical conditions. Initial open system weathering followed by closed system weathering can allow CO2 supersaturation when sulfide oxidation is considered. We use this result to analyze pH and alkalinity measurements from a geographically and geologically diverse selection of subglacial waters. The PCO2 of most of the subglacial waters is near or above atmospheric values. This implies that exchange of gases between subglacial waters and the atmosphere is typical and widespread. This input of atmospheric CO2 into the glacial weathering environment implies that about 5 mg of CO2 are typically removed from the atmosphere per l of glacial discharge water. Similar PCO2 values can be produced in an entirely closed system if

  7. 10 CFR 1.3 - Sources of additional information.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    .../cfr/. Final opinions made in the adjudication of cases are published in “Nuclear Regulatory Commission... Regional Offices. In addition, NRC Functional Organization Charts, NUREG-0325, contains...

  8. Binderless carbon nanotube/carbon fibre composites for electrochemical micropower sources.

    PubMed

    Bordjiba, Tarik; Mohamedi, Mohamed; Dao, Lê H

    2007-01-24

    Interesting architectures built with electrically conductive substrates of interest for microelectrochemical power sources were obtained by directly growing carbon nanotubes on each microfibre constituting a carbon paper. The carbon nanotubes were fabricated by the chemical vapour deposition technique. Results of electrochemical tests showed high-resolution responses in different chemical media, which indicate good electrical contact between the carbon nanotubes and the carbon paper substrate. These architectures hold great promise for incorporation into microelectrochemical power sources. PMID:19636112

  9. 10 CFR 1.3 - Sources of additional information.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    .../cfr/. Final opinions made in the adjudication of cases are published in “Nuclear Regulatory Commission... NUCLEAR REGULATORY COMMISSION STATEMENT OF ORGANIZATION AND GENERAL INFORMATION Introduction § 1.3 Sources..., assignments of responsibility, and delegations of authority is in the Nuclear Regulatory Commission...

  10. 10 CFR 1.3 - Sources of additional information.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    .../cfr/. Final opinions made in the adjudication of cases are published in “Nuclear Regulatory Commission... NUCLEAR REGULATORY COMMISSION STATEMENT OF ORGANIZATION AND GENERAL INFORMATION Introduction § 1.3 Sources..., assignments of responsibility, and delegations of authority is in the Nuclear Regulatory Commission...

  11. 10 CFR 1.3 - Sources of additional information.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    .../cfr/. Final opinions made in the adjudication of cases are published in “Nuclear Regulatory Commission... NUCLEAR REGULATORY COMMISSION STATEMENT OF ORGANIZATION AND GENERAL INFORMATION Introduction § 1.3 Sources..., assignments of responsibility, and delegations of authority is in the Nuclear Regulatory Commission...

  12. 10 CFR 1.3 - Sources of additional information.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    .../cfr/. Final opinions made in the adjudication of cases are published in “Nuclear Regulatory Commission... NUCLEAR REGULATORY COMMISSION STATEMENT OF ORGANIZATION AND GENERAL INFORMATION Introduction § 1.3 Sources..., assignments of responsibility, and delegations of authority is in the Nuclear Regulatory Commission...

  13. Diagnostic Evaluation of Carbon Sources in CMAQ

    EPA Science Inventory

    Traditional monitoring networks measure only total elemental carbon (EC) and organic carbon (OC) routinely. Diagnosing model biases with such limited information is difficult. Measurements of organic tracer compounds have recently become available and allow for more detailed di...

  14. Enhancement of nitrate removal at the sediment-water interface by carbon addition plus vertical mixing.

    PubMed

    Chen, Xuechu; He, Shengbing; Zhang, Yueping; Huang, Xiaobo; Huang, Yingying; Chen, Danyue; Huang, Xiaochen; Tang, Jianwu

    2015-10-01

    Wetlands and ponds are frequently used to remove nitrate from effluents or runoffs. However, the efficiency of this approach is limited. Based on the assumption that introducing vertical mixing to water column plus carbon addition would benefit the diffusion across the sediment-water interface, we conducted simulation experiments to identify a method for enhancing nitrate removal. The results suggested that the sediment-water interface has a great potential for nitrate removal, and the potential can be activated after several days of acclimation. Adding additional carbon plus mixing significantly increases the nitrate removal capacity, and the removal of total nitrogen (TN) and nitrate-nitrogen (NO3(-)-N) is well fitted to a first-order reaction model. Adding Hydrilla verticillata debris as a carbon source increased nitrate removal, whereas adding Eichhornia crassipe decreased it. Adding ethanol plus mixing greatly improved the removal performance, with the removal rate of NO3(-)-N and TN reaching 15.0-16.5 g m(-2) d(-1). The feasibility of this enhancement method was further confirmed with a wetland microcosm, and the NO3(-)-N removal rate maintained at 10.0-12.0 g m(-2) d(-1) at a hydraulic loading rate of 0.5 m d(-1). PMID:25556005

  15. Application of plant carbon source for denitrification by constructed wetland and bioreactor: review of recent development.

    PubMed

    Hang, Qianyu; Wang, Haiyan; Chu, Zhaosheng; Ye, Bibi; Li, Chunmei; Hou, Zeying

    2016-05-01

    Water quality standard for nitrate becomes more and more strict, and the plant carbon source is widely used for denitrification by constructed wetland (CW) and bioreactor. However, the nitrate removal efficiency by different types of plant carbon source are not evaluated comprehensively. Denitrification performance of different plant carbon sources, and the influence of dosing method and pretreatment are thoroughly reviewed in this paper, which aims to investigate the accurate utilization of plant carbon source for nitrogen (as nitrate) removal. It is concluded that plant carbon source addition for all types of CWs and bioreactors can improve the nitrate removal efficiency to some extent, and the dosing method of plant carbon source for denitrification should be further studied and optimized in the future. The popular carbon sources for CW and bioreactor denitrification enhancement are woodchip, chopped macrophytes, crop plants, macrophytes litters, etc. The recommended optimum C:N ratios for CW and bioreactor are 4.0:5.0 and 1.8:3.0, respectively. The physical and biological pretreatments are selected to supply organic carbon for long-term denitrification. PMID:26971521

  16. Source attribution of black carbon in Arctic snow.

    PubMed

    Hegg, Dean A; Warren, Stephen G; Grenfell, Thomas C; Doherty, Sarah J; Larson, Timothy V; Clarke, Antony D

    2009-06-01

    Snow samples obtained at 36 sites in Alaska, Canada, Greenland, Russia, and the Arctic Ocean in early 2007 were analyzed for light-absorbing aerosol concentration together with a suite of associated chemical species. The light absorption data, interpreted as black carbon concentrations, and other chemical data were input into the EPA PMF 1.1 receptor model to explore the sources for black carbon in the snow. The analysis found four factors or sources: two distinct biomass burning sources, a pollution source, and a marine source. The first three of these were responsible for essentially all of the black carbon, with the two biomass sources (encompassing both open and closed combustion) together accounting for >90% of the black carbon. PMID:19569324

  17. Kupier prize lecture: Sources of solar-system carbon

    NASA Technical Reports Server (NTRS)

    Anders, Edward; Zinner, Ernst

    1994-01-01

    We have tried to deconvolve Solar-System carbon into its sources, on the basis of C-12/C-13 ratios (equivalent to R). Interstellar SiC in meteorites, representing greater than 4.6-Ga-old stardust from carbon stars, is isotopically heavier (bar R = 38 +/- 2) than Solar-System carbon (89), implying that the latter contains an additional, light component. A likely source are massive stars, mainly Type II supernovae and Wolf-Rayet stars, which, being O-rich, eject their C largely as CO rather than carbonaceous dust. The fraction of such light C in the Solar System depends on R(sub light) in the source. For R(sub light) = 180-1025 (as in 'Group 4' meteoritic graphite spherules, which apparently came from massive stars greater than 4.6 Ga ago), the fraction of light C is 0.79-0.61. Similar results are obtained for present-day data on red giants and interstellar gas. Although both have become enriched in C-13 due to galactic evolution (to bar-R = 20 and 57), the fraction of the light component in interstellar gas again is near 0.7. (Here bar R represents the mean of a mixture calculated via atom fractions; it is not identical to the arithmetic mean R). Interstellar graphite, unlike SiC, shows a large peak at R approximately equal 90, near the solar value. Although some of the grains may be of local origin, others show anomalies in other elements and hence are exotic. Microdiamonds, with R = 93, also are exotic on the basis of their Xe and N. Apparently R approximately 90 was a fairly common composition 4.6 Ga ago, of stars as well as the ISM.

  18. Dopamine as a Carbon Source: The Controlled Synthesis of Hollow Carbon Spheres and Yolk-Structured Carbon Nanocomposites

    SciTech Connect

    Dai, Sheng; Liu, Rui; Mahurin, Shannon Mark; Li, Chen; Unocic, Raymond R; Idrobo Tapia, Juan C; Gao, Hongjun; Pennycook, Stephen J

    2011-01-01

    A facile and versatile synthesis using dopamine as a carbon source gives hollow carbon spheres and yolk-shell Au{at}Carbon nanocomposites. The uniform nature of dopamine coatings and their high carbon yield endow the products with high structural integrity. The Au{at}C nanocomposites are catalytically active.

  19. Production of Feruloyl Esterase from Aspergillus niger by Solid-State Fermentation on Different Carbon Sources

    PubMed Central

    Ou, Shiyi; Zhang, Jing; Wang, Yong; Zhang, Ning

    2011-01-01

    A mixture of wheat bran with maize bran as a carbon source and addition of (NH4)SO4 as nitrogen source was found to significantly increase production of feruloyl esterase (FAE) enzyme compared with wheat bran as a sole carbon and nitrogen source. The optimal conditions in conical flasks were carbon source (30 g) to water 1 : 1, maize bran to wheat bran 1 : 2, (NH4)SO4 1.2 g and MgSO4 70 mg. Under these conditions, FAE activity was 7.68 mU/g. The FAE activity on the mixed carbon sources showed, high activity against the plant cell walls contained in the cultures. PMID:21603274

  20. 12 Years of NPK Addition Diminishes Carbon Sink Potential of a Nutrient Limited Peatland

    NASA Astrophysics Data System (ADS)

    Larmola, T.; Bubier, J. L.; Juutinen, S.; Moore, T. R.

    2011-12-01

    Peatlands store about a third of global soil carbon. Our aim was to study whether the vegetation feedbacks of nitrogen (N) deposition lead to stronger carbon sink or source in a nutrient limited peatland ecosystem. We investigated vegetation structure and ecosystem CO2 exchange at Mer Bleue Bog, Canada, that has been fertilized for 7-12 years. We have applied 5 and 20 times ambient annual wet N deposition (0.8 g N m-2) with or without phosphorus (P) and potassium (K). Gross photosynthesis, ecosystem respiration and net CO2 exchange (NEE) were measured weekly during the growing season using chamber technique. Under the highest N(PK) treatments, the light saturated photosynthesis (PSmax) was reduced by 20-30% compared to the control treatment, whereas under moderate N and PK additions PSmax slightly increased or was similar to the control. The ecosystem respiration showed similar trends among the treatments, but changes in the rates were less pronounced. High nutrient additions led to up to 65% lower net CO2 uptake than that in the control: In the NPK plots with cumulative N additions of 70, 19, and 0 g N m-2, the daytime NEE in May-July 2011 averaged 0.8 (se. 0.3), 2.0 (se. 0.4), and 2.4 (se. 0.3) μmol m-2 s-1, respectively. In the N only plots with cumulative N additions of 45, 19, and 0 g N m-2, the daytime NEE in May-July 2011 averaged 0.8 (se. 0.2), 2.6 (se. 0.4), and 1.8 (se. 0.3) μmol m-2 s-1, respectively. The reduced plant photosynthetic capacity and diminished carbon sink potential in the highest nutrient treatments correlated with the loss of peat mosses and were not compensated for by the increased vascular plant biomass that has mainly been allocated to woody shrub stems.

  1. A comparison of black carbon measurement methods for combustion sources

    NASA Astrophysics Data System (ADS)

    Holder, A. L.; Pavlovic, J.; Yelverton, T.; Hagler, G.; Aurell, J.; Ebersviller, S.; Seay, B.; Jetter, J.; Gullett, B.; Hays, M. D.

    2015-12-01

    Black carbon is an important short-term climate forcer that has been linked with adverse health effects. Multiple black carbon measurement methodologies exist, but no standard measurement method or calibration material has been agreed upon. Moreover, the U.S. Environmental Protection Agency uses elemental carbon in its ambient monitoring networks and in its emissions inventory, assuming that elemental carbon is equivalent to black carbon. Instrument comparisons with ambient aerosols have demonstrated considerable differences between black carbon and elemental carbon, as well as among different black carbon measurements. However, there have been few published comparable studies for source emissions. We used multiple measurement methods to quantify black carbon and elemental carbon emissions from a range of combustion sources (diesel gensets, coal fired boilers, prescribed fires and cookstoves) emitting particles of varying composition and physical characteristics. The ratio of black carbon to elemental carbon (BC/EC) ranged from 0.50 to 2.8 and depended upon the combustion source. The greatest agreement was observed for emissions from cookstoves (BC/EC = 1.1 ± 0.3). The largest differences were seen for emissions from large stationary diesel genset (BC/EC = 2.3 ± 0.5) and were most pronounced when a diesel particulate filter was used (BC/EC 2.5 ± 0.6). This suggests that this source category may be underrepresented in emissions inventories based on elemental carbon. Black carbon concentrations derived from filter-based attenuation were highly correlated with photo-acoustic absorption measurements, but were generally 50% greater. This is likely due to the choice of calibration factor, which is currently ambiguously defined. These results highlight the importance of developing a standard calibration material to improve comparability among measurements.

  2. Shunting arc plasma source for pure carbon ion beam.

    PubMed

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse. PMID:22380206

  3. Shunting arc plasma source for pure carbon ion beama)

    NASA Astrophysics Data System (ADS)

    Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y.

    2012-02-01

    A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA/mm2 at the peak of the pulse.

  4. Evaluation of phenyl carbonates as electrolyte additives in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Petibon, R.; Rotermund, L. M.; Dahn, J. R.

    2015-08-01

    The impact of the electrolyte additives methyl phenyl carbonate, ethyl phenyl carbonate, and diphenyl carbonate was evaluated in Li[Ni0.33Mn0.33Co0.33]O2/graphite pouch cells with or without 2% vinylene carbonate. Experiments included high precision coulometry, automated storage, electrochemical impedance spectroscopy on symmetric cells and gas chromatography coupled with mass spectrometry. Gas chromatography/mass spectrometry analysis, electrochemical studies during the first charge and impedance spectroscopy on symmetric cells indicated that phenyl carbonates act as solid electrolyte interphase modifiers rather than formers. High precision coulometry showed that cells containing 1-4 wt% methyl phenyl carbonate, ethyl phenyl carbonate or diphenyl carbonate had similar coulombic efficiencies and charge-endpoint capacity slippage as cells filled with 2 wt% vinylene carbonate. Impedance spectroscopy showed that cells containing phenyl carbonates have substantially lower impedance than cells filled with 2 wt% vinylene carbonate and produced minimal volumes of gas during cell use. Results presented in the report show that phenyl carbonates are competitive additives for 4.2 V class cells and should lead to good cycle life, low polarization and low gas evolution during normal use. Phenyl carbonates can also be used as gas-producing safety agents (to trip pressure activated disconnects) in combination with vinylene carbonate in cylindrical or prismatic cells without adverse effects.

  5. Comparing carbon sequestration potential of pyrogenic carbon from natural and anthropogenic sources

    NASA Astrophysics Data System (ADS)

    Santin, Cristina; Doerr, Stefan; Merino, Augustin

    2014-05-01

    The enhanced resistance to environmental degradation of Pyrogenic Carbon (PyC), both produced in wildfires (charcoal), and man-made (biochar), gives it the potential to sequester carbon by preventing it to be released into the atmosphere. Sustainable addition of biochar to soils is seen as a viable global approach for carbon sequestration and climate change mitigation. Also the role of its 'natural counterpart', i.e. wildfire charcoal, as a long-term carbon sink in soils is widely recognized. However, in spite of their fundamental similarities, research on the potential of 'man-made' biochar and wildfire charcoal for carbon sequestration has been carried out essentially in isolation as analogous materials for accurate comparison are not easily available. Here we assess the carbon sequestration potential of man-made biochar and wildfire charcoal generated from the same material under known production conditions: (i) charcoal from forest floor and down wood produced during an experimental boreal forest fire (FireSmart, June 2012, NWT- Canada) and (ii) biochar produced from the same feedstock by slow pyrolysis [three treatments: 2 h at 350, 500 and 650°C, respectively]. The carbon sequestration potential of these PyC materials is given by the recalcitrance index, R50, proposed by Harvey et al. (2012). R50 is based on the relative thermal stability of a given PyC material to that of graphite and is calculated using thermogravimetric analyses. Our results show highest R50 for PyC materials produced from down wood than from forest floor, which points to the importance of feedstock chemical composition in determining the C sequestration potential of PyC both from natural (charcoal) and anthropogenic (biochar) sources. Moreover, production temperature is also a major factor affecting the carbon sequestration potential of the studied PyC materials, with higher R50 for PyC produced at higher temperatures. Further investigation on the similarities and differences between man

  6. Pulsed addition of limiting-carbon during Aspergillus oryzae fermentation leads to improved productivity of a recombinant enzyme.

    PubMed

    Bhargava, Swapnil; Wenger, Kevin S; Marten, Mark R

    2003-04-01

    Fungal morphology in many filamentous fungal fermentations leads to high broth viscosity which limits oxygen mass transfer, and often results in reduced productivity. The objective in this study was to determine if a simple, fed-batch, process strategy-pulsed addition of limiting-carbon source-could be used to reduce fungal broth viscosity, and increase productivity of an industrially relevant recombinant enzyme (glucoamylase). As a control, three Aspergillus oryzae fed-batch fermentations were carried out with continuous addition of limiting-carbon. To determine the effect of pulse-feeding, three additional fermentations were carried out with limiting-carbon added in 90-second pulses, during repeated five-minute cycles. In both cases, overall carbon feed-rate was used to control dissolved oxygen concentration, such that increased oxygen availability led to increased addition of limiting-carbon. Pulse-fed fermentations were found to have smaller fungal mycelia, lower broth viscosity, and improved oxygen mass transfer. As a result, more carbon was added to pulse-fed fermentations that led to increased enzyme productivity by as much as 75%. This finding has significant implications for the bioprocessing industry, as a simple process modification which is likely to cost very little to implement in most production facilities, has the potential to substantially increase productivity. PMID:12569630

  7. Waste tires: A future source of activated carbon?

    SciTech Connect

    1996-01-01

    Millions of used tires are disposed in the United States each year, causing major environmental problems and representing a loss of valuable resources. Currently, over 80% of discarded tires are landfilled (approximately 200 million per year). Because tires disposed in municipal landfills rarely stay buried, regulators, landfill operators, and even the general public are constantly reminded of this problem. These ever-surfacing tires can serve as a breeding ground for disease-causing mosquitoes; in addition, large mounds of tires often catch fire, causing significant air pollution. Recent research indicates that used tires may soon represent a source of carbon-based adsorbents and energy-rich liquid and gaseous hydrocarbons. Details of this research are discussed briefly in this paper. 3 refs., 2 figs.

  8. METHOD FOR MEASURING CARBON FIBER EMISSIONS FROM STATIONARY SOURCES

    EPA Science Inventory

    Carbon fibers are highly conductive, lightweight and of small dimensions. When released as emissions from production, manufacturing, processing and disposal sources they may become airborne and disperse over wide areas. If they settle onto electronic or electrical components they...

  9. Microbial Diversity Indexes Can Explain Soil Carbon Dynamics as a Function of Carbon Source

    PubMed Central

    Maron, Pierre-Alain; Menasseri-Aubry, Safya; Sarr, Amadou; Lévêque, Jean; Mathieu, Olivier; Jolivet, Claudy; Leterme, Philippe; Viaud, Valérie

    2016-01-01

    Mathematical models do not explicitly represent the influence of soil microbial diversity on soil organic carbon (SOC) dynamics despite recent evidence of relationships between them. The objective of the present study was to statistically investigate relationships between bacterial and fungal diversity indexes (richness, evenness, Shannon index, inverse Simpson index) and decomposition of different pools of soil organic carbon by measuring dynamics of CO2 emissions under controlled conditions. To this end, 20 soils from two different land uses (cropland and grassland) were incubated with or without incorporation of 13C-labelled wheat-straw residue. 13C-labelling allowed us to study residue mineralisation, basal respiration and the priming effect independently. An innovative data-mining approach was applied, based on generalized additive models and a predictive criterion. Results showed that microbial diversity indexes can be good covariates to integrate in SOC dynamics models, depending on the C source and the processes considered (native soil organic carbon vs. fresh wheat residue). Specifically, microbial diversity indexes were good candidates to help explain mineralisation of native soil organic carbon, while priming effect processes seemed to be explained much more by microbial composition, and no microbial diversity indexes were found associated with residue mineralisation. Investigation of relationships between diversity and mineralisation showed that higher diversity, as measured by the microbial diversity indexes, seemed to be related to decreased CO2 emissions in the control soil. We suggest that this relationship can be explained by an increase in carbon yield assimilation as microbial diversity increases. Thus, the parameter for carbon yield assimilation in mathematical models could be calculated as a function of microbial diversity indexes. Nonetheless, given limitations of the methods used, these observations should be considered with caution and

  10. Microbial Diversity Indexes Can Explain Soil Carbon Dynamics as a Function of Carbon Source.

    PubMed

    Louis, Benjamin P; Maron, Pierre-Alain; Menasseri-Aubry, Safya; Sarr, Amadou; Lévêque, Jean; Mathieu, Olivier; Jolivet, Claudy; Leterme, Philippe; Viaud, Valérie

    2016-01-01

    Mathematical models do not explicitly represent the influence of soil microbial diversity on soil organic carbon (SOC) dynamics despite recent evidence of relationships between them. The objective of the present study was to statistically investigate relationships between bacterial and fungal diversity indexes (richness, evenness, Shannon index, inverse Simpson index) and decomposition of different pools of soil organic carbon by measuring dynamics of CO2 emissions under controlled conditions. To this end, 20 soils from two different land uses (cropland and grassland) were incubated with or without incorporation of 13C-labelled wheat-straw residue. 13C-labelling allowed us to study residue mineralisation, basal respiration and the priming effect independently. An innovative data-mining approach was applied, based on generalized additive models and a predictive criterion. Results showed that microbial diversity indexes can be good covariates to integrate in SOC dynamics models, depending on the C source and the processes considered (native soil organic carbon vs. fresh wheat residue). Specifically, microbial diversity indexes were good candidates to help explain mineralisation of native soil organic carbon, while priming effect processes seemed to be explained much more by microbial composition, and no microbial diversity indexes were found associated with residue mineralisation. Investigation of relationships between diversity and mineralisation showed that higher diversity, as measured by the microbial diversity indexes, seemed to be related to decreased CO2 emissions in the control soil. We suggest that this relationship can be explained by an increase in carbon yield assimilation as microbial diversity increases. Thus, the parameter for carbon yield assimilation in mathematical models could be calculated as a function of microbial diversity indexes. Nonetheless, given limitations of the methods used, these observations should be considered with caution and

  11. Additives

    NASA Technical Reports Server (NTRS)

    Smalheer, C. V.

    1973-01-01

    The chemistry of lubricant additives is discussed to show what the additives are chemically and what functions they perform in the lubrication of various kinds of equipment. Current theories regarding the mode of action of lubricant additives are presented. The additive groups discussed include the following: (1) detergents and dispersants, (2) corrosion inhibitors, (3) antioxidants, (4) viscosity index improvers, (5) pour point depressants, and (6) antifouling agents.

  12. A Novel Airborne Carbon Isotope Analyzer for Methane and Carbon Dioxide Source Fingerprinting

    NASA Astrophysics Data System (ADS)

    Berman, E. S.; Huang, Y. W.; Owano, T. G.; Leifer, I.

    2014-12-01

    Recent field studies on major sources of the important greenhouse gas methane (CH4) indicate significant underestimation of methane release from fossil fuel industrial (FFI) and animal husbandry sources, among others. In addition, uncertainties still exist with respect to carbon dioxide (CO2) measurements, especially source fingerprinting. CO2 isotopic analysis provides a valuable in situ measurement approach to fingerprint CH4 and CO2as associated with combustion sources, leakage from geologic reservoirs, or biogenic sources. As a result, these measurements can characterize strong combustion source plumes, such as power plant emissions, and discriminate these emissions from other sources. As part of the COMEX (CO2 and MEthane eXperiment) campaign, a novel CO2 isotopic analyzer was installed and collected data aboard the CIRPAS Twin Otter aircraft. Developing methods to derive CH4 and CO2 budgets from remote sensing data is the goal of the summer 2014 COMEX campaign, which combines hyperspectral imaging (HSI) and non-imaging spectroscopy (NIS) with in situ airborne and surface data. COMEX leverages the synergy between high spatial resolution HSI and moderate spatial resolution NIS. The carbon dioxide isotope analyzer developed by Los Gatos Research (LGR) uses LGR's patented Off-Axis ICOS (Integrated Cavity Output Spectroscopy) technology and incorporates proprietary internal thermal control for high sensitivity and optimal instrument stability. This analyzer measures CO2 concentration as well as δ13C, δ18O, and δ17O from CO2 at natural abundance (100-3000 ppm). The laboratory accuracy is ±1.2 ppm (1σ) in CO2 from 370-1000 ppm, with a long-term (1000 s) precision of ±0.012 ppm. The long-term precision for both δ13C and δ18O is 0.04 ‰, and for δ17O is 0.06 ‰. The analyzer was field-tested as part of the COWGAS campaign, a pre-cursor campaign to COMEX in March 2014, where it successfully discriminated plumes related to combustion processes associated with

  13. Highly oriented carbon fiber–polymer composites via additive manufacturing

    DOE PAGESBeta

    Tekinalp, Halil L.; Kunc, Vlastimil; Velez-Garcia, Gregorio M.; Duty, Chad E.; Love, Lonnie J.; Naskar, Amit K.; Blue, Craig A.; Ozcan, Soydan

    2014-10-16

    Additive manufacturing, diverging from traditional manufacturing techniques, such as casting and machining materials, can handle complex shapes with great design flexibility without the typical waste. Although this technique has been mainly used for rapid prototyping, interest is growing in using this method to directly manufacture actual parts of complex shape. To use 3D-printing additive manufacturing in wide spread applications, the technique and the feedstock materials require improvements to meet the mechanical requirements of load-bearing components. Thus, we investigated the short fiber (0.2 mm to 0.4 mm) reinforced acrylonitrile-butadiene-styrene composites as a feedstock for 3D-printing in terms of their processibility, microstructuremore » and mechanical performance; and also provided comparison with traditional compression molded composites. The tensile strength and modulus of 3D-printed samples increased ~115% and ~700%, respectively. 3D-printer yielded samples with very high fiber orientation in printing direction (up to 91.5 %), whereas, compression molding process yielded samples with significantly less fiber orientation. Microstructure-mechanical property relationships revealed that although the relatively high porosity is observed in the 3D-printed composites as compared to those produced by the conventional compression molding technique, they both exhibited comparable tensile strength and modulus. Furthermore, this phenomena is explained based on the changes in fiber orientation, dispersion and void formation.« less

  14. Highly oriented carbon fiber–polymer composites via additive manufacturing

    SciTech Connect

    Tekinalp, Halil L.; Kunc, Vlastimil; Velez-Garcia, Gregorio M.; Duty, Chad E.; Love, Lonnie J.; Naskar, Amit K.; Blue, Craig A.; Ozcan, Soydan

    2014-10-16

    Additive manufacturing, diverging from traditional manufacturing techniques, such as casting and machining materials, can handle complex shapes with great design flexibility without the typical waste. Although this technique has been mainly used for rapid prototyping, interest is growing in using this method to directly manufacture actual parts of complex shape. To use 3D-printing additive manufacturing in wide spread applications, the technique and the feedstock materials require improvements to meet the mechanical requirements of load-bearing components. Thus, we investigated the short fiber (0.2 mm to 0.4 mm) reinforced acrylonitrile-butadiene-styrene composites as a feedstock for 3D-printing in terms of their processibility, microstructure and mechanical performance; and also provided comparison with traditional compression molded composites. The tensile strength and modulus of 3D-printed samples increased ~115% and ~700%, respectively. 3D-printer yielded samples with very high fiber orientation in printing direction (up to 91.5 %), whereas, compression molding process yielded samples with significantly less fiber orientation. Microstructure-mechanical property relationships revealed that although the relatively high porosity is observed in the 3D-printed composites as compared to those produced by the conventional compression molding technique, they both exhibited comparable tensile strength and modulus. Furthermore, this phenomena is explained based on the changes in fiber orientation, dispersion and void formation.

  15. 5 CFR 3601.103 - Additional exceptions for gifts from outside sources.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 5 Administrative Personnel 3 2013-01-01 2013-01-01 false Additional exceptions for gifts from outside sources. 3601.103 Section 3601.103 Administrative Personnel DEPARTMENT OF DEFENSE SUPPLEMENTAL STANDARDS OF ETHICAL CONDUCT FOR EMPLOYEES OF THE DEPARTMENT OF DEFENSE § 3601.103 Additional exceptions for gifts from outside sources. In addition...

  16. Enhanced life ion source for germanium and carbon ion implantation

    SciTech Connect

    Hsieh, Tseh-Jen; Colvin, Neil; Kondratenko, Serguei

    2012-11-06

    Germanium and carbon ions represent a significant portion of total ion implantation steps in the process flow. Very often ion source materials that used to produce ions are chemically aggressive, especially at higher temperatures, and result in fast ion source performance degradation and a very limited lifetime [B.S. Freer, et. al., 2002 14th Intl. Conf. on Ion Implantation Technology Proc, IEEE Conf. Proc., p. 420 (2003)]. GeF{sub 4} and CO{sub 2} are commonly used to generate germanium and carbon beams. In the case of GeF{sub 4} controlling the tungsten deposition due to the de-composition of WF{sub 6} (halogen cycle) is critical to ion source life. With CO{sub 2}, the materials oxidation and carbon deposition must be controlled as both will affect cathode thermionic emission and anti-cathode (repeller) efficiencies due to the formation of volatile metal oxides. The improved ion source design Extended Life Source 3 (Eterna ELS3) together with its proprietary co-gas material implementation has demonstrated >300 hours of stable continuous operation when using carbon and germanium ion beams. Optimizing cogas chemistries retard the cathode erosion rate for germanium and carbon minimizes the adverse effects of oxygen when reducing gas is introduced for carbon. The proprietary combination of hardware and co-gas has improved source stability and the results of the hardware and co-gas development are discussed.

  17. Effects of light and autochthonous carbon additions on microbial turnover of allochthonous organic carbon and community composition.

    PubMed

    Attermeyer, Katrin; Tittel, Jörg; Allgaier, Martin; Frindte, Katharina; Wurzbacher, Christian; Hilt, Sabine; Kamjunke, Norbert; Grossart, Hans-Peter

    2015-02-01

    The fate of allochthonous dissolved organic carbon (DOC) in aquatic systems is primarily controlled by the turnover of heterotrophic bacteria. However, the roles that abiotic and biotic factors such as light and DOC release by aquatic primary producers play in the microbial decomposition of allochthonous DOC is not well understood. We therefore tested if light and autochthonous DOC additions would increase allochthonous DOC decomposition rates and change bacterial growth efficiencies and community composition (BCC). We established continuous growth cultures with different inocula of natural bacterial communities and alder leaf leachates (DOCleaf) with and without light exposure before amendment. Furthermore, we incubated DOCleaf together with autochthonous DOC from lysed phytoplankton cultures (DOCphyto). Our results revealed that pretreatments of DOCleaf with light resulted in a doubling of bacterial growth efficiency (BGE), whereas additions of DOCphyto or combined additions of DOCphyto and light had no effect on BGE. The change in BGE was not accompanied by shifts in the phylogenetic structure of the BCC, but BCC was influenced by the DOC source. Our results highlight that a doubling of BGE is not necessarily accompanied by a shift in BCC and that BCC is more strongly affected by resource properties. PMID:25515425

  18. Freshwater ecology. Experimental nutrient additions accelerate terrestrial carbon loss from stream ecosystems.

    PubMed

    Rosemond, Amy D; Benstead, Jonathan P; Bumpers, Phillip M; Gulis, Vladislav; Kominoski, John S; Manning, David W P; Suberkropp, Keller; Wallace, J Bruce

    2015-03-01

    Nutrient pollution of freshwater ecosystems results in predictable increases in carbon (C) sequestration by algae. Tests of nutrient enrichment on the fates of terrestrial organic C, which supports riverine food webs and is a source of CO2, are lacking. Using whole-stream nitrogen (N) and phosphorus (P) additions spanning the equivalent of 27 years, we found that average terrestrial organic C residence time was reduced by ~50% as compared to reference conditions as a result of nutrient pollution. Annual inputs of terrestrial organic C were rapidly depleted via release of detrital food webs from N and P co-limitation. This magnitude of terrestrial C loss can potentially exceed predicted algal C gains with nutrient enrichment across large parts of river networks, diminishing associated ecosystem services. PMID:25745171

  19. Source contributions to atmospheric fine carbon particle concentrations

    NASA Astrophysics Data System (ADS)

    Andrew Gray, H.; Cass, Glen R.

    A Lagrangian particle-in-cell air quality model has been developed that facilitates the study of source contributions to atmospheric fine elemental carbon and fine primary total carbon particle concentrations. Model performance was tested using spatially and temporally resolved emissions and air quality data gathered for this purpose in the Los Angeles area for the year 1982. It was shown that black elemental carbon (EC) particle concentrations in that city were dominated by emissions from diesel engines including both on-highway and off-highway applications. Fine primary total carbon particle concentrations (TC=EC+organic carbon) resulted from the accumulation of small increments from a great variety of emission source types including both gasoline and diesel powered highway vehicles, stationary source fuel oil and gas combustion, industrial processes, paved road dust, fireplaces, cigarettes and food cooking (e.g. charbroilers). Strategies for black elemental carbon particle concentration control will of necessity need to focus on diesel engines, while controls directed at total carbon particle concentrations will have to be diversified over a great many source types.

  20. Additional characteristics of one-carbon-compound utilization by Eubacterium limosum and Acetobacterium woodii.

    PubMed

    Sharak Genthner, B R; Bryant, M P

    1987-03-01

    Growth characteristics of Eubacterium limosum and Acetobacterium woodii during one-carbon-compound utilization were investigated. E. limosum RF grew with formate as the sole energy source. Formate also replaced a requirement for CO2 during growth with methanol. Growth with methanol required either rumen fluid, yeast extract, or acetate, but their effects were not additive. Cultures were adapted to grow in concentrations of methanol of up to 494 mM. Growth occurred with methanol in the presence of elevated levels of Na+ (576 mM). The pH optima for growth with methanol, H2-CO2, and carbon monoxide were similar (7.0 to 7.2). Growth occurred with glucose at a pH of 4.7, but not at 4.0. The apparent Km values for methanol and hydrogen were 2.7 and 0.34 mM, respectively. The apparent Vmax values for methanol and hydrogen were 1.7 and 0.11 mumol/mg of protein X min-1, respectively. The Ks value for CO was estimated to be less than 75 microM. Cellular growth yields were 70.5, 7.1, 3.38, and 0.84 g (dry weight) per mol utilized for glucose, methanol, CO, and hydrogen (in H2-CO2), respectively. E. limosum was also able to grow with methoxylated aromatic compounds as energy sources. Glucose apparently repressed the ability of E. limosum to use methanol, hydrogen, or isoleucine but not CO. Growth with mixtures of methanol, H2, CO, or isoleucine was not diauxic. The results, especially the relatively high apparent Km values for H2 and methanol, may indicate why E. limosum does not usually compete with rumen methanogens for these energy sources.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3579266

  1. Novel molecular sources for dispersing boron in carbon-carbon composites. Final report, 1 Jun-30 Nov 91

    SciTech Connect

    Chen, P.S.; Stevens, W.C.

    1991-12-31

    Improving the oxidation resistance of carbon-carbon composites is key to expanding the use of this material system into higher temperature applications. While boron particles have been added to these materials to seal cracks in protective coatings, oxidation of the carbon matrix neighboring the boron particles seriously affects composite strength. This problem is exacerbate by a natural segregation of the boron particles to fiber rich areas of the composites. Carborane, a robust molecular source of boron, was used as the precursor for atomically dispersed boron in a phenolic derived carbon matrix. Modifications of the chemical structure of carborane were used to improve the solubility in phenolic. Additions of carboranes into the phenolic resins dramatically improved the oxidation resistance of the carbonized char. The char yield of the phenolic resin was also increased significantly.

  2. Effect of Additives and pH on the Formation of Carbonate Mineral by CO2 Sequestration of Cement Paste

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Hwang, J.; Lee, H.; Son, B. S.; Oh, J.

    2015-12-01

    CO2 in the atmosphere causes a global warming that is a big issue nowadays. Many studies of CO2 capture and storage (CCS) technologies have been studied all over the world. Waste cement is a good source for aqueous carbonation because it is rich in calcium. Therefore, this study was performed to develop the aqueous carbonation method for waste cement powder. Cement paste was made with water/cement ratio of 6:4 and cured for 28 days in water bath. The cement paste was pulverized into a fine powder sizing less than 0.15 mm. To study effect of additives and pH on the formation of carbonate minerals, aqueous carbonation experiments were conducted. The mineral compositions and morphology of carbonate mineral were identified by XRD and SEM/EDS analysis. 1.0 M NaCl and 0.25 M MgCl2 were applied as additives. Aqueous carbonation experiment was conducted with injecting pure CO2 gas (99.9%) to a reactor containing 200 ㎖ of reacting solution. The pH of reacting solution was controled to determine formational condition of carbonate minerals. In 0.25 M MgCl2 solution, calcite was dominant mineral at high pH. More aragonite, however, formed as decreasing pH of solution with injection of CO2. The presence of Mg2+ in solution makes aragonite more dominant than calcite. Aragonite was mainly formed at the high pH of solution with 1.0 M NaCl additive, whereas calcite was more preponderant mineral than aragonite as falling pH. It show that unstable aragonite transformed to calcite as decreasing pH. In no additive solution, vaterite was dominantly formed at the initial stage of experiement, but unstable vaterite transformed to well crystallized calcite with further carbonation.

  3. Comparison of aerobic denitrifying activity among three cultural species with various carbon sources.

    PubMed

    Otani, Y; Hasegawa, K; Hanaki, K

    2004-01-01

    Abilities of three aerobic denitrifiers such as Alcaligenes faecalis, Microvirgula aerodenitrificans and Paracoccus pantotrophus were compared from the viewpoints of nitrate removal efficiency and organic matter utilization. First, the effect of carbon source was investigated. Although nitrate reduction was observed in all strains under aerobic conditions, a change of carbon source considerably affected the denitrification ability. In the case of P. pantotrophus, nitrate and nitrite were completely removed in three days under sodium acetate or leucine as a carbon source. In the case of A. faecalis, sufficient nitrate removal was observed only when sodium acetate or ethanol was added. P. pantotrophus and A. faecalis showed a higher ability of nitrate removal than that of M. aerodenitrificans. Therefore, P. pantotrophus was selected in order to investigate the effects of concentration and repetitive addition of carbon. Sodium acetate was used as a sole carbon source. Nitrate was not reduced when the carbon concentration was below 500 mgC/L. However, when carbon source was added repeatedly, nitrate was reduced under 100 mgC/L after the optical density of the bacterium reached above 1.0. This result indicated that a high enough level of bacterial density was necessary to express aerobic denitrification activity. PMID:15566182

  4. Organic Carbon Sources in Coastal Southeast Alaskan Streams

    NASA Astrophysics Data System (ADS)

    Hood, E.; Edwards, R. T.; D'Amore, D. V.; Lange, B. J.

    2003-12-01

    Dissolved organic matter (DOM) is abundant in southeast Alaskan watersheds and plays an important role in the biological and physical processes in these aquatic systems. Nearly 30% of the land area in southeast Alaska is classified as wetlands, a large proportion of which are peatlands. Peatlands are thought to provide substantial DOM to surface waters. Another important source of carbon to streams is spawning anadromous salmon. This study examines how streamwater concentrations of DOC are influenced by 1) catchments soils and vegetation, particularly wetland extent and 2) the presence or absence of anadromous fish. Our goal is to characterize the quantity and quality of different DOM sources and to develop an understanding of how these sources influence seasonal trends in streamwater DOM in coastal freshwater systems in southeast Alaska. Surface water and well samples were collected on two contrasting streams near Juneau, Alaska: Peterson Creek, a brownwater, high-carbon stream in a wetland-dominated catchment and McGinnis Creek, a clearwater stream draining upland spruce forest and alpine tundra. Both streams have runs of pink, coho, and chum salmon from July-September. Streamwater DOC concentrations on Peterson Creek averaged 5-6 mg C L-1 during the early summer and increased to 8-12 mg C L-1 during late July and August. Streamwater DOC concentrations on McGinnis Creek were typically less than 1 mg C L-1 during the early summer but increased dramatically to 4-9 mg C L-1 during spates in August. Well samples collected upslope from the streamwater sampling sites on Peterson and McGinnis Creeks had a similar range in DOC concentrations (10-40 mg C L-1), however the wells on McGinnis Creek showed much higher seasonal variability. Our initial results suggest that the seasonal increase in DOC in both streams is primarily associated with the flushing of soluble organic carbon from catchment soils by late summer rains. However, leaching of DOC from salmon carcasses may

  5. Sources of carbon in inclusion bearing diamonds

    NASA Astrophysics Data System (ADS)

    Stachel, Thomas; Harris, Jeff W.; Muehlenbachs, Karlis

    2009-11-01

    The carbon isotopic composition ( δ13C) of diamonds containing peridotitic, eclogitic, websteritic and ultra-deep inclusions is re-evaluated on a detailed level. Applying a binning interval of 0.25‰, the previously recognized mode of peridotitic and eclogitic diamonds at about - 5‰ is shown to reflect at least two subpopulations with abundance peaks at ˜ - 5.75 to - 4.75‰ and ˜ - 4.50 to - 3.50‰. Within the peridotitic suite, diamonds with lherzolitic inclusions overall show higher δ13C values. Evolution away from a δ13C value of ˜ - 5‰, towards both 13C depleted and enriched compositions, is accompanied by decreasing maximum nitrogen contents of peridotitic diamonds. In combination with data on diamonds synthesized under reducing (metal melts) and more oxidizing conditions (carbonate-silicate interactions), this is taken to indicate that nitrogen is a compatible element in diamond that becomes depleted in the growth medium during progressive diamond precipitation. The observed co-variations of nitrogen content and δ13C around - 5‰ can then be modelled as reflecting closed system Rayleigh fractionation during crystallization of diamond from fluids/melts that are both reducing (i.e. methane bearing; evolution from ˜ - 5 to - 10‰) and oxidizing (i.e. CO 32- bearing; evolution from starting points varying between ˜ - 9 to - 5‰ and extending to about 0‰). Lherzolitic diamonds are believed to be mainly derived from diamond forming events subsequent to precipitation of predominantly Mesoarchean harzburgitic diamonds. The shift of lherzolitic diamonds towards higher δ13C values thus may relate to a temporal evolution, with carbonate bearing fluids with an initial isotopic composition ranging between about - 5.5 and - 1.5‰, derived from subducting oceanic crust, becoming increasingly important subsequent to the Mesoarchean. Devolatilization of marine carbonates ( δ13C ˜ 0‰) drives their isotopic composition towards mantle like values and

  6. Development of a stationary carbon emission inventory for Shanghai using pollution source census data

    NASA Astrophysics Data System (ADS)

    Li, Xianzhe; Jiang, Ping; Zhang, Yan; Ma, Weichun

    2016-03-01

    This study utilizes 521,631 activity data points from the 2007 Shanghai Pollution Source Census to compile a stationary carbon emission inventory for Shanghai. The inventory generated from our dataset shows that a large portion of Shanghai's total energy use consists of coal-oriented energy consumption. The electricity and heat production industries, iron and steel mills, and the petroleum refining industry are the main carbon emitters. In addition, most of these industries are located in Baoshan District, which is Shanghai's largest contributor of carbon emissions. Policy makers can use the enterpriselevel carbon emission inventory and the method designed in this study to construct sound carbon emission reduction policies. The carbon trading scheme to be established in Shanghai based on the developed carbon inventory is also introduced in this paper with the aim of promoting the monitoring, reporting and verification of carbon trading. Moreover, we believe that it might be useful to consider the participation of industries, such as those for food processing, beverage, and tobacco, in Shanghai's carbon trading scheme. Based on the results contained herein, we recommend establishing a comprehensive carbon emission inventory by inputting data from the pollution source census used in this study.

  7. Effect of carbon source type on intracellular stored polymers during endogenous denitritation (ED) treating landfill leachate.

    PubMed

    Miao, Lei; Wang, Shuying; Li, Baikun; Cao, Tianhao; Zhang, Fangzhai; Wang, Zhong; Peng, Yongzhen

    2016-09-01

    Glycogen accumulating organisms (GAOs) capable of storing organic compounds as polyhydroxyalkanoate (PHA) have been used for endogenous denitritation (ED), but the effect of carbon sources type on nitrogen removal performance of GAOs treating landfill leachate is unclear. In this study, a successful ED system treating landfill leachate (COD/NH4(+)-N (C/N): 4) without external carbon source addition was applied. The mature leachate with C/N of 1 was used as the feeding base solution, with acetate, propionate, and glucose examined as the carbon sources, and their effects on yields and compositions of PHA produced by GAOs were determined and associated with nitrogen removal performance. In the case of sole carbon source, acetate was much easier to be stored than propionate and glucose, which led to a higher nitrogen removal efficiency. Glucose had the lowest amount of PHA storage and led to the lowest performance. In the case of composite carbon sources (two scenarios: acetate + propionate; acetate + propionate + glucose), GAOs stored sufficient PHA and exhibited similar nitrogen removal efficiencies. Moreover, type of carbon source influenced the compositions of PHA. The polyhydroxybutyrate (PHB) fraction in PHA was far more than polyhydroxyvalerate (PHV) in all tests. PHV was synthesized only when acetate existed in carbon source. The microbial diversity analysis revealed that Proteobacteria was the most abundant phylum. Among the 108 genera detected in this ED system, the genera responsible for denitritation were Thauera, Paracoccus, Ottowia and Comamonadaceae_unclassified, accounting for 46.21% of total bacteria. Especially, Paracoccus and Comamonadaceae_unclassified transformed the carbon source into PHA for denitritation, and carried out endogenous denitritation. PMID:27232984

  8. What's on the menu? Assessing microbial carbon sources and cycling in soils using natural abundance radiocarbon analysis

    NASA Astrophysics Data System (ADS)

    Mahmoudi, N.; Burns, L.; Mancini, S.; Fulthorpe, R.; Slater, G. F.

    2011-12-01

    Organic matter in soils is composed of diverse materials in various stages of decomposition. Soil organic matter is not in a single pool but rather in multiple carbon pools with different intrinsic turnover times that can be on annual to decadal and even millennial timescales. Microorganisms can influence the total amount of carbon stored in soils and the turnover rates of these different pools. However, the links between microbes and their ability to utilize these various carbon pools are not well understood. Moreover, microbes have been shown to co-utilize a number of available carbon sources rather than a single carbon source under soil conditions which creates difficulties in identifying microbial carbon sources in the natural environment. Compound-specific radiocarbon analysis of microbial phospholipid fatty acids (PLFA) has become a useful tool in elucidating microbial carbon sources in complex environments with multiple carbon sources. We investigated microbial carbon cycling at an industrial site in Ontario which included a variety of carbon sources including vegetation, PAHs and natural organic matter (NOM). Using this approach, the 14C content of microbial membrane lipids (which reflects their carbon source) can be compared to surrounding carbon sources in order to assess which carbon source they are metabolizing and incorporating into their lipids. In addition, we assessed microbial community structure and diversity by analyzing amplified bacterial, eukaryotic and archaeal rDNA fragments with denaturing gel gradient electrophoresis (DGGE). The Δ14C value for PLFAs ranged from +54 to -697% which indicates that microbial carbon sources across soils differ. The Δ14CPLFA for some soils is consistent with modern carbon sources while Δ14CPLFA for other soils is consistent with natural organic matter including older pools of carbon. The microbial communities at this site are not metabolizing PAHs but rather they are utilizing various pools of natural organic

  9. Source of silicate and carbonate cements during deep burial diagenesis

    SciTech Connect

    Dutta, P.K.

    1986-05-01

    Detrital silicate minerals and silicate cements (formed during shallow burial) of siliciclastic sandstones commonly dissolve during deep burial diagenesis. Quartz, feldspars, mica, and garnet among detrital silicate minerals, and quartz and kaolinite among authigenic silicate minerals show extensive dissolution features during deep burial diagenesis of siliciclastic sandstones of the Gondwana Supergroup, India. No dissolution features were observed in zircon, tourmalene, and rutile among detrital minerals or in chlorite and smectite among early formed authigenic minerals. Dissolution enriched the pore fluids in silica, potassium, sodium, calcium, magnesium, iron, and aluminum. Authigenic cements formed during this stage are illite, quartz, feldspar, iron oxide, and carbonates of calcium, magnesium, and iron. Mass-balance calculations show that the source of all silicate cements formed during deep burial diagenesis was internally derived from the dissolution of both detrital and early formed authigenic cements. However, a considerable gap exists between the amounts of cations (calcium, magnesium, and iron) derived internally and the respective amounts of these cations needed to form the various carbonate cements at this stage. Therefore, an outside source for these cations is needed to explain the formation of carbonate cements. A large mass transfer of cations from outside the sediment source seems remote since ground-water movement, which probably carried cement from an external source, is extremely restricted at great burial depths. Therefore, carbonate cements may have been major constituents during shallow burial diagenesis in Gondwana sandstones. Subsequently, these early formed carbonates were completely dissolved and remobilized as late-stage carbonate cement.

  10. Modulation of Candida albicans Biofilm by Different Carbon Sources.

    PubMed

    Pemmaraju, Suma C; Pruthi, Parul A; Prasad, R; Pruthi, Vikas

    2016-06-01

    In the present investigation, the role of carbon sources (glucose, lactate, sucrose, and arabinose) on Candida albicans biofilm development and virulence factors was studied on polystyrene microtiter plates. Besides this, structural changes in cell wall component β-glucan in presence of different carbon sources have also been highlighted. Biofilm formation was analyzed by XTT (2,3-bis[2-Methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide) reduction assay. Glucose-grown cells exhibited the highest metabolic activity during adhesion among all carbon sources tested (p < 0.05). However, cells exposed to sucrose exhibited highest biofilm formation and matrix polysaccharides secretion after 48 h. The results also correlated with the biofilm height and roughness measurements by atomic force microscopy. Exposure to lactate induced hyphal structures with the highest proteinase activity while arabinose-grown cells formed pseudohyphal structures possessing the highest phospholipase activity. Structural changes in β-glucan characterized by Fourier transform infrared (FTIR) spectroscopy displayed characteristic band of β-glucan at 892 cm(-1) in all carbon sources tested. The β(1→6) to β(1→3) glucan ratio calculated as per the band area of the peak was less in lactate (1.15) as compared to glucose (1.73), sucrose (1.62), and arabinose (2.85). These results signify that carbon sources influence C. albicans biofilm development and modulate virulence factors and structural organization of cell wall component β-glucan. PMID:26899861

  11. Denitrification of high nitrate concentration wastewater using alternative carbon sources.

    PubMed

    Fernández-Nava, Y; Marañón, E; Soons, J; Castrillón, L

    2010-01-15

    The use of different organic carbon sources in the denitrification of wastewater containing 2500 mg nitrates/L in a SBR was studied. Three alternative sources of carbon were tested: wastewater from a sweet factory, a residue from a soft drinks factory and a residue from a dairy plant. The first two are sugar-rich, whereas the third presents a high content in lactic acid. Maximum specific denitrification rates of between 42 and 48 mg NO(3)-N/g VSS h were obtained. The effluents were nitrate-free and very low COD concentrations were obtained in 4-6h reaction time, especially with the sugar-rich carbon sources. The values of the denitrifier net yield coefficient were higher than when using methanol (0.93-1.75 g VSS(formed)/g NO(x)-N(reduced)). The lowest value was obtained using the lactic acid-rich residue. The optimum COD/N ratios varied between 4.6 for the lactic acid-rich carbon source and 5.5-6.5 for the sugar-rich carbon sources. PMID:19782470

  12. Carbon-14 in methane sources and in atmospheric methane - The contribution from fossil carbon

    NASA Astrophysics Data System (ADS)

    Wahlen, M.; Tanaka, N.; Henry, R.; Deck, B.; Zeglen, J.

    1989-07-01

    Measurements of carbon-14 in small samples of methane from major biogenic sources, from biomass burning, and in clean air samples from both the Northern and Southern hemispheres reveal that methane from ruminants contains contemporary carbon, whereas that from wetlands, peat bogs, rice fields, and tundra, is somewhat depleted in carbon-14. Atmospheric (C-14)H4 seems to have increased from 1986 to 1987, and levels at the end of 1987 were 123.3 + or - 0.8 percent modern carbon in the Northern Hemisphere and 120.0 + or - 0.7 percent modern carbon in the Southern Hemisphere.

  13. Carbon-14 in methane sources and in atmospheric methane - The contribution from fossil carbon

    NASA Technical Reports Server (NTRS)

    Wahlen, M.; Tanaka, N.; Henry, R.; Deck, B.; Zeglen, J.

    1989-01-01

    Measurements of carbon-14 in small samples of methane from major biogenic sources, from biomass burning, and in clean air samples from both the Northern and Southern hemispheres reveal that methane from ruminants contains contemporary carbon, whereas that from wetlands, peat bogs, rice fields, and tundra, is somewhat depleted in carbon-14. Atmospheric (C-14)H4 seems to have increased from 1986 to 1987, and levels at the end of 1987 were 123.3 + or - 0.8 percent modern carbon in the Northern Hemisphere and 120.0 + or - 0.7 percent modern carbon in the Southern Hemisphere.

  14. A series of tufted carbon fiber cathodes designed for different high power microwave sources.

    PubMed

    Liu, Lie; Li, Limin; Zhang, Jun; Zhang, Xiaoping; Wen, Jianchun; Liu, Yonggui

    2008-06-01

    We report the fabrication technique of tufted carbon fiber cathodes for different microwave sources. Three carbon fiber cathodes were constructed, including a planar cathode, an annular cathode, and a cylindrical cathode for radial emission. Experimental investigations on these cathodes were performed in a reflex triode virtual cathode oscillator (vircator), a backward wave oscillator (BWO), and a magnetically insulated transmission line oscillator (MILO), respectively. The pulse duration of microwave emission from the reflex triode vircator was lengthened by using the planar carbon fiber cathode. In the BWO with the annular carbon fiber cathode, the uniform electron beam with a kA/cm(2) current density was observed. In addition, carbon fiber has great promise as field emitter for MILOs. These results show that the carbon fiber cathodes can be utilized for electron emission in high power diodes with different structures. PMID:18601423

  15. A series of tufted carbon fiber cathodes designed for different high power microwave sources

    NASA Astrophysics Data System (ADS)

    Liu, Lie; Li, Limin; Zhang, Jun; Zhang, Xiaoping; Wen, Jianchun; Liu, Yonggui

    2008-06-01

    We report the fabrication technique of tufted carbon fiber cathodes for different microwave sources. Three carbon fiber cathodes were constructed, including a planar cathode, an annular cathode, and a cylindrical cathode for radial emission. Experimental investigations on these cathodes were performed in a reflex triode virtual cathode oscillator (vircator), a backward wave oscillator (BWO), and a magnetically insulated transmission line oscillator (MILO), respectively. The pulse duration of microwave emission from the reflex triode vircator was lengthened by using the planar carbon fiber cathode. In the BWO with the annular carbon fiber cathode, the uniform electron beam with a kA /cm2 current density was observed. In addition, carbon fiber has great promise as field emitter for MILOs. These results show that the carbon fiber cathodes can be utilized for electron emission in high power diodes with different structures.

  16. IMPROVING SOURCE PROFILES AND APPORTIONMENT OF COMBUSTION SOURCES USING THERMAL CARBON FRACTIONS IN MULTIVARIATE RECEPTOR MODELS

    EPA Science Inventory

    The purpose of this study was to improve combustion source profiles and apportionment of a PM2.5 urban aerosol by using 7 individual organic and elemental carbon thermal fractions in place of total organic and elemental carbon. This study used 3 years (96-99) of speciated data...

  17. Chemical and biological consequences of using carbon dioxide versus acid additions in ocean acidification experiments

    USGS Publications Warehouse

    Yates, Kimberly K.; DuFore, Christopher M.; Robbins, Lisa L.

    2013-01-01

    Use of different approaches for manipulating seawater chemistry during ocean acidification experiments has confounded comparison of results from various experimental studies. Some of these discrepancies have been attributed to whether addition of acid (such as hydrochloric acid, HCl) or carbon dioxide (CO2) gas has been used to adjust carbonate system parameters. Experimental simulations of carbonate system parameter scenarios for the years 1766, 2007, and 2100 were performed using the carbonate speciation program CO2SYS to demonstrate the variation in seawater chemistry that can result from use of these approaches. Results showed that carbonate system parameters were 3 percent and 8 percent lower than target values in closed-system acid additions, and 1 percent and 5 percent higher in closed-system CO2 additions for the 2007 and 2100 simulations, respectively. Open-system simulations showed that carbonate system parameters can deviate by up to 52 percent to 70 percent from target values in both acid addition and CO2 addition experiments. Results from simulations for the year 2100 were applied to empirically derived equations that relate biogenic calcification to carbonate system parameters for calcifying marine organisms including coccolithophores, corals, and foraminifera. Calculated calcification rates for coccolithophores, corals, and foraminifera differed from rates at target conditions by 0.5 percent to 2.5 percent in closed-system CO2 gas additions, from 0.8 percent to 15 percent in the closed-system acid additions, from 4.8 percent to 94 percent in open-system acid additions, and from 7 percent to 142 percent in open-system CO2 additions.

  18. Production of biodiesel from carbon sources of macroalgae, Laminaria japonica.

    PubMed

    Xu, Xu; Kim, Ji Young; Oh, Yu Ri; Park, Jong Moon

    2014-10-01

    As aquatic biomass which is called "the third generation biomass", Laminaria japonica (also known as Saccharina japonica) consists of mannitol and alginate which are the main polysaccharides of algal carbohydrates. In this study, oleaginous yeast (Cryptococcus curvatus) was used to produce lipid from carbon sources derived from Laminaria japonica. Volatile fatty acids (VFAs) were produced by fermentation of alginate extracted from L. japonica. Thereafter, mannitol was mixed with VFAs to culture the oleaginous yeast. The highest lipid content was 48.30%. The composition of the fatty acids was similar to vegetable oils. This is the first confirmation of the feasibility of using macroalgae as a carbon source for biodiesel production. PMID:25084043

  19. USE OF FATTY ACID STABLE CARBON ISOTOPE RATIO TO INDICATE MICROBIAL CARBON SOURCE IN TROPICAL SOILS

    EPA Science Inventory


    We use measurements of the concentration and stable carbon isotope ratio of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels, broad microbial community structure, and microbial carbon source. For studies of soil o...

  20. 36 CFR 1290.3 - Sources of assassination records and additional records and information.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... records and additional records and information. 1290.3 Section 1290.3 Parks, Forests, and Public Property... Sources of assassination records and additional records and information. Assassination records and additional records and information may be located at, or under the control of, without limitation:...

  1. Effects of Litter and Nutrient Additions on Soil Carbon Cycling in a Tropical Forest

    NASA Astrophysics Data System (ADS)

    Cusack, D. F.; Halterman, S.; Turner, B. L.; Tanner, E.; Wright, S. J.

    2014-12-01

    Soil carbon (C) dynamics present one of the largest sources of uncertainty in global C cycle models, with tropical forest soils containing some of the largest terrestrial C stocks. Drastic changes in soil C storage and loss are likely to occur if global change alters plant net primary production (NPP) and/or nutrient availability in these ecosystems. We assessed the effects of litter removal and addition, as well as fertilization with nitrogen (N), phosphorus (P), and/or potassium (K), on soil C stocks in a tropical seasonal forest in Panama after ten and sixteen years, respectively. We used a density fractionation scheme to assess manipulation effects on rapidly and slowly cycling pools of C. Soil samples were collected in the wet and dry seasons from 0-5 cm and 5-10 cm depths in 15- 45x45 m plots with litter removal, 2x litter addition, and control (n=5), and from 32- 40x40 m fertilization plots with factorial additions of N, P, and K. We hypothesized that litter addition would increase all soil C fractions, but that the magnitude of the effect on rapidly-cycling C would be dampened by a fertilization effect. Results for the dry season show that the "free light" C fraction, or rapidly cycling soil C pool, was significantly different among the three litter treatments, comprising 5.1 ± 0.9 % of total soil mass in the litter addition plots, 2.7 ± 0.3 % in control plots, and 1.0 ± 0.1 % in litter removal plots at the 0-5cm depth (means ± one standard error, p < 0.05). Bulk soil C results are similar to observed changes in the rapidly cycling C pool for the litter addition and removal. Fertilization treatments on average diminished this C pool size relative to control plots, although there was substantial variability among fertilization treatments. In particular, addition of N and P together did not significantly alter rapidly cycling C pool sizes (4.1 ± 1.2 % of total soil mass) relative to controls (3.5 ± 0.4 %), whereas addition of P alone resulted in

  2. Carbon additions and grain defect formation in directionally solidified nickel-base superalloys

    NASA Astrophysics Data System (ADS)

    Tin, Sammy

    Over the past fifty years, technological advances leading up to the development of modern high-performance turbine engines for aircraft and power generation applications have coincided with significant engineering accomplishments in the area of Ni-base superalloy metallurgy. As the levels of refractory alloying additions to these Ni-base superalloys increase to enhance high-temperature mechanical properties, grain defect formation, particularly the development of freckle chains, during directional solidification has become an increasingly important problem. In this dissertation, the effect of carbon additions on the solidification characteristics of single crystal Ni-base superalloys has been investigated over a wide range of composition. Using statistically designed experiments, carbon additions of 0.1 to 0.125 wt. % were shown to be beneficial in stabilizing against the formation of grain defects due to thermosolutal convective instabilities. Detailed analyses were performed on the single crystal castings to identify the underlying mechanisms by which the carbon additions improve the solidification characteristics. In addition to forming Ta-rich MC carbides during solidification, the carbon additions were also revealed to influence the segregation behavior of the constituent elements in a manner that was beneficial in suppressing the formation of freckle defects during solidification. Using a segregation mapping technique, less segregation of rhenium, tungsten and tantalum was measured in the carbon containing alloys. Carbide formation during solidification was studied using differential thermal analysis. The influence of carbon additions on the solidification characteristics of the experimental single crystal alloys was assessed using a dimensionless Rayleigh analysis. Based on these analyses, the physical presence of carbides during the initial stages of solidification was also shown to inhibit the formation of freckle defects. In this investigation, carbon

  3. Possibilities of Application of Carbon-Fluorine Containing Additions in Submerged-Arc Welding

    NASA Astrophysics Data System (ADS)

    Kozyrev, N. A.; Kryukov, N. E.; Kryukov, R. E.; Igushev, V. F.; Kovalskii, I. I.

    2015-09-01

    The paper provides results of comparative analysis of the effect of carbonaceous components introduced into welding fluxes on molten metal - slag interaction. A positive influence of carbonaceous additives on gas content and mechanical properties of welds is demonstrated. Carbon and fluorine containing additives are emphasized to be promising for automatic submerged arc welding.

  4. Distribution of organic carbon and petroleum source rock potential of Cretaceous and lower Tertiary carbonates, South Florida Basin: preliminary results

    USGS Publications Warehouse

    Palacas, James George

    1978-01-01

    Analyses of 134 core samples from the South Florida Basin show that the carbonates of Comanchean age are relatively richer in average organic carbon (0.41 percent) than those of Coahuilan age (0.28 percent), Gulfian age (0.18 percent) and Paleocene age (0.20 percent). They are also nearly twice as rich as the average world, wide carbonate (average 0.24 percent). The majority of carbonates have organic carbons less than 0.30 percent but the presence of many relatively organic rich beds composed of highly bituminous, argillaceous, highly stylolitic, and algal-bearing limestones and dolomites accounts for the higher percentage of organic carbon in some of the stratigraphic units. Carbonate rocks that contain greater than 0.4 percent organic carbon and that might be considered as possible petroleum sources were noted in almost each subdivision of the Coahuilan and Comanchean Series but particularly the units of Fredericksburg 'B', Trinity 'A', Trinity 'F', and Upper Sunniland. Possible source rocks have been ascribed by others to the Lower Sunniland, but lack of sufficient samples precluded any firm assessment in this initial report. In the shallower section of the basin, organic-rich carbonates containing as much as 3.2 percent organic carbon were observed in the lowermost part of the Gulfian Series and carbonate rocks with oil staining or 'dead' and 'live oil' were noted by others in the uppermost Gulfian and upper Cedar Keys Formation. It is questionable whether these shallower rocks are of sufficient thermal maturity to have generated commercial oil. The South Florida basin is still sparsely drilled and produces only from the Sunniland Limestone at an average depth of 11,500 feet (3500 m). Because the Sunniland contains good reservoir rocks and apparently adequate source rocks, and because the success rate of new oil field discoveries has increased in recent years, the chances of finding additional oil reserves in the Sunniland are promising. Furthermore, the

  5. Carbonate fuel cell and components thereof for in-situ delayed addition of carbonate electrolyte

    DOEpatents

    Johnsen, Richard; Yuh, Chao-Yi; Farooque, Mohammad

    2011-05-10

    An apparatus and method in which a delayed carbonate electrolyte is stored in the storage areas of a non-electrolyte matrix fuel cell component and is of a preselected content so as to obtain a delayed time release of the electrolyte in the storage areas in the operating temperature range of the fuel cell.

  6. Chemoselective Synthesis of Carbamates using CO2 as Carbon Source.

    PubMed

    Riemer, Daniel; Hirapara, Pradipbhai; Das, Shoubhik

    2016-08-01

    Synthesis of carbamates directly from amines using CO2 as the carbon source is a straightforward and sustainable approach. Herein, we describe a highly effective and chemoselective methodology for the synthesis of carbamates at room temperature and atmospheric pressure. This methodology can also be applied to protect the amino group in amino acids and peptides, and also to synthesize important pharmaceuticals. PMID:27376902

  7. A mobile light source for carbon/nitrogen cameras

    NASA Astrophysics Data System (ADS)

    Trower, W. P.; Karev, A. I.; Melekhin, V. N.; Shvedunov, V. I.; Sobenin, N. P.

    1995-05-01

    The pulsed light source for carbon/nitrogen cameras developed to image concealed narcotics/explosives is described. This race-track microtron will produce 40 mA pulses of 70 MeV electrons, have minimal size and weight, and maximal ruggedness and reliability, so that it can be transported on a truck.

  8. Quantifying Sequestration of Carbon in the Ocean following Addition of Macronutrient

    NASA Astrophysics Data System (ADS)

    Harrison, D. P.; Lawrence, M. W.

    2011-12-01

    The effects of addition of limiting nutrients to the surface waters of the deep ocean has been investigated for the last twenty years, partly to explore ocean biogeochemical processes and partly because of the potential for sequestration of carbon in the deep ocean. Investigations have been performed for micronutrients (iron) and macronutrients (nitrogen and phosphorous). A methodology of estimating carbon stored is introduced here based on fertilization with nitrogen in those regions in which nitrogen is the limiting nutrient. The basis of the methodology is a combination of measurements in the photic zone and numerical modelling of the biogeochemical cycle. The calculation of the quantity of sequestered carbon is, after allowance for losses, equal to the carbon that is taken up by photosynthesis (new primary production equals export production) resulting from the added nitrogen. An essential feature of the biogeochemical process is that the added nitrogen is not lost from the upper waters by export to the deep ocean unless accompanied by carbon, in approximately the Redfield ratio. Determination of the quantity of carbon sequestered consists of three steps: (1.) Determination of the quantity of carbon converted by photosynthesis to biological form (new primary production). (2.) Allowance for factors potentially affecting carbon sequestration, such as: Loss of reactive nitrogen from the ocean; Greenhouse Gas (GHG) production by photosynthesis; GHG production by denitrification; GHG production following upwelling; Air-sea carbon transfer efficiency; Calcium carbonate production; Alkalinity change; and Respiration. (3.) Allowance for carbon dioxide released to the atmosphere during the manufacture and transport processes involved in providing added nutrients to the ocean. With these three steps, the net quantity of carbon sequestered by fertilisation may be determined.

  9. 5 CFR 3601.103 - Additional exceptions for gifts from outside sources.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... gifts from outside sources. In addition to the gifts which come within the exceptions set forth in 5 CFR 2635.204, and subject to all provisions of 5 CFR 2635.201 through 2635.205, a DoD employee may accept gifts from outside sources otherwise prohibited by 5 CFR 2635.202(a) as follows: (a) Events sponsored...

  10. Tracing the sources of organic carbon in freshwater systems

    NASA Astrophysics Data System (ADS)

    Glendell, Miriam; Meersmans, Jeroen; Barclay, Rachel; Yvon-Durocher, Gabriel; Barker, Sam; Jones, Richard; Hartley, Iain; Dungait, Jennifer; Quine, Timothy

    2016-04-01

    Quantifying the lateral fluxes of carbon from land to inland waters is critical for the understanding of the global carbon cycle and climate change mitigation. However, the crucial role of rivers in receiving, transporting and processing the equivalent of terrestrial net primary production in their watersheds has only recently been recognised. In addition, the fluxes of carbon from land to ocean, and the impact of anthropogenic perturbation, are poorly quantified. Therefore, a mechanistic understanding of the processes involved in the loss and preservation of C along the terrestrial-aquatic continuum is required to predict the present and future contribution of aquatic C fluxes to the global C budget. This pilot study examines the effect of land use on the fate of organic matter within two headwater catchments in Cornwall (UK) in order to develop a methodological framework for investigating C-cycling across the entire terrestrial-aquatic continuum. To this end, we aim to characterise the spatial heterogeneity of soil erosion driven lateral fluxes of SOC to identify areas of erosion and deposition using 137Cs radio-isotope and trace the terrestrial versus aquatic origin of C along the river reaches and in lake sediments at the catchment outlet. The 3D spatial distribution of SOC has been investigated by sampling three depth increments (i.e. 0-15cm, 15-30cm and 30-50cm) along 14 hillslope transects within two sub-catchments of ˜km2 each. In total, 80 terrestrial sites were monitored and analysed for total C and N, and bulk stable 13C/15N isotope values, while 137Cs was used to obtain a detailed understanding of the spatial - temporal variability in erosion driven lateral fluxes of SOC within the catchments. The relative contribution of terrestrial and aquatic C was examined along the river reaches as well as in lake sediments at the catchment outlet by considering n-alkane signatures. By linking the C accumulation rates in lake sediments over decadal timescales from

  11. Different carbon sources affect PCB accumulation by marine bivalves.

    PubMed

    Laitano, M V; Silva Barni, M F; Costa, P G; Cledón, M; Fillmann, G; Miglioranza, K S B; Panarello, H O

    2016-02-01

    Pampean creeks were evaluated in the present study as potential land-based sources of PCB marine contamination. Different carbon and nitrogen sources from such creeks were analysed as boosters of PCB bioaccumulation by the filter feeder bivalve Brachidontes rodriguezii and grazer limpet Siphonaria lessoni. Carbon of different source than marine and anthropogenic nitrogen assimilated by organisms were estimated through their C and N isotopic composition. PCB concentration in surface sediments and mollusc samples ranged from 2.68 to 6.46 ng g(-1) (wet weight) and from 1074 to 4583 ng g(-1) lipid, respectively, reflecting a punctual source of PCB contamination related to a landfill area. Thus, despite the low flow of creeks, they should not be underestimated as contamination vectors to the marine environment. On the other hand, mussels PCB bioaccumulation was related with the carbon source uptake which highlights the importance to consider this factor when studying PCB distribution in organisms of coastal systems. PMID:26606107

  12. Enhanced Production of Green Tide Algal Biomass through Additional Carbon Supply

    PubMed Central

    de Paula Silva, Pedro H.; Paul, Nicholas A.; de Nys, Rocky; Mata, Leonardo

    2013-01-01

    Intensive algal cultivation usually requires a high flux of dissolved inorganic carbon (Ci) to support productivity, particularly for high density algal cultures. Carbon dioxide (CO2) enrichment can be used to overcome Ci limitation and enhance productivity of algae in intensive culture, however, it is unclear whether algal species with the ability to utilise bicarbonate (HCO3−) as a carbon source for photosynthesis will benefit from CO2 enrichment. This study quantified the HCO3− affinity of three green tide algal species, Cladophora coelothrix, Cladophora patentiramea and Chaetomorpha linum, targeted for biomass and bioenergy production. Subsequently, we quantified productivity and carbon, nitrogen and ash content in response to CO2 enrichment. All three species had similar high pH compensation points (9.7–9.9), and grew at similar rates up to pH 9, demonstrating HCO3− utilization. Algal cultures enriched with CO2 as a carbon source had 30% more total Ci available, supplying twenty five times more CO2 than the control. This higher Ci significantly enhanced the productivity of Cladophora coelothrix (26%), Chaetomorpha linum (24%) and to a lesser extent for Cladophora patentiramea (11%), compared to controls. We demonstrated that supplying carbon as CO2 can enhance the productivity of targeted green tide algal species under intensive culture, despite their clear ability to utilise HCO3−. PMID:24324672

  13. Intensified nitrogen removal in immobilized nitrifier enhanced constructed wetlands with external carbon addition.

    PubMed

    Wang, Wei; Ding, Yi; Wang, Yuhui; Song, Xinshan; Ambrose, Richard F; Ullman, Jeffrey L

    2016-10-01

    Nitrogen removal performance response of twelve constructed wetlands (CWs) to immobilized nitrifier pellets and different influent COD/N ratios (chemical oxygen demand: total nitrogen in influent) were investigated via 7-month experiments. Nitrifier was immobilized on a carrier pellet containing 10% polyvinyl alcohol (PVA), 2.0% sodium alginate (SA) and 2.0% calcium chloride (CaCl2). A batch experiment demonstrated that 73% COD and 85% ammonia nitrogen (NH4-N) were degraded using the pellets with immobilized nitrifier cells. In addition, different carbon source supplement strategies were applied to remove the nitrate (NO3-N) transformed from NH4-N. An increase in COD/N ratio led to increasing reduction in NO3-N. Efficient nitrification and denitrification promoted total nitrogen (TN) removal in immobilized nitrifier biofortified constructed wetlands (INB-CWs). The results suggested that immobilized nitrifier pellets combined with high influent COD/N ratios could effectively improve the nitrogen removal performance in CWs. PMID:27396293

  14. Identification of haze-creating sources from fine particulate matter in Dhaka aerosol using carbon fractions.

    PubMed

    Begum, Bilkis A; Hopke, Philip K

    2013-09-01

    Fine particulate matter (PM2.5) samples were simultaneously collected on Teflon and quartz filters between February 2010 and February 2011 at an urban monitoring site (CAMS2) in Dhaka, Bangladesh. The samples were collected using AirMetrics MiniVol samplers. The samples on Teflon filters were analyzed for their elemental composition by PIXE and PESA. Particulate carbon on quartz filters was analyzed using the IMPROVE thermal optical reflectance (TOR) method that divides carbon into four organic carbons (OC), pyrolized organic carbon (OP), and three elemental carbon (EC) fractions. The data were analyzed by positive matrix factorization using the PMF2 program. Initially, only total OC and total EC were included in the analysis and five sources, including road dust, sea salt and Zn, soil dust, motor vehicles, and brick kilns, were obtained. In the second analysis, the eight carbon fractions (OC1, OC2, OC3, OC4, OP, EC1, EC2, EC3) were included in order to ascertain whether additional source information could be extracted from the data. In this case, it is possible to identify more sources than with only total OC and EC. The motor vehicle source was separated into gasoline and diesel emissions and a fugitive Pb source was identified. Brick kilns contribute 7.9 microg/m3 and 6.0 microg/m3 of OC and EC, respectively, to the fine particulate matter based on the two results. From the estimated mass extinction coefficients and the apportioned source contributions, soil dust, brick kiln, diesel, gasoline, and the Pb sources were found to contribute most strongly to visibility degradation, particularly in the winter. PMID:24151680

  15. Investigation of organic carbon transformation in soils of dominant dissolved organic carbon source zones

    NASA Astrophysics Data System (ADS)

    Pissarello, Anna; Miltner, Anja; Oosterwoud, Marieke; Fleckenstein, Jan; Kästner, Matthias

    2014-05-01

    Over the past 20 years both a decrease in soil organic matter (SOM) and an increase in the dissolved organic carbon (DOC) concentrations in surface water bodies, including drinking water reservoirs, have been recorded in the northern hemisphere. This development has severe consequences for soil fertility and for drinking water purification. As both processes occur simultaneously, we assume that microbial SOM degradation, which transforms SOM into CO2 and DOC, is a possible source of the additional DOC in the surface water. In addition we speculate that both processes are initially triggered by physical mechanisms, resulting in a modification of the organic matter solubility equilibria and thus in higher SOM availability and DOC mobilization. The general hypothesis of the study is therefore that SOM loss and DOC increase are combined consequences of enhanced microbial degradation of SOM and that this is a result of climate variations and global change, e.g. the increase of the temperature, the alteration of the water regime (i.e. increase of the frequency of drying and rewetting cycles and a higher number of heavy rain events), but also the decrease of the atmospheric acid deposition resulting in an increase of soil pH values. The general goal of the study is the identification of the dominant processes and controlling factors involved in soil microbial carbon turnover and mobilization of DOC in soils from catchment areas that contribute DOC to the receiving waters and the downstream Rappbode reservoir, which showed a pronounced increase in DOC concentration in recent years. This reservoir is the source of drinking water for about one million people in northern Germany. Preliminary screening experiments, consisting of 65-day soil batch incubation experiments, have been conducted in order to select the parameters (and the parameter ranges) of relevance for further in-depth experiments. During the experiments, different soil systems were exposed to different

  16. Carbon Sources for Polyhydroxyalkanoates and an Integrated Biorefinery

    PubMed Central

    Jiang, Guozhan; Hill, David J.; Kowalczuk, Marek; Johnston, Brian; Adamus, Grazyna; Irorere, Victor; Radecka, Iza

    2016-01-01

    Polyhydroxyalkanoates (PHAs) are a group of bioplastics that have a wide range of applications. Extensive progress has been made in our understanding of PHAs’ biosynthesis, and currently, it is possible to engineer bacterial strains to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are primarily derived from food-based carbon sources, raising concerns over the sustainability of their production in terms of their impact on food prices. This paper gives an overview of the current carbon sources used for PHA production and the methods used to transform these sources into fermentable forms. This allows us to identify the opportunities and restraints linked to future sustainable PHA production. Hemicellulose hydrolysates and crude glycerol are identified as two promising carbon sources for a sustainable production of PHAs. Hemicellulose hydrolysates and crude glycerol can be produced on a large scale during various second generation biofuels’ production. An integration of PHA production within a modern biorefinery is therefore proposed to produce biofuels and bioplastics simultaneously. This will create the potential to offset the production cost of biofuels and reduce the overall production cost of PHAs. PMID:27447619

  17. Carbon Sources for Polyhydroxyalkanoates and an Integrated Biorefinery.

    PubMed

    Jiang, Guozhan; Hill, David J; Kowalczuk, Marek; Johnston, Brian; Adamus, Grazyna; Irorere, Victor; Radecka, Iza

    2016-01-01

    Polyhydroxyalkanoates (PHAs) are a group of bioplastics that have a wide range of applications. Extensive progress has been made in our understanding of PHAs' biosynthesis, and currently, it is possible to engineer bacterial strains to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are primarily derived from food-based carbon sources, raising concerns over the sustainability of their production in terms of their impact on food prices. This paper gives an overview of the current carbon sources used for PHA production and the methods used to transform these sources into fermentable forms. This allows us to identify the opportunities and restraints linked to future sustainable PHA production. Hemicellulose hydrolysates and crude glycerol are identified as two promising carbon sources for a sustainable production of PHAs. Hemicellulose hydrolysates and crude glycerol can be produced on a large scale during various second generation biofuels' production. An integration of PHA production within a modern biorefinery is therefore proposed to produce biofuels and bioplastics simultaneously. This will create the potential to offset the production cost of biofuels and reduce the overall production cost of PHAs. PMID:27447619

  18. Climatic variability, hydrologic anomaly, and methane emission can turn productive freshwater marshes into net carbon sources.

    PubMed

    Chu, Housen; Gottgens, Johan F; Chen, Jiquan; Sun, Ge; Desai, Ankur R; Ouyang, Zutao; Shao, Changliang; Czajkowski, Kevin

    2015-03-01

    Freshwater marshes are well-known for their ecological functions in carbon sequestration, but complete carbon budgets that include both methane (CH4 ) and lateral carbon fluxes for these ecosystems are rarely available. To the best of our knowledge, this is the first full carbon balance for a freshwater marsh where vertical gaseous [carbon dioxide (CO2 ) and CH4 ] and lateral hydrologic fluxes (dissolved and particulate organic carbon) have been simultaneously measured for multiple years (2011-2013). Carbon accumulation in the sediments suggested that the marsh was a long-term carbon sink and accumulated ~96.9 ± 10.3 (±95% CI) g C m(-2)  yr(-1) during the last ~50 years. However, abnormal climate conditions in the last 3 years turned the marsh to a source of carbon (42.7 ± 23.4 g C m(-2)  yr(-1) ). Gross ecosystem production and ecosystem respiration were the two largest fluxes in the annual carbon budget. Yet, these two fluxes compensated each other to a large extent and led to the marsh being a CO2 sink in 2011 (-78.8 ± 33.6 g C m(-2)  yr(-1) ), near CO2 -neutral in 2012 (29.7 ± 37.2 g C m(-2)  yr(-1) ), and a CO2 source in 2013 (92.9 ± 28.0 g C m(-2)  yr(-1) ). The CH4 emission was consistently high with a three-year average of 50.8 ± 1.0 g C m(-2)  yr(-1) . Considerable hydrologic carbon flowed laterally both into and out of the marsh (108.3 ± 5.4 and 86.2 ± 10.5 g C m(-2)  yr(-1) , respectively). In total, hydrologic carbon fluxes contributed ~23 ± 13 g C m(-2)  yr(-1) to the three-year carbon budget. Our findings highlight the importance of lateral hydrologic inflows/outflows in wetland carbon budgets, especially in those characterized by a flow-through hydrologic regime. In addition, different carbon fluxes responded unequally to climate variability/anomalies and, thus, the total carbon budgets may vary drastically among years. PMID:25287051

  19. Carbon-14 in methane sources and in atmospheric methane: The contribution from fossil carbon

    SciTech Connect

    Wahlen, M.; Tanaka, N.; Henry, R.; Deck, B.; Zeglen, J. ); Vogel, J.S.; Southon, J. ); Shemesh, A.; Fairbanks, R.; Broecker, W. )

    1989-07-21

    Measurements of carbon-14 in small samples of methane from major biogenic sources, from biomass burning, and in clean air samples from both the Northern and Southern hemispheres reveal that methane from ruminants contains contemporary carbon, whereas that from wetlands, peat bogs, rice fields, and tundra is somewhat, depleted in carbon-14. Atmospheric {sup 14}CH{sub 4} seems to have increased from 1986 to 1987, and levels at the end of 1987 were 123.3 {plus minus} 0.8% modern carbon (pMC) in the Northern Hemisphere and 120.0 {plus minus} 0.7 pMC in the Southern Hemisphere. Model calculations of source partitioning based on the carbon-14 data, CH{sub 4} concentrations, and {delta}{sup 13}C in CH{sub 4} indicate that 21 {plus minus} 3% of atmospheric CH{sub 4} was derived from fossil carbon at the end of 1987. The data also indicate that pressurized water reactors are an increasingly important source of {sup 14}CH{sub 4}. 38 refs., 3 figs., 2 tabs.

  20. CO2 mitigation potential of mineral carbonation with industrial alkalinity sources in the United States.

    PubMed

    Kirchofer, Abby; Becker, Austin; Brandt, Adam; Wilcox, Jennifer

    2013-07-01

    The availability of industrial alkalinity sources is investigated to determine their potential for the simultaneous capture and sequestration of CO2 from point-source emissions in the United States. Industrial alkalinity sources investigated include fly ash, cement kiln dust, and iron and steel slag. Their feasibility for mineral carbonation is determined by their relative abundance for CO2 reactivity and their proximity to point-source CO2 emissions. In addition, the available aggregate markets are investigated as possible sinks for mineral carbonation products. We show that in the U.S., industrial alkaline byproducts have the potential to mitigate approximately 7.6 Mt CO2/yr, of which 7.0 Mt CO2/yr are CO2 captured through mineral carbonation and 0.6 Mt CO2/yr are CO2 emissions avoided through reuse as synthetic aggregate (replacing sand and gravel). The emission reductions represent a small share (i.e., 0.1%) of total U.S. CO2 emissions; however, industrial byproducts may represent comparatively low-cost methods for the advancement of mineral carbonation technologies, which may be extended to more abundant yet expensive natural alkalinity sources. PMID:23738892

  1. Carbon nitride films formed using sputtering and negative carbon ion sources

    SciTech Connect

    Murzin, I.H.; Tompa, G.S.; Wei, J.; Muratov, V.; Fischer, T.E.; Yakovlev, V.

    1997-12-01

    The authors report the results of using sputtering and negative carbon ion sources to prepare thin films of carbon nitride. In this work, they compare the structural, tribological, and optical properties of the carbon nitride films that were prepared by two different ion assisted techniques. In the first approach they used a magnetron gun to sputter deposit carbon in a nitrogen atmosphere. The second method utilized a beam of negatively charged carbon ions of 1 to 5 {micro}A/cm{sup 2} current density impinging the substrate simultaneously with a positive nitrogen ion beam produced by a Kaufman source. They were able to synthesize microscopically smooth coatings with the carbon to nitrogen ratio of 1:0.47. These films possess wear rates lower than 5 {times} 10{sup {minus}7} mm{sup 3}/Nm and friction coefficients in the range of 0.16 to 0.6. Raman spectroscopy revealed that the magnetron sputtered films are more structurally disordered than those formed with the negative carbon ion gun. FTIR showed the presence of the C{triple_bond}N stretching mode in both types of films. Finally, spectroscopic ellipsometry produced films with dielectric constants as low as 2.3 in the photon energy range from 1.2 to 5 eV.

  2. Determination of primary and secondary sources of organic acids and carbonaceous aerosols using stable carbon isotopes

    NASA Astrophysics Data System (ADS)

    Fisseha, Rebeka; Saurer, Matthias; Jäggi, Maya; Siegwolf, Rolf T. W.; Dommen, Josef; Szidat, Sönke; Samburova, Vera; Baltensperger, Urs

    Stable carbon isotope ratio ( δ13C) data can provide important information regarding the sources and the processing of atmospheric organic carbon species. Formic, acetic and oxalic acid were collected from Zurich city in August-September 2002 and March 2003 in the gas and aerosol phase, and the corresponding δ13C analysis was performed using a wet oxidation method followed by isotope ratio mass spectrometry. In August, the δ13C values of gas phase formic acid showed a significant correlation with ozone (coefficient of determination ( r2) = 0.63) due to the kinetic isotope effect (KIE). This indicates the presence of secondary sources (i.e. production of organic acids in the atmosphere) in addition to direct emission. In March, both gaseous formic and acetic acid exhibited similar δ13C values and did not show any correlation with ozone, indicating a predominantly primary origin. Even though oxalic acid is mainly produced by secondary processes, the δ13C value of particulate oxalic acid was not depleted and did not show any correlation with ozone, which may be due to the enrichment of 13C during the gas - aerosol partitioning. The concentrations and δ13C values of the different aerosol fractions (water soluble organic carbon, water insoluble organic carbon, carbonate and black carbon) collected during the same period were also determined. Water soluble organic carbon (WSOC) contributed about 60% to the total carbon and was enriched in 13C compared to other fractions indicating a possible effect of gas - aerosol partitioning on δ13C of carbonaceous aerosols. The carbonate fraction in general was very low (3% of the total carbon).

  3. Fluorescently tuned nitrogen-doped carbon dots from carbon source with different content of carboxyl groups

    SciTech Connect

    Wang, Hao; Wang, Yun; Dai, Xiao; Zou, Guifu E-mail: zouguifu@suda.edu.cn; Gao, Peng; Zhang, Ke-Qin E-mail: zouguifu@suda.edu.cn; Du, Dezhuang; Guo, Jun

    2015-08-01

    In this study, fluorescent nitrogen-doped carbon dots (NCDs) were tuned via varying the sources with different number of carboxyl groups. Owing to the interaction between amino and carboxyl, more amino groups conjugate the surface of the NCDs by the source with more carboxyl groups. Fluorescent NCDs were tuned via varying the sources with different content of carboxyl groups. Correspondingly, the nitrogen content, fluorescence quantum yields and lifetime of NCDs increases with the content of carboxyl groups from the source. Furthermore, cytotoxicity assay and cell imaging test indicate that the resultant NCDs possess low cytotoxicity and excellent biocompatibility.

  4. Impacts of biochar (black carbon) additions on the sorption and efficacy of herbicides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is renewed interest in the soil application of charcoal (biochar) as a means of increasing carbon sequestration and combating climate change. The land areas that are targeted for biochar applications are agricultural land, due to the potential positive impacts that charcoal additions have on o...

  5. EVALUATION OF FULL SCALE ACTIVATED SLUDGE SYSTEMS UTILIZING POWDERED ACTIVATED CARBON ADDITION WITH WET AIR REGENERATION

    EPA Science Inventory

    The addition of powdered activated carbon (PAC) to activated sludge systems is a proven method of wastewater treatment. Of eleven POTWs in the U.S. that were designed for PAC use, ten included wet air regeneration (WAR) for the destruction of secondary sludge solids and recovery ...

  6. Rare Potassium-Bearing Mica in Allan Hills 84001: Additional Constraints on Carbonate Formation

    NASA Technical Reports Server (NTRS)

    Brearley, A. J.

    1998-01-01

    There have been presented several intriguing observations suggesting evidence of fossil life in martian orthopyroxenite ALH 84001. These exciting and controversial observations have stimulated extensive debate over the origin and history of ALH 84001, but many issues still remain unresolved. Among the most important is the question of the temperature at which the carbonates, which host the putative microfossils, formed. Oxygen- isotopic data, while showing that the carbonates are generally out of isotopic equilibria with the host rock, cannot constrain their temperature of formation. Both low- and high-temperature scenarios are plausible depending on whether carbonate growth occurred in an open or closed system. Petrographic arguments have generally been used to support a high-temperature origin but these appear to be suspect because they assume equilibrium between carbonate compositions that are not in contact. Some observations appear to be consistent with shock mobilization and growth from immiscible silicate-carbonate melts at high temperatures. Proponents of a low-temperature origin for the carbonates are hampered by the fact that there is currently no evidence of hydrous phases that would indicate low temperatures and the presence of a hydrous fluid during the formation of the carbonates. However, the absence of hydrous phases does not rule out carbonate formation at low temperatures, because the carbonate forming fluids may have been extremely CO2 rich, such that hydrous phases would not have been stabilized. In this study, I have carried out additional Transmission electron microscopy (TEM) studies of ALH-84001 and have found evidence of very rare phyllosilicates, which appear to be convincingly of pre-terrestrial origin. At present these observations are limited to one occurrence: further studies are in progress to determine if the phyllosilicates are more widespread.

  7. Terrestrial sources and sinks of carbon inferred from terrestrial data

    NASA Astrophysics Data System (ADS)

    Houghton, R. A.

    1996-09-01

    Two approaches have been used to calculate changes in terrestrial carbon storage with data obtained from terrestrial ecosystems, rather than with atmospheric or oceanographic data. One approach is based on the changes in carbon that result from changes in land use (conversion of forest to agricultural land, abandonment of agricultural land, harvest and regrowth). The other approach uses measurements of forest biomass obtained through forests inventories to determine change directly. These latter studies may also calculate changes in the amount of carbon stored in wood products and soil, but in this respect the two approaches are similar. If a significant fraction of the missing carbon sink is to be found in mid-latitude forests, one would expect direct measurement of biomass to show greater accumulations of carbon than analyses in which calculated accumulations result only from regrowth following previous harvests or abandonment of agricultural land. Data from Canada, the conterminous US, Europe, and the former USSR show this circumstance to be correct. Accumulations of carbon in biomass and soil are 0.8 PgC yr-1 greater than expected from past management practices (land-use change). In the tropics (where forest inventories are rare), the total net flux of carbon from changes in land use (1.6 PgC yr-1) is consistent with recent estimates of flux based on atmospheric data, but the geographic distribution of the flux is not the same. Globally, terrestrial ecosystems are calculated to have been a net source of 0.8±0.6 PgC yr-1 during the 1980s.

  8. Ultrasmooth submicrometer carbon spheres as lubricant additives for friction and wear reduction.

    PubMed

    Alazemi, Abdullah A; Etacheri, Vinodkumar; Dysart, Arthur D; Stacke, Lars-Erik; Pol, Vilas G; Sadeghi, Farshid

    2015-03-11

    Ultrasmooth submicrometer carbon spheres are demonstrated as an efficient additive for improving the tribological performance of lubricating oils. Carbon spheres with ultrasmooth surfaces are fabricated by ultrasound assisted polymerization of resorcinol and formaldehyde followed by controlled heat treatment. The tribological behavior of the new lubricant mixture is investigated in the boundary and mixed lubrication regimes using a pin-on-disk apparatus and cylinder-on-disk tribometer, respectively. The new lubricant composition containing 3 wt % carbon spheres suspended in a reference SAE 5W30 engine oil exhibited a substantial reduction in friction and wear (10-25%) compared to the neat oil, without change in the viscosity. Microscopic and spectroscopic investigation of the carbon spheres after the tribological experiments illustrated their excellent mechanical and chemical stability. The significantly better tribological performance of the hybrid lubricant is attributed to the perfectly spherical shape and ultrasmooth surface of carbon sphere additive filling the gap between surfaces and acting as a nanoscale ball bearing. PMID:25690952

  9. Validating a nondestructive optical method for apportioning colored particulate matter into black carbon and additional components

    NASA Astrophysics Data System (ADS)

    Yan, Beizhan; Kennedy, Daniel; Miller, Rachel L.; Cowin, James P.; Jung, Kyung-hwa; Perzanowski, Matt; Balletta, Marco; Perera, Federica P.; Kinney, Patrick L.; Chillrud, Steven N.

    2011-12-01

    Exposure of black carbon (BC) is associated with a variety of adverse health outcomes. A number of optical methods for estimating BC on Teflon filters have been adopted but most assume all light absorption is due to BC while other sources of colored particulate matter exist. Recently, a four-wavelength-optical reflectance measurement for distinguishing second hand cigarette smoke (SHS) from soot-BC was developed (Brook et al., 2010; Lawless et al., 2004). However, the method has not been validated for soot-BC nor SHS and little work has been done to look at the methodological issues of the optical reflectance measurements for samples that could have SHS, BC, and other colored particles. We refined this method using a lab-modified integrating sphere with absorption measured continuously from 350 nm to 1000 nm. Furthermore, we characterized the absorption spectrum of additional components of particulate matter (PM) on PM 2.5 filters including ammonium sulfate, hematite, goethite, and magnetite. Finally, we validate this method for BC by comparison to other standard methods. Use of synthesized data indicates that it is important to optimize the choice of wavelengths to minimize computational errors as additional components (more than 2) are added to the apportionment model of colored components. We found that substantial errors are introduced when using 4 wavelengths suggested by Lawless et al. to quantify four substances, while an optimized choice of wavelengths can reduce model-derived error from over 10% to less than 2%. For environmental samples, the method was sensitive for estimating airborne levels of BC and SHS, but not mass loadings of iron oxides and sulfate. Duplicate samples collected in NYC show high reproducibility (points consistent with a 1:1 line, R2 = 0.95). BC data measured by this method were consistent with those measured by other optical methods, including Aethalometer and Smoke-stain Reflectometer (SSR); although the SSR looses sensitivity at

  10. Validating a nondestructive optical method for apportioning colored particulate matter into black carbon and additional components

    PubMed Central

    Yan, Beizhan; Kennedy, Daniel; Miller, Rachel L.; Cowin, James P.; Jung, Kyung-hwa; Perzanowski, Matt; Balletta, Marco; Perera, Federica P.; Kinney, Patrick L.; Chillrud, Steven N.

    2011-01-01

    Exposure of black carbon (BC) is associated with a variety of adverse health outcomes. A number of optical methods for estimating BC on Teflon filters have been adopted but most assume all light absorption is due to BC while other sources of colored particulate matter exist. Recently, a four-wavelength-optical reflectance measurement for distinguishing second hand cigarette smoke (SHS) from soot-BC was developed (Brook et al., 2010; Lawless et al., 2004). However, the method has not been validated for soot-BC nor SHS and little work has been done to look at the methodological issues of the optical reflectance measurements for samples that could have SHS, BC, and other colored particles. We refined this method using a lab-modified integrating sphere with absorption measured continuously from 350 nm to 1000 nm. Furthermore, we characterized the absorption spectrum of additional components of particulate matter (PM) on PM2.5 filters including ammonium sulfate, hematite, goethite, and magnetite. Finally, we validate this method for BC by comparison to other standard methods. Use of synthesized data indicates that it is important to optimize the choice of wavelengths to minimize computational errors as additional components (more than 2) are added to the apportionment model of colored components. We found that substantial errors are introduced when using 4 wavelengths suggested by Lawless et al. to quantify four substances, while an optimized choice of wavelengths can reduce model-derived error from over 10% to less than 2%. For environmental samples, the method was sensitive for estimating airborne levels of BC and SHS, but not mass loadings of iron oxides and sulfate. Duplicate samples collected in NYC show high reproducibility (points consistent with a 1:1 line, R2 = 0.95). BC data measured by this method were consistent with those measured by other optical methods, including Aethalometer and Smoke-stain Reflectometer (SSR); although the SSR looses sensitivity at

  11. Immune response and disease resistance of shrimp fed biofloc grown on different carbon sources.

    PubMed

    Ekasari, Julie; Hanif Azhar, Muhammad; Surawidjaja, Enang H; Nuryati, Sri; De Schryver, Peter; Bossier, Peter

    2014-12-01

    The objective of this study was to document the immunological effects of growing shrimp in biofloc systems. The experiment consisted of four types of biofloc systems in which bioflocs were produced by daily supplementation of four different carbon sources, i.e. molasses, tapioca, tapioca-by-product, and rice bran, at an estimated C/N ratio of 15 and a control system without any organic carbon addition. Each biofloc system was stocked with Pacific white shrimp (Litopenaeus vannamei) juveniles that were reared for 49 days. The use of tapioca-by-product resulted in a higher survival (93%) of the shrimp as compared to the other carbon sources and the control. The highest yield and protein assimilation was observed when tapioca was used as the carbon source. After 49 days, phenoloxidase (PO) activity of the shrimp grown in all biofloc systems was higher than that of the shrimp from the control system. Following a challenge test by injection with infectious myonecrosis virus (IMNV), the levels of PO and respiratory burst (RB) activity in the shrimp of all biofloc treatments were higher than that of the challenged shrimp from the control treatment. An increased immunity was also suggested by the survival of the challenged shrimp from the experimental biofloc groups that was significantly higher as compared to the challenged shrimp from the control treatment, regardless of the organic carbon source used to grow the bioflocs. Overall, this study demonstrated that the application of biofloc technology may contribute to the robustness of cultured shrimp by immunostimulation and that this effect is independent of the type of carbon source used to grow the flocs. PMID:25218685

  12. Role of metabolite transporters in source-sink carbon allocation

    PubMed Central

    Ludewig, Frank; Flügge, Ulf-Ingo

    2013-01-01

    Plants assimilate carbon dioxide during photosynthesis in chloroplasts. Assimilated carbon is subsequently allocated throughout the plant. Generally, two types of organs can be distinguished, mature green source leaves as net photoassimilate exporters, and net importers, the sinks, e.g., roots, flowers, small leaves, and storage organs like tubers. Within these organs, different tissue types developed according to their respective function, and cells of either tissue type are highly compartmentalized. Photoassimilates are allocated to distinct compartments of these tissues in all organs, requiring a set of metabolite transporters mediating this intercompartmental transfer. The general route of photoassimilates can be briefly described as follows. Upon fixation of carbon dioxide in chloroplasts of mesophyll cells, triose phosphates either enter the cytosol for mainly sucrose formation or remain in the stroma to form transiently stored starch which is degraded during the night and enters the cytosol as maltose or glucose to be further metabolized to sucrose. In both cases, sucrose enters the phloem for long distance transport or is transiently stored in the vacuole, or can be degraded to hexoses which also can be stored in the vacuole. In the majority of plant species, sucrose is actively loaded into the phloem via the apoplast. Following long distance transport, it is released into sink organs, where it enters cells as source of carbon and energy. In storage organs, sucrose can be stored, or carbon derived from sucrose can be stored as starch in plastids, or as oil in oil bodies, or – in combination with nitrogen – as protein in protein storage vacuoles and protein bodies. Here, we focus on transport proteins known for either of these steps, and discuss the implications for yield increase in plants upon genetic engineering of respective transporters. PMID:23847636

  13. Trace metal source terms in carbon sequestration environments.

    PubMed

    Karamalidis, Athanasios K; Torres, Sharon G; Hakala, J Alexandra; Shao, Hongbo; Cantrell, Kirk J; Carroll, Susan

    2013-01-01

    Carbon dioxide sequestration in deep saline and depleted oil geologic formations is feasible and promising; however, possible CO(2) or CO(2)-saturated brine leakage to overlying aquifers may pose environmental and health impacts. The purpose of this study was to experimentally define a range of concentrations that can be used as the trace element source term for reservoirs and leakage pathways in risk simulations. Storage source terms for trace metals are needed to evaluate the impact of brines leaking into overlying drinking water aquifers. The trace metal release was measured from cements and sandstones, shales, carbonates, evaporites, and basalts from the Frio, In Salah, Illinois Basin, Decatur, Lower Tuscaloosa, Weyburn-Midale, Bass Islands, and Grand Ronde carbon sequestration geologic formations. Trace metal dissolution was tracked by measuring solution concentrations over time under conditions (e.g., pressures, temperatures, and initial brine compositions) specific to the sequestration projects. Existing metrics for maximum contaminant levels (MCLs) for drinking water as defined by the U.S. Environmental Protection Agency (U.S. EPA) were used to categorize the relative significance of metal concentration changes in storage environments because of the presence of CO(2). Results indicate that Cr and Pb released from sandstone reservoir and shale cap rocks exceed the MCLs by an order of magnitude, while Cd and Cu were at or below drinking water thresholds. In carbonate reservoirs As exceeds the MCLs by an order of magnitude, while Cd, Cu, and Pb were at or below drinking water standards. Results from this study can be used as a reasonable estimate of the trace element source term for reservoirs and leakage pathways in risk simulations to further evaluate the impact of leakage on groundwater quality. PMID:23215015

  14. Trace Metal Source Terms in Carbon Sequestration Environments

    SciTech Connect

    Karamalidis, Athanasios; Torres, Sharon G.; Hakala, Jacqueline A.; Shao, Hongbo; Cantrell, Kirk J.; Carroll, Susan A.

    2013-01-01

    ABSTRACT: Carbon dioxide sequestration in deep saline and depleted oil geologic formations is feasible and promising; however, possible CO2 or CO2-saturated brine leakage to overlying aquifers may pose environmental and health impacts. The purpose of this study was to experimentally define to provide a range of concentrations that can be used as the trace element source term for reservoirs and leakage pathways in risk simulations. Storage source terms for trace metals are needed to evaluate the impact of brines leaking into overlying drinking water aquifers. The trace metal release was measured from cements and sandstones, shales, carbonates, evaporites, and basalts from the Frio, In Salah, Illinois Basin, Decatur, Lower Tuscaloosa, Weyburn-Midale, Bass Islands, and Grand Ronde carbon sequestration geologic formations. Trace metal dissolution was tracked by measuring solution concentrations over time under conditions (e.g., pressures, temperatures, and initial brine compositions) specific to the sequestration projects. Existing metrics for maximum contaminant levels (MCLs) for drinking water as defined by the U.S. Environmental Protection Agency (U.S. EPA) were used to categorize the relative significance of metal concentration changes in storage environments because of the presence of CO2. Results indicate that Cr and Pb released from sandstone reservoir and shale cap rocks exceed the MCLs byan order of magnitude, while Cd and Cu were at or below drinking water thresholds. In carbonate reservoirs As exceeds the MCLs by an order of magnitude, while Cd, Cu, and Pb were at or below drinking water standards. Results from this study can be used as a reasonable estimate of the trace element source term for reservoirs and leakage pathways in risk simulations to further evaluate the impact of leakage on groundwater quality.

  15. Trace Metal Source Terms in Carbon Sequestration Environments

    SciTech Connect

    Karamalidis, Athanasios K; Torres, Sharon G; Hakala, J Alexandra; Shao, Hongbo; Cantrell, Kirk J; Carroll, Susan

    2012-02-05

    Carbon dioxide sequestration in deep saline and depleted oil geologic formations is feasible and promising, however, possible CO₂ or CO₂-saturated brine leakage to overlying aquifers may pose environmental and health impacts. The purpose of this study was to experimentally define trace metal source terms from the reaction of supercritical CO₂, storage reservoir brines, reservoir and cap rocks. Storage reservoir source terms for trace metals are needed to evaluate the impact of brines leaking into overlying drinking water aquifers. The trace metal release was measured from sandstones, shales, carbonates, evaporites, basalts and cements from the Frio, In Salah, Illinois Basin – Decatur, Lower Tuscaloosa, Weyburn-Midale, Bass Islands and Grand Ronde carbon sequestration geologic formations. Trace metal dissolution is tracked by measuring solution concentrations over time under conditions (e.g. pressures, temperatures, and initial brine compositions) specific to the sequestration projects. Existing metrics for Maximum Contaminant Levels (MCLs) for drinking water as defined by the U.S. Environmental Protection Agency (U.S. EPA) were used to categorize the relative significance of metal concentration changes in storage environments due to the presence of CO₂. Results indicate that Cr and Pb released from sandstone reservoir and shale cap rock exceed the MCLs by an order of magnitude while Cd and Cu were at or below drinking water thresholds. In carbonate reservoirs As exceeds the MCLs by an order of magnitude, while Cd, Cu, and Pb were at or below drinking water standards. Results from this study can be used as a reasonable estimate of the reservoir and caprock source term to further evaluate the impact of leakage on groundwater quality.

  16. Sources and sinks of carbon dioxide in the Arctic regions

    SciTech Connect

    Gosink, T. A.; Kelley, J. J.

    1982-01-01

    The data base required to adequately ascertain seasonal source and sink strengths in the arctic regions is difficult to obtain. However, there are now a reasonable quantity of data for this polar region to estimate sources and sinks within the Arctic which may contribute significantly to the annual tropospheric CO/sub 2/ concentration fluctuation. The sea-ice-air and the sea-air interfaces account for most of the contribution to the sources and sinks for carbon dioxide. Although the arctic and subarctic region is small in extent, it certainly is not impervious and ice sealed. Our estimate, based on historical data and current research, indicates that the Arctic, which is about 4% of the earth's surface, is an annual net sink for approx. 10/sup 15/ g CO/sub 2/ accounting for an equivalent of approx. 3% of the annual anthropogenic contribution of CO/sub 2/ to the troposphere.

  17. A Carbon Nanotube Electron Source Based Ionization Vacuum Gauge

    SciTech Connect

    Changkun Dong; Ganapati Myneni

    2003-10-01

    The results of fabrication and performance of an ionization vacuum gauge using a carbon nanotube (CNT) electron source are presented. The electron source was constructed with multi-wall nanotubes (MWNT), which were grown using thermal chemical vapor deposition (CVD) process. The electron emission of the source was stable in vacuum pressure up to 10-7 Torr, which is better than the metal field emitters. The measurement linearity of the gauge was better than {+-}10% from 10-6 to 10-10 Torr. The gauge sensitivity of 4 Torr-1 was achieved under 50 {micro}A electron emission in nitrogen. The gauge is expected to find applications in vacuum measurements from 10-7 Torr to below 10-11 Torr.

  18. [Some considerations about the use of carbon sources in jasmonic acid production.].

    PubMed

    Almeida González, G; Klibansky Delgado, M; Altuna Seijas, B; Eng Sánchez, F; Legrá Mora, S; Armenteros Galarraga, S

    1999-09-01

    The effect of different carbon sources as sucrose, fructose, glucose and molasses were studied in relation to jasmonic acid production. The best results were obtained with a simple medium made up by final molasses, potassium nitrate and acid potassium phosphate, without the addition of other salts like Fe, Zn, Cu, Mo, etc. This alternative guaranteed a 100% increase in jasmonic acid production, compared to pattern medium, since a concentration of 2.08 g/l was obtained. PMID:18473562

  19. Proteome-wide quantitative multiplexed profiling of protein expression: carbon-source dependency in Saccharomyces cerevisiae.

    PubMed

    Paulo, Joao A; O'Connell, Jeremy D; Gaun, Aleksandr; Gygi, Steven P

    2015-11-01

    The global proteomic alterations in the budding yeast Saccharomyces cerevisiae due to differences in carbon sources can be comprehensively examined using mass spectrometry-based multiplexing strategies. In this study, we investigate changes in the S. cerevisiae proteome resulting from cultures grown in minimal media using galactose, glucose, or raffinose as the carbon source. We used a tandem mass tag 9-plex strategy to determine alterations in relative protein abundance due to a particular carbon source, in triplicate, thereby permitting subsequent statistical analyses. We quantified more than 4700 proteins across all nine samples; 1003 proteins demonstrated statistically significant differences in abundance in at least one condition. The majority of altered proteins were classified as functioning in metabolic processes and as having cellular origins of plasma membrane and mitochondria. In contrast, proteins remaining relatively unchanged in abundance included those having nucleic acid-related processes, such as transcription and RNA processing. In addition, the comprehensiveness of the data set enabled the analysis of subsets of functionally related proteins, such as phosphatases, kinases, and transcription factors. As a resource, these data can be mined further in efforts to understand better the roles of carbon source fermentation in yeast metabolic pathways and the alterations observed therein, potentially for industrial applications, such as biofuel feedstock production. PMID:26399295

  20. Proteome-wide quantitative multiplexed profiling of protein expression: carbon-source dependency in Saccharomyces cerevisiae

    PubMed Central

    Paulo, Joao A.; O’Connell, Jeremy D.; Gaun, Aleksandr; Gygi, Steven P.

    2015-01-01

    The global proteomic alterations in the budding yeast Saccharomyces cerevisiae due to differences in carbon sources can be comprehensively examined using mass spectrometry–based multiplexing strategies. In this study, we investigate changes in the S. cerevisiae proteome resulting from cultures grown in minimal media using galactose, glucose, or raffinose as the carbon source. We used a tandem mass tag 9-plex strategy to determine alterations in relative protein abundance due to a particular carbon source, in triplicate, thereby permitting subsequent statistical analyses. We quantified more than 4700 proteins across all nine samples; 1003 proteins demonstrated statistically significant differences in abundance in at least one condition. The majority of altered proteins were classified as functioning in metabolic processes and as having cellular origins of plasma membrane and mitochondria. In contrast, proteins remaining relatively unchanged in abundance included those having nucleic acid–related processes, such as transcription and RNA processing. In addition, the comprehensiveness of the data set enabled the analysis of subsets of functionally related proteins, such as phosphatases, kinases, and transcription factors. As a resource, these data can be mined further in efforts to understand better the roles of carbon source fermentation in yeast metabolic pathways and the alterations observed therein, potentially for industrial applications, such as biofuel feedstock production. PMID:26399295

  1. Notable improvement of capacitive performance of highly nanoporous carbon materials simply by a redox additive electrolyte of p-nitroaniline

    NASA Astrophysics Data System (ADS)

    Zhu, Yan Qi; Zhang, Lei; Chen, Xiang Ying; Xiao, Zheng Hui; Zhang, Zhong Jie

    2015-12-01

    Highly nanoporous carbon materials have been produced by a synchronous carbonization/graphitization process, using magnesium citrate serves as the carbon source and nickel nitrate as graphitization catalyst. The carbonization temperature plays a crucial role in determining the porosity and graphitization. The lower temperature favors for the formation of larger porosity, whilst higher temperature for better crystallinity. Resultantly, a high BET surface area of 2587.13 m2 g-1 and large total pore volume of 4.64 cm3 g-1 appear, the case of C-800 sample, thereby resulting in a large specific capacitance of 305.3 F g-1 at 1 A g-1 from the contribution of electric double layer capacitances. More importantly, we demonstrate a novel redox active additive of p-nitroaniline (PNA) into the 6 mol L-1 KOH electrolyte to largely improve the capacitance by the quick self-discharge redox reaction of H+/e-. The C-800-2 sample with the PNA concentration of 2 mmol delivers largely improved capacitance of 502.1 F g-1 at 1 A g-1, which is almost 1.65 fold increase. Apparently, the present PNA is commercially available, and highly effective for elevating the specific capacitance and might be implemented for the wide supercapacitor application.

  2. HUMAN HEALTH DAMAGES FROM MOBILE SOURCE AIR POLLUTION: ADDITIONAL DELPHI DATA ANALYSIS. VOLUME II

    EPA Science Inventory

    The report contains the results of additional analyses of the data generated by a panel of medical experts for a study of Human Health Damages from Mobile Source Air Pollution (hereafter referred to as HHD) conducted by the California Air Resources Board in 1973-75 for the U.S. E...

  3. 5 CFR 3601.103 - Additional exceptions for gifts from outside sources.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... sponsor in accordance with 5 CFR 2635.204(g)(5); and (3) The gift of free attendance meets the definition... gifts from outside sources. In addition to the gifts which come within the exceptions set forth in 5 CFR 2635.204, and subject to all provisions of 5 CFR 2635.201 through 2635.205, a DoD employee may...

  4. Additive effect of BPA and Gd-DTPA for application in accelerator-based neutron source.

    PubMed

    Yoshida, F; Yamamoto, T; Nakai, K; Zaboronok, A; Matsumura, A

    2015-12-01

    Because of its fast metabolism gadolinium as a commercial drug was not considered to be suitable for neutron capture therapy. We studied additive effect of gadolinium and boron co-administration using colony forming assay. As a result, the survival of tumor cells with additional 5 ppm of Gd-DTPA decreased to 1/10 compared to the cells with boron only. Using gadolinium to increase the effect of BNCT instead of additional X-ray irradiation might be beneficial, as such combination complies with the short-time irradiation regimen at the accelerator-based neutron source. PMID:26242560

  5. Utilization of carbon sources in a northern Brazilian mangrove ecosystem

    NASA Astrophysics Data System (ADS)

    Giarrizzo, Tommaso; Schwamborn, Ralf; Saint-Paul, Ulrich

    2011-12-01

    Carbon and nitrogen stable isotope ratios ( 13C and 15N) and trophic level (TL) estimates based on stomach content analysis and published data were used to assess the contribution of autotrophic sources to 55 consumers in an intertidal mangrove creek of the Curuçá estuary, northern Brazil. Primary producers showed δ 13C signatures ranging between -29.2 and -19.5‰ and δ 15N from 3.0 to 6.3‰. The wide range of the isotopic composition of carbon of consumers (-28.6 to -17.1‰) indicated that different autotrophic sources are important in the intertidal mangrove food webs. Food web segregation structures the ecosystem into three relatively distinct food webs: (i) mangrove food web, where vascular plants contribute directly or indirectly via POM to the most 13C-depleted consumers (e.g. Ucides cordatus and zooplanktivorous food chains); (ii) algal food web, where benthic algae are eaten directly by consumers (e.g. Uca maracoani, mullets, polychaetes, several fishes); (iii) mixed food web where the consumers use the carbon from different primary sources (mainly benthivorous fishes). An IsoError mixing model was used to determine the contributions of primary sources to consumers, based on δ 13C values. Model outputs were very sensitive to the magnitude of trophic isotope fractionation and to the variability in 13C data. Nevertheless, the simplification of the system by a priori aggregation of primary producers allowed interpretable results for several taxa, revealing the segregation into different food webs.

  6. Increasing addition of autochthonous to allochthonous carbon in nutrient-rich aquatic systems stimulates carbon consumption but does not alter bacterial community composition

    NASA Astrophysics Data System (ADS)

    Attermeyer, K.; Hornick, T.; Kayler, Z. E.; Bahr, A.; Zwirnmann, E.; Grossart, H.-P.; Premke, K.

    2013-08-01

    Dissolved organic carbon (DOC) concentrations - mainly of terrestrial origin - are increasing worldwide in inland waters. The biodegradability of the DOC varies depending on quantity and chemical quality. Heterotrophic bacteria are the main consumers of DOC and thus determine DOC temporal dynamics and availability for higher trophic levels. It is therefore crucial to understand the processes controlling the bacterial turnover of additional allochthonous and autochthonous DOC in aquatic systems. Our aim was to study bacterial carbon (C) turnover with respect to DOC quantity and chemical quality using both allochthonous and autochthonous DOC sources. We incubated a natural bacterial community with allochthonous C (13C-labeled beech leachate) and increased concentrations and pulses (intermittent occurrence of organic matter input) of autochthonous C (algae lysate). We then determined bacterial carbon consumption, activities, and community composition together with the carbon flow through bacteria using stable C isotopes. The chemical analysis of single sources revealed differences in aromaticity and fractions of low and high molecular weight substances (LMWS and HMWS, respectively) between allochthonous and autochthonous C sources. In parallel to these differences in chemical composition, we observed a higher availability of allochthonous C as evidenced by increased DOC consumption and bacterial growth efficiencies (BGE) when solely allochthonous C was provided. In treatments with mixed sources, rising concentrations of added autochthonous DOC resulted in a further, significant increase in bacterial DOC consumption from 52 to 68% when nutrients were not limiting. This rise was accompanied by a decrease in the humic substances (HS) fraction and an increase in bacterial biomass. Stable C isotope analyses of phospholipid fatty acids (PLFA) and respired dissolved inorganic carbon (DIC) supported a preferential assimilation of autochthonous C and respiration of the

  7. Carbon sources and fates in the Gulf of Papua

    NASA Astrophysics Data System (ADS)

    Goni, M. A.; Monacci, N. M.; Gisewhite, R. A.; Ogston, A.; Crockett, J.; Nittrouer, C.

    2006-12-01

    Seabed sediments were collected along the particle-dispersal system associated with the Fly River-Gulf of Papua continental margin as part of the source to sink program in Papua New Guinea. Box and kasten cores were collected from the subaqueous delta located adjacent to the mouth of the Fly River as well as from the topset, foreset and bottomset regions of the active clinoform in the northern region of the Gulf of Papua. Analyses of elemental (organic carbon, inorganic carbon, nitrogen), stable isotopic (d13C and d15N), radiocarbon (14C), and biomarker (CuO oxidation products) signatures reveal significant differences in the content and composition of sedimentary organic matter (OM) along the dispersal system. The major sources of OM to the system appear to be remains of vascular plants, soil OM from the drainage basin, and materials derived from autochthonous productivity. The geographical contrasts in the concentrations and accumulation fluxes of these distinct types of allochthonous and autochthonous OM are presented in the context of patterns of sediment transport and deposition within the region. An overall OM budget for the whole dispersal system will be presented and its implication for carbon sequestration in fluvial-dominated continental margins discussed.

  8. Optimization of membrane bioreactors by the addition of powdered activated carbon.

    PubMed

    Ng, Choon Aun; Sun, Darren; Bashir, Mohammed J K; Wai, Soon Han; Wong, Ling Yong; Nisar, Humaira; Wu, Bing; Fane, Anthony G

    2013-06-01

    It was found that with replenishment, powdered activated carbon (PAC) in the membrane bioreactor (MBR) would develop biologically activated carbon (BAC) which could enhance filtration performance of a conventional MBR. This paper addresses two issues (i) effect of PAC size on MBR (BAC) performance; and (ii) effect of sludge retention time (SRT) on the MBR performance with and without PAC. To interpret the trends, particle/floc size, concentration of mixed liquor suspended solid (MLSS), total organic carbon (TOC), short-term filtration properties and transmembrane pressure (TMP) versus time are measured. The results showed improved fouling control with fine, rather than coarse, PAC provided the flux did not exceed the deposition flux for the fine PAC. Without PAC, the longer SRT operation gave lower fouling at modest fluxes. With PAC addition, the shorter SRT gave better fouling control, possibly due to greater replenishment of the fresh PAC. PMID:23612160

  9. Effects of additional HONO sources on visibility over the North China Plain

    NASA Astrophysics Data System (ADS)

    Li, Ying; An, Junling; Gultepe, Ismail

    2014-09-01

    The objective of the present study was to better understand the impacts of the additional sources of nitrous acid (HONO) on visibility, which is an aspect not considered in current air quality models. Simulations of HONO contributions to visibility over the North China Plain (NCP) during August 2007 using the fully coupled Weather Research and Forecasting/Chemistry (WRF/Chem) model were performed, including three additional HONO sources: (1) the reaction of photo-excited nitrogen dioxide (NO * 2) with water vapor; (2) the NO2 heterogeneous reaction on aerosol surfaces; and (3) HONO emissions. The model generally reproduced the spatial patterns and diurnal variations of visibility over the NCP well. When the additional HONO sources were included in the simulations, the visibility was occasionally decreased by 20%-30% (3-4 km) in local urban areas of the NCP. Monthly-mean concentrations of NO{3/-}, NH{4/+}, SO{4/2-} and PM2.5 were increased by 20%-52% (3-11 μg m-3), 10%-38%, 6%-10%, and 6%-11% (9-17 μg m-3), respectively; and in urban areas, monthly-mean accumulationmode number concentrations (AMNC) and surface concentrations of aerosols were enhanced by 15%-20% and 10%-20%, respectively. Overall, the results suggest that increases in concentrations of PM2.5, its hydrophilic components, and AMNC, are key factors for visibility degradation. A proposed conceptual model for the impacts of additional HONO sources on visibility also suggests that visibility estimation should consider the heterogeneous reaction on aerosol surfaces and the enhanced atmospheric oxidation capacity due to additional HONO sources, especially in areas with high mass concentrations of NO x and aerosols.

  10. Carbon Isotopic Constraints on Arctic Methane Sources, 2008-2010

    NASA Astrophysics Data System (ADS)

    Fisher, R. E.; Lowry, D.; Lanoiselle, M.; Sriskantharajah, S.; Nisbet, E. G.

    2010-12-01

    Arctic methane source strengths are particularly vulnerable to large changes with year-to year meteorological variations and with climatic change. A global increase in methane seen in 2007 (Dlugokencky et al., 2009) may have been in part be due to elevated wetland emissions caused by a warm, wet summer over large parts of Siberia. In 2010 wildfires over large areas of Russia will have added methane to the Arctic atmosphere. Carbon isotopic composition of methane in air from the Arctic arriving at a measurement station can be used to identify sources of the gas. Measurement of methane δ13C in air close to sources, including wetlands, permafrost, pine forest and submarine methane clathrate has extended the available data of source signatures of methane from northern sources. Keeling plot analysis of diurnal records from field campaigns in Arctic wetlands show that bulk wetland methane emissions are typically close to δ13CCH4 -69±1 ‰. Air samples from Zeppelin (Spitsbergen, Norway), Pallas (Finland) and Barra (Outer Hebrides, Scotland) have been regularly analysed for methane δ13C. Summer campaigns at Zeppelin point to a 13C depleted bulk Arctic source of dominantly biogenic origin, at -67‰. In spring, while the wetlands are still frozen, the source signature is more enriched, -53‰, with trajectory analysis implying a large contribution from onshore gas fields. Arctic methane emissions respond rapidly to warming with strong positive feedbacks. With rapid warming there is the potential to release large stores of carbon from permafrost and methane hydrates. Isotopic data are powerful discriminants of sources. High frequency, ideally continuous, monitoring of methane δ13C from a number of Arctic sites, onshore and offshore, coupled with back-trajectory analysis and regional modelling, will be important if future changes in Arctic source strengths are to be quantified. Reference: Dlugokencky, E. J., et al. (2009), Observational constraints on recent increases

  11. Testing sources and size of carbon release during the PETM

    NASA Astrophysics Data System (ADS)

    Chun, C. O.; Ridgwell, A. J.; Marsh, R.

    2010-12-01

    Using an intermediate complexity Earth system model (GENIE) configured for the early Eocene, we aim to test hypotheses about the size and magnitude of carbon release during the PETM. We have improved the model by adding a background wetland CH4 flux at x5 preindustrial levels. Ensemble simulations of varying alkalinity, detrital flux, and CaCO3:POC ratios are compared with pre-PETM observations of wt% CaCO3 determined initial conditions. We are then able to compare a series of transient experiments of varying amounts and sources of carbon to the same initial conditions, noting the effects of subtle changes in deep ocean ventilation that are due to perturbed surface heat and freshwater fluxes. Finally, we will discuss the potential role of CH4 released to the atmosphere during the PETM and implications for climate sensitivity.

  12. High temperature hydrogen sulfide adsorption on activated carbon - I. Effects of gas composition and metal addition

    USGS Publications Warehouse

    Cal, M.P.; Strickler, B.W.; Lizzio, A.A.

    2000-01-01

    Various types of activated carbon sorbents were evaluated for their ability to remove H2S from a simulated coal gas stream at a temperature of 550 ??C. The ability of activated carbon to remove H2S at elevated temperature was examined as a function of carbon surface chemistry (oxidation, thermal desorption, and metal addition), and gas composition. A sorbent prepared by steam activation, HNO3 oxidation and impregnated with Zn, and tested in a gas stream containing 0.5% H2S, 50% CO2 and 49.5% N2, had the greatest H2S adsorption capacity. Addition of H2, CO, and H2O to the inlet gas stream reduced H2S breakthrough time and H2S adsorption capacity. A Zn impregnated activated carbon, when tested using a simulated coal gas containing 0.5% H2S, 49.5% N2, 13% H2, 8.5% H2O, 21% CO, and 7.5% CO2, had a breakthrough time of 75 min, which was less than 25 percent of the length of breakthrough for screening experiments performed with a simplified gas mixture of 0.5% H2S, 50% CO2, and 49.5% N2.

  13. Kinetics of dechlorination by Dehalococcoides mccartyi using different carbon sources.

    PubMed

    Schneidewind, Uwe; Haest, Pieter Jan; Atashgahi, Siavash; Maphosa, Farai; Hamonts, Kelly; Maesen, Miranda; Calderer, Montse; Seuntjens, Piet; Smidt, Hauke; Springael, Dirk; Dejonghe, Winnie

    2014-02-01

    Stimulated anaerobic dechlorination is generally considered a valuable step for the remediation of aquifers polluted with chlorinated ethenes (CEs). Correct simulation and prediction of this process in situ, however, require good knowledge of the associated biological reactions. The aim of this study was to evaluate the dechlorination reaction in an aquifer contaminated with trichloroethene (TCE) and its daughter products, discharging into the Zenne River. Different carbon sources were used in batch cultures and these were related to the dechlorination reaction, together with the monitored biomarkers. Appropriate kinetic formulations were assessed. Reductive dechlorination of TCE took place only when external carbon sources were added to microcosms, and occurred concomitant with a pronounced increase in the Dehalococcoides mccartyi cell count as determined by 16S rRNA gene-targeted qPCR. This indicates that native dechlorinating bacteria are present in the aquifer of the Zenne site and that the oligotrophic nature of the aquifer prevents a complete degradation to ethene. The type of carbon source, the cell number of D. mccartyi or the reductive dehalogenase genes, however, did not unequivocally explain the observed differences in degradation rates or the extent of dechlorination. Neither first-order, Michaelis-Menten nor Monod kinetics could perfectly simulate the dechlorination reactions in TCE spiked microcosms. A sensitivity analysis indicated that the inclusion of donor limitation would not significantly enhance the simulations without a clear process understanding. Results point to the role of the supporting microbial community but it remains to be verified how the complexity of the microbial (inter)actions should be represented in a model framework. PMID:24275111

  14. Kinetics of dechlorination by Dehalococcoides mccartyi using different carbon sources

    NASA Astrophysics Data System (ADS)

    Schneidewind, Uwe; Haest, Pieter Jan; Atashgahi, Siavash; Maphosa, Farai; Hamonts, Kelly; Maesen, Miranda; Calderer, Montse; Seuntjens, Piet; Smidt, Hauke; Springael, Dirk; Dejonghe, Winnie

    2014-02-01

    Stimulated anaerobic dechlorination is generally considered a valuable step for the remediation of aquifers polluted with chlorinated ethenes (CEs). Correct simulation and prediction of this process in situ, however, require good knowledge of the associated biological reactions. The aim of this study was to evaluate the dechlorination reaction in an aquifer contaminated with trichloroethene (TCE) and its daughter products, discharging into the Zenne River. Different carbon sources were used in batch cultures and these were related to the dechlorination reaction, together with the monitored biomarkers. Appropriate kinetic formulations were assessed. Reductive dechlorination of TCE took place only when external carbon sources were added to microcosms, and occurred concomitant with a pronounced increase in the Dehalococcoides mccartyi cell count as determined by 16S rRNA gene-targeted qPCR. This indicates that native dechlorinating bacteria are present in the aquifer of the Zenne site and that the oligotrophic nature of the aquifer prevents a complete degradation to ethene. The type of carbon source, the cell number of D. mccartyi or the reductive dehalogenase genes, however, did not unequivocally explain the observed differences in degradation rates or the extent of dechlorination. Neither first-order, Michaelis-Menten nor Monod kinetics could perfectly simulate the dechlorination reactions in TCE spiked microcosms. A sensitivity analysis indicated that the inclusion of donor limitation would not significantly enhance the simulations without a clear process understanding. Results point to the role of the supporting microbial community but it remains to be verified how the complexity of the microbial (inter)actions should be represented in a model framework.

  15. When Forest become carbon sources: Impact of herbivory on carbon balance

    NASA Astrophysics Data System (ADS)

    Schafer, K. V.; Clark, K. L.; Skowronski, N. S.

    2008-12-01

    Traditionally forests are thought to be carbon sinks and are becoming important trading commodities in the carbon trading markets. However, disturbances such as fire, hurricanes and herbivory can lead to forests being sources rather than sinks of carbon. Here, we investigate the carbon balance of an oak/pine forest in the New Jersey Pine Barrens under herbivory attack in summer 2007. Net primary productivity (NPP) was reduced to ca 70% of previous year NPP (535 g m-2 a-1 in 2006) and canopy net assimilation (AnC), as modeled with the Canopy Conductance Constrained Carbon Assimilation model (4C-A), was reduced to ca 65 % of previous year (1335 g m-2 a-1 in 2006) AnC or ca 1015 g C m-2 a-1. Although the trees were defoliated for only 15 % of the normal annual growing season, the impact amounted to ca 30 % of C accumulation loss when integrated over the year. Overall NPP in 2007 was ca 378 g C m-2 a-1 with 50 % of NPP being allocated to foliage production which constitutes a short term carbon pool. On an ecosystem level net ecosystem exchange amounted to a release of 293 g C m-2 a-1 thus becoming a carbon source over the course of the year rather than being a sink for C. The overall impact of the defoliation spanned 21% of upland forests (320 km2) in the New Jersey Pine Barrens thus representing a significant amount of overall C being emitted back to the atmosphere rather than being accumulated in the biosphere.

  16. North Siberian lakes: A methane source fueled by Pleistocene carbon

    SciTech Connect

    Zimov, S.A.; Davidov, S.P.; Prosiannikov, S.F.; Trumbore, S.

    1997-08-08

    The sizes of major sources and sinks of atmospheric methane (CH{sub 4}), an important greenhouse gas, are poorly known. CH{sub 4} from north Siberian lakes contributes {approximately}1.5 teragrams CH{sub 4} year{sup -1} to observed winter increases in atmospheric CH{sub 4} concentration at high northern latitudes. CH{sub 4} emitted from these lakes in winter had a radiocarbon age of 27,200 years and was derived largely from Pleistocene-aged carbon.

  17. PCB bioavailability control in Lumbriculus variegatus through different modes of activated carbon addition to sediments

    SciTech Connect

    Xueli Sun; Upal Ghosh

    2007-07-01

    PCB bioavailability to a freshwater oligochaete (Lumbriculus variegatus) was studied using sediments from a PCB-impacted river that was treated with different modes of granular activated carbon (GAC) addition. The GAC used was bituminous coal-based type TOP. For sediment treated with 2.6% GAC and mixed for 2 min prior to L. variegatus addition, the reduction in total PCB biouptake was 70% for 75-300 {mu}m size carbon, and 92% for the 45-180 {mu}m size carbon. For the case where the GAC was placed as a thin layer on top of the sediments without mixing, the reduction in total PCB uptake was 70%. PCB biouptake kinetics study using treated and untreated sediment showed that the maximum PCB uptake in tissue was achieved at 28 days and decreased after that time. Although the absolute uptake of PCB changed over time, the percent reduction in total PCB uptake upon GAC amendment remained constant after the first few days. Our results indicated that PCB bioavailability was reduced upon the addition and little or no mixing of GAC into sediments. PCB aqueous equilibrium concentration and desorption rates were greatly reduced after GAC amendment, indicating reductions in the two primary mechanisms of PCB bioavailability in sediments: chemical activity and chemical accessibility. 29 refs., 5 figs., 1 tab.

  18. Quantification of carbon sources for isoprene emission in poplar leaves

    NASA Astrophysics Data System (ADS)

    Kreutzwieseer, J.; Graus, M.; Schnitzler, J. P.; Heizmann, U.; Rennenberg, H.; Hansel, A.

    2003-12-01

    Isoprene is the most abundant volatile organic compound emitted by plants and in particular by trees. Current interest in understanding its biosynthesis in chloroplasts is forced by the important role isoprene plays in atmospheric chemistry. Leaf isoprene formation is closely linked to photosynthesis by a dynamic use of recently fixed photosynthetic precursors in the chloroplast. Under steady state conditions in [13C]CO2 atmosphere approximately 75 % of isoprene became labeled within minutes. The source of unlabeled C is suggested to be of extra-chloroplastidic and/or from starch degradation. In order to test whether these alternative carbon sources - leaf internal C-pools and xylem-transported carbohydrates, contribute to leaf isoprene formation in poplar (Populus tremula x P. alba) on-line proton-transfer-reaction-mass spectrometry (PTR-MS) was used to follow 13C-labeling kinetics.

  19. Multi-Walled Carbon Nanotube Functionalization by Radical Addition Using Hydroxymethylene Groups.

    PubMed

    Rodríguez-Jiménez, Rubén; Alonso-Núñez, Gabriel; Paraguay-Delgado, Francisco; Espinoza-Gómez, Heriberto; Vélez-López, Ernesto; Rogel-Hernández, Eduardo

    2016-01-01

    Synthetic methodology and characterization of multi-walled carbon nanotubes (MWCNTs) function- alized with hydroxymethylene groups are reported. The MWCNTs were synthesized by the spray pyrolysis technique using toluene as carbon source and ferrocene as catalyst. Hydroxymethylation of MWCNTs was carried out by methanol using benzoyl peroxide (BPO) at different quantities (300 to 900 mg); the optimum BPO quantity was 300 mg. The resulting materials were characterized by FT-IR, Raman Spectroscopy, Thermal Gravimetric Analysis (TGA) and Transmission Electron Microscopy (TEM). The presence of the hydroxymethylene group on the MWCNTs surface was demonstrated by FT-IR, Raman Spectroscopy, TGA, EDS, TEM and Mass Spectrometry. The func- tionalized MWCNTs were not damaged by this methodology. PMID:27398563

  20. Does the Use of Diamond-Like Carbon Coating and Organophosphate Lubricant Additive Together Cause Excessive Tribochemical Material Removal?

    DOE PAGESBeta

    Zhou, Yan; Leonard, Donovan N.; Meyer, Harry M.; Luo, Huimin; Qu, Jun

    2015-08-22

    We observe unexpected wear increase on a steel surface that rubbed against diamond-like carbon (DLC) coatings only when lubricated by phosphate-based antiwear additives. Contrary to the literature hypothesis of a competition between zinc dialkyldithiophosphate produced tribofilms and DLC-induced carbon transfer, here a new wear mechanism based on carbon-catalyzed tribochemical interactions supported by surface characterization is proposed

  1. Addition Laws for Intensities of Radiation Emerging from Scattering Atmospheres Containing Energy Sources

    NASA Astrophysics Data System (ADS)

    Nikoghossian, A. G.; Kapanadze, N. G.

    2016-03-01

    A group theoretical approach is developed for solving astrophysical radiative transfer problems described in a previous series of papers. Addition laws for observed radiative intensities are derived for the case in which atmospheres not only absorb and scatter radiation incident on them, but radiate themselves because of energy sources contained within them. As an illustration of the application of these laws, several special radiative transfer problems which we believe are of practical interest are discussed.

  2. Carbon Nanotube Based Deuterium Ion Source for Improved Neutron Generators

    SciTech Connect

    Fink, R. L.; Jiang, N.; Thuesen, L.; Leung, K. N.; Antolak, A. J.

    2009-03-10

    Field ionization uses high electric fields to cause the ionization and emission of ions from the surface of a sharp electrode. We are developing a novel field ionization neutron generator using carbon nanotubes (CNT) to produce the deuterium ion current. The generator consists of three major components: a deuterium ion source made of carbon nanotubes, a smooth negatively-biased target electrode, and a secondary electron suppression system. When a negative high voltage is applied on the target electrode, a high gradient electric field is formed at the tips of the carbon nanotubes. This field is sufficiently strong to create deuterium (D) ions at or near the nanotubes which are accelerated to the target causing D-D reactions to occur and the production of neutrons. A cross magnetic field is used to suppress secondary emission electrons generated on the target surface. We have demonstrated field ionization currents of 70 nA (1 {mu}A/cm{sup 2}) at hydrogen gas pressure of 10 mTorr. We have found that the current scales proportionally with CNT area and also with the gas pressure in the range of 1 mTorr to 10 mTorr. We have demonstrated pulse cut-off times as short as 2 {mu}sec. Finally, we have shown the feasibility of generating neutrons using deuterium gas.

  3. Barrow Black Carbon Source and Impact Study Final Campaign Report

    SciTech Connect

    Barrett, Tate

    2014-07-01

    The goal of the Barrow Black Carbon Source and Impact (BBCSI) Study was to characterize the concentration and isotopic composition of carbonaceous atmospheric particulate matter (PM) at the Atmospheric Radiation Measurement site in Barrow, AK. The carbonaceous component was characterized via measurement of the organic and black carbon (OC and BC) components of the total PM. To facilitate complete characterization of the particulate matter, filter-based collections were used, including a medium volume PM2.5 sampler and a high volume PM10 sampler. Thirty-eight fine (PM2.5) and 49 coarse (PM10) particulate matter fractions were collected at weekly and bi-monthly intervals. The PM2.5 sampler operated with minimal maintenance during the 12 month campaign. The PM10 sampler used for the BBCSI used standard Tisch hi-vol motors which have a known lifetime of ~1 month under constant use; this necessitated monthly maintenance and it is suggested that the motors be upgraded to industrial blowers for future deployment in the Arctic. The BBCSI sampling campaign successfully collected and archived 87 ambient atmospheric particulate matter samples from Barrow, AK from July 2012 to June 2013. Preliminary analysis of the organic and black carbon concentrations has been completed. This campaign confirmed known trends of high BC lasting from the winter through to spring haze periods and low BC concentrations in the summer.

  4. Barrow Black Carbon Source and Impact Study Final Campaign Report

    SciTech Connect

    Barrett, Tate

    2014-07-01

    The goal of the Barrow Black Carbon Source and Impact campaign was to characterize the concentration and isotopic composition of carbonaceous atmospheric particulate matter (PM) at the Atmospheric Radiation Measurement (ARM) Climate Research Facility site in Barrow, Alaska. The carbonaceous component was characterized by measuring the organic and black carbon (OC and BC) components of the total PM. To facilitate complete characterization of the PM, filter-based collections were used, including a medium volume PM2.5 sampler and a high volume PM10 sampler. Thirty-eight fine PM fractions (PM2.5) and 49 coarse (PM10) PM fractions were collected at weekly and bi-monthly intervals. The PM2.5 sampler operated with minimal maintenance during the 12 month campaign. The PM10 sampler used for the Barrow Black Carbon Source and Impact (BBCSI) study used standard Tisch “hi-vol” motors that have a known lifetime of approximately 1 month under constant use; this necessitated monthly maintenance, and it is suggested that, for future deployment in the Arctic, the motors be upgraded to industrial blowers. The BBCSI sampling campaign successfully collected and archived 87 ambient atmospheric PM samples from Barrow, Alaska, from July 2012 to June 2013. Preliminary analysis of the OC and BC concentrations has been completed. This campaign confirmed known trends of high BC lasting from the winter through to spring haze periods and low BC concentrations in the summer. However, the annual OC concentrations had a very different seasonal pattern with the highest concentrations during the summer, lowest concentrations during the fall, and increased concentrations during the winter and spring (Figure 1).

  5. Diagnostic air quality model evaluation of source-specific primary and secondary fine particulate carbon.

    PubMed

    Napelenok, Sergey L; Simon, Heather; Bhave, Prakash V; Pye, Havala O T; Pouliot, George A; Sheesley, Rebecca J; Schauer, James J

    2014-01-01

    Ambient measurements of 78 source-specific tracers of primary and secondary carbonaceous fine particulate matter collected at four midwestern United States locations over a full year (March 2004-February 2005) provided an unprecedented opportunity to diagnostically evaluate the results of a numerical air quality model. Previous analyses of these measurements demonstrated excellent mass closure for the variety of contributing sources. In this study, a carbon-apportionment version of the Community Multiscale Air Quality (CMAQ) model was used to track primary organic and elemental carbon emissions from 15 independent sources such as mobile sources and biomass burning in addition to four precursor-specific classes of secondary organic aerosol (SOA) originating from isoprene, terpenes, aromatics, and sesquiterpenes. Conversion of the source-resolved model output into organic tracer concentrations yielded a total of 2416 data pairs for comparison with observations. While emission source contributions to the total model bias varied by season and measurement location, the largest absolute bias of -0.55 μgC/m(3) was attributed to insufficient isoprene SOA in the summertime CMAQ simulation. Biomass combustion was responsible for the second largest summertime model bias (-0.46 μgC/m(3) on average). Several instances of compensating errors were also evident; model underpredictions in some sectors were masked by overpredictions in others. PMID:24245475

  6. Tuning the oscillation of nested carbon nanotubes by insertion of an additional inner tube

    NASA Astrophysics Data System (ADS)

    Motevalli, B.; Liu, Jefferson Z.

    2013-12-01

    Different mechanisms of nano-oscillators with telescopic oscillations have attracted lots of attention due to the possible generation of GHz frequencies. In particular, nested carbon nanotubes are of special interest for which different mechanisms have been examined. In this paper, we will show that insertion of an additional inner tube into a conventional double walled carbon nanotube (DWCNT) oscillator not only can increase the oscillatory frequency considerably but also provides a wide range of system parameters for tuning the oscillatory behavior as well as its frequency. The insertion of an additional tube results in a number of different vdW force profiles (which only depend on the length ratios of the three tubes). Being subject to these different vdW force profiles and trigged with different initial velocity, an oscillating tube can exhibit various types of motions. We use a phase division diagram to discriminate the system parameters according to the different types of motions. Accordingly, a comprehensive study of the oscillatory frequency is also carried out. To perceive an insight into the effectiveness of insertion, a comparison is also made with the counterpart DWCNT oscillator. It is observed that this new mechanism offers a number of new possibilities in designing and characterizing a carbon nanotube based oscillator.

  7. Seasonal Sources of Carbon Exports in a Headwater Stream

    NASA Astrophysics Data System (ADS)

    Argerich, A.; Johnson, S. L.

    2013-12-01

    Climate change is intimately tied to changes in carbon (C) budgets. Understanding the compartments and processes involved in the global C cycle across a landscape is essential to predict future climate change scenarios. While most C budgets focus on terrestrial contributions, river systems contribute to the C cycle by the export of total organic carbon (TOC) and dissolved inorganic carbon (DIC) to the ocean and by exporting CO2 to the atmosphere. Although headwater streams constitute between 60 and 80 percent of fluvial systems their role in the C cycle has often been neglected due to the methodological constrains derived from their heterogeneous morphology. Here we present an analysis of the temporal variation of C export both downstream and evaded to the atmosphere for a headwater stream draining a forested watershed. We relate it to in-stream metabolic processes (respiration and primary production) and to different carbon pools. Specifically, we estimate downstream exports of C in the form of dissolved organic (DOC), dissolved inorganic (DIC), and particulate organic (POC); we estimate the C content in the fine benthic organic matter (FBOM), dead wood, algae, and macroinvertebrate pools; and finally, the amount of CO2 originated and fixed by stream respiration and primary production. Organic exports, both particulate and dissolved, represented 39.7% of the annual downstream export of C while dissolved inorganic C represented 60.3%. Higher exports were observed during periods of high flow (late fall and winter). Highest seasonality in downstream exports was observed for POC (89.5% coefficient of variation in mean monthly fluxes), followed by DOC and DIC (24.3% and 15.9% respectively). Dissolved CO2 had mostly an autochthonous origin during summer (i.e. from stream ecosystem respiration) and originated from allochthonous sources during the rain-dominated months in Oregon (late fall and winter). The stream was net heterotrophic and the amount of C cycled through

  8. Wood decomposition in Amazonian hydropower reservoirs: An additional source of greenhouse gases

    NASA Astrophysics Data System (ADS)

    Abril, Gwenaël; Parize, Marcelo; Pérez, Marcela A. P.; Filizola, Naziano

    2013-07-01

    Amazonian hydroelectric reservoirs produce abundant carbon dioxide and methane from large quantities of flooded biomass that decompose anaerobically underwater. Emissions are extreme the first years after impounding and progressively decrease with time. To date, only water-to-air fluxes have been considered in these estimates. Here, we investigate in two Amazonian reservoirs (Balbina and Petit Saut) the fate of above water standing dead trees, by combining a qualitative analysis of wood state and density through time and a quantitative analysis of the biomass initially flooded. Dead wood was much more decomposed in the Balbina reservoir 23 years after flooding than in the Petit Saut reservoir 10 years after flooding. Termites apparently played a major role in wood decomposition, occurring mainly above water, and resulting in a complete conversion of this carbon biomass into CO2 and CH4 at a timescale much shorter than reservoir operation. The analysis of pre-impounding wood biomass reveals that above-water decomposition in Amazonian reservoirs is a large, previously unrecognized source of carbon emissions to the atmosphere, representing 26-45% of the total reservoir flux integrated over 100 years. Accounting for both below- and above-water fluxes, we could estimate that each km2 of Amazonian forest converted to reservoir would emit over 140 Gg CO2-eq in 100 years. Hydropower plants in the Amazon should thus generate 0.25-0.4 MW h per km2 flooded area to produce lower greenhouse gas emissions than gas power plants. They also have the disadvantage to emit most of their greenhouse gases the earliest years of operation.

  9. Microstructure development in hot-pressed silicon carbide: Effects of aluminum, boron, and carbon additives

    SciTech Connect

    Zhang, Xiao Feng; Yang, Qing; De Jonghe, Lutgard C.

    2002-12-18

    SiC was hot-pressed with aluminum, boron, and carbon additives. The Al content was modified either to obtain SiC samples containing a continuous Al gradient, or to vary the average Al content. In both cases, dramatic changes in microstructure, phase composition, and grain boundary structure were observed as a result of the Al variation. Similar processing and characterization were done with modified boron and carbon average contents. The systematic experiments allowed identification of the roles of Al, B, and C in developing grain morphology and phase composition. The experiments also clarified the mechanical property responses to microstructural modification. Tailoring of the SiC microstructure to suit different applications would be possible.

  10. Hydrocarbon generation and expulsion in shale Vs. carbonate source rocks

    SciTech Connect

    Leythaeuser, D. ); Krooss, B.; Hillebrand, T.; Primio, R. di )

    1993-09-01

    For a number of commercially important source rocks of shale and of carbonate lithologies, which were studied by geochemical, microscopical, and petrophysical techniques, a systematic comparison was made of the processes on how hydrocarbon generation and migration proceed with maturity progress. In this way, several fundamental differences between both types of source rocks were recognized, which are related to differences of sedimentary facies and, more importantly, of diagenetic processes responsible for lithification. Whereas siliciclastic sediments lithify mainly by mechanical compaction, carbonate muds get converted into lithified rocks predominantly by chemical diagenesis. With respect to their role as hydrocarbon source rocks, pressure solution processes appear to be key elements. During modest burial stages and prior to the onset of hydrocarbon generation reactions by thermal decomposition of kerogen, pressure solution seams and stylolites. These offer favorable conditions for hydrocarbon generation and expulsion-a three-dimensional kerogen network and high organic-matter concentrations that lead to effective saturation of the internal pore fluid system once hydrocarbon generation has started. As a consequence, within such zones pore fluids get overpressured, leading ultimately to fracturing. Petroleum expulsion can then occur at high efficiencies and in an explosive fashion, whereby clay minerals and residual kerogen particles are squeezed in a toothpaste-like fashion into newly created fractures. In order to elucidate several of the above outlined steps of hydrocarbon generation and migration processes, open-system hydrous pyrolysis experiments were performed. This approach permits one to monitor changes in yield and composition of hydrocarbon products generated and expelled at 10[degrees]C temperature increments over temperature range, which mimics in the laboratory the conditions prevailing in nature over the entire liquid window interval.

  11. Effects of Nitrogen and Phosphorus Additions on Carbon Cycling of Tropical Mountain Rainforests in Hainan, China

    NASA Astrophysics Data System (ADS)

    Lai, J.

    2015-12-01

    Nitrogen (N) and Phosphorus (P) deposition is projected to increase significantly in tropical regions in the coming decades, which has changed and will change the structure and function of ecosystems, and affects on ecosystem Carbon (C) cycle. As an important part in global C cycle, how the C cycle of tropical rainforests will be influenced by the N and P deposition should be focused on. This study simulated N and P deposition in a primary and secondary forest of tropical mountain rainforest in Jianfengling, Hainan, China, during five-year field experiment to evaluate the effects of N and P deposition on C cycling processes and relate characteristics. Six levels of N and P treatments were treated: Control, Low-N, Medium-N, High-N, P and N+P. The relative growth rates (RGR) of tree layer in treatment plots were different from that in control plots after years of N and P addition. Simulated N and P deposition also increased ANPP in primary forest. N and P addition changed the growth of trees by altering soil nutrient and microbial activities. N and P addition increased soil organic carbon (SOC) and total N (TN) content, and significantly increased soil total P (TP) content, not changing soil pH. During the whole process of N and P addition, as net nitrification rate and net N mineralization rate were promoted by N and P addition, and effective N content (nitrate) of soil increased in the plot treated with N treatments compared to the control treatment. The microbial P content was increased by N and P addition, and microbial N was not changed. The increasing N deposition may enhance soil nutrient and stimulate growth of trees, which will lead to an increase of the C sequestration.

  12. Soil microbial community structure and nitrogen cycling responses to agroecosystem management and carbon substrate addition

    NASA Astrophysics Data System (ADS)

    Berthrong, S. T.; Buckley, D. H.; Drinkwater, L. E.

    2011-12-01

    Fertilizer application in conventional agriculture leads to N saturation and decoupled soil C and N cycling, whereas organic practices, e.g. complex rotations and legume incorporation, often results in increased SOM and tightly coupled cycles of C and N. These legacy effects of management on soils likely affect microbial community composition and microbial process rates. This project tested if agricultural management practices led to distinct microbial communities and if those communities differed in ability to utilize labile plant carbon substrates and to produce more plant available N. We addressed several specific questions in this project. 1) Do organic and conventional management legacies on similar soils produce distinct soil bacterial and fungal community structures and abundances? 2) How do these microbial community structures change in response to carbon substrate addition? 3) How do the responses of the microbial communities influence N cycling? To address these questions we conducted a laboratory incubation of organically and conventionally managed soils. We added C-13 labelled glucose either in one large dose or several smaller pulses. We extracted genomic DNA from soils before and after incubation for TRFLP community fingerprinting. We measured C in soil pools and respiration and N in soil extracts and leachates. Management led to different compositions of bacteria and fungi driven by distinct components in organic soils. Biomass did not differ across treatments indicating that differences in cycling were due to composition rather than abundance. C substrate addition led to convergence in bacterial communities; however management still strongly influenced the difference in communities. Fungal communities were very distinct between managements and plots with substrate addition not altering this pattern. Organic soils respired 3 times more of the glucose in the first week than conventional soils (1.1% vs 0.4%). Organic soils produced twice as much

  13. Size distributions, sources and source areas of water-soluble organic carbon in urban background air

    NASA Astrophysics Data System (ADS)

    Timonen, H.; Saarikoski, S.; Tolonen-Kivimäki, O.; Aurela, M.; Saarnio, K.; Petäjä, T.; Aalto, P. P.; Kulmala, M.; Pakkanen, T.; Hillamo, R.

    2008-04-01

    This paper represents the results of one year long measurement period of the size distributions of water-soluble organic carbon (WSOC), inorganic ions and gravimetric mass of particulate matter. Measurements were done at an urban background station (SMEAR III) by using a micro-orifice uniform deposit impactor (MOUDI). The site is located in northern European boreal region in Helsinki, Finland. The WSOC size distribution measurements were completed with the chemical analysis of inorganic ions, organic carbon (OC) and monosaccharide anhydrides from the filter samples. During the measurements gravimetric mass in the MOUDI collections varied between 3.4 and 55.0 μg m-3 and the WSOC concentration was between 0.3 and 7.4 μg m-3. On average, water-soluble particulate organic matter (WSPOM, WSOC multiplied by 1.6) comprised 25±7.7% and 7.5±3.4% of aerosol PM1 mass and the PM1-10 mass, respectively. Inorganic ions contributed 33±12% and 28±19% of the analyzed PM1 and PM1-10 aerosol mass. Five different aerosol categories corresponding to different sources or source areas were identified (long-range transport aerosols, biomass burning aerosols from wild land fires and from small-scale wood combustion, aerosols originating from marine areas and from the clean arctic areas). Clear differences in WSOC concentrations and size distributions originating from different sources or source areas were observed, although there are also many other factors which might affect the results. E.g. the local conditions and sources of volatile organic compounds (VOCs) and aerosols as well as various transformation processes are likely to have an impact on the measured aerosol composition. Using the source categories, it was identified that especially the oxidation products of biogenic VOCs in summer had a clear effect on WSOC concentrations.

  14. Stable carbon isotope analysis in a South Texas cave: Investigating sources of CO2 production

    NASA Astrophysics Data System (ADS)

    Thompson, Reece

    Studies of interactions between modern local climate, cave atmosphere, and ?13C ratios are needed to determine sources of CO2 in caves, and the cycles of seasonal variations that alter karst geochemistry. A seasonal study, focusing on the analysis of stable isotopes collected from a modern cave system, was conducted in Robber Baron Cave (RBC) in order to identify sources of CO2 in its atmosphere. Determining what conditions affect cave morphology and the transfer path of carbon through a cave system is necessary in order to assess the role of caves in the carbon cycle and correctly interpret past ecological changes. This study investigates the extent that stable isotopic values of carbon in CO2 are affected by CO2 sourced from soils, bedrock, atmospheric air, and vegetation, and how ?13C signals are transmitted in a modern cave system. This study also measures how ventilation affects CO2 concentration and ?13C on seasonal scales. In-cave air grab samples were collected monthly at various transects located in RBC in order to measure CO2 composition in addition to factors such as temperature, and barometric pressure. Soil gas and limestone bedrock were also collected and tested for ?13C composition. Air samples were analyzed using an Ambient Air-Model G2101-I Picarro Cavity Ring-Down Spectroscopy Analyzer for both the concentration and ?13C isotopic value of CO2. These values were then compared to isotopic values of known sources of CO2 in order to determine possible sources of CO2 that result in high CO2 concentrations found in RBC. The background stable isotopic value of carbon from CO2 measured in RBC is -19.1‰ VPDB.

  15. [Effects of nitrogen and carbon addition and arbuscular mycorrhiza on alien invasive plant Ambrosia artemisiifolia].

    PubMed

    Huang, Dong; Sang, Wei-guo; Zhu, Li; Song, Ying-ying; Wang, Jin-ping

    2010-12-01

    A greenhouse control experiment was conducted to explore the effects of nitrogen and carbon addition and arbuscular mycorrhiza (AM) on the growth of alien invasive plant Ambrosia artemisiifolia (common ragweed). Nitrogen addition had no significant effects on the morphological indices, biomass and its allocation, and absolute growth rate of A. artemisiifolia, but increased the nitrogen content in the aboveground and underground parts of the plant significantly. Carbon addition increased the content of soil available nitrogen. In this case, the biomass allocation in root system for nutrient (nitrogen) absorption promoted, resulting in a remarkable decrease of branch number, total leaf area, specific leaf area (SLA), and leaf mass ratio. As a result, the total biomass decreased significantly. The symbiosis of A. artemisiifolia and AM fungi had great influence on the common ragweed's soil nitrogen acclimation, which enhanced its resource-capture by the increase of SLA, and this effect was more significant when the soil nitrogen content was low. AM fungi played an important role in the growth of A. artemisiifolia in low-nitrogen environment. PMID:21442989

  16. Stimulation of terrestrial ecosystem carbon storage by nitrogen addition: a meta-analysis.

    PubMed

    Yue, Kai; Peng, Yan; Peng, Changhui; Yang, Wanqin; Peng, Xin; Wu, Fuzhong

    2016-01-01

    Elevated nitrogen (N) deposition alters the terrestrial carbon (C) cycle, which is likely to feed back to further climate change. However, how the overall terrestrial ecosystem C pools and fluxes respond to N addition remains unclear. By synthesizing data from multiple terrestrial ecosystems, we quantified the response of C pools and fluxes to experimental N addition using a comprehensive meta-analysis method. Our results showed that N addition significantly stimulated soil total C storage by 5.82% ([2.47%, 9.27%], 95% CI, the same below) and increased the C contents of the above- and below-ground parts of plants by 25.65% [11.07%, 42.12%] and 15.93% [6.80%, 25.85%], respectively. Furthermore, N addition significantly increased aboveground net primary production by 52.38% [40.58%, 65.19%] and litterfall by 14.67% [9.24%, 20.38%] at a global scale. However, the C influx from the plant litter to the soil through litter decomposition and the efflux from the soil due to microbial respiration and soil respiration showed insignificant responses to N addition. Overall, our meta-analysis suggested that N addition will increase soil C storage and plant C in both above- and below-ground parts, indicating that terrestrial ecosystems might act to strengthen as a C sink under increasing N deposition. PMID:26813078

  17. Stimulation of terrestrial ecosystem carbon storage by nitrogen addition: a meta-analysis

    PubMed Central

    Yue, Kai; Peng, Yan; Peng, Changhui; Yang, Wanqin; Peng, Xin; Wu, Fuzhong

    2016-01-01

    Elevated nitrogen (N) deposition alters the terrestrial carbon (C) cycle, which is likely to feed back to further climate change. However, how the overall terrestrial ecosystem C pools and fluxes respond to N addition remains unclear. By synthesizing data from multiple terrestrial ecosystems, we quantified the response of C pools and fluxes to experimental N addition using a comprehensive meta-analysis method. Our results showed that N addition significantly stimulated soil total C storage by 5.82% ([2.47%, 9.27%], 95% CI, the same below) and increased the C contents of the above- and below-ground parts of plants by 25.65% [11.07%, 42.12%] and 15.93% [6.80%, 25.85%], respectively. Furthermore, N addition significantly increased aboveground net primary production by 52.38% [40.58%, 65.19%] and litterfall by 14.67% [9.24%, 20.38%] at a global scale. However, the C influx from the plant litter to the soil through litter decomposition and the efflux from the soil due to microbial respiration and soil respiration showed insignificant responses to N addition. Overall, our meta-analysis suggested that N addition will increase soil C storage and plant C in both above- and below-ground parts, indicating that terrestrial ecosystems might act to strengthen as a C sink under increasing N deposition. PMID:26813078

  18. Stimulation of terrestrial ecosystem carbon storage by nitrogen addition: a meta-analysis

    NASA Astrophysics Data System (ADS)

    Yue, Kai; Peng, Yan; Peng, Changhui; Yang, Wanqin; Peng, Xin; Wu, Fuzhong

    2016-01-01

    Elevated nitrogen (N) deposition alters the terrestrial carbon (C) cycle, which is likely to feed back to further climate change. However, how the overall terrestrial ecosystem C pools and fluxes respond to N addition remains unclear. By synthesizing data from multiple terrestrial ecosystems, we quantified the response of C pools and fluxes to experimental N addition using a comprehensive meta-analysis method. Our results showed that N addition significantly stimulated soil total C storage by 5.82% ([2.47%, 9.27%], 95% CI, the same below) and increased the C contents of the above- and below-ground parts of plants by 25.65% [11.07%, 42.12%] and 15.93% [6.80%, 25.85%], respectively. Furthermore, N addition significantly increased aboveground net primary production by 52.38% [40.58%, 65.19%] and litterfall by 14.67% [9.24%, 20.38%] at a global scale. However, the C influx from the plant litter to the soil through litter decomposition and the efflux from the soil due to microbial respiration and soil respiration showed insignificant responses to N addition. Overall, our meta-analysis suggested that N addition will increase soil C storage and plant C in both above- and below-ground parts, indicating that terrestrial ecosystems might act to strengthen as a C sink under increasing N deposition.

  19. Microwave-induced electrophilic addition of single-walled carbon nanotubes with alkylhalides

    NASA Astrophysics Data System (ADS)

    Xu, Yang; Wang, Xianbao; Tian, Rong; Li, Shaoqing; Wan, Li; Li, Mingjian; You, Haijun; Li, Qin; Wang, Shimin

    2008-02-01

    We report the microwave-induced electrophilic addition of single-walled carbon nanotubes (SWNTs) with alkylhalides using Lewis acid as a catalyst followed by hydrolysis. The reaction results in the attachment of alkyl and hydroxyl groups to the surface of the nanotubes. This rapid and high-energy microwave radiation is found to be highly efficient for this reaction, which only needs as low as several minutes. The resulting nanotubes were characterized with FTIR, UV-vis-NIR, Raman, TGA, TEM and AFM. It demonstrates that iodo-alkanes show higher reaction activity with SWNTs than chloro- and bromo-alkanes.

  20. Distinct carbon sources indicate strong differentiation between tropical forest and farmland bird communities.

    PubMed

    Ferger, Stefan W; Böhning-Gaese, Katrin; Wilcke, Wolfgang; Oelmann, Yvonne; Schleuning, Matthias

    2013-02-01

    The conversion of forest into farmland has resulted in mosaic landscapes in many parts of the tropics. From a conservation perspective, it is important to know whether tropical farmlands can buffer species loss caused by deforestation and how different functional groups of birds respond to land-use intensification. To test the degree of differentiation between farmland and forest bird communities across feeding guilds, we analyzed stable C and N isotopes in blood and claws of 101 bird species comprising four feeding guilds along a tropical forest-farmland gradient in Kenya. We additionally assessed the importance of farmland insectivores for pest control in C(4) crops by using allometric relationships, C stable isotope ratios and estimates of bird species abundance. Species composition differed strongly between forest and farmland bird communities. Across seasons, forest birds primarily relied on C(3) carbon sources, whereas many farmland birds also assimilated C(4) carbon. While C sources of frugivores and omnivores did not differ between forest and farmland communities, insectivores used more C(4) carbon in the farmland than in the forest. Granivores assimilated more C(4) carbon than all other guilds in the farmland. We estimated that insectivorous farmland birds consumed at least 1,000 kg pest invertebrates km(-2) year(-1). We conclude that tropical forest and farmland understory bird communities are strongly separated and that tropical farmlands cannot compensate forest loss for insectivorous forest understory birds. In tropical farmlands, insectivorous bird species provide a quantitatively important contribution to pest control. PMID:22898920

  1. Addressing sources of uncertainty in a global terrestrial carbon model

    NASA Astrophysics Data System (ADS)

    Exbrayat, J.; Pitman, A. J.; Zhang, Q.; Abramowitz, G.; Wang, Y.

    2013-12-01

    Several sources of uncertainty exist in the parameterization of the land carbon cycle in current Earth System Models (ESMs). For example, recently implemented interactions between the carbon (C), nitrogen (N) and phosphorus (P) cycles lead to diverse changes in land-atmosphere C fluxes simulated by different models. Further, although soil organic matter decomposition is commonly parameterized as a first-order decay process, the formulation of the microbial response to changes in soil moisture and soil temperature varies tremendously between models. Here, we examine the sensitivity of historical land-atmosphere C fluxes simulated by an ESM to these two major sources of uncertainty. We implement three soil moisture (SMRF) and three soil temperature (STRF) respiration functions in the CABLE-CASA-CNP land biogeochemical component of the coarse resolution CSIRO Mk3L climate model. Simulations are undertaken using three degrees of biogeochemical nutrient limitation: C-only, C and N, and C and N and P. We first bring all 27 possible combinations of a SMRF with a STRF and a biogeochemical mode to a steady-state in their biogeochemical pools. Then, transient historical (1850-2005) simulations are driven by prescribed atmospheric CO2 concentrations used in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Similarly to some previously published results, representing N and P limitation on primary production reduces the global land carbon sink while some regions become net C sources over the historical period (1850-2005). However, the uncertainty due to the SMRFs and STRFs does not decrease relative to the inter-annual variability in net uptake when N and P limitations are added. Differences in the SMRFs and STRFs and their effect on the soil C balance can also change the sign of some regional sinks. We show that this response is mostly driven by the pool size achieved at the end of the spin-up procedure. Further, there exists a six-fold range in the level

  2. Effect of carbon source on pyrimidine biosynthesis in Pseudomonas oryzihabitans.

    PubMed

    West, Thomas P

    2010-08-01

    The effect of carbon source on the regulation of pyrimidine biosynthesis in the opportunistic human pathogen Pseudomonas oryzihabitans was studied at the level of enzyme synthesis. Although pyrimidine supplementation of glucose-grown Ps. oryzihabitans cells produced a slight but statistically significant effect on the de novo pyrimidine biosynthetic pathway enzyme activities, catabolite repression of the enzyme activities by glucose appeared to be occurring. Pyrimidine limitation experiments undertaken using an orotidine 5'-monophosphate decarboxylase mutant strain grown on glucose indicated that repression of enzyme synthesis by pyrimidines was occurring. Following pyrimidine limitation of the mutant strain cells, dihydroorotase and dihydroorotate dehydrogenase activities were found to about double while aspartate transcarbamoylase and orotate phosphoribosyltransferase activities were slightly elevated compared to their activities in the mutant strain cells grown on excess uracil. PMID:20473969

  3. Size distributions, sources and source areas of water-soluble organic carbon in urban background air

    NASA Astrophysics Data System (ADS)

    Timonen, H.; Saarikoski, S.; Tolonen-Kivimäki, O.; Aurela, M.; Saarnio, K.; Petäjä, T.; Aalto, P. P.; Kulmala, M.; Pakkanen, T.; Hillamo, R.

    2008-09-01

    This paper represents the results of one year long measurement period of the size distributions of water-soluble organic carbon (WSOC), inorganic ions and gravimetric mass of particulate matter. Measurements were done at an urban background station (SMEAR III) by using a micro-orifice uniform deposit impactor (MOUDI). The site is located in northern European boreal region in Helsinki, Finland. The WSOC size distribution measurements were completed with the chemical analysis of inorganic ions, organic carbon (OC) and monosaccharide anhydrides from the filter samples (particle aerodynamic diameter smaller than 1 μm, PM1). Gravimetric mass concentration varied during the MOUDI samplings between 3.4 and 55.0 μg m-3 and the WSOC concentrations were between 0.3 and 7.4 μg m-3. On average, water-soluble particulate organic matter (WSPOM, WSOC multiplied by 1.6 to convert the analyzed carbon mass to organic matter mass) comprised 25±7.7% and 7.5±3.4% of aerosol PM1 mass and the PM1-10 mass, respectively. Inorganic ions contributed 33±12% and 28±19% of the analyzed PM1 and PM1-10 aerosol mass. Five different aerosol categories corresponding to different sources or source areas were identified (long-range transport aerosols, biomass burning aerosols from wild land fires and from small-scale wood combustion, aerosols originating from marine areas and from the clean arctic areas). Categories were identified mainly using levoglucosan concentration level for wood combustion and air mass backward trajectories for other groups. Clear differences in WSOC concentrations and size distributions originating from different sources or source areas were observed, although there are also many other factors which might affect the results. E.g. the local conditions and sources of volatile organic compounds (VOCs) and aerosols as well as various transformation processes are likely to have an impact on the measured aerosol composition. Using the source categories, it was identified that

  4. Trends in the sources and sinks of carbon dioxide

    SciTech Connect

    Le Quere, Corrine; Raupach, Mike; Canadell, J.G.; Marland, Gregg; Bopp, Laurent; Ciais, Philippe; Friedlingstein, Pierre; Viovy, Nicolas; Conway, T.J.; Doney, Scott C.; Feely, R. A.; Foster, Pru; House, Joanna I; Prentice, Colin I.; Gurney, Kevin; Houghton, R.A.; Huntingford, Chris; Levy, Peter E.; Lomas, M. R.; Woodward, F. I.; Majkut, Joseph; Sarmiento, Jorge L.; Metzl, Nicolas; Ometto, Jean P; Randerson, James T.; Peters, Glen P; Running, Steven; Sitch, Stephen; Takahashi, Taro; Van der Werf, Guido

    2009-12-01

    Efforts to control climate change require the stabilization of atmospheric CO2 concentrations. This can only be achieved through a drastic reduction of global CO2 emissions. Yet fossil fuel emissions increased by 29% between 2000 and 2008, in conjunction with increased contributions from emerging economies, from the production and international trade of goods and services, and from the use of coal as a fuel source. In contrast, emissions from land-use changes were nearly constant. Between 1959 and 2008, 43% of each year's CO2 emissions remained in the atmosphere on average; the rest was absorbed by carbon sinks on land and in the oceans. In the past 50 years, the fraction of CO2 emissions that remains in the atmosphere each year has likely increased, from about 40% to 45%, and models suggest that this trend was caused by a decrease in the uptake of CO2 by the carbon sinks in response to climate change and variability. Changes in the CO2 sinks are highly uncertain, but they could have a significant influence on future atmospheric CO2 levels. It is therefore crucial to reduce the uncertainties.

  5. Carbon Nanotube/Magnesium Composite as a Hydrogen Source.

    PubMed

    Yu, Min Kyu; Se, Kwon Oh; Kim, Min Joong; Hwang, Jae Won; Yoon, Byoung Young; Kwon, Hyuk Sang

    2015-11-01

    Hydrogen produced using the steam reforming process contains sulfur and carbon monoxide that are harmful to the Pt catalyst in proton-exchange-membrane fuel cells (PEMFCs). However, CO-free hydrogen can be generated from the hydrolysis of either Al in strongly alkaline water or Mg in neutral water with chlorides such as sea water. The hydrogen generation rate from the hydrolysis of Mg is extremely slow and linearly proportional to the corrosion rate of Mg in chloride water. In this work, we fabricated a carbon nanotube (CNT)--reinforced Mg--matrix composite by Spark Plasma Sintering as a fast hydrogen generation source for a PEMFC. The CNTs distributed in the Mg matrix act as numerous local cathodes, and hence cause severe galvanic corrosion between the Mg-matrix anode and CNT-cathode in NaCl solution. It was found that the hydrogen generation rate from the hydrolysis of the 5 vol.% CNT/Mg composite is 3300 times faster than that of the Mg without CNTs due primarily to the galvanic corrosion effect. PMID:26726603

  6. Do Vermont's Floodplains Constitute an Important Source of Labile Carbon?

    NASA Astrophysics Data System (ADS)

    Perdrial, J. N.; Dolan, A.; Kemsley, M.

    2014-12-01

    Floodplains are extremely heterogeneous landscapes with respect to soil and sediment composition and can present an important source of carbon (C) during floods. For example, stream bank soils and sediments are zones of active erosion and deposition of sediment associated C. Due to the presence of plants, riparian soils contain high amounts of C that is exchanged between stream waters and banks. Abandoned channels and meander wetlands that remain hydrologically connected to the main channel contain high amounts of organic matter that can be flushed into the stream during high discharge. This heterogeneity, result of floodplain geomorphology, land cover and use, can profoundly impact the amount and type of dissolved organic matter (DOM) introduced into streams. In order to assess DOM characteristics leached from heterogeneous floodplain soils, aqueous soil extracts were performed on soil samples representative of different land covers (n=20) at four depths. Extracts were analyzed for dissolved organic C and total dissolved nitrogen with a Shimadzu C analyzer. Colored dissolved organic matter characteristics was measured with the Aqualog Fluorescence Spectrometer and quantified with parallel factor analysis (PARAFAC). Preliminary data from three floodplains in Vermont (Connecticut, Missisquoi and Mad River) show a 3D variability of longitudinal, lateral, and vertical extents on water-extractable, mobile C. Dissolved organic carbon concentrations in meander swamp samples were found up to 9 times higher than in those of soils from agricultural field indicative of an important C source. Although C concentrations in adjacent fields were low, high abundance of labile C (indicated by tryptophan-like fluorescence) in water extracts from fields indicates recent biological production of C. This labile C is easily processed by microbes and transformed to the greenhouse gas CO2. These results provide important information on the contribution and lability of different floodplain

  7. Black carbon from the Mississippi River: quantities, sources, and potential implications for the global carbon cycle.

    PubMed

    Mitra, Siddhartha; Bianchi, Thomas S; McKee, Brent A; Sutula, Martha

    2002-06-01

    Black carbon (BC) may be a major component of riverine carbon exported to the ocean, but its flux from large rivers is unknown. Furthermore, the global distribution of BC between natural and anthropogenic sources remains uncertain. We have determined BC concentrations in suspended sediments of the Mississippi River, the 7th largest river in the world in terms of sediment and water discharge, during high flow and low flow in 1999. The 1999 annual flux of BC from the Mississippi River was 5 x 10(-4) petagrams (1 Pg = 10(15) g = 1 gigaton). We also applied a principal components analysis to particulate-phase high molecular weight polycyclic aromatic hydrocarbon isomer ratios in Mississippi River suspended sediments. In doing so, we determined that approximately 27% of the BC discharged from the Mississippi River in 1999 originated from fossil fuel combustion (coal and smelter-derived combustion), implicating fluvial BC as an important source of anthropogenic BC contamination into the ocean. Using our value for BC flux and the annual estimate for BC burial in ocean sediments, we calculate that, in 1999, the Mississippi River discharged approximately 5% of the BC buried annually in the ocean. These results have important implications, not only for the global carbon cycle but also for the fluvial discharge of particulate organic contaminants into the world's oceans. PMID:12075780

  8. Controlling a toxic shock of pentachlorophenol (PCP) to anaerobic digestion using activated carbon addition.

    PubMed

    Xiao, Yeyuan; De Araujo, Cecilia; Sze, Chun Chau; Stuckey, David C

    2015-04-01

    Several powdered and granular activated carbons (PACs and GACs) were tested for adsorption of pentachlorophenol (PCP) in bench-scale anaerobic digestion reactors to control the toxicity of PCP to acetoclastic methanogenesis. Results showed that the adsorption capacities of PAC were reduced by 21-54%, depending on the PAC addition time, in the presence of the methanogenic sludge compared to the controls without sludge. As a preventive measure, PAC at a low dose of 20% (mass ratio to the VSS) added 24 h prior to, or simultaneously with, the addition of PCP could completely eliminate the toxic effects of PCP. At the same dose, PAC also enabled methanogenesis to recover immediately after the sludge had been exposed to PCP for 24h. GAC was not effective in enabling the recovery of methanogenesis due to its slow adsorption kinetics; however, at a dose of 80% it could partially ameliorate the toxic shock of PCP. PMID:25665874

  9. Cassava stillage and its anaerobic fermentation liquid as external carbon sources in biological nutrient removal.

    PubMed

    Bu, Fan; Hu, Xiang; Xie, Li; Zhou, Qi

    2015-04-01

    The aim of this study was to investigate the effects of one kind of food industry effluent, cassava stillage and its anaerobic fermentation liquid, on biological nutrient removal (BNR) from municipal wastewater in anaerobic-anoxic-aerobic sequencing batch reactors (SBRs). Experiments were carried out with cassava stillage supernatant and its anaerobic fermentation liquid, and one pure compound (sodium acetate) served as an external carbon source. Cyclic studies indicated that the cassava by-products not only affected the transformation of nitrogen, phosphorus, poly-β-hydroxyalkanoates (PHAs), and glycogen in the BNR process, but also resulted in higher removal efficiencies for phosphorus and nitrogen compared with sodium acetate. Furthermore, assays for phosphorus accumulating organisms (PAOs) and denitrifying phosphorus accumulating organisms (DPAOs) demonstrated that the proportion of DPAOs to PAOs reached 62.6% (Day 86) and 61.8% (Day 65) when using cassava stillage and its anaerobic fermentation liquid, respectively, as the external carbon source. In addition, the nitrate utilization rates (NURs) of the cassava by-products were in the range of 5.49-5.99 g N/(kg MLVSS⋅h) (MLVSS is mixed liquor volatile suspended solids) and 6.63-6.81 g N/(kg MLVSS⋅h), respectively. The improvement in BNR performance and the reduction in the amount of cassava stillage to be treated in-situ make cassava stillage and its anaerobic fermentation liquid attractive alternatives to sodium acetate as external carbon sources for BNR processes. PMID:25845364

  10. Cassava stillage and its anaerobic fermentation liquid as external carbon sources in biological nutrient removal*

    PubMed Central

    Bu, Fan; Hu, Xiang; Xie, Li; Zhou, Qi

    2015-01-01

    The aim of this study was to investigate the effects of one kind of food industry effluent, cassava stillage and its anaerobic fermentation liquid, on biological nutrient removal (BNR) from municipal wastewater in anaerobic-anoxic-aerobic sequencing batch reactors (SBRs). Experiments were carried out with cassava stillage supernatant and its anaerobic fermentation liquid, and one pure compound (sodium acetate) served as an external carbon source. Cyclic studies indicated that the cassava by-products not only affected the transformation of nitrogen, phosphorus, poly-β-hydroxyalkanoates (PHAs), and glycogen in the BNR process, but also resulted in higher removal efficiencies for phosphorus and nitrogen compared with sodium acetate. Furthermore, assays for phosphorus accumulating organisms (PAOs) and denitrifying phosphorus accumulating organisms (DPAOs) demonstrated that the proportion of DPAOs to PAOs reached 62.6% (Day 86) and 61.8% (Day 65) when using cassava stillage and its anaerobic fermentation liquid, respectively, as the external carbon source. In addition, the nitrate utilization rates (NURs) of the cassava by-products were in the range of 5.49–5.99 g N/(kg MLVSS∙h) (MLVSS is mixed liquor volatile suspended solids) and 6.63–6.81 g N/(kg MLVSS∙h), respectively. The improvement in BNR performance and the reduction in the amount of cassava stillage to be treated in-situ make cassava stillage and its anaerobic fermentation liquid attractive alternatives to sodium acetate as external carbon sources for BNR processes. PMID:25845364

  11. On the effect of carbon monoxide addition on soot formation in a laminar ethylene/air coflow diffusion flame

    SciTech Connect

    Guo, Hongsheng; Thomson, Kevin A.; Smallwood, Gregory J.

    2009-06-15

    The effect of carbon monoxide addition on soot formation in an ethylene/air diffusion flame is investigated by experiment and detailed numerical simulation. The paper focuses on the chemical effect of carbon monoxide addition by comparing the results of carbon monoxide and nitrogen diluted flames. Both experiment and simulation show that although overall the addition of carbon monoxide monotonically reduces the formation of soot, the chemical effect promotes the formation of soot in an ethylene/air diffusion flame. The further analysis of the details of the numerical result suggests that the chemical effect of carbon monoxide addition may be caused by the modifications to the flame temperature, soot surface growth and oxidation reactions. Flame temperature increases relative to a nitrogen diluted flame, which results in a higher surface growth rate, when carbon monoxide is added. Furthermore, the addition of carbon monoxide increases the concentration of H radical owing to the intensified forward rate of the reaction CO + OH = CO{sub 2} + H and therefore increases the surface growth reaction rates. The addition of carbon monoxide also slows the oxidation rate of soot because the same reaction CO + OH = CO{sub 2} + H results in a lower concentration of OH. (author)

  12. Fluxes of carbon, phosphorylation, and redox intermediates during growth of Saccharomyces cerevisiae on different carbon sources

    SciTech Connect

    Cortassa, S.; Aon, J.C.; Aon, M.A.

    1995-07-20

    In the present work the authors developed a method for estimating anabolic fluxes when yeast are growing on various carbon substrates (glucose, glycerol, lactate, pyruvate, acetate, or ethanol) in minimal medium. Fluxes through the central amphibolic pathways were calculated from the product of the total required amount of a specified carbon intermediate times the growth rate. The required amount of each carbon intermediate was estimated from the experimentally determined macromolecular composition of cells grown in each carbon source and the monomer composition of macromolecules. Substrates sharing most metabolic pathways such as ethanol and acetate, despite changes in the macromolecular composition, namely carbohydrate content, did not show large variations in the overall fluxes through the main amphibolic pathways. For instance, in order to supply anabolic precursors to sustain growth rates in the range of 0.16/h to 0.205/h, similar large fluxes through Acetyl CoA synthase were required by acetate or ethanol. The V{sub max} activities of key enzymes of the main amphibolic pathways measured in permeabilized yeast cells allowed to confirm, qualitatively, the operation of those pathways for all substrates and were consistent on most substrates with the estimate fluxes required to sustain growth.

  13. Aquatic carbon and GHG export from a permafrost catchment; identifying source areas and primary flow paths.

    NASA Astrophysics Data System (ADS)

    Lessels, J. S.; Dinsmore, K. J.; Billett, M. F.; Street, L. E.; Wookey, P. A.; Tetzlaff, D.; Baxter, R.; Subke, J. A.; Dean, J.; Washbourne, I. J.

    2014-12-01

    The aquatic pathway is increasingly being recognized as an important component of landscape scale greenhouse gas (GHG) budgets. Due to low temperatures and short residence times limiting in-stream production in northern headwater catchments, much of the exported carbon is likely to be allochthonous, transported via throughflow to the surface drainage system. Identifying sources and primary flow pathways is therefore essential in understanding and predicting changes in the aquatic flux magnitude. Arctic landscapes are now widely recognised as being particularly vulnerable to climate driven changes. The HYDRA project ("Permafrost catchments in transition: hydrological controls on carbon cycling and greenhouse gas budgets") aims to understand the fundamental role that hydrological processes play in regulating landscape-scale carbon fluxes, and predict how changes in vegetation and active layer depth in permafrost environments influence the delivery and export of aquatic carbon. In this study we present aquatic concentrations and fluxes of carbon and GHG species collected across two field seasons (2013, 2014) from an arctic headwater catchment in northern Canada. Measured species include dissolved organic (DOC) and inorganic carbon (DIC), CO2, CH4 and N2O. Measurements were made across a range of freshwater types within the tundra landscape, including lakes, ice-wedge polygons, and the 'Siksik' stream which drains the (c.a. 1 km2) primary study catchment. A nested sub-catchment approach was used along the 'Siksik' stream; 'snapshot' sampling of eight points along the stream length allowed specific vegetation communities to be targeted to assess individually their contribution to aquatic export. A combination of stable isotopes and major ion concentrations measured at each sampling point provide additional information to trace source areas and flow paths within the main study catchment. Catchment scale evasion and downstream export were calculated and an initial

  14. Utilization of Glyphosate as Phosphate Source: Biochemistry and Genetics of Bacterial Carbon-Phosphorus Lyase

    PubMed Central

    Zechel, David L.; Jochimsen, Bjarne

    2014-01-01

    SUMMARY After several decades of use of glyphosate, the active ingredient in weed killers such as Roundup, in fields, forests, and gardens, the biochemical pathway of transformation of glyphosate phosphorus to a useful phosphorus source for microorganisms has been disclosed. Glyphosate is a member of a large group of chemicals, phosphonic acids or phosphonates, which are characterized by a carbon-phosphorus bond. This is in contrast to the general phosphorus compounds utilized and metabolized by microorganisms. Here phosphorus is found as phosphoric acid or phosphate ion, phosphoric acid esters, or phosphoric acid anhydrides. The latter compounds contain phosphorus that is bound only to oxygen. Hydrolytic, oxidative, and radical-based mechanisms for carbon-phosphorus bond cleavage have been described. This review deals with the radical-based mechanism employed by the carbon-phosphorus lyase of the carbon-phosphorus lyase pathway, which involves reactions for activation of phosphonate, carbon-phosphorus bond cleavage, and further chemical transformation before a useful phosphate ion is generated in a series of seven or eight enzyme-catalyzed reactions. The phn genes, encoding the enzymes for this pathway, are widespread among bacterial species. The processes are described with emphasis on glyphosate as a substrate. Additionally, the catabolism of glyphosate is intimately connected with that of aminomethylphosphonate, which is also treated in this review. Results of physiological and genetic analyses are combined with those of bioinformatics analyses. PMID:24600043

  15. Utilization of glyphosate as phosphate source: biochemistry and genetics of bacterial carbon-phosphorus lyase.

    PubMed

    Hove-Jensen, Bjarne; Zechel, David L; Jochimsen, Bjarne

    2014-03-01

    After several decades of use of glyphosate, the active ingredient in weed killers such as Roundup, in fields, forests, and gardens, the biochemical pathway of transformation of glyphosate phosphorus to a useful phosphorus source for microorganisms has been disclosed. Glyphosate is a member of a large group of chemicals, phosphonic acids or phosphonates, which are characterized by a carbon-phosphorus bond. This is in contrast to the general phosphorus compounds utilized and metabolized by microorganisms. Here phosphorus is found as phosphoric acid or phosphate ion, phosphoric acid esters, or phosphoric acid anhydrides. The latter compounds contain phosphorus that is bound only to oxygen. Hydrolytic, oxidative, and radical-based mechanisms for carbon-phosphorus bond cleavage have been described. This review deals with the radical-based mechanism employed by the carbon-phosphorus lyase of the carbon-phosphorus lyase pathway, which involves reactions for activation of phosphonate, carbon-phosphorus bond cleavage, and further chemical transformation before a useful phosphate ion is generated in a series of seven or eight enzyme-catalyzed reactions. The phn genes, encoding the enzymes for this pathway, are widespread among bacterial species. The processes are described with emphasis on glyphosate as a substrate. Additionally, the catabolism of glyphosate is intimately connected with that of aminomethylphosphonate, which is also treated in this review. Results of physiological and genetic analyses are combined with those of bioinformatics analyses. PMID:24600043

  16. Effects of addition of different carbon materials on the electrochemical performance of nickel hydroxide electrode

    NASA Astrophysics Data System (ADS)

    Sierczynska, Agnieszka; Lota, Katarzyna; Lota, Grzegorz

    Nickel hydroxide is used as an active material in positive electrodes of rechargeable alkaline batteries. The capacity of nickel-metal hydride (Ni-MH) batteries depends on the specific capacity of the positive electrode and utilization of the active material because of the Ni(OH) 2/NiOOH electrode capacity limitation. The practical capacity of the positive nickel electrode depends on the efficiency of the conductive network connecting the Ni(OH) 2 particle with the current collector. As β-Ni(OH) 2 is a kind of semiconductor, the additives are necessary to improve the conductivity between the active material and the current collector. In this study the effect of adding different carbon materials (flake graphite, multi-walled carbon nanotubes (MWNT)) on the electrochemical performance of pasted nickel-foam electrode was established. A method of production of MWNT special type of catalysts had an influence on the performance of the nickel electrodes. The electrochemical tests showed that the electrode with added MWNT (110-170 nm diameter) exhibited better electrochemical properties in the chargeability, specific discharge capacity, active material utilization, discharge voltage and cycling stability. The nickel electrodes with MWNT addition (110-170 nm diameter) have exhibited a specific capacity close to 280 mAh g -1 of Ni(OH) 2, and the degree of active material utilization was ∼96%.

  17. Role of Carbon-Addition and Hydrogen-Migration Reactions in Soot Surface Growth.

    PubMed

    Zhang, Hong-Bo; Hou, Dingyu; Law, Chung K; You, Xiaoqing

    2016-02-11

    Using density functional theory and master equation modeling, we have studied the kinetics of small unsaturated aliphatic molecules reacting with polycyclic aromatic hydrocarbon (PAH) molecules having a diradical character. We have found that these reactions follow the mechanism of carbon addition and hydrogen migration (CAHM) on both spin-triplet and open-shell singlet potential energy surfaces at a rate that is about ten times those of the hydrogen-abstraction-carbon-addition (HACA) reactions at 1500 K in the fuel-rich postflame region. The results also show that the most active reaction sites are in the center of the zigzag edges of the PAHs. Furthermore, the reaction products are more likely to form straight rather than branched aliphatic side chains in the case of reacting with diacetylene. The computed rate constants are also found to be independent of pressure at conditions of interest in soot formation, and the activation barriers of the CAHM reactions are linearly correlated with the diradical characters. PMID:26799641

  18. Anthropogenic carbon dioxide source regions observed from space

    NASA Astrophysics Data System (ADS)

    Schneising, Oliver; Heymann, Jens; Buchwitz, Michael; Reuter, Maximilian; Bovensmann, Heinrich; Burrows, John P.

    2013-04-01

    Urban areas, which are home to the majority of today's world population, are responsible for more than two-thirds of the global energy-related carbon dioxide emissions. Given the ongoing demographic growth and rising energy consumption in metropolitan regions particularly in the developing world, urban-based emissions are expected to further increase in the future. As a consequence, monitoring and independent verification of reported anthropogenic emissions is becoming more and more important. It is demonstrated using CO2 column-averaged mole fraction data retrieved from the SCIAMACHY instrument onboard ENVISAT that anthropogenic CO2 emissions can be detected from space and that emission trends might be tracked using satellite observations. This is promising with regard to future satellite missions with high spatial resolution and wide swath imaging capability aiming at constraining anthropogenic emissions down to the point-source scale. By subtracting retrieved background values from those retrieved over urban areas the regional contrasts are quantified and significant CO2 enhancements are found for several anthropogenic source regions around the world. The order of magnitude of the enhancements is in agreement with what is expected for anthropogenic CO2 signals. The validity of the retrieved spatial enhancement patterns and of the temporal trends of the retrieved enhancements is assessed by comparison with anthropogenic emissions from the Emission Database for Global Atmospheric Research (EDGAR).

  19. Preparation and Physicochemical Evaluation of Controlled-release Carbon Source Tablet for Groundwater in situ Denitrification

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Kang, J. H.; Yeum, Y.; Han, K. J.; Kim, D. W.; Park, C. W.

    2015-12-01

    Nitric nitrogen could be the one of typical pollution source such asNO3-through domestic sewage, livestock and agricultural wastewater. Resident microflorain aquifer has known to remove the nitric nitrogen spontaneously following the denitration process with the carbon source (CS) as reactant. However, it could be reacted very slowly with the rack of CS and there have been some studies for controlled addition of CS (Ref #1-3). The aim of this study was to prepare the controlled-release carbon source (CR-CS) tablet and to evaluate in vitro release profile for groundwater in situ denitrification. CR-CS tablet could be manufactured by direct compression method using hydraulic laboratory press (Caver® 3850) with 8 mm rounded concave punch/ die.Seven kinds of CR-CS tablet were prepared to determine the nature of the additives and their ratio such as sodium silicate, dicalcium phosphate, bentonite and sand#8.For each formulation, the LOD% and flowability of pre-mixed powders and the hardness of compressed tablets were analyzed. In vitro release study was performed to confirm the dissolution profiles following the USP Apparatus 2 method with Distilled water of 900mL, 20 °C. As a result, for each lubricated powders, they were compared in terms of ability to give an acceptable dry pre-mixed powder for tableting process. The hardness of the compressed tablets is acceptable whatever the formulations tested. After in vitro release study, it could confirm that the different formulations of CR-CS tablet have a various release rate patterns, which could release 100% at 3 hrs, 6 hrs and 12 hrs. The in vitro dissolution profiles were in good correlation of Higuchi release kinetic model. In conclusion, this study could be used as a background for development and evaluation of the controlled-release carbon source (CR-CS) tablet for the purification of groundwater following the in situ denitrification.

  20. Mineral elements of subtropical tree seedlings in response to elevated carbon dioxide and nitrogen addition.

    PubMed

    Huang, Wenjuan; Zhou, Guoyi; Liu, Juxiu; Zhang, Deqiang; Liu, Shizhong; Chu, Guowei; Fang, Xiong

    2015-01-01

    Mineral elements in plants have been strongly affected by increased atmospheric carbon dioxide (CO2) concentrations and nitrogen (N) deposition due to human activities. However, such understanding is largely limited to N and phosphorus in grassland. Using open-top chambers, we examined the concentrations of potassium (K), calcium (Ca), magnesium (Mg), aluminum (Al), copper (Cu) and manganese (Mn) in the leaves and roots of the seedlings of five subtropical tree species in response to elevated CO2 (ca. 700 μmol CO2 mol(-1)) and N addition (100 kg N ha(-1) yr(-1)) from 2005 to 2009. These mineral elements in the roots responded more strongly to elevated CO2 and N addition than those in the leaves. Elevated CO2 did not consistently decrease the concentrations of plant mineral elements, with increases in K, Al, Cu and Mn in some tree species. N addition decreased K and had no influence on Cu in the five tree species. Given the shifts in plant mineral elements, Schima superba and Castanopsis hystrix were less responsive to elevated CO2 and N addition alone, respectively. Our results indicate that plant stoichiometry would be altered by increasing CO2 and N deposition, and K would likely become a limiting nutrient under increasing N deposition in subtropics. PMID:25794046

  1. Mineral Elements of Subtropical Tree Seedlings in Response to Elevated Carbon Dioxide and Nitrogen Addition

    PubMed Central

    Huang, Wenjuan; Zhou, Guoyi; Liu, Juxiu; Zhang, Deqiang; Liu, Shizhong; Chu, Guowei; Fang, Xiong

    2015-01-01

    Mineral elements in plants have been strongly affected by increased atmospheric carbon dioxide (CO2) concentrations and nitrogen (N) deposition due to human activities. However, such understanding is largely limited to N and phosphorus in grassland. Using open-top chambers, we examined the concentrations of potassium (K), calcium (Ca), magnesium (Mg), aluminum (Al), copper (Cu) and manganese (Mn) in the leaves and roots of the seedlings of five subtropical tree species in response to elevated CO2 (ca. 700 μmol CO2 mol-1) and N addition (100 kg N ha-1 yr-1) from 2005 to 2009. These mineral elements in the roots responded more strongly to elevated CO2 and N addition than those in the leaves. Elevated CO2 did not consistently decrease the concentrations of plant mineral elements, with increases in K, Al, Cu and Mn in some tree species. N addition decreased K and had no influence on Cu in the five tree species. Given the shifts in plant mineral elements, Schima superba and Castanopsis hystrix were less responsive to elevated CO2 and N addition alone, respectively. Our results indicate that plant stoichiometry would be altered by increasing CO2 and N deposition, and K would likely become a limiting nutrient under increasing N deposition in subtropics. PMID:25794046

  2. Towards a Carbon Nanotube Ionization Source for Planetary Atmosphere Exploration

    NASA Astrophysics Data System (ADS)

    Oza, A. V.; Leblanc, F.; Berthelier, J. J.; Becker, J.; Coulomb, R.; Gilbert, P.; Hong, N. T.; Lee, S.; Vettier, L.

    2015-12-01

    The characterization of planetary exospheres today, relies on the development of a highly efficient ionization source, due to the scant neutral molecules (n < 108 cm -3) present in diffuse planetary coronae. These tenuous atmospheres provide insight on to physical processes known to occur such as: space weathering, magneto-atmosphere interactions, as well as atmospheric escape mechanisms, all of which are being heavily investigated via current 3D Monte Carlo simulations (Turc et al. 2014, Leblanc et al. 2016 in prep) at LATMOS. Validation of these studies will rely on in-situ observations in the coming decades. Neutral detection strongly depends on electron-impact ionization which via conventional cathode-sources, such as thermal filaments (heated up to 2000 K), may only produce the target ionization essential for energy-measurements with large power consumption. Carbon nanotubes (CNTs) however are ideal low-power, cold cathodes, when subject to moderate electric fields (E ~ 1 MV / m). We present our current device, a small CNT chip, of emission area 15 mm2, emitting electrons that pass through an anode grid and subsequent electrostatic analyzer. The device currently extracts hundreds of µAmperes with applied external voltages ~ -150 Volts, approaching minimum power consumption < 0.1 Watts. The 3D modeling of field effect electrons ionizing a standard influx of neutrals is shown, using the multiphysics suite COMSOL. To better anticipate the species an ideal in-situ spacecraft equipped with such an ionization source would observe, we discuss Europa's exosphere. Europa's environment is largely shaped by the Jovian plasma sputtering the icy regolith with heavy ions and electrons (keV < E < MeV), producing predominately molecular oxygen (Johnson et al. 2002).

  3. DISCOVERY OF THE SECOND WARM CARBON-CHAIN-CHEMISTRY SOURCE, IRAS15398 - 3359 IN LUPUS

    SciTech Connect

    Sakai, Nami; Yamamoto, Satoshi; Sakai, Takeshi; Hirota, Tomoya; Burton, Michael

    2009-05-20

    We have conducted a search for carbon-chain molecules toward 16 protostars with the Mopra 22 m and Nobeyama 45 m telescopes, and have detected high excitation lines from several species, such as C{sub 4}H (N = 9-8), C{sub 4}H{sub 2}(J = 10{sub 0,10}-9{sub 0,9}), CH{sub 3}CCH(J = 5-4, K = 2), and HC{sub 5}N(J = 32-31), toward the low-mass protostar, IRAS15398 - 3359 in Lupus. The C{sub 4}H line is as bright as 2.4 K measured with the Nobeyama 45 m telescope. The kinetic temperature is derived to be 12.6 {+-} 1.5 K from the K = 1 and K = 2 lines of CH{sub 3}CCH. These results indicate that the carbon-chain molecules exist in a region of warm and dense gas near the protostar. The observed features are similar to those found toward IRAS04368+2557 in L1527, which shows warm carbon-chain chemistry (WCCC). In WCCC, carbon-chain molecules are produced efficiently by the evaporation of CH{sub 4} from the grain mantles in a lukewarm region near the protostar. Our data clearly indicate that WCCC is no longer specific to L1527, but occurs in IRAS15398 - 3359. In addition, we draw attention to a remarkable contrast between WCCC and hot corino chemistry in low-mass star-forming regions. Carbon-chain molecules are deficient in hot corino sources like NGC1333 IRAS4B, whereas complex organic molecules seem to be less abundant in the WCCC sources. A possible origin for such source-to-source chemical variations is suggested to arise from the timescale of the starless-core phase in each source. If this is the case, the chemical composition provides an important clue to explore the variation of star formation processes between sources and/or molecular clouds.

  4. Dual-Carbon sources fuel the OCS deep-reef Community, a stable isotope investigation

    USGS Publications Warehouse

    Sulak, Kenneth J.; Berg, J.; Randall, Michael; Dennis, George D., III; Brooks, R.A.

    2008-01-01

    The hypothesis that phytoplankton is the sole carbon source for the OCS deep-reef community (>60 m) was tested. Trophic structure for NE Gulf of Mexico deep reefs was analyzed via carbon and nitrogen stable isotopes. Carbon signatures for 114 entities (carbon sources, sediment, fishes, and invertebrates) supported surface phytoplankton as the primary fuel for the deep reef. However, a second carbon source, the macroalga Sargassum, with its epiphytic macroalgal associate, Cladophora liniformis, was also identified. Macroalgal carbon signatures were detected among 23 consumer entities. Most notably, macroalgae contributed 45 % of total carbon to the 13C isotopic spectrum of the particulate-feeding reef-crest gorgonian Nicella. The discontinuous spatial distribution of some sessile deep-reef invertebrates utilizing pelagic macroalgal carbon may be trophically tied to the contagious distribution of Sargassum biomass along major ocean surface features.

  5. Sources and light absorption of water-soluble organic carbon aerosols in the outflow from northern China

    NASA Astrophysics Data System (ADS)

    Kirillova, E. N.; Andersson, A.; Han, J.; Lee, M.; Gustafsson, Ö.

    2014-02-01

    High loadings of anthropogenic carbonaceous aerosols in Chinese air influence the air quality for over one billion people and impact the regional climate. A large fraction (17-80%) of this aerosol carbon is water-soluble, promoting cloud formation and thus climate cooling. Recent findings, however, suggest that water-soluble carbonaceous aerosols also absorb sunlight, bringing additional direct and indirect climate warming effects, yet the extent and nature of light absorption by this water-soluble "brown carbon" and its relation to sources is poorly understood. Here, we combine source estimates constrained by dual carbon isotopes with light-absorption measurements of water-soluble organic carbon (WSOC) for a March 2011 campaign at the Korea Climate Observatory at Gosan (KCOG), a receptor station in SE Yellow Sea for the outflow from northern China. The mass absorption cross section at 365 nm (MAC365) of WSOC for air masses from N. China were in general higher (0.8-1.1 m2 g-1), than from other source regions (0.3-0.8 m2 g-1). However, this effect corresponds to only 2-10% of the radiative forcing caused by light absorption by elemental carbon. Radiocarbon constraints show that the WSOC in Chinese outflow had significantly higher fraction fossil sources (30-50%) compared to previous findings in S. Asia, N. America and Europe. Stable carbon (δ13C) measurements were consistent with aging during long-range air mass transport for this large fraction of carbonaceous aerosols.

  6. Biomass burning sources of nitrogen oxides, carbon monoxide, and non-methane hydrocarbons

    SciTech Connect

    Atherton, C.S.

    1995-11-01

    Biomass burning is an important source of many key tropospheric species, including aerosols, carbon dioxide (CO{sub 2}), nitrogen oxides (NO{sub {times}}=NO+NO{sub 2}), carbon monoxide (CO), methane (CH{sub 4}), nitrous oxide (N{sub 2}O), methyl bromide (CH{sub 3}Br), ammonia (NH{sub 3}), non-methane hydrocarbons (NMHCs) and other species. These emissions and their subsequent products act as pollutants and affect greenhouse warming of the atmosphere. One important by-product of biomass burning is tropospheric ozone, which is a pollutant that also absorbs infrared radiation. Ozone is formed when CO, CH{sub 4}, and NMHCs react in the presence of NO{sub {times}} and sunlight. Ozone concentrations in tropical regions (where the bulk of biomass burning occurs) may increase due to biomass burning. Additionally, biomass burning can increase the concentration of nitric acid (HNO{sub 3}), a key component of acid rain.

  7. Carbon Nanotube Bundle Array Cold Cathodes for THz Vacuum Tube Sources

    NASA Astrophysics Data System (ADS)

    Manohara, Harish M.; Toda, Risaku; Lin, Robert H.; Liao, Anna; Bronikowski, Michael J.; Siegel, Peter H.

    2009-12-01

    We present high performance cold cathodes composed of arrays of carbon nanotube bundles that routinely produce > 15 A/cm2 at applied fields of 5 to 8 V/µm without any beam focusing. They have exhibited robust operation in poor vacuums of 10-6 to 10-4 Torr- a typically achievable range inside hermetically sealed microcavities. A new double-SOI process was developed to monolithically integrate a gate and additional beam tailoring electrodes. The ability to design the electrodes for specific requirements makes carbon nanotube field emission sources extremely flexible. The lifetime of these cathodes is found to be affected by two effects: a gradual decay of emission due to anode sputtering, and catastrophic failure because of dislodging of CNT bundles at high fields ( > 10 V/µm).

  8. Carbon Nanotube/Conductive Additive/Space Durable Polymer Nanocomposite Films for Electrostatic Charge Dissipation

    NASA Technical Reports Server (NTRS)

    Smith, Joseph G., Jr.; Watson, Kent A.; Delozier, Donavon M.; Connell, John W.

    2003-01-01

    Thin film membranes of space environmentally stable polymeric materials possessing low color/solar absorptivity (alpha) are of interest for potential applications on Gossamer spacecraft. In addition to these properties, sufficient electrical conductivity is required in order to dissipate electrostatic charge (ESC) build-up brought about by the charged orbital environment. One approach to achieve sufficient electrical conductivity for ESC mitigation is the incorporation of single wall carbon nanotubes (SWNTs). However, when the SWNTs are dispersed throughout the polymer matrix, the nanocomposite films tend to be significantly darker than the pristine material resulting in a higher alpha. The incorporation of conductive additives in combination with a decreased loading level of SWNTs is one approach for improving alpha while retaining conductivity. Taken individually, the low loading level of conductive additives and SWNTs is insufficient in achieving the percolation level necessary for electrical conductivity. When added simultaneously to the film, conductivity is achieved through a synergistic effect. The chemistry, physical, and mechanical properties of the nanocomposite films will be presented.

  9. Additive-induced morphological tuning of self-assembled silica-barium carbonate crystal aggregates

    NASA Astrophysics Data System (ADS)

    Kellermeier, Matthias; Glaab, Fabian; Carnerup, Anna M.; Drechsler, Markus; Gossler, Benjamin; Hyde, Stephen T.; Kunz, Werner

    2009-04-01

    Crystallisation of barium carbonate from alkaline silica solutions results in the formation of extraordinary micron-scale architectures exhibiting non-crystallographic curved shapes, such as helical filaments and worm-like braids. These so-called "silica biomorphs" consist of a textured assembly of uniform elongated witherite nanocrystallites, which is occasionally sheathed by a skin of amorphous silica. Although great efforts have been devoted to clarifying the physical origin of these fascinating materials, to date little is known about the processes underlying the observed self-organisation. Herein, we describe the effect of two selected additives, a cationic surfactant and a cationic polymer, on the morphology of the forming crystal aggregates, and relate changes to experiments conducted in the absence of additives. Minor amounts of both substances are shown to exert a significant influence on the growth process, leading to the formation of predominantly flower-like spherulitic aggregates. The observed effects are discussed in terms of feasible morphogenesis pathways. Based on the assumption of a template membrane steering biomorph formation, it is proposed that the two additives are capable of performing specific bridging functions promoting the aggregation of colloidal silica which constitutes the membrane. Morphological changes are tentatively ascribed to varying colloid coordination effecting distinct membrane curvatures.

  10. Performance enhancement with powdered activated carbon (PAC) addition in a membrane bioreactor (MBR) treating distillery effluent.

    PubMed

    Satyawali, Yamini; Balakrishnan, Malini

    2009-10-15

    This work investigated the effect of powdered activated carbon (PAC) addition on the operation of a membrane bioreactor (MBR) treating sugarcane molasses based distillery wastewater (spentwash). The 8L reactor was equipped with a submerged 30 microm nylon mesh filter with 0.05 m(2) filtration area. Detailed characterization of the commercial wood charcoal based PAC was performed before using it in the MBR. The MBR was operated over 200 days at organic loading rates (OLRs) varying from 4.2 to 6.9 kg m(-3)d(-1). PAC addition controlled the reactor foaming during start up and enhanced the critical flux by around 23%; it also prolonged the duration between filter cleaning. Operation at higher loading rates was possible and for a given OLR, the chemical oxygen demand (COD) removal was higher with PAC addition. However, biodegradation in the reactor was limited and the high molecular weight compounds were not affected by PAC supplementation. The functional groups on PAC appear to interact with the polysaccharide portion of the sludge, which may reduce its propensity to interact with the nylon mesh. PMID:19467782

  11. Enhancing the adsorption of ionic liquids onto activated carbon by the addition of inorganic salts

    PubMed Central

    Neves, Catarina M. S. S.; Lemus, Jesús; Freire, Mara G.; Palomar, Jose; Coutinho, João A. P.

    2014-01-01

    Most ionic liquids (ILs) are either water soluble or present a non-negligible miscibility with water that may cause some harmful effects upon their release into the environment. Among other methods, adsorption of ILs onto activated carbon (AC) has shown to be an effective technique to remove these compounds from aqueous solutions. However, this method has proved to be viable only for hydrophobic ILs rather than for the hydrophilic that, being water soluble, have a larger tendency for contamination. In this context, an alternative approach using the salting-out ability of inorganic salts is here proposed to enhance the adsorption of hydrophilic ILs onto activated carbon. The effect of the concentrations of Na2SO4 on the adsorption of five ILs onto AC was investigated. A wide range of ILs that allow the inspection of the IL cation family (imidazolium- and pyridinium-based) and the anion nature (accounting for its hydrophilicity and fluorination) through the adsorption onto AC was studied. In general, it is shown that the use of Na2SO4 enhances the adsorption of ILs onto AC. In particular, this effect is highly relevant when dealing with hydrophilic ILs that are those that are actually poorly removed by AC. In addition, the COnductor like Screening MOdel for Real Solvents (COSMO-RS) was used aiming at complementing the experimental data obtained. This work contributes with the development of novel methods to remove ILs from water streams aiming at creating “greener” processes. PMID:25516713

  12. In silico carbon molecular beam epitaxial growth of graphene on the h-BN substrate: carbon source effect on van der Waals epitaxy

    NASA Astrophysics Data System (ADS)

    Lee, Jonghoon; Varshney, Vikas; Park, Jeongho; Farmer, Barry L.; Roy, Ajit K.

    2016-05-01

    Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon molecular beam epitaxy (CMBE) techniques using solid carbon sublimation have reported relatively poor quality of the graphene. In this article, the CMBE growth of graphene on the h-BN substrate is numerically studied in order to identify the effect of the carbon source on the quality of the graphene film. The carbon molecular beam generated by the sublimation of solid carbon source materials such as graphite and glassy carbon is mostly composed of atomic carbon, carbon dimers and carbon trimers. Therefore, the graphene film growth becomes a complex process involving various deposition characteristics of a multitude of carbon entities. Based on the study of surface adsorption and film growth characteristics of these three major carbon entities comprising graphite vapour, we report that carbon trimers convey strong traits of vdW epitaxy prone to high quality graphene growth, while atomic carbon deposition is a surface-reaction limited process accompanied by strong chemisorption. The vdW epitaxial behaviour of carbon trimers is found to be substantial enough to nucleate and develop into graphene like planar films within a nanosecond of high flux growth simulation, while reactive atomic carbons tend to impair the structural integrity of the crystalline h-BN substrate upon deposition to form an amorphous interface between the substrate and the growing carbon film. The content of reactive atomic carbons in the molecular beam is suspected to be the primary cause of low quality graphene reported in the literature. A possible optimization of the molecular beam composition towards the synthesis of better quality graphene films is suggested.Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon

  13. Changing temperature response turned boreal forest from carbon sink into carbon source

    NASA Astrophysics Data System (ADS)

    Grelle, Achim; Hadden, David

    2015-04-01

    19 years of flux measurements reveal that a boreal forest in northern Sweden has turned from a carbon sink into a carbon source. A consistent annual uptake of about 4 tonnes CO2 per hectare turned into annual emissions of the same magnitude within a few years. While biomass increment and gross CO2 uptake remained unchanged, gross respiration has increased, mainly during the autumn periods. This increasingly reduced the annual number of days with net CO2 uptake. No significant trend towards higher temperatures could be observed during the measurement period. However, the temperature responses of ecosystem respiration have changed with time, leading to higher respiration rates in the temperature range between 0 °C and 5 °C, which is the most common range during spring and autumn. Consequently, respiration fluxes under those temperature conditions have increased, both in spring and - even more - in autumn. Thus the change of the carbon balance is not directly caused by climate warming, as stated in other studies, but by changes in ecosystem functioning. The reasons for the rapid change in temperature response are still unknown and may be sought in changes of litterfall and dead wood distribution, changes in fungi- and microbial communities, or hydrological changes.

  14. A study of the effects of an additional sound source on RASS performance

    SciTech Connect

    Coulter, R.L.

    1998-12-31

    The Southern Great Plains (SGP) Cloud and Radiation Testbed (CART) site of the Atmospheric Radiation Measurements (ARM) Program continuously operates a nine panel 915 MHz wind profiler with Radio Acoustic Sounding System (RASS), measuring wind profiles for 50 minutes and virtual temperature profiles for the remaining 10 minutes during each hour. It is well recognized that one of the principal limits on RASS performance is high horizontal wind speed that moves the acoustic wave front sufficiently to prevent the microwave energy produced by the radar and scattered from the acoustic wave from being reflected back t the radar antenna. With this limitation in mind, the ARM program purchased an additional, portable acoustic source that could be mounted on a small trailer and placed in strategic locations to enhance the RASS performance (when it was not being used for spare parts). A test of the resulting improvement in RASS performance was performed during the period 1995--1997.

  15. Styrofoam Debris as a Source of Hazardous Additives for Marine Organisms.

    PubMed

    Jang, Mi; Shim, Won Joon; Han, Gi Myung; Rani, Manviri; Song, Young Kyoung; Hong, Sang Hee

    2016-05-17

    There is growing concern over plastic debris and their fragments as a carrier for hazardous substances in marine ecosystem. The present study was conducted to provide field evidence for the transfer of plastic-associated chemicals to marine organisms. Hexabromocyclododecanes (HBCDs), brominated flame retardants, were recently detected in expanded polystyrene (styrofoam) marine debris. We hypothesized that if styrofoam debris acts as a source of the additives in the marine environment, organisms inhabiting such debris might be directly influenced by them. Here we investigated the characteristics of HBCD accumulation by mussels inhabiting styrofoam. For comparison, mussels inhabiting different substrates, such as high-density polyethylene (HDPE), metal, and rock, were also studied. The high HBCD levels up to 5160 ng/g lipid weight and the γ-HBCD dominated isomeric profiles in mussels inhabiting styrofoam strongly supports the transfer of HBCDs from styrofoam substrate to mussels. Furthermore, microsized styrofoam particles were identified inside mussels, probably originating from their substrates. PMID:27100560

  16. Effect of small additions of carbon nanotubes on the electrical conductivity of polyurethane elastomer

    NASA Astrophysics Data System (ADS)

    Novikov, G. F.; Rabenok, E. V.; Estrin, Ya. I.; Ol'hov, Yu. A.; Badamshina, E. R.

    2014-10-01

    The effect of small (0.002-0.018 wt %) additions of single-walled carbon nanotubes on the dielectric properties and electrical conductivity of crosslinked polyurethane elastomer is studied in the temperature range of 133-453 K and the 10-3 to 105 Hz range of electric field frequencies. It is shown that the dependence of direct current conductivity σ dc on temperature deviates significantly from the Arrhenius dependence and is described by the Vogel-Fulcher-Tamman equation σ dc = σ dc0exp{- DT 0/( T - T 0)}, where T 0 is the Vogel temperature and D is the strength parameter. A correlation is found between the nonmonotonic dependences of the glass transition temperature ( T g), D parameter, and σ dc and the concentration of nanotubes with earlier results for their effects on the physicomechanical characteristics (strength and Young's modulus) of these systems.

  17. Mechanism of wiggling enhancement due to HBr gas addition during amorphous carbon etching

    NASA Astrophysics Data System (ADS)

    Kofuji, Naoyuki; Ishimura, Hiroaki; Kobayashi, Hitoshi; Une, Satoshi

    2015-06-01

    The effect of gas chemistry during etching of an amorphous carbon layer (ACL) on wiggling has been investigated, focusing especially on the changes in residual stress. Although the HBr gas addition reduces critical dimension loss, it enhances the surface stress and therefore increases wiggling. Attenuated total reflectance Fourier transform infrared spectroscopy revealed that the increase in surface stress was caused by hydrogenation of the ACL surface with hydrogen radicals. Three-dimensional (3D) nonlinear finite element method analysis confirmed that the increase in surface stress is large enough to cause the wiggling. These results also suggest that etching with hydrogen compound gases using an ACL mask has high potential to cause the wiggling.

  18. Carbon–carbon bond activation of cyclobutenones enabled by the addition of chiral organocatalyst to ketone

    PubMed Central

    Li, Bao-Sheng; Wang, Yuhuang; Jin, Zhichao; Zheng, Pengcheng; Ganguly, Rakesh; Chi, Yonggui Robin

    2015-01-01

    The activation of carbon–carbon (C–C) bonds is an effective strategy in building functional molecules. The C–C bond activation is typically accomplished via metal catalysis, with which high levels of enantioselectivity are difficult to achieve due to high reactivity of metal catalysts and the metal-bound intermediates. It remains largely unexplored to use organocatalysis for C–C bond activation. Here we describe an organocatalytic activation of C–C bonds through the addition of an NHC to a ketone moiety that initiates a C–C single bond cleavage as a key step to generate an NHC-bound intermediate for chemo- and stereo-selective reactions. This reaction constitutes an asymmetric functionalization of cyclobutenones using organocatalysts via a C–C bond activation process. Structurally diverse and multicyclic compounds could be obtained with high optical purities via an atom and redox economic process. PMID:25652912

  19. Structure and mass transportation model of slow-release organic carbon-source material for groundwater in situ denitrification.

    PubMed

    Zhang, Dayi; Zhou, Guizhong; Zhang, Xu; Wang, Yun; Li, Guanghe

    2015-01-01

    Based on the theories of organic polymer and chemical kinetics, the structure and mass transportation model of slow-release organic carbon-source (SOC) material was developed in this study to reveal and predict the carbon release mechanisms of polymer carbon source, which was feasible for in situ denitrification in nitrate-contaminated groundwater. Composed of polyvinyl alcohol (PVA) and starch, the SOC material formed the interlocking/disperse-phase structure. PVA performed as continuous phase and skeleton, whereas the starch or cellulose behaved as release component. Carbon release process was identified in two stages: solid-phase (inner) and interface (gel layer) diffusion. Solid-phase diffusion was affected by material porous medium parameters, for example, distance between the crosslinking points and starch free energy. The interface diffusion depended mostly on the groundwater dynamics and interface energy distribution. The interface diffusion was found as the limiting step of carbon release process, and the carbon release coefficient corresponded to kD,I as static coefficient and kC,I as dynamic coefficient. As the key indicator to evaluate carbon release capacity, kD,I and kC,I represented appropriate boundary conditions and interface properties. Sensitivity analysis showed that the key parameters of the carbon release model were the distance between the crosslinking points and the free energy of polymer, influenced by regulation of preparation technique, raw material composition and additive dosage. PMID:25342089

  20. Effect of various carbon and nitrogen sources on decolorization of textile dye remazol golden yellow using bacterial species.

    PubMed

    Palanivelan, R; Rajakumar, S; Ayyasamy, P M

    2014-09-01

    Textile dyes with different chemical structures are consistently used in textile industries and they are being recalcitrant xenobiotic in nature. The aim of present research is directed to finding the preference of striking carbon and nitrogen sources on remazol golden yellow decolorization. Bacterial strains were isolated, screened and tested for dye degradation of remazol golden yellow in basal medium amended with different carbon and nitrogen sources. This study was carried out for the period of 12 d at 37 degrees C. Among various carbon and nitrogen sources, starch and yeast extracts promote maximum decolorization in the medium inoculated with Bacillus. sp. (ESL-52). Nevertheless, the rate of decolorization was less in the medium amended with various carbon and nitrogen sources in the presence of Bacillus sp. (TSL-9), Micrococcus sp. (TSL-7), Pseudomonas sp. (M-1) and Staphylococcus sp. (ES-37) respectively. The results clearly showed that addition of significant organic carbon and nitrogen sources are only desirable co-substrates for bacterial dye decolorization process. PMID:25204047

  1. Enhanced biotransformation of carbon tetrachloride by Acetobacterium woodii upon addition of hydroxocobalamin and fructose

    SciTech Connect

    Hashsham, S.A.; Freedman, D.L.

    1999-10-01

    The objective of this study was to evaluate the effect of hydroxocobalamin (OH-Cbl) on transformation of high concentrations of carbon tetrachloride (CT) by Acetobacterium woodii. Complete transformation of 470 {micro}M CT was achieved by A. woodii within 2.5 days, when 10 {micro}M OH-Cbl was added along with 25.2 mM fructose. This was approximately 30 times faster than A. woodii cultures and medium that did not receive OH-Cbl and 5 times faster than those controls that did receive OH-Cbl, but either live A. woodii or fructose was missing. CT transformation in treatments with only OH-Cbl was indicative of the important contribution of nonenzymatic reactions. Besides increasing the rate of CT transformation, addition of fructose and OH-Cbl to live cultures increased the percentage of [{sup 14}C]CT transformed to {sup 14}CO{sub 2} and {sup 14}C-labeled soluble materials, while decreasing the percentage of CT reduced to chloroform and abiotically transformed to carbon disulfide. {sup 14}CS{sub 2} represented more than 35% of the [{sup 14}C]CT in the presence of reduced medium and OH-Cbl. Conversion of CT to CO was a predominant pathway in formation of CO{sub 2} in the presence of live cells and added fructose and OH-Cbl. These results indicate that the rate and distribution of products during cometabolic transformation of CT by A. woodii can be improved by the addition of fructose and OH-Cbl.

  2. Enhanced biotransformation of carbon tetrachloride by Acetobacterium woodii upon addition of hydroxocobalamin and fructose.

    PubMed

    Hashsham, S A; Freedman, D L

    1999-10-01

    The objective of this study was to evaluate the effect of hydroxocobalamin (OH-Cbl) on transformation of high concentrations of carbon tetrachloride (CT) by Acetobacterium woodii (ATCC 29683). Complete transformation of 470 microM (72 mg/liter [aqueous]) CT was achieved by A. woodii within 2.5 days, when 10 microM OH-Cbl was added along with 25.2 mM fructose. This was approximately 30 times faster than A. woodii cultures (live or autoclaved) and medium that did not receive OH-Cbl and 5 times faster than those controls that did receive OH-Cbl, but either live A. woodii or fructose was missing. CT transformation in treatments with only OH-Cbl was indicative of the important contribution of nonenzymatic reactions. Besides increasing the rate of CT transformation, addition of fructose and OH-Cbl to live cultures increased the percentage of [(14)C]CT transformed to (14)CO(2) (up to 31%) and (14)C-labeled soluble materials (principally L-lactate and acetate), while decreasing the percentage of CT reduced to chloroform and abiotically transformed to carbon disulfide. (14)CS(2) represented more than 35% of the [(14)C]CT in the presence of reduced medium and OH-Cbl. Conversion of CT to CO was a predominant pathway in formation of CO(2) in the presence of live cells and added fructose and OH-Cbl. These results indicate that the rate and distribution of products during cometabolic transformation of CT by A. woodii can be improved by the addition of fructose and OH-Cbl. PMID:10508086

  3. Global Transcriptomic Analysis of Desulfovibrio vulgaris Grown on Different Carbon Sources

    SciTech Connect

    Zhang, Weiwen; Culley, David E.; Scholten, Johannes C.; Hogan, Mike; Vitiritti, Luigi; Brockman, Fred J.

    2006-02-01

    Abstract Whole-genome microarrays of Desulfovibrio vulgaris were used to determine relative transcript levels in cells grown to exponential or stationary phase on a minimal medium containing either lactate or formate as electron donor. The results showed that 158 and 477 genes were differentially expressed when comparing exponential to stationary phase in lactate- or formate-based media, respectively; and 505 and 355 genes were responsive to the electron donor used at exponential or stationary phase, respectively. Functional analyses suggested that genes differentially regulated were involved in almost every aspect of cellular metabolism, with the genes involved in protein synthesis, carbon, and energy metabolism being the most regulated. The results suggested that hynAB-1 might function as a primary periplasmic hydrogenase responsible for oxidation of H2 inked to the proton gradient in lactate-based medium, while several periplasmic hydrogenases including hynAB-1 and hyd might carry out this role in formate-based medium. The results also indicated the proton gradient pathway catalyzed by alcohol dehydrogenase and heterodisulfide reductase might be actively functioning for ATP synthesis in D. vulgaris. The possible pathways for ethanol generation from lactate and formate metabolism were also discussed. In addition, hierarchical clustering analysis using expression data across carbon sources and growth phases allowed the identification of the common change specifically associated with the exponential to stationary phase transition, and that specifically associated with the carbon source change from lactate to formate. The study provides the first global description and a functional interpretation of transcriptomic response to growth phase and carbon source in D. vulgaris.

  4. Nitrogen Additions Increase the Diversity of Carbon Compounds Degraded by Fungi in Boreal Forests

    NASA Astrophysics Data System (ADS)

    Gartner, T. B.; Turner, K. M.; Treseder, K. K.

    2004-12-01

    Boreal forest soils in North America harbor a large reservoir of organic C, and this region is increasingly exposed to long-range atmospheric N transport from Eurasia. By examining the responses of decomposers to N deposition in these forests, we hope to improve predictions of the fate of boreal carbon pools under global change. We tested the hypothesis that the functional diversity of decomposer fungi would increase under N fertilization in boreal forests where fungal growth was otherwise N-limited, owing to a reduction in competitive exclusion of fungal groups. We collected soil and leaf litter from three Alaskan sites that represent different successional stages at 5, 17, or 80 years following severe forest fire. Each site had been exposed for two years to nitrogen and phosphorus fertilization in a factorial design, with four plots per treatment. Nutrient limitation of fungal growth varied depending on successional stage. The standing hyphal length of decomposer fungi in soil (i.e. Ascomycota and Basidiomycota) responded to neither N nor P in the 5-year old site, increased under N fertilization in the 17-year old site, and increased where N and P was added simultaneously in the 80-year old site (site x N x P interaction: P = 0.001). We used BIOLOG microplates for filamentous fungi to obtain an index of the diversity of carbon use by decomposer fungi; each of 95 wells of these plates contains a different carbon-based compound, as well as a dye that changes color upon metabolism of the compound. Saline leaf litter extracts were mixed with fungal growth medium and then added to the microplates. The number of wells displaying metabolic activity was counted following incubation for five days. We found that N fertilization raised the average number of positive wells per plate from 14 to 27 (P = 0.012), with no significant differences in responses among sites. Phosphorus additions did not alter functional diversity of fungi in any site. Since increases in functional

  5. Effects of auxiliary carbon sources and electron acceptors on methanogenic degradation of chlorinated phenols

    SciTech Connect

    Haeggblom, M.M.; Rivera, M.D.; Young, L.Y. )

    1993-08-01

    The authors studied the degradation of chlorinated phenols under methanogenic conditions by establishing enrichment cultures on 4-chlorophenol and 2,4-dichlorophenol with or without a supplementary substrate. p-Cresol was chosen as a nonchlorinated aromatic compound structurally similar to the chlorophenols, and propionate was chosen as a readily utilizable carbon source. 2,4-Dichlorophenol was dechlorinated to 4-chlorophenol, which was degraded without further detection of metabolites. The rates of chlorophenols and supplementary substrates. The addition of p-cresol or propionate as an auxiliary carbon source enhanced the rate of 4-chlorophenol degradation. Methanogenic cultures capable of ortho dechlorination were repeatedly subcultured by dilution into fresh media and refeeding of 2,6-dichlorophenol and either p-cresol or propionate as auxiliary substrates. 2,6-Dichlorophenol was sequentially dechlorinated to 2-chlorophenol and phenol and ultimately mineralized to methane and carbon dioxide. Cultures adapted to 2,4- or 2,6-dichlorophenol also readily dechlorinated other dichlorophenols containing an ortho chlorine. The alternative electron acceptors nitrate, sulfite, and thiosulfate completely inhibited dechlorination of 2,6-dichlorophenol, whereas sulfate slowed the dechlorination rate.

  6. Compound specific radiocarbon analyses to apportion sources of combustion products in sedimentary pyrogenic carbon deposits

    NASA Astrophysics Data System (ADS)

    Hanke, Ulrich M.; Schmidt, Michael W. I.; McIntyre, Cameron P.; Reddy, Christopher M.; Wacker, Lukas; Eglinton, Timothy I.

    2016-04-01

    Pyrogenic carbon (PyC) is a collective term for carbon-rich residues comprised of a continuum of products generated during biomass burning and fossil fuel combustion. PyC is a key component of the global carbon cycle due to its slow intrinsic decomposition rate and its ubiquity in the environment. It can originate from natural or anthropogenic vegetation fires, coal mining, energy production, industry and transport. Subsequently, PyC can be transported over long distances by wind and water and can eventually be buried in sediments. Information about the origin of PyC (biomass burning vs. fossil fuel combustion) deposited in estuarine sediments is scarce. We studied the highly anoxic estuarine sediments of the Pettaquamscutt River (Rhode Island, U.S.) in high temporal resolution over 250 years and found different combustion proxies reflect local and regional sources of PyC (Hanke et al. in review; Lima et al. 2003). The polycyclic aromatic hydrocarbons (PAH) originate from long-range atmospheric transport, whereas bulk PyC, detected as benzene polycarboxylic acids (BPCA), mainly stems from local catchment run-off. However, to unambiguously apportion PyC sources, we need additional information, such as compound specific radiocarbon (14C) measurements. We report 14C data for individual BPCA including error analysis and for combustion-related PAH. First results indicate that biomass burning is the main source of PyC deposits, with additional minor contributions from fossil fuel combustion. References Hanke U.M., T.I. Eglinton, A.L.L. Braun, C. Reddy, D.B. Wiedemeier, M.W.I. Schmidt. Decoupled sedimentary records of combustion: causes and implications. In review. Lima, A. L.; Eglinton, T. I.; Reddy, C. M., High-resolution record of pyrogenic polycyclic aromatic hydrocarbon deposition during the 20th century. ES&T, 2003, 37 (1), 53-61.

  7. Preliminary study on preparation of BCNO phosphor particles using citric acid as carbon source

    SciTech Connect

    Nuryadin, Bebeh W.; Pratiwi, Tripuspita; Faryuni, Irfana D.; Iskandar, Ferry Abdullah, Mikrajuddin; Khairurrijal; Ogi, Takashi; Okuyama, Kikuo

    2015-04-16

    A citric acid was used as a carbon source in the preparation of boron carbon oxy-nitride (BCNO) phosphor particles by a facile process. The preparation process was conducted at relatively low temperature 750 °C and at ambient pressure. The prepared BCNO phosphors showed a high photoluminescence (PL) performance at peak emission wavelength of 470 nm under excitation by a UV light 365 nm. The effects of carbon/boron and nitrogen/boron molar ratios on the PL properties were also investigated. The result showed that the emission spectra with a wavelength peak ranging from 444 nm to 496 nm can be obtained by varying carbon/boron ratios from 0.1 to 0.9. In addition, the observations showed that the BCNO phosphor material has two excitation peaks located at the 365 nm (UV) and 420 nm (blue). Based on these observations, we believe that the citric acid derived BCNO phosphor particles can be a promising inexpensive material for phosphor conversion-based white LED.

  8. Anaerobic biogranulation using phenol as the sole carbon source

    SciTech Connect

    Tay, J.H.; He, Y.X.; Yan, Y.G.

    2000-04-01

    The granulation process was extensively examined using phenol as sole carbon source in a 2-L laboratory upflow anaerobic sludge blanket (UASB) reactor. The study was conducted mesophilically at 35 C. Anaerobically digested sludge was used as seed after a 14-day activation period with glucose feed. Massive initial granules were developed after 3 months of startup, grew at an accelerated pace for 6 months, then became fully grown. The granulation process can be broken into three phases: acclimation, granulation, and maturation. However, granulation with phenol proceeded more slowly than it did in UASB reactors fed with readily biodegradable carbohydrates studied previously. The granular sludge cultivated had a median diameter of 1.8 mm, phenol-degrading activity of 0.65 g chemical oxygen demand (COD)/g volatile suspended solids (VSS){sm_bullet}d, and a sludge volume index of 14 mL/g. Phenol COD removal efficiency of 86% was achieved when the reactor was operating at an influent phenol concentration of 1,260 mg/L (corresponding to 3,000 mg COD/L), hydraulic retention time of 12 hours, and volumetric loading rate of 6 g COD/L{sm_bullet}d. However, the lower-than-expected phenol COD removal efficiency could be attributed to inhibition by the high influent phenol concentration or loading. The batch test demonstrated that the sludge methanogenic activity was reduced by 52 and 75% at phenol concentrations of 420 and 840 mg/L, respectively.

  9. Carbon nanotube based field emission X-ray sources

    NASA Astrophysics Data System (ADS)

    Cheng, Yuan

    This dissertation describes the development of field emission (FE) x-ray sources with a carbon-nanotube (CNT) cathode. Field emission x-rays have advantages over conventional x-rays by replacing the thermionic cathode with a cold cathode so that electrons are emitted at room temperature and emission is voltage controllable. CNTs are found to be excellent electron emitters with low threshold fields and high current density which makes them ideal for generate field emission x-rays. Macroscopic CNT cold cathodes are prepared and the parameters to tune their field emission properties are studied: structure and morphology of CNT cathodes, temperature as well as electronic work function of CNT. Macroscopic CNT cathodes with optimized performance are chosen to build a high-resolution x-ray imaging system. The system can readily generate x-ray radiation with continuous variation of temporal resolution up to nanoseconds and spatial resolution down to 10 micron. Its potential applications for dynamic x-ray imaging and micro-computed tomography are also demonstrated. The performance characteristics of this compact and versatile system are promising for non-destructive testing and for non-invasive small-animal imaging for biomedical research.

  10. USE OF STABLE CARBON ISOTOPE RATIOS OF FATTY ACIDS TO EVALUATE MICROBIAL CARBON SOURCES IN TERRESTRIAL ENVIRONMENTS

    EPA Science Inventory

    We use measurements of the concentration and stable carbon isotopic ratio (D 13C) of individual microbial phospholipid fatty acids (PLFAs) in soils as indicators of live microbial biomass levels and microbial carbon source. We found that intensive sugar cane cultivation leads to ...

  11. Young organic matter as a source of carbon dioxide outgassing from Amazonian rivers

    SciTech Connect

    Mayorga, E; Aufdenkampe, A K; Masiello, C A; Krusche, A V; Hedges, J I; Quay, P D; Richey, J E; Brown, T A

    2005-06-23

    Rivers are generally supersaturated with respect to carbon dioxide, resulting in large gas evasion fluxes that can be a significant component of regional net carbon budgets. Amazonian rivers were recently shown to outgas more than ten times the amount of carbon exported to the ocean in the form of total organic carbon or dissolved inorganic carbon. High carbon dioxide concentrations in rivers originate largely from in situ respiration of organic carbon, but little agreement exists about the sources or turnover times of this carbon. Here we present results of an extensive survey of the carbon isotope composition ({sup 13}C and {sup 14}C) of dissolved inorganic carbon and three size-fractions of organic carbon across the Amazonian river system. We find that respiration of contemporary organic matter (less than 5 years old) originating on land and near rivers is the dominant source of excess carbon dioxide that drives outgassing in mid-size to large rivers, although we find that bulk organic carbon fractions transported by these rivers range from tens to thousands of years in age. We therefore suggest that a small, rapidly cycling pool of organic carbon is responsible for the large carbon fluxes from land to water to atmosphere in the humid tropics.

  12. Modulation of the Reactivity of a WO3/Al Energetic Material with Graphitized Carbon Black as Additive

    NASA Astrophysics Data System (ADS)

    Bach, Arnaud; Gibot, Pierre; Vidal, Loïc; Gadiou, Roger; Spitzer, Denis

    2015-10-01

    Although pyrotechnic performance is fundamental, the strong mechanical and electrostatic intrinsic sensitivities of nanothermite energetic composites represent an obstacle to their development. The addition of a ternary component to the classical binary energetic composite appears to be a promising idea to overcome the problem. A carbon black additive (V3G) was used on a WO3/Al nanothermite. The effect of the pristine and modified carbon particles on the mechanical and electrical sensitivities of the composites was measured together with the pyrotechnic properties. The results show a complete desensitization to friction with a ball-milled carbon when the combustion velocity is slightly reduced.

  13. Carbon and nitrogen additions induce distinct priming effects along an organic-matter decay continuum

    PubMed Central

    Qiao, Na; Xu, Xingliang; Hu, Yuehua; Blagodatskaya, Evgenia; Liu, Yongwen; Schaefer, Douglas; Kuzyakov, Yakov

    2016-01-01

    Decomposition of organic matter (OM) in soil, affecting carbon (C) cycling and climate feedbacks, depends on microbial activities driven by C and nitrogen (N) availability. However, it remains unknown how decomposition of various OMs vary across global supplies and ratios of C and N inputs. We examined OM decomposition by incubating four types of OM (leaf litter, wood, organic matter from organic and mineral horizons) from a decay continuum in a subtropical forest at Ailao Mountain, China with labile C and N additions. Decomposition of wood with high C:N decreased for 3.9 to 29% with these additions, while leaf decomposition was accelerated only within a narrow C:N range of added C and N. Decomposition of OM from organic horizon was accelerated by high C:N and suppressed by low C:N, but mineral soil was almost entirely controlled by high C:N. These divergent responses to C and N inputs show that mechanisms for priming (i.e. acceleration or retardation of OM decomposition by labile inputs) vary along this decay continuum. We conclude that besides C:N ratios of OM, those of labile inputs control the OM decay in the litter horizons, while energy (labile C) regulates decomposition in mineral soil. This suggests that OM decomposition can be predicted from its intrinsic C:N ratios and those of labile inputs. PMID:26806914

  14. Carbon and nitrogen additions induce distinct priming effects along an organic-matter decay continuum

    NASA Astrophysics Data System (ADS)

    Qiao, Na; Xu, Xingliang; Hu, Yuehua; Blagodatskaya, Evgenia; Liu, Yongwen; Schaefer, Douglas; Kuzyakov, Yakov

    2016-01-01

    Decomposition of organic matter (OM) in soil, affecting carbon (C) cycling and climate feedbacks, depends on microbial activities driven by C and nitrogen (N) availability. However, it remains unknown how decomposition of various OMs vary across global supplies and ratios of C and N inputs. We examined OM decomposition by incubating four types of OM (leaf litter, wood, organic matter from organic and mineral horizons) from a decay continuum in a subtropical forest at Ailao Mountain, China with labile C and N additions. Decomposition of wood with high C:N decreased for 3.9 to 29% with these additions, while leaf decomposition was accelerated only within a narrow C:N range of added C and N. Decomposition of OM from organic horizon was accelerated by high C:N and suppressed by low C:N, but mineral soil was almost entirely controlled by high C:N. These divergent responses to C and N inputs show that mechanisms for priming (i.e. acceleration or retardation of OM decomposition by labile inputs) vary along this decay continuum. We conclude that besides C:N ratios of OM, those of labile inputs control the OM decay in the litter horizons, while energy (labile C) regulates decomposition in mineral soil. This suggests that OM decomposition can be predicted from its intrinsic C:N ratios and those of labile inputs.

  15. Carbon and nitrogen additions induce distinct priming effects along an organic-matter decay continuum.

    PubMed

    Qiao, Na; Xu, Xingliang; Hu, Yuehua; Blagodatskaya, Evgenia; Liu, Yongwen; Schaefer, Douglas; Kuzyakov, Yakov

    2016-01-01

    Decomposition of organic matter (OM) in soil, affecting carbon (C) cycling and climate feedbacks, depends on microbial activities driven by C and nitrogen (N) availability. However, it remains unknown how decomposition of various OMs vary across global supplies and ratios of C and N inputs. We examined OM decomposition by incubating four types of OM (leaf litter, wood, organic matter from organic and mineral horizons) from a decay continuum in a subtropical forest at Ailao Mountain, China with labile C and N additions. Decomposition of wood with high C:N decreased for 3.9 to 29% with these additions, while leaf decomposition was accelerated only within a narrow C:N range of added C and N. Decomposition of OM from organic horizon was accelerated by high C:N and suppressed by low C:N, but mineral soil was almost entirely controlled by high C:N. These divergent responses to C and N inputs show that mechanisms for priming (i.e. acceleration or retardation of OM decomposition by labile inputs) vary along this decay continuum. We conclude that besides C:N ratios of OM, those of labile inputs control the OM decay in the litter horizons, while energy (labile C) regulates decomposition in mineral soil. This suggests that OM decomposition can be predicted from its intrinsic C:N ratios and those of labile inputs. PMID:26806914

  16. Salt additions alter short-term nitrogen and carbon mobilization in a coastal Oregon Andisol.

    PubMed

    Compton, Jana E; Church, M Robbins

    2011-01-01

    Deposition of sea salts is commonly elevated along the coast relative to inland areas, yet little is known about the effects on terrestrial ecosystem biogeochemistry. We examined the influence of NaCl concentrations on N, C, and P leaching from a coastal Oregon forest Andisol in two laboratory studies: a rapid batch extraction (approximately 1 d) and a month-long incubation using microlysimeters. In the rapid extractions, salt additions immediately mobilized significant amounts of ammonium and phosphate but not nitrate. In the month-long incubations, salt additions at concentrations in the range of coastal precipitation increased nitrate leaching from the microcosms by nearly 50% and reduced the mobility of dissolved organic carbon. Our findings suggest that coupled abiotic-biotic effects increase nitrate mobility in these soils: exchange of sodium for ammonium, then net nitrification. Changes in sea salt deposition to land and the interactions with coastal soils could alter the delivery of N and C to sensitive coastal waters. PMID:21869523

  17. Additive Manufacturing of Multifunctional Components Using High Density Carbon Nanotube Yarn Filaments

    NASA Technical Reports Server (NTRS)

    Gardner, John M.; Sauti, Godfrey; Kim, Jae-Woo; Cano, Roberto J.; Wincheski, Russell A.; Stelter, Christopher J.; Grimsley, Brian W.; Working, Dennis C.; Siochi, Emilie J.

    2016-01-01

    Additive manufacturing allows for design freedom and part complexity not currently attainable using traditional manufacturing technologies. Fused Filament Fabrication (FFF), for example, can yield novel component geometries and functionalities because the method provides a high level of control over material placement and processing conditions. This is achievable by extrusion of a preprocessed filament feedstock material along a predetermined path. However if fabrication of a multifunctional part relies only on conventional filament materials, it will require a different material for each unique functionality printed into the part. Carbon nanotubes (CNTs) are an attractive material for many applications due to their high specific strength as well as good electrical and thermal conductivity. The presence of this set of properties in a single material presents an opportunity to use one material to achieve multifunctionality in an additively manufactured part. This paper describes a recently developed method for processing continuous CNT yarn filaments into three-dimensional articles, and summarizes the mechanical, electrical, and sensing performance of the components fabricated in this way.

  18. Sensitivity of Arctic Permafrost Carbon in the Mackenzie River Basin: A substrate addition and incubation experiment

    NASA Astrophysics Data System (ADS)

    Hedgpeth, A.; Beilman, D.; Crow, S. E.

    2014-12-01

    Arctic soil organic matter (SOM) mineralization processes are fundamental to the functioning of high latitude soils in relation to nutrients, stability, and feedbacks to atmospheric CO2 and climate. The arctic permafrost zone covers 25% of the northern hemisphere and contains 1672Pg of soil carbon (C). 88% of this C currently resides in frozen soils that are vulnerable to environmental change. For instance, arctic growing seasons may be lengthened, resulting in an increase in plant productivity and rate of below ground labile C inputs as root exudates. Understanding controls on Arctic SOM dynamics requires recognition that labile C inputs have the potential to significantly affect mineralization of previously stable SOM, also known as 'priming effects'. We conducted a substrate addition incubation experiment to quantify and compare respiration in highly organic (42-48 %C) permafrost soils along a north-south transect in western Canada. Near surface soils (10-20 cm) were collected from permafrost peatland sites in the Mackenzie River Basin from 69.2-62.6°N. The surface soils are fairly young (Δ14C values > -140.0) and can be assumed to contain relatively reactive soil carbon. To assess whether addition of labile substrate alters SOM decomposition dynamics, 4.77-11.75 g of permafrost soil were spiked with 0.5 mg D-glucose g-1 soil and incubated at 5°C. A mass balance approach was used to determin substrate-induced respiration and preliminary results suggest a potential for positive priming in these C-rich soils. Baseline respiration rates from the three sites were similar (0.067-0.263 mg CO2 g-1 soil C) yet show some site-specific trends. The rate at which added substrate was utilized within these soils suggests that other factors besides temperature and soil C content are controlling substrate consumption and its effect on SOM decomposition. Microbial activity can be stimulated by substrate addition to such an extent that SOM turnover is enhanced, suggesting that

  19. The Effect of Carbon Source and Fluoride Concentrations in the "Streptococcus Mutans" Biofilm Formation

    ERIC Educational Resources Information Center

    Paulino, Tony P.; Andrade, Ricardo O.; Bruschi-Thedei, Giuliana C. M.; Thedei, Geraldo, Jr.; Ciancaglini, Pietro

    2004-01-01

    The main objective of this class experiment is to show the influence of carbon source and of different fluoride concentrations on the biofilm formation by the bacterium "Streptococcus mutans." The observation of different biofilm morphology as a function of carbon source and fluoride concentration allows an interesting discussion regarding the…

  20. Batch fermentation model of propionic acid production by Propionibacterium acidipropionici in different carbon sources.

    PubMed

    Coral, Jefferson; Karp, Susan Grace; Porto de Souza Vandenberghe, Luciana; Parada, José Luis; Pandey, Ashok; Soccol, Carlos Ricardo

    2008-12-01

    Propionic acid (PA) is widely used as additive in animal feed and also in the manufacturing of cellulose-based plastics, herbicides, and perfumes. Salts of propionic acid are used as preservative in food. PA is mainly produced by chemical synthesis. Nowadays, PA production by fermentation of low-cost industrial wastes or renewable sources has been an interesting alternative. In the present investigation, PA production by Propionibacterium acidipropionici ATCC 4965 was studied using a basal medium with sugarcane molasses (BMSM), glycerol or lactate (BML) in small batch fermentation at 30 and 36 degrees C. Bacterial growth was carried out under low dissolved oxygen concentration and without pH control. Results indicated that P. acidipropionici produced more biomass in BMSM than in other media at 30 degrees C (7.55 g l(-1)) as well as at 36 degrees C (3.71 g l(-1)). PA and biomass production were higher at 30 degrees C than at 36 degrees C in all cases studied. The best productivity was obtained by using BML (0.113 g l(-1) h(-1)), although the yielding of this metabolite was higher when using glycerol as carbon source (0.724 g g(-1)) because there was no detection of acetic acid. By the way, when using the other two carbon sources, acetic acid emerged as an undesirable by-product for further PA purification. PMID:18386184

  1. Production of bacterial cellulose using different carbon sources and culture media.

    PubMed

    Mohammadkazemi, Faranak; Azin, Mehrdad; Ashori, Alireza

    2015-03-01

    In this work, the effects of carbon sources and culture media on the production and structural properties of bacterial cellulose (BC) have been studied. BC nanofibers were synthesized using Gluconacetobacter xylinus strain PTCC 1734. Media used were Hestrin-Schramm (H), Yamanaka (Y), and Zhou (Z). Five different carbon sources, namely date syrup, glucose, mannitol, sucrose, and food-grade sucrose were used in these media. All the produced BC pellicles were characterized in terms of dry weight production, biomass yield, thermal stability, crystallinity and morphology by thermogravimetric analysis (TGA), x-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The obtained results showed that mannitol lead to the highest yield, followed by sucrose. The highest production efficiency of mannitol might be due to the nitrogen source, which plays an important role. The maximum improvement on the thermal stability of the composites was achieved when mannitol was used in H medium. In addition, the crystallinity was higher in BC formed in H medium compared to other media. FE-SEM micrographs illustrated that the BC pellicles, synthesized in the culture media H and Z, were stable, unlike those in medium Y that were unstable. The micrographs of BC produced in media containing mannitol and sucrose provided evidence of the strong interfacial adhesion between the BC fibers without noticeable aggregates. PMID:25498666

  2. Mechanism of hydrofluoric acid formation in ethylene carbonate electrolytes with fluorine salt additives

    NASA Astrophysics Data System (ADS)

    Tebbe, Jonathon L.; Fuerst, Thomas F.; Musgrave, Charles B.

    2015-11-01

    We utilized density functional theory to examine HF generation in lithium-ion battery electrolytes from reactions between H2O and the decomposition products of three electrolyte additives: LiPF6, LiPOF4, and LiAsF6. Decomposition of these additives produces PF5, AsF5, and POF3 along with LiF precipitates. We found PF5 and AsF5 react with H2O in two sequential steps to form two HF molecules and POF3 and AsOF3, respectively. PF5 (or AsF5) complexes with H2O and undergoes ligand exchange to form HF and PF4OH (AsF4OH) with an activation barrier of 114.2 (30.5) kJ mol-1 and reaction enthalpy of 14.6 (-11.3) kJ mol-1. The ethylene carbonate (EC) electrolyte forms a Lewis acid-base complex with the PF4OH (AsF4OH) product, reducing the barrier to HF formation. Reactions of POF3 were examined and are not characterized by complexation of POF3 with H2O or EC, while PF5 and AsF5 complex favorably with H2O and EC. HF formation from POF3 occurs with a reaction enthalpy of -3.8 kJ mol-1 and a 157.7 kJ mol-1 barrier, 43.5 kJ mol-1 higher than forming HF from PF5. HF generation in electrolytes employing LiPOF4 should be significantly lower than those using LiPF6 or LiAsF6 and LiPOF4 should be further investigated as an alternative electrolyte additive.

  3. OT2_jalcolea_2: Additional Hpoint observations of large post-AGB sources from HIFIStars

    NASA Astrophysics Data System (ADS)

    Alcolea, J.

    2011-09-01

    One of the most spectacular phases in the evolution of intermediate mass stars takes place at the end of their lives. At the end of the AGB, the central star dashes across the HR diagram from the red giant to the blue dwarf region. At the same time, the spherically symmetric and slowly expanding circumstellar envelopes around AGB stars become planetary nebulae (PNe), displaying a large variety of shapes and structures far more complex. This transformation takes place at the very end of the AGB, and it is due to the interaction of fast and bipolar molecular winds with the fossil AGB circumstellar envelope. The origin of these post-AGB winds is still unclear, but we know that the resulting two-wind interactions are only active during a very short period of time, ~ 100 yr, but still they are able to strongly modify the kinematics of the nebulae and re-shape them. To better understand these processes we must study the warm molecular gas component of early post-AGB sources, both pre-planetary nebulae (pPNe) and young PNe. Herschel/HIFI is very well suited at this, because its spectral coverage, high velocity resolution, and superb sensitivity. For these reasons, 10 pPNe and young PNe were included in the KPGT HIFISTARS, were a large number of spectral lines are observed in a moderate number of frequency setups, but just at the central point. In many cases this is simply enough, since most post-AGB sources in HIFIStars are compact. However there are three cases in which the non spherically symmetric structures seen in the warm gas are larger than the telescope beam: OH231.8+4.2, NGC7027 and NGC6302. Therefore we propose to perform some additional points in these three sources in a selected sample of HIFISTARS frequency setups, were we have detected strong lines of CO, H2O, NH3 and OH. These observations are crucial to understand the kinematics and interactions traced by these warm gas probes, and gain insight in the intricate problem of the post-AGB dynamics.

  4. Carbon flux from plants to soil microbes is highly sensitive to nitrogen addition and biochar amendment

    NASA Astrophysics Data System (ADS)

    Kaiser, C.; Solaiman, Z. M.; Kilburn, M. R.; Clode, P. L.; Fuchslueger, L.; Koranda, M.; Murphy, D. V.

    2012-04-01

    The release of carbon through plant roots to the soil has been recognized as a governing factor for soil microbial community composition and decomposition processes, constituting an important control for ecosystem biogeochemical cycles. Moreover, there is increasing awareness that the flux of recently assimilated carbon from plants to the soil may regulate ecosystem response to environmental change, as the rate of the plant-soil carbon transfer will likely be affected by increased plant C assimilation caused by increasing atmospheric CO2 levels. What has received less attention so far is how sensitive the plant-soil C transfer would be to possible regulations coming from belowground, such as soil N addition or microbial community changes resulting from anthropogenic inputs such as biochar amendments. In this study we investigated the size, rate and sensitivity of the transfer of recently assimilated plant C through the root-soil-mycorrhiza-microbial continuum. Wheat plants associated with arbuscular mycorrhizal fungi were grown in split-boxes which were filled either with soil or a soil-biochar mixture. Each split-box consisted of two compartments separated by a membrane which was penetrable for mycorrhizal hyphae but not for roots. Wheat plants were only grown in one compartment while the other compartment served as an extended soil volume which was only accessible by mycorrhizal hyphae associated with the plant roots. After plants were grown for four weeks we used a double-labeling approach with 13C and 15N in order to investigate interactions between C and N flows in the plant-soil-microorganism system. Plants were subjected to an enriched 13CO2 atmosphere for 8 hours during which 15NH4 was added to a subset of split-boxes to either the root-containing or the root-free compartment. Both, 13C and 15N fluxes through the plant-soil continuum were monitored over 24 hours by stable isotope methods (13C phospho-lipid fatty acids by GC-IRMS, 15N/13C in bulk plant

  5. Investigating effectiveness of activated carbons of natural sources on various supercapacitors

    NASA Astrophysics Data System (ADS)

    Faisal, Md. Shahnewaz Sabit; Rahman, Muhammad M.; Asmatulu, Ramazan

    2016-04-01

    Activated carbon can be produced from natural sources, such as pistachio and acorn shells, which can be an inexpensive and sustainable sources of natural wastes for the energy storage devices, such as supercapacitors. The carbonaceous materials used in this study were carbonized at the temperatures of 700°C and 900°C after the stabilization process at 240°C for two hours. These shells showed approximately 60% carbon yield. Carbonized nutshells were chemically activated using1wt% potassium hydroxide (KOH). Activated carbon powders with polyvinylidene fluoride (PVdF) were used to construct carbon electrodes. A 1M of tetraethylammonium tetrafluoroborate (TEABF4) and propylene carbonate (PC) were used as electrolytes. Electrochemical techniques, such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for the characterization of the supercapacitors. Scanning electron microscopy (SEM) was used to inspect the surface texture of the activated carbons. Activated pistachio shells carbonized at 700°C showed more porous surface texture than those carbonized at 900°C. Effects of the carbonization temperatures were studied for their electrochemical characteristics. The shells carbonized at 700°C showed better electrochemical characteristics compared to those carbonized at 900°C. The test results provided about 27,083 μF/g specific capacitance at a scan rate of 10mV/s. This study showed promising results for using these activated carbons produced from the natural wastes for supercapacitor applications.

  6. Brines as Possible Cation Sources for Biomimetic Carbon Dioxide Sequestration

    NASA Astrophysics Data System (ADS)

    Bond, G. M.; Abel, A.; McPherson, B. J.; Stringer, J.

    2002-12-01

    The utility industry is currently producing 2.1 x 109 tonnes of CO2 per year from burning coal. The amounts of CO2 produced by a single coal-burning station are typically around 0.1 tonnes/MW/h for a coal burn of 0.04 tonnes/MW/h. These large fixed sources of CO2 constitute an obvious target for carbon sequestration to minimize greenhouse-gas emissions. The generally favored approach in present sequestration research is to achieve a CO2 stream that is highly concentrated, compress it, and transport it to geologic sequestration sites, such as deep saline aquifers. The volume of the CO2 is of some interest here. Supercritical CO2, as supplied for example from natural wells to enhanced oil recovery (EOR) sites, has a density of approximately 0.9, and is relatively incompressible, which means that the volume of sequestered supercritical CO2 will be somewhat greater than that of the coal from which it was formed. The volume of water displaced by CO2 injection into aquifers would be closely comparable to the volume of the CO2 itself. An alternative path, which we have been following, would capture the gas as calcium carbonate, CaCO3, in a biomimetic approach that offers some obvious advantages. Sequestration, in this case, is in the form of a safe, stable, environmentally benign product. On a geologic timeframe, considerable amounts of CO2 have been sequestered as, for example, oolitic limestone deposits and dolomite deposits, suggesting that very long-lived or even permanent sequestration is possible in solid carbonate form. Not only would our approach remove the costly steps of concentrating and compressing the CO2, but also it is anticipated that it would remove the need for long-term monitoring to check for CO2 leakage. In a separate collaborative study detailed by Abel and others (this volume), ramifications of geologic sequestration of CO2 and/or bicarbonate-enriched brines are evaluated with laboratory flow experiments and computer model simulations. Porosity and

  7. The open-ocean source of atmospheric carbon monoxide

    NASA Astrophysics Data System (ADS)

    Stubbins, Aron; Uher, Günther; Kitidis, Vassilis; Law, Cliff S.; Upstill-Goddard, Robert C.; Woodward, E. Malcolm S.

    2006-07-01

    Carbon monoxide (CO) atmospheric mixing ratios and surface-water concentrations were determined during Atlantic Meridional Transect cruise number 10, April-May 2000. Atmospheric CO increased from south (mean=74±9 ppbv) to north (mean=151±19 ppbv) with a steep increase around the intertropical convergence zone. Surface-water CO (0.2-2.6 nmol L -1) showed pronounced diurnal variations with afternoon maxima exceeding pre-dawn minima 5-7 fold. Modest regional variations, as indicated by maximum daily CO concentrations, were also observed. Highest CO maxima occurred at ˜11.5°N, where high solar irradiance was combined with elevated coloured dissolved organic matter (CDOM) levels and modest winds, while lowest CO maxima occurred during periods of high winds and lowest solar irradiance near the western European margin at 45°N. Atlantic Ocean CO emissions were estimated to be 1.5±1.1 Tg CO-C yr -1 based on near-instantaneous atmospheric CO, sea-surface CO and windspeeds from the cruise. However, as spatial and temporal variability in both terms was considered to be unique to the timing and path of the cruise, the mean Atlantic diel cycle of sea-surface CO concentration was estimated by pooling all cruise data into 1-h sections, yielding a mean of 0.94 nmol L -1; and diurnal variations from 0.4 to 1.6 nmol L -1. Using the mean diurnal cycle, the Atlantic and global open-ocean sources of CO to the atmosphere were estimated to be 0.9±0.6 and 3.7±2.6 Tg CO-C yr -1, respectively. Therefore it is our contention that IPCC-2001 (Prather, M., Ehhalt, D., Dentener, F., Derwent, R., Dlugokencky, E., Holland, E., Isaksen, I., Katima, J., Kirchhoff, V., Matson, P., Midgley, P., Wang, M., 2001. Chapter 4: Atmospheric chemistry and greenhouse gases. In: Houghton, J.T., Ding, Y., Griggs, D.J., Noguer, M., van der Linden, P.J., Dai, X., Maskell, K., Johnson, C.A. (Eds.), Climate Change 2001: The Scientific Basis. Contribution of working group 1 to the third assessment report of the

  8. North American rivers a sizable source of atmospheric carbon

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2012-04-01

    To fulfill the need for an ever more granular, accurate, and complete understanding of the flow of carbon through the Earth system, a flurry of research has taken place in the past decade on previously overlooked aspects of the carbon cycle. Researchers have investigated the roles of rivers, lakes, and streams in transporting carbon, often with mixed, or only broadly constrained, results. Further, many investigations have traditionally focused on a small number of sites. Although such focused measurements are important for pinning down spatial and temporal changes in the local exchange of carbon, they make expanding the results to broader regions difficult.

  9. The CERN antiproton source: Controls aspects of the additional collector ring and fast sampling devices

    NASA Astrophysics Data System (ADS)

    Chohan, V.

    1990-08-01

    The upgrade of the CERN antiproton source, meant to gain an order of magnitude in antiproton flux, required the construction of an additional ring to complement the existing antiproton accumulator (AA) and an entire rebuild of the target zone. The AA also needed major modifications to handle the increased flux and perform purely as an accumulator, preceded by collection in the collector ring (AC). The upgrade, known as the ACOL (antiproton collector) project, was approved under strict time and budgetary constraints and the existing AA control system, based on the Proton Synchrotron (PS) Divisional norms of CAMAC and Norsk-Data computers, had to be extended in the light of this. The limited (9 months) installation period for the whole upgrade meant that substantial preparatory and planning activities had to be carried out during the normal running of the AA. Advantage was taken of the upgrade to improve and consolidate the AA. Some aspects of the control system related to this upgrade are discussed together with the integration of new applications and instrumentation. The overall machine installation and running-in was carried out within the defined milestones and the project has now achieved the physics design goals.

  10. Carbon Dioxide Capture and Separation Techniques for Gasification-based Power Generation Point Sources

    SciTech Connect

    Pennline, H.W.; Luebke, D.R.; Jones, K.L.; Morsi, B.I.; Heintz, Y.J.; Ilconich, J.B.

    2007-06-01

    The capture/separation step for carbon dioxide (CO2) from large-point sources is a critical one with respect to the technical feasibility and cost of the overall carbon sequestration scenario. For large-point sources, such as those found in power generation, the carbon dioxide capture techniques being investigated by the in-house research area of the National Energy Technology Laboratory possess the potential for improved efficiency and reduced costs as compared to more conventional technologies. The investigated techniques can have wide applications, but the research has focused on capture/separation of carbon dioxide from flue gas (post-combustion from fossil fuel-fired combustors) and from fuel gas (precombustion, such as integrated gasification combined cycle or IGCC). With respect to fuel gas applications, novel concepts are being developed in wet scrubbing with physical absorption; chemical absorption with solid sorbents; and separation by membranes. In one concept, a wet scrubbing technique is being investigated that uses a physical solvent process to remove CO2 from fuel gas of an IGCC system at elevated temperature and pressure. The need to define an ideal solvent has led to the study of the solubility and mass transfer properties of various solvents. Pertaining to another separation technology, fabrication techniques and mechanistic studies for membranes separating CO2 from the fuel gas produced by coal gasification are also being performed. Membranes that consist of CO2-philic ionic liquids encapsulated into a polymeric substrate have been investigated for permeability and selectivity. Finally, dry, regenerable processes based on sorbents are additional techniques for CO2 capture from fuel gas. An overview of these novel techniques is presented along with a research progress status of technologies related to membranes and physical solvents.

  11. Effect of Different Carbon Sources on the Growth of Single-Walled Carbon Nanotube from MCM-41 Containing Nickel

    SciTech Connect

    Chen,Y.; Wang, B.; Li, L.; Yang, Y.; Ciuparu, D.; Lim, S.; Haller, G.; Pfefferle, L.

    2007-01-01

    Chemical vapor deposition growth of single-walled carbon nanotubes (SWCNTs) was studied using three representative carbon source sources: CO, ethanol, and methane, and a catalyst of Ni ions incorporated in MCM-41. The resulting SWCNTs were compared for similar reaction conditions. Carbon deposits were analyzed by multi-excitation wavelength Raman, TGA, TEM and AFM. Catalytic particles in the Ni-MCM-41 catalysts were characterized by TEM and synchrotron light source X-ray absorption spectroscopy. Under similar synthesis conditions, SWCNTs produced from CO had a relatively smaller diameter, while those from ethanol had a larger diameter. Methane could not produce SWCNTs on Ni-MCM-41 under the conditions used in this research. These results demonstrate that three carbon sources affect the dynamic balances between metallic cluster formation and carbon deposition/precipitation on the metallic cluster surface. Controlling SWCNT diameter relies on precisely regulating this dynamic process. Using different carbon sources we are able to shift this dynamic balance and produce SWCNTs with different mean diameters.

  12. The combination of different carbon sources enhances bacterial growth efficiency in aquatic ecosystems.

    PubMed

    Fonte, Ellen S; Amado, André M; Meirelles-Pereira, Frederico; Esteves, Francisco A; Rosado, Alexandre S; Farjalla, Vinicius F

    2013-11-01

    The dissolved organic carbon (DOC) pool is composed of several organic carbon compounds from different carbon sources. Each of these sources may support different bacterial growth rates, but few studies have specifically analyzed the effects of the combination of different carbon sources on bacterial metabolism. In this study, we evaluated the response of several metabolic parameters, including bacterial biomass production (BP), bacterial respiration (BR), bacterial growth efficiency (BGE), and bacterial community structure, on the presence of three DOC sources alone and in combination. We hypothesized that the mixture of different DOC sources would increase the efficiency of carbon use by bacteria (BGE). We established a full-factorial substitutive design (seven treatments) in which the effects of the number and identity of DOC sources on bacterial metabolism were evaluated. We calculated the expected metabolic rates of the combined DOC treatments based on the single-DOC treatments and observed a positive interaction on BP, a negative interaction on BR, and, consequently, a positive interaction on BGE for the combinations. The bacterial community composition appeared to have a minor impact on differences in bacterial metabolism among the treatments. Our data indicate that mixtures of DOC sources result in a more efficient biological use of carbon. This study provides strong evidence that the mixture of different DOC sources is a key factor affecting the role of bacteria in the carbon flux of aquatic ecosystems. PMID:23963223

  13. As-cast uranium-molybdenum based metallic fuel candidates and the effects of carbon addition

    NASA Astrophysics Data System (ADS)

    Blackwood, Van Stephen

    The objective of this research was to develop and recommend a metallic nuclear fuel candidate that lowered the onset temperature of gamma phase formation comparable or better than the uranium-10 wt. pct. molybdenum alloy, offered a solidus temperature as high or higher than uranium-10 wt. pct. zirconium (1250°C), and stabilized the fuel phase against interaction with iron and steel at least as much as uranium-10 wt. pct. zirconium stabilized the fuel phase. Two new as-cast alloy compositions were characterized to assess thermal equilibrium boundaries of the gamma phase field and the effect of carbon addition up to 0.22 wt. pct. The first system investigated was uranium- x wt. pct. M where x ranged between 5-20 wt. pct. M was held at a constant ratio of 50 wt. pct. molybdenum, 43 wt. pct. titanium, and 7 wt. pct. zirconium. The second system investigated was the uranium-molybdenum-tungsten system in the range 90 wt. pct. uranium - 10 wt. pct. molybdenum - 0 wt. pct. tungsten to 80 wt. pct. uranium - 10 wt. pct. molybdenum - 10 wt. pct. tungsten. The results showed that the solidus temperature increased with increased addition of M up to 12.5 wt. pct. for the uranium-M system. Alloy additions of titanium and zirconium were removed from uranium-molybdenum solid solution by carbide formation and segregation. The uranium-molybdenum-tungsten system solidus temperature increased to 1218°C at 2.5 wt. pct. with no significant change in temperature up to 5 wt. pct. tungsten suggesting the solubility limit of tungsten had been reached. Carbides were observed with surrounding areas enriched in both molybdenum and tungsten. The peak solidus temperatures for the alloy systems were roughly the same at 1226°C for the uranium-M system and 1218°C for the uranium-molybdenum-tungsten system. The uranium-molybdenum-tungsten system required less alloy addition to achieve similar solidus temperatures as the uranium-M system.

  14. Glucosamine as carbon source for amino acid-producing Corynebacterium glutamicum.

    PubMed

    Uhde, Andreas; Youn, Jung-Won; Maeda, Tomoya; Clermont, Lina; Matano, Christian; Krämer, Reinhard; Wendisch, Volker F; Seibold, Gerd M; Marin, Kay

    2013-02-01

    Corynebacterium glutamicum grows with a variety of carbohydrates and carbohydrate derivatives as sole carbon sources; however, growth with glucosamine has not yet been reported. We isolated a spontaneous mutant (M4) which is able to grow as fast with glucosamine as with glucose as sole carbon source. Glucosamine also served as a combined source of carbon, energy and nitrogen for the mutant strain. Characterisation of the M4 mutant revealed a significantly increased expression of the nagB gene encoding the glucosamine-6P deaminase NagB involved in degradation of glucosamine, as a consequence of a single mutation in the promoter region of the nagAB-scrB operon. Ectopic nagB overexpression verified that the activity of the NagB enzyme is in fact the growth limiting factor under these conditions. In addition, glucosamine uptake was studied, which proved to be unchanged in the wild-type and M4 mutant strains. Using specific deletion strains, we identified the PTS(Glc) transport system to be responsible for glucosamine uptake in C. glutamicum. The affinity of this uptake system for glucosamine was about 40-fold lower than that for its major substrate glucose. Because of this difference in affinity, glucosamine is efficiently taken up only if external glucose is absent or present at low concentrations. C. glutamicum was also examined for its suitability to use glucosamine as substrate for biotechnological purposes. Upon overexpression of the nagB gene in suitable C. glutamicum producer strains, efficient production of both the amino acid L-lysine and the diamine putrescine from glucosamine was demonstrated. PMID:22854894

  15. Sources and Residence Times of Exported Organic Carbon From High-standing Tropical Island

    NASA Astrophysics Data System (ADS)

    Hemingway, J. D.; Galy, V.; Hilton, R. G.; Hovius, N.

    2015-12-01

    Steep, mountainous rivers draining high standing islands within the ITCZ export a disproportionately high amount of sediment given their small area - up to 20% of global export in 3% of the total exorheic land area. Typhoons strongly influence climate in this region, leading to increased sediment discharge, hyperpycnal flow, and efficient burial of terrestrial particulate organic carbon (POC) in marine sediments. Here, we investigate the exported POC from high-resolution (~hours) sampling on the LiWu River, Taiwan, during three sequential typhoons in 2008 as well as from soil profiles taken throughout the catchment. We utilize the recently developed Ramped Pyrox technique to investigate the chemical structure and isotopic distribution (14C, δ13C) of different OC sources by separating OC components based on thermo-stability. We show that even the most labile OCbio can exhibit protracted storage in soils (up to ca. 2000 14C years), and that soil OC displays a large increase in apparent age with increasing thermal stability, likely due to contribution by microbially re-worked petrogenic carbon. Additionally, exported POCbio is too depleted and POCpetro too enriched in δ13C to be sourced from upper-catchment soil biomass. Rather, exported POC during large storm events can be best explained by a downstream source. Our results therefore offer an updated view on the mechanisms of organic carbon export from steep mountainous rivers by showing that: (i.) high erosion rates do not preclude significant pre-ageing of soil OC and (ii.) exported POC during large storm events is dominated by a local, downstream signal.

  16. Effects of nitrogen additions on above- and belowground carbon dynamics in two tropical forests

    SciTech Connect

    Cusack, D.; Silver, W.L.; Torn, M.S.; McDowell, W.H.

    2011-04-15

    Anthropogenic nitrogen (N) deposition is increasing rapidly in tropical regions, adding N to ecosystems that often have high background N availability. Tropical forests play an important role in the global carbon (C) cycle, yet the effects of N deposition on C cycling in these ecosystems are poorly understood. We used a field N-fertilization experiment in lower and upper elevation tropical rain forests in Puerto Rico to explore the responses of above- and belowground C pools to N addition. As expected, tree stem growth and litterfall productivity did not respond to N fertilization in either of these Nrich forests, indicating a lack of N limitation to net primary productivity (NPP). In contrast, soil C concentrations increased significantly with N fertilization in both forests, leading to larger C stocks in fertilized plots. However, different soil C pools responded to N fertilization differently. Labile (low density) soil C fractions and live fine roots declined with fertilization, while mineral-associated soil C increased in both forests. Decreased soil CO2 fluxes in fertilized plots were correlated with smaller labile soil C pools in the lower elevation forest (R2 = 0.65, p\\0.05), and with lower live fine root biomass in the upper elevation forest (R2 = 0.90, p\\0.05). Our results indicate that soil C storage is sensitive to N deposition in tropical forests, even where plant productivity is not N-limited. The mineral-associated soil C pool has the potential to respond relatively quickly to N additions, and can drive increases in bulk soil C stocks in tropical forests.

  17. High-field properties of carbon-doped MgB2 thin films by hybrid physical-chemical vapor deposition using different carbon sources

    NASA Astrophysics Data System (ADS)

    Dai, Wenqing; Ferrando, V.; Pogrebnyakov, A. V.; Wilke, R. H. T.; Chen, Ke; Weng, Xiaojun; Redwing, Joan; Wung Bark, Chung; Eom, Chang-Beom; Zhu, Y.; Voyles, P. M.; Rickel, Dwight; Betts, J. B.; Mielke, C. H.; Gurevich, A.; Larbalestier, D. C.; Li, Qi; Xi, X. X.

    2011-12-01

    We have studied the high-field properties of carbon-doped MgB2 thin films prepared by hybrid physical-chemical vapor deposition (HPCVD). Carbon doping was accomplished by adding carbon-containing gas, such as bis(methylcyclopentadienyl)magnesium and trimethylboron, into the hydrogen carrier gas during the deposition. In both cases, Tc drops slowly and residual resistivity increases considerably with carbon doping. Both the a and c lattice constants increase with carbon content in the films, a behavior different from that of bulk carbon-doped MgB2 samples. The films heavily doped with trimethylboron show very high parallel Hc2 over 70 T at low temperatures and a large temperature derivative -\\rmd H_{ {c2}}^{\\parallel } /\\rmd T near Tc. These behaviors are found to depend on the unique microstructure of the films, which consists of MgB2 layers a few-nanometers thick separated by non-superconducting MgB2C2 layers. This leads to an increase in the parallel Hc2 by the geometrical effect, which is in addition to the significant enhancement of Hc2 due to changes in the scattering rates within and between the two bands present in films doped using both carbon sources. The high Hc2 and high-field Jc(H) values observed in this work are very promising for the application of MgB2 in high magnetic fields.

  18. Enhancing the effectiveness of silicone thermal grease by the addition of functionalized carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chen, Hongyuan; Wei, Hanxing; Chen, Minghai; Meng, Fancheng; Li, Hongbo; Li, Qingwen

    2013-10-01

    Functionalized carbon nanotubes (CNTs) were introduced into silicone grease to accompany the subsistent metallic oxide particles (micron-sized Al2O3, submicron-sized ZnO) with the aim of enhancing the thermal contact conductance of the composite grease as thermal interface materials (TIMs). The well-dispersed CNTs located among the metallic oxide particles to construct a three dimensional network structure and cooperated with them to form a highly efficient thermal transferring path. The functionalization of CNTs played a key role in achieving a good dispersion of CNTs in silicone grease matrix. The carboxylated CNTs were observed to show better dispersion in silicone grease and weaker reaction with oxide particles than pristine CNTs and amino-functionalized CNTs. Thus the thermal impedance of the silicone grease could be further decreased by 35% (as low as 0.18 cm2 K/W) with the addition of 2 wt.% carboxylated CNTs. Finally, such CNT-modified silicone grease was used to enhance the performance of high-power light emitting diode and showed the prospective applications in TIMs.

  19. Magnetically anisotropic additive for scalable manufacturing of polymer nanocomposite: iron-coated carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yamamoto, Namiko; Manohara, Harish; Platzman, Ellen

    2016-02-01

    Novel nanoparticles additives for polymer nanocomposites were prepared by coating carbon nanotubes (CNTs) with ferromagnetic iron (Fe) layers, so that their micro-structures can be bulk-controlled by external magnetic field application. Application of magnetic fields is a promising, scalable method to deliver bulk amount of nanocomposites while maintaining organized nanoparticle assembly throughout the uncured polymer matrix. In this work, Fe layers (˜18 nm thick) were deposited on CNTs (˜38 nm diameter and ˜50 μm length) to form thin films with high aspect ratio, resulting in a dominance of shape anisotropy and thus high coercivity of ˜50-100 Oe. The Fe-coated CNTs were suspended in water and applied with a weak magnetic field of ˜75 G, and yet preliminary magnetic assembly was confirmed. Our results demonstrate that the fabricated Fe-coated CNTs are magnetically anisotropic and effectively respond to magnetic fields that are ˜103 times smaller than other existing work (˜105 G). We anticipate this work will pave the way for effective property enhancement and bulk application of CNT-polymer nanocomposites, through controlled micro-structure and scalable manufacturing.

  20. Theoretical study of addition reactions of carbene, silylene, and germylene to carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Chu, Ying-Ying; Su, Ming-Der

    2004-08-01

    A theoretical study of the mechanism of the reaction of a single-walled carbon nanotube (SWCNT) with carbene (H 2C), silylene (H 2Si), and germylene (H 2Ge) has been carried out using a two-layered ONIOM(B3LYP/6-311G ∗:PM3) approach. The main findings are as follows: (1) The computational results based on the method used in this work are in good agreement with recent theoretical findings [Angew. Chem. Int. Ed. 41 (2002) 1853]. That is, SWCNTs with H 2C, H 2Si, and H 2Ge addends favor opened structures rather than three-membered rings. (2) The greater the atomic number of the carbene center, the larger the activation energy and the less exothermic (or the more endothermic) the cycloaddition reaction becomes. Therefore, addition to the C dbnd C bond of a SWCNT is more difficult the heavier the carbene center. (3) The theoretical observations suggest that the singlet-triplet splitting of a carbene can be used as a guide to its reactivity during the SWCNT cycloaddition process.

  1. Badlands and the Carbon cycle: a significant source of petrogenic organic carbon in rivers and marine environments?

    NASA Astrophysics Data System (ADS)

    Copard, Yoann; Eyrolle-Boyer, Frederique; Radakovitch, Olivier; Poirel, Alain; Raimbault, Patrick; Lebouteiller, Caroline; Gairoard, Stéphanie; Di-Giovanni, Christian

    2016-04-01

    A key issue in the study of carbon biogeochemical cycle is to well constrain each carbon origin in term of fluxes between all C-reservoirs. From continental surfaces to oceans, rivers convey particulate organic carbon originate from the biomass (biospheric OC) and /or from the sedimentary rocks (petrogenic OC). Existence and importance of this petrogenic OC export to oceans was debated for several decades (see Copard et al., 2007 and ref.), but it is now assumed that 20% of the global carbon export to ocean has a geological origin (Galy et al., 2015). The main current challenge is to constrain the major contributors to this petrogenic OC flux. Amongst the expected sedimentary sources of petrogenic OC in rivers, sedimentary rocks forming badlands can be rightly considered as some viable candidates. Indeed these rocks show a strong erosion rate, may exceed 50 kt km-2 y-1 and in addition, shales, marls and argillaceous rocks, frequently forming badlands (see Nadal-Romero et al., 2011 for the Mediterranean area), contain a significant amount of petrogenic OC (frequently over 0.50 wt. %, Ronov and Yaroshevsky 1976). Our work illustrates the contribution of badlands, mainly distributed within the Durance catchment (a main tributary of the Rhône river), in the petrogenic OC export to the Mediterranean Sea. The approach is based on (i) the use of previous and new data on radiogenic carbon, (ii) bulk organic geochemistry (Rock-Eval pyrolysis), (iii) optical quantification of particulate OM (palynofacies), performed on suspended sediments from the Durance, the Rhône rivers and from small rivers draining the badlands. A mean erosion rate of badlands, previously calculated for instrumented catchments (SOERE Draix-Bléone, Graz et al., 2012) was also applied to the badlands disseminated within the Durance catchment. These different methodologies converge to a petrogenic contribution of the OC export to the Mediterranean Sea close to 30 %. Badlands from the Durance catchment

  2. Solar neutrinos and the influences of opacity, thermal instability, additional neutrino sources, and a central black hole on solar models

    NASA Technical Reports Server (NTRS)

    Stothers, R. B.; Ezer, D.

    1972-01-01

    Significant quantities that affect the internal structure of the sun are examined for factors that reduce the temperature near the sun's center. The four factors discussed are: opacity, central black hole, thermal instability, and additional neutrino sources.

  3. The roles of inoculants' carbon source use in the biocontrol of potato scab disease.

    PubMed

    Sun, Pingping; Zhao, Xinbei; Shangguan, Nini; Chang, Dongwei; Ma, Qing

    2015-04-01

    Despite the application of multiple strains in the biocontrol of plant diseases, multistrain inoculation is still constrained by its inconsistency in the field. Nutrients, especially carbons, play an important role in the biocontrol processes. However, little work has been done on the systematic estimation of inoculants' carbon source use on biocontrol efficacies in vivo. In the present study, 7 nonpathogenic Streptomyces strains alone and in different combinations were inoculated as biocontrol agents against the potato scab disease, under field conditions and greenhouse treatments. The influence of the inoculants' carbon source use properties on biocontrol efficacies was investigated. The results showed that increasing the number of inoculated strains did not necessarily result in greater biocontrol efficacy in vivo. However, single strains with higher growth rates or multiple strains with less carbon source competition had positive effects on the biocontrol efficacies. These findings may shed light on optimizing the consistent biocontrol of plant disease with the consideration of inoculants' carbon source use properties. PMID:25756527

  4. Dissolved black carbon in Antarctic lakes: Chemical signatures of past and present sources

    NASA Astrophysics Data System (ADS)

    Khan, Alia L.; Jaffé, Rudolf; Ding, Yan; McKnight, Diane M.

    2016-06-01

    The perennially ice-covered, closed-basin lakes in the McMurdo Dry Valleys, Antarctica, serve as sentinels for understanding the fate of dissolved black carbon from glacial sources in aquatic ecosystems. Here we show that dissolved black carbon can persist in freshwater and saline surface waters for thousands of years, while preserving the chemical signature of the original source materials. The ancient brines of the lake bottom waters have retained dissolved black carbon with a woody chemical signature, representing long-range transport of black carbon from wildfires. In contrast, the surface waters are enriched in contemporary black carbon from fossil fuel combustion. Comparison of samples collected 25 years apart from the same lake suggests that the enrichment in anthropogenic black carbon is recent. Differences in the chemical composition of dissolved black carbon among the lakes are likely due to biogeochemical processing such as photochemical degradation and sorption on metal oxides.

  5. Artificial stimulation of soil amine production by addition of organic carbon and nitrogen transforming enzymes

    NASA Astrophysics Data System (ADS)

    Kieloaho, Antti-Jussi; Parshintsev, Jevgeni; Riekkola, Marja-Liisa; Kulmala, Markku; Pumpanen, Jukka; Heinonsalo, Jussi

    2013-04-01

    The major part of nitrogen (N) in boreal forest soil is in organic form (Soil Organic Nitrogen, SON). One of the main pathways for amine production is the decay of SON in soil. Amino acids react with specific decarboxylase enzymes which transform them to amines. Amino acid turnover time in forest soil is relatively fast (in hours) because amino acids can be used as N and C source by plants and microbes. Therefore, amino acid production by protease enzymes might be the critical step for amine production and release from forest soil. The aim of the study was to artificially introduce enzymes responsible for protein transformation into amino acids (proteases) as well as soil organic matter (SOM) decomposition (laccase and manganese peroxidase) in order to increase SON transformation and amine synthesis. Glucose addition has been shown to induce natural soil protease activity. Bovine serum albumin (BSA) was used as control protein. Treatments were conducted both in Scots pine seedlings containing as well as non-planted microcosms. N transformations were examined, as well as amine concentration in soil. The experiment consisted of eight different treatments; two as controls concerning enzyme addition, four treatments were planted with one year old nursery grown Scots pine (Pinus sylvestris L.) seedlings and four were non-planted. The experiment lasted approximately six months and the treatments with the additions were conducted within one more month. The protease activity was discovered more commonly after the treatment with protease or glucose additions. In planted BSA-control some natural protease activity was found but not in non-planted controls. Different substrate additions did not cause any differences in total N percentage, but the presence of the seedlings diminished soil N% by approximately 20%. In addition, the same effect was clearly seen in dissolved N, NH4+ and NO3-. Plant has exploited the soluble N forms almost entirely from the system, irrespective of

  6. Enantioselective Assembly of Spirolactones through NHC-Catalyzed Remote γ-Carbon Addition of Enals with Isatins.

    PubMed

    Rong, Xianfeng; Yao, Hong; Xia, Wenjing; Du, Yonglei; Zhou, Yu; Liu, Hong

    2016-05-01

    A chiral N-heterocyclic carbene (NHC)-catalyzed formal [4 + 2] annulation of β-methyl substituted enals with isatins was developed to construct six-membered spirolactones bearing highly congested quaternary carbon stereocentersin good yields and high enantioselectivities. The strategy realized a challenging remote γ-carbon addition of enals and chiral control of β-methyl substituted enals in the presence of the NHC catalyst only. PMID:27029906

  7. Forced and natural carbonation of lime-based mortars with and without additives: Mineralogical and textural changes

    SciTech Connect

    Cultrone, G.

    2005-12-15

    We have studied the carbonation process in different types of mortars, with and without pozzolana or air-entraining additives, subject to a CO{sub 2}-rich atmosphere and compared the results with those of similar naturally carbonated mortars. We used X-ray diffraction technique to demonstrate that high CO{sub 2} concentrations favour a faster, more complete carbonation process with 8 days being sufficient to convert portlandite into 90 wt.% calcite. Full carbonation, however, is not reached during the life-span of the tests, not even in forced carbonation experiments. This could be due to at least one of the following phenomena: a premature drying of samples during carbonation reaction, the temperature at which the carbonation process was carried out or the reduction of pore volume occupied by newly formed calcite crystals. This last option seems to be the least probable. We observed a more prolific development of calcite crystals in the pores and fissures through which the carbonic anhydride flows. Under natural conditions, carbonation is much slower and similar levels are not reached for 6 months. These differences suggest that the carbonation process is influenced by the amount of CO{sub 2} used. Both the mineralogy and texture of mortars vary depending on the type of additive used but the speed of the portlandite-calcite transformation does not change significantly. Pozzolana produces hydraulic mortars although the quantity of calcium aluminosilicate crystals is low. The air-entraining agent significantly alters the texture of the mortars creating rounded pores and eliminating or reducing the drying cracks.

  8. Topsoil organic carbon content of Europe, a new map based on a generalised additive model

    NASA Astrophysics Data System (ADS)

    de Brogniez, Delphine; Ballabio, Cristiano; Stevens, Antoine; Jones, Robert J. A.; Montanarella, Luca; van Wesemael, Bas

    2014-05-01

    There is an increasing demand for up-to-date spatially continuous organic carbon (OC) data for global environment and climatic modeling. Whilst the current map of topsoil organic carbon content for Europe (Jones et al., 2005) was produced by applying expert-knowledge based pedo-transfer rules on large soil mapping units, the aim of this study was to replace it by applying digital soil mapping techniques on the first European harmonised geo-referenced topsoil (0-20 cm) database, which arises from the LUCAS (land use/cover area frame statistical survey) survey. A generalized additive model (GAM) was calibrated on 85% of the dataset (ca. 17 000 soil samples) and a backward stepwise approach selected slope, land cover, temperature, net primary productivity, latitude and longitude as environmental covariates (500 m resolution). The validation of the model (applied on 15% of the dataset), gave an R2 of 0.27. We observed that most organic soils were under-predicted by the model and that soils of Scandinavia were also poorly predicted. The model showed an RMSE of 42 g kg-1 for mineral soils and of 287 g kg-1 for organic soils. The map of predicted OC content showed the lowest values in Mediterranean countries and in croplands across Europe, whereas highest OC content were predicted in wetlands, woodlands and in mountainous areas. The map of standard error of the OC model predictions showed high values in northern latitudes, wetlands, moors and heathlands, whereas low uncertainty was mostly found in croplands. A comparison of our results with the map of Jones et al. (2005) showed a general agreement on the prediction of mineral soils' OC content, most probably because the models use some common covariates, namely land cover and temperature. Our model however failed to predict values of OC content greater than 200 g kg-1, which we explain by the imposed unimodal distribution of our model, whose mean is tilted towards the majority of soils, which are mineral. Finally, average

  9. The influence of polyaspartate additive on the growth and morphology of calcium carbonate crystals

    NASA Astrophysics Data System (ADS)

    Gower, Laurie Anne

    The addition of low levels of polyaspartate to a supersaturated calcium carbonate (CaCOsb3) solution leads to unusual morphologies in the inorganic phase. Spherulitic vaterite aggregates with helical protrusions, and distorted calcite crystals that contain spiral pits, have been produced. The helical particles are coated with an inorganic membrane that appears to be responsible for the helical twist. The polymer also causes deposition of thin CaCOsb3 tablets and films on the glass substrate. Two distinct types of films are deposited; the first is a mosaic of calcite crystals, and the second is spherulitic vaterite. In situ observations of the crystallization reaction have determined that the thin-film morphology is a result of the phase separation of a hydrated CaCOsb3/polymer liquid-precursor, whereby accumulation of isotropic droplets creates a coating on the substrate, and subsequent dehydration and crystallization yields birefringent CaCOsb3 films. During the amorphous to crystalline transition, incremental growth steps lead to "transition bars" and sectored calcite tablets. This in vitro system was originally modeled after certain aspects of CaCOsb3 biomineralization, in which the soluble proteins extracted from biominerals tend to have high levels of aspartic acid residues. Based on the similarities between features exhibited by the products of this system and those in biominerals, an argument has been presented to suggest that this polymer-induced liquid-precursor (PILP) process is involved in the morphogenesis of CaCOsb3 biominerals. These features include the following: thin CaCOsb3 tablets that grow laterally; tablets that express unstable crystallographic faces; non-faceted single crystals with curved surfaces; spatially-delineated single crystals; sectored calcite tablets; hollow-shell spheres; calcium carbonate cements; and magnesium-bearing calcites. This work has demonstrated that a means of morphological control can be accomplished through non

  10. Wetlands as a large carbon source for inland waters

    NASA Astrophysics Data System (ADS)

    Abril, Gwenaël; Martinez, Jean-Michel; Artigas, L. Felipe; Moreira-Turcq, Patricia; Benedetti, Marc F.; Vidal, Luciana; Meziane, Tarik; Kim, Jung-Hyun; Bernardes, Marcelo C.; Deborde, Jonathan; Lima Souza, Edivaldo; Albéric, Patrick; Landim de Souza, Marcelo F.; Roland, Fabio

    2014-05-01

    Recent estimates suggests that up to 3 PgC y-1 could be emitted as CO2 from global inland waters, offsetting the carbon uptake by terrestrial ecosystems. It is generally assumed that inland waters emit carbon previously fixed upstream by land plant photosynthesis and subsequently transported downstream with runoff. But the observed carbon fluxes from first-order streams do not account for all of the CO2 outgassing at the scale of entire watersheds. Three-quarters of the world's flooded land are temporary wetlands. However, the contribution of these productive ecosystems to the inland water carbon budget has been largely overlooked. Based on observations in rivers and floodplains of the central Amazon, we suggest that wetlands pump large amounts of atmospheric CO2 into river waters. Indeed, the magnitude of CO2 outgassing in Amazonian waters is spatially and temporally related to their connection with the semi-aquatic vegetation that performs aerial photosynthesis (Flooded forests and floating macrophytes). These wetlands export half of their gross primary production to waters as dissolved CO2 and organic carbon, compared to only a few percent of gross primary production in upland ecosystems. Global carbon budgets should explicitly address temporary or vegetated flooded areas, as these ecosystems combine high aerial primary production with a large and fast carbon export capacity, potentially supporting a significant fraction of CO2 evasion from inland waters.

  11. Natural sources of greenhouse gases: carbon dioxide emissions from volcanoes

    USGS Publications Warehouse

    Gerlach, Terrence

    1990-01-01

    Volcanic degassing of carbon dioxide plays an important role in keeping the atmosphere-ocean portion of the carbon geochemical cycle in balance. The atmosphere-ocean carbon deficit requires replenishment of 6??1012 mol CO2/yr, and places an upper limit on the output of carbon dioxide from volcanoes. The CO2 output of the global mid-oceanic ridge system is ca. 0.7??1012 mol/yr, thus supplying only a fraction of the amount needed to balance the carbon deficit. The carbon dioxide flux from subaerial volcanoes is poorly known, but it appears to be at least as large as the mid-oceanic ridge flux. Much (perhaps most) of the CO2 emitted from volcanoes is degassed noneruptively. This mode of degassing may lead to impacts on the environment and biosphere that are fundamentally different in character from those envisioned in published scenarios, which are based on the assumption that CO2 degassing occurs predominantly by eruptive processes. Although the flux of carbon dioxide from volcanoes is poorly constrained at present, it is clearly two orders of magnitude lower than the anthropogenic output of CO2.

  12. Multiple Phosphatases Regulate Carbon Source-Dependent Germination and Primary Metabolism in Aspergillus nidulans

    PubMed Central

    de Assis, Leandro José; Ries, Laure Nicolas Annick; Savoldi, Marcela; Dinamarco, Taisa Magnani; Goldman, Gustavo Henrique; Brown, Neil Andrew

    2015-01-01

    Aspergillus nidulans is an important mold and a model system for the study of fungal cell biology. In addition, invasive A. nidulans pulmonary infections are common in humans with chronic granulomatous disease. The morphological and biochemical transition from dormant conidia into active, growing, filamentous hyphae requires the coordination of numerous biosynthetic, developmental, and metabolic processes. The present study exhibited the diversity of roles performed by seven phosphatases in regulating cell cycle, development, and metabolism in response to glucose and alternative carbon sources. The identified phosphatases highlighted the importance of several signaling pathways regulating filamentous growth, the action of the pyruvate dehydrogenase complex as a metabolic switch controlling carbon usage, and the identification of the key function performed by the α-ketoglutarate dehydrogenase during germination. These novel insights into the fundamental roles of numerous phosphatases in germination and carbon sensing have provided new avenues of research into the identification of inhibitors of fungal germination, with implications for the food, feed, and pharmaceutical industries. PMID:25762568

  13. Multiple Phosphatases Regulate Carbon Source-Dependent Germination and Primary Metabolism in Aspergillus nidulans.

    PubMed

    de Assis, Leandro José; Ries, Laure Nicolas Annick; Savoldi, Marcela; Dinamarco, Taisa Magnani; Goldman, Gustavo Henrique; Brown, Neil Andrew

    2015-05-01

    Aspergillus nidulans is an important mold and a model system for the study of fungal cell biology. In addition, invasive A. nidulans pulmonary infections are common in humans with chronic granulomatous disease. The morphological and biochemical transition from dormant conidia into active, growing, filamentous hyphae requires the coordination of numerous biosynthetic, developmental, and metabolic processes. The present study exhibited the diversity of roles performed by seven phosphatases in regulating cell cycle, development, and metabolism in response to glucose and alternative carbon sources. The identified phosphatases highlighted the importance of several signaling pathways regulating filamentous growth, the action of the pyruvate dehydrogenase complex as a metabolic switch controlling carbon usage, and the identification of the key function performed by the α-ketoglutarate dehydrogenase during germination. These novel insights into the fundamental roles of numerous phosphatases in germination and carbon sensing have provided new avenues of research into the identification of inhibitors of fungal germination, with implications for the food, feed, and pharmaceutical industries. PMID:25762568

  14. Sources of dissolved inorganic carbon to the Canada Basin halocline: A multitracer study

    NASA Astrophysics Data System (ADS)

    Brown, Kristina A.; McLaughlin, Fiona; Tortell, Philippe D.; Yamamoto-Kawai, Michiyo; Francois, Roger

    2016-05-01

    We examine the dissolved inorganic carbon maximum in the Canada Basin halocline using a suite of geochemical tracers to gain insight into the factors that contribute to the persistence of this feature. Hydrographic and geochemical samples were collected in the upper 500 m of the southwestern Canada Basin water column in the summer of 2008 and fall of 2009. These observations were used to identify conservative and nonconservative processes that contribute dissolved inorganic carbon to halocline source waters, including shelf sediment organic matter remineralization, air-sea gas exchange, and sea-ice brine export. Our results indicate that the remineralization of organic matter that occurs along the Bering and Chukchi Sea shelves is the overwhelming contributor of dissolved inorganic carbon to Pacific Winter Water that occupies the middle halocline in the southwestern Canada Basin. Nonconservative contributions from air-sea exchange and sea-ice brine are not significant. The broad salinity range associated with the DIC maximum, compared to the narrow salinity range of the nutrient maximum, is due to mixing between Pacific and Atlantic water and not abiotic addition of DIC.

  15. Biosurfactant production by Pseudomonas aeruginosa A41 using palm oil as carbon source.

    PubMed

    Thaniyavarn, Jiraporn; Chongchin, Aree; Wanitsuksombut, Nopparat; Thaniyavarn, Suthep; Pinphanichakarn, Pairoh; Leepipatpiboon, Natthanant; Morikawa, Masaaki; Kanaya, Shigenori

    2006-08-01

    Biosurfactant production by Pseudomonas aeruginosa A41, a strain isolated from seawater in the gulf of Thailand, was examined when grown in defined medium containing 2% vegetable oil or fatty acid as a carbon source in the presence of vitamins, trace elements and 0.4% NH(4)NO(3), at pH 7 and 30 degrees C with 200 rpm-shaking for 7 days. The yield of biosurfactant steadily increased even after a stationary phase. Under such conditions the surface tension of the medium was lowered from 55-70 mN/m to 27.8-30 mN/m with every carbon source tested. However, types of carbon sources were found to affect biosurfactant yield. The yields of rhamnolipid biosurfactant were 6.58 g/L, 2.91 g/L and 2.93 g/L determined as rhamnose content when olive oil, palm oil and coconut oil, respectively, were used as a carbon source. Among them, biosurfactant obtained from palm oil was the best in lowering surface tension of the medium. Increase in biosurfactant activities in terms of oil displacement test and rhamnose content were observed to be higher with shorter chain fatty acids than that of the longer chains (C12>C14>C16). In addition, we found that C18:2, highly unsaturated fatty acid, showed higher oil displacement activity and rhamnose content than that of C18:1. The optimal oil displacement activity was found at pH 7-9 and in the presence of 0.5-3% NaCl. The oil displacement activity was stable to temperatures up to 100 degrees C for 15 h. Surface tension reduction activity was relatively stable at pH 2-12 and 0-5% of NaCl. Emusification activity tested with various types of hydrocarbons and vegetable oils showed similarity of up to 60% stability. The partially purified biosurfactant via TLC and silica gel column chromatography gave three main peaks on HPLC with mass spectra of 527, 272, and 661 m/z respectively, corresponding to sodium-monorhamnodecanoate, hydroxyhexadecanoic acid and an unknown compound, respectively. PMID:17116970

  16. Arylsulfatase in Salmonella typhimurium: detection and influence of carbon source and tyramine on its synthesis.

    PubMed Central

    Henderson, M J; Milazzo, F H

    1979-01-01

    Arylsulfatase synthesis was shown to occur in Salmonella typhimurium LT2. The enzyme had a molecular weight of approximately 50,000 and was separated into five forms by isoelectrofocusing. The optimal pH for substrate hydrolysis was pH 6.7, with Michaelis constants for nitrocatechol sulfate and nitrophenyl sulfate being 4.1 and 7.9 mM, respectively. Enzyme synthesis was strongly influenced by the presence of tyramine in the growth medium. The uptake of [14C]tyramine and arylsulfatase synthesis were initiated during the second phase of a diauxie growth response, when the organism was cultured with different carbon sources. Adenosine 3',5'-cyclic monophosphoric acid enhanced the uptake of tyramine and the levels of arylsulfatase synthesized. However, the addition of glucose and glycerol to organisms actively transporting tyramine and synthesizing enzyme caused a rapid inhibition of both of these processes. This inhibition was not reversed by adding adenosine 3',5'-cyclic monophosphoric acid. The results suggest that the effect of the carbon source on tyramine transport and arylsulfatase synthesis may be explained in terms of inducer exclusion. PMID:222733

  17. Health effects of carbon-containing particulate matter: focus on sources and recent research program results.

    PubMed

    Rohr, Annette; McDonald, Jacob

    2016-02-01

    Air pollution is a complex mixture of gas-, vapor-, and particulate-phase materials comprised of inorganic and organic species. Many of these components have been associated with adverse health effects in epidemiological and toxicological studies, including a broad spectrum of carbonaceous atmospheric components. This paper reviews recent literature on the health impacts of organic aerosols, with a focus on specific sources of organic material; it is not intended to be a comprehensive review of all the available literature. Specific emission sources reviewed include engine emissions, wood/biomass combustion emissions, biogenic emissions and secondary organic aerosol (SOA), resuspended road dust, tire and brake wear, and cooking emissions. In addition, recent findings from large toxicological and epidemiological research programs are reviewed in the context of organic PM, including SPHERES, NPACT, NERC, ACES, and TERESA. A review of the extant literature suggests that there are clear health impacts from emissions containing carbon-containing PM, but difficulty remains in apportioning responses to certain groupings of carbonaceous materials, such as organic and elemental carbon, condensed and gas phases, and primary and secondary material. More focused epidemiological and toxicological studies, including increased characterization of organic materials, would increase understanding of this issue. PMID:26635181

  18. Reduction of nitrous oxide emissions from partial nitrification process by using innovative carbon source (mannitol).

    PubMed

    Zhang, Xinwen; Wang, Xiaoqing; Zhang, Jian; Huang, Xiaoyu; Wei, Dong; Lan, Wei; Hu, Zhen

    2016-10-01

    The purpose of this study was to evaluate the effect of mannitol as carbon source on nitrogen removal and nitrous oxide (N2O) emission during partial nitrification (PN) process. Laboratory-scale PN sequencing batch reactors (SBRs) were operated with mannitol and sodium acetate as carbon sources, respectively. Results showed that mannitol could remarkably reduce N2O-N emission by 41.03%, without influencing the removal efficiency of NH4(+)-N. However, it has a significant influence on nitrite accumulation ratio (NAR) and TN removal, which were 19.97% and 13.59% lower than that in PN with sodium acetate, respectively. Microbial analysis showed that the introduction of mannitol could increase the abundance of bacteria encoding nosZ genes. In addition, anti-oxidant enzymes (T-SOD, POD and CAT) activities were significantly reduced and the dehydrogenase activity had an obvious increase in mannitol system, indicating that mannitol could alleviate the inhibition of N2O reductase (N2OR) activities caused by high NO2(-)-N concentration. PMID:27423546

  19. Plant-Soil Relationships of Bromus tectorum L.: Interactions among Labile Carbon Additions, Soil Invasion Status, and Fertilizer.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasion of western North America by the annual exotic grass Bromus tectorum L. (cheatgrass) has been an ecological disaster. High soil bioavailability of nitrogen is a contributing factor in the invasive potential of B. tectorum. Application of labile carbon sources to the soil can immobilize soil ...

  20. An audit of the global carbon budget: identifying and reducing sources of uncertainty

    NASA Astrophysics Data System (ADS)

    Ballantyne, A. P.; Tans, P. P.; Marland, G.; Stocker, B. D.

    2012-12-01

    Uncertainties in our carbon accounting practices may limit our ability to objectively verify emission reductions on regional scales. Furthermore uncertainties in the global C budget must be reduced to benchmark Earth System Models that incorporate carbon-climate interactions. Here we present an audit of the global C budget where we try to identify sources of uncertainty for major terms in the global C budget. The atmospheric growth rate of CO2 has increased significantly over the last 50 years, while the uncertainty in calculating the global atmospheric growth rate has been reduced from 0.4 ppm/yr to 0.2 ppm/yr (95% confidence). Although we have greatly reduced global CO2 growth rate uncertainties, there remain regions, such as the Southern Hemisphere, Tropics and Arctic, where changes in regional sources/sinks will remain difficult to detect without additional observations. Increases in fossil fuel (FF) emissions are the primary factor driving the increase in global CO2 growth rate; however, our confidence in FF emission estimates has actually gone down. Based on a comparison of multiple estimates, FF emissions have increased from 2.45 ± 0.12 PgC/yr in 1959 to 9.40 ± 0.66 PgC/yr in 2010. Major sources of increasing FF emission uncertainty are increased emissions from emerging economies, such as China and India, as well as subtle differences in accounting practices. Lastly, we evaluate emission estimates from Land Use Change (LUC). Although relative errors in emission estimates from LUC are quite high (2 sigma ~ 50%), LUC emissions have remained fairly constant in recent decades. We evaluate the three commonly used approaches to estimating LUC emissions- Bookkeeping, Satellite Imagery, and Model Simulations- to identify their main sources of error and their ability to detect net emissions from LUC.; Uncertainties in Fossil Fuel Emissions over the last 50 years.

  1. Metabolism of various carbon sources by Azospirillum brasilense.

    PubMed Central

    Westby, C A; Cutshall, D S; Vigil, G V

    1983-01-01

    Azospirillum brasilense Sp7 and two mutants were examined for 19 carbon metabolism enzymes. The results indicate that this nitrogen fixer uses the Entner-Doudoroff pathway for gluconate dissimilation, lacks a catabolic but has an anabolic Embden-Meyerhof-Parnas hexosephosphate pathway, has amphibolic triosephosphate enzymes, lacks a hexose monophosphate shunt, and has lactate dehydrogenase, malate dehydrogenase, and glycerokinase. The mutants are severely deficient in phosphoglycerate and pyruvate kinase and also have somewhat reduced levels of other carbon enzymes. PMID:6417113

  2. Black carbon and carbon monoxide over Bay of Bengal during W_ICARB: Source characteristics

    NASA Astrophysics Data System (ADS)

    Girach, I. A.; Nair, Vijayakumar S.; Babu, S. Suresh; Nair, Prabha R.

    2014-09-01

    The ship borne measurements of near-surface black carbon (BC) and carbon monoxide (CO) were carried out over Bay of Bengal (BoB) during the winter period of 2009 under W_ICARB, the second phase of ‘Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB)'. The CO mixing ratio and BC mass concentration varied in the ranges of 80-480 ppbv and 75-10,000 ng m-3, respectively over this marine region. The BC and CO showed similar variations over northern BoB where airmass from Indo-Gangetic Plain (IGP) region prevailed during the observations period leading to a very strong positive correlation. The association of BC and CO was poor over the eastern and southern part of BoB could be due to the removal of BC aerosols by rain and/or processes of dilution and mixing while transported over to BoB. The highest value of CO observed over eastern BoB was partially due to biomass burning over East Asia. The BC/CO ratio for IGP airmass found to be 20.3 ng m-3 ppb-1 and ∼16 ng m-3 ppb-1 during winter and pre-monsoon, respectively which indicate the role of biomass burning as the source of BC over the region. Based on the emission flux of CO from various inventories and observed BC/CO ratios during pre-monsoon and winter, the BC emission for India is estimated to be in the range of 0.78-1.23 Tg year-1. The analysis of scavenging of BC revealed the loss rate of BC due to relative humidity 0.39 ± 0.08 ng m-3 ppb-1 RH (%)-1 over northern BoB and 0.53 ± 0.04 ng m-3 ppb-1 RH (%)-1 over the southern-BoB during winter.

  3. The effect of oligo(trimethylene carbonate) addition on the stiffness of acrylic bone cement.

    PubMed

    Persson, Cecilia; López, Alejandro; Fathali, Hoda; Hoess, Andreas; Rojas, Ramiro; Ott, Marjam Karlsson; Hilborn, Jöns; Engqvist, Håkan

    2016-01-01

    With the increasing elderly population an increase in the number of bony fractures associated to age-related diseases such as osteoporosis also follows. The relatively high stiffness of the acrylic bone cements used in these patients has been suggested to give raise to a suboptimal load distribution surrounding the cement in vivo, and hence contribute to clinical complications, such as additional fractures. The aim of this study was to develop a low-modulus bone cement, based on currently used, commercially available poly(methyl methacrylate) (PMMA) cements for vertebroplasty. To this end, acrylate end-functionalized oligo(trimethylene carbonate) (oTMC) was incorporated into the cements, and the resulting compressive mechanical properties were evaluated, as well as the cytotoxic and handling properties of selected formulations. Sixteen wt%oTMC was needed in the vertebroplastic cement Osteopal V to achieve an elastic modulus of 1063 MPa (SD 74), which gave a corresponding compressive strength of 46.1 MPa (SD 1.9). Cement extracts taken at 1 and 12 hours gave a reduced MG-63 cell viability in most cases, while extracts taken at 24 hours had no significant effect on cell behavior. The modification also gave an increase in setting time, from 14.7 min (SD 1.7) to 18.0 min (SD 0.9), and a decrease in maximum polymerization temperature, from 41.5°C (SD 3.4) to 30.7°C (SD 1.4). While further evaluation of other relevant properties, such as injectability and in vivo biocompatibility, remains to be done, the results presented herein are promising in terms of approaching clinically applicable bone cements with a lower stiffness. PMID:26727581

  4. The effect of oligo(trimethylene carbonate) addition on the stiffness of acrylic bone cement

    PubMed Central

    Persson, Cecilia; López, Alejandro; Fathali, Hoda; Hoess, Andreas; Rojas, Ramiro; Ott, Marjam Karlsson; Hilborn, Jöns; Engqvist, Håkan

    2016-01-01

    Abstract With the increasing elderly population an increase in the number of bony fractures associated to age-related diseases such as osteoporosis also follows. The relatively high stiffness of the acrylic bone cements used in these patients has been suggested to give raise to a suboptimal load distribution surrounding the cement in vivo, and hence contribute to clinical complications, such as additional fractures. The aim of this study was to develop a low-modulus bone cement, based on currently used, commercially available poly(methyl methacrylate) (PMMA) cements for vertebroplasty. To this end, acrylate end-functionalized oligo(trimethylene carbonate) (oTMC) was incorporated into the cements, and the resulting compressive mechanical properties were evaluated, as well as the cytotoxic and handling properties of selected formulations. Sixteen wt%oTMC was needed in the vertebroplastic cement Osteopal V to achieve an elastic modulus of 1063 MPa (SD 74), which gave a corresponding compressive strength of 46.1 MPa (SD 1.9). Cement extracts taken at 1 and 12 hours gave a reduced MG-63 cell viability in most cases, while extracts taken at 24 hours had no significant effect on cell behavior. The modification also gave an increase in setting time, from 14.7 min (SD 1.7) to 18.0 min (SD 0.9), and a decrease in maximum polymerization temperature, from 41.5°C (SD 3.4) to 30.7°C (SD 1.4). While further evaluation of other relevant properties, such as injectability and in vivo biocompatibility, remains to be done, the results presented herein are promising in terms of approaching clinically applicable bone cements with a lower stiffness. PMID:26727581

  5. Degraded peatlands as a source of riverine organic carbon and enhanced river outgassing in Sumatra, Indonesia

    NASA Astrophysics Data System (ADS)

    Wit, Francisca; Rixen, Tim

    2014-05-01

    Sumatra, Indonesia, is well known for its widespread tropical peat lands. However, silvi- and agricultural purposes are currently inducing large-scale degradation of peat lands, transforming the landscape into mainly palm-oil plantations. The degradation induces loss of carbon via direct CO2 emissions, but also via riverine outflow of dissolved and particulate organic carbon (DOC and POC, respectively) due to leaching. This organic carbon is then decomposed along the way towards the coast and is hypothesized to enhance coastal and river outgassing of CO2. In the framework of SPICE III, Science for the Protection of Indonesian Coastal Ecosystems, we are quantifying these carbon budgets and fluxes in the rivers and coastal areas of northeast Sumatra. Using underway instruments, we have gathered continuous measurements of various parameters, including pCO2, pH, temperature, salinity and oxygen. In addition, water samples were obtained for DOC, POC, δ13CDIC, alkalinity and nutrient analyses. The results of the first analyses show that pCO2 values in the coastal areas range between 400-600 μatm. However, in the vicinity of the rivers pCO2 concentrations increase tremendously, ranging from 600 near the estuaries to a staggering 9000 μatm further upstream. These values are much higher than the marine pCO2 value of 390 μatm in the South China Sea. When adding carbon isotope results into the story, while knowing that upstream river life is greatly reduced due to oxygen depletion as a result of high DOC decomposition, it appears to be clear from the values, which range between -20 to -24‰ δ13CDIC, that the main source of the organic carbon is indeed originating from the degrading peat lands. In conclusion, our hypothesis can be deemed correct: degrading peat lands enhance organic carbon outflow and therefore elevated decomposition in the rivers, which results in increased river outgassing of CO2. Further analyses will be conducted to precisely quantify the budgets and

  6. Mass spectrometry of refractory black carbon particles from six sources: carbon-cluster and oxygenated ions

    NASA Astrophysics Data System (ADS)

    Corbin, J. C.; Sierau, B.; Gysel, M.; Laborde, M.; Keller, A.; Kim, J.; Petzold, A.; Onasch, T. B.; Lohmann, U.; Mensah, A. A.

    2014-03-01

    We discuss the major mass spectral features of different types of refractory carbonaceous particles, ionized after laser vaporization with an Aerodyne high-resolution soot-particle aerosol mass spectrometer (SP-AMS). The SP-AMS was operated with a switchable 1064 nm laser and a 600 °C thermal vaporizer, yielding respective measurements of the refractory and non-refractory particle components. Six samples were investigated, all of which were composed primarily of refractory material: fuel-rich and fuel-lean propane/air diffusion-flame combustion particles; graphite-spark-generated particles; a commercial fullerene-enriched soot; Regal Black, a commercial carbon black; and nascent aircraft-turbine combustion particles. All samples exhibited a spectrum of carbon-cluster ions Cxn+ in their refractory mass spectrum. Smaller clusters (x < 6) were found to dominate the Cxn+ distribution. For fullerene soot, fuel-rich-flame particles and spark-generated particles, significant Cxn+ clusters at x ≫ 6 were present, with significant contributions from multiply charged ions (n > 1). In all six cases, the ions C1+ and C3+ contributed over 60% to the total C1 5 were present. When such signals were present, C1+ / C3+ was close to 1. When absent, C1+ / C3+ was < 0.8. This ratio may therefore serve as a proxy to distinguish between the two types of spectra in atmospheric SP-AMS measurements. Significant refractory oxygenated ions such as CO+ and CO2+ were also observed for all samples. We discuss these signals in detail for Regal Black, and describe their formation via decomposition of oxygenated moieties incorporated into the refractory carbon structure. These species may be of importance in atmospheric processes such as water uptake and heterogeneous chemistry. If atmospherically stable, these oxidized species may be useful for distinguishing

  7. Regulation of Soil Microbial Carbon-use Efficiency by Soil Moisture, Substrate Addition, and Incubation Time

    NASA Astrophysics Data System (ADS)

    Stark, J.

    2015-12-01

    Microbial carbon-use efficiency (CUE) is a key variable in biogeochemical cycling that regulates soil C sequestration, greenhouse gas emissions, and retention of inorganic nutrients. Microbial CUE is the fraction of C converted to biomass rather than respired as CO2. Biogeochemical models have been shown to be highly sensitive to variation in CUE; however, we currently have a poor understanding of how CUE responds to environmental variables such as soil moisture and nutrient limitations. We examined the effect of soil moisture and C supply on CUE in soil from a western hemlock / sitka spruce forest in Oregon, USA, using a novel technique which supplies 13C and 15N substrates through the gas phase so that water addition is not necessary. Soil samples (28 g oven-dry equiv. wt) at two water potentials (-0.03 and -3.55 MPa) were exposed to 13C-acetic acid vapor for either 6 or 30 sec to provide two different concentrations of acetate to soil microbial communities. The soils were also injected with small amounts of 15NH3 gas to allow quantification of microbial N assimilation rates and to provide an alternate method of calculating CUE. Rates of 13CO2 respiration were measured continuously during a 48-h incubation using cavity ring-down spectroscopy. Soil samples were extracted at seven time intervals (0, 0.5, 1.5, 4.5, 12, 24, and 48 h) in 0.5 M K2SO4 and analyzed for DO13C, microbial 13C, DO15N, inorganic 15N, and microbial 15N to calculate how gross rates of C and N assimilation and microbial CUE change with incubation time. As expected, microbial C and N assimilation rates and CUE increased with soil moisture and the quantity of acetate added; however, C:N assimilated was higher at lower soil moisture, suggesting that either C-storage compounds were being created, or that fungal communities were responsible for a greater proportion of the assimilation in drier soils. Assimilation rates and CUE also changed with incubation time, demonstrating that estimates of CUE

  8. Metabolomics reveals differences of metal toxicity in cultures of Pseudomonas pseudoalcaligenes KF707 grown on different carbon sources

    PubMed Central

    Booth, Sean C.; Weljie, Aalim M.; Turner, Raymond J.

    2015-01-01

    Co-contamination of metals and organic pollutants is a global problem as metals interfere with the metabolism of complex organics by bacteria. Based on a prior observation that metal tolerance was altered by the sole carbon source being used for growth, we sought to understand how metal toxicity specifically affects bacteria using an organic pollutant as their sole carbon source. To this end metabolomics was used to compare cultures of Pseudomonas pseudoalcaligenes KF707 grown on either biphenyl (Bp) or succinate (Sc) as the sole carbon source in the presence of either aluminum (Al) or copper (Cu). Using multivariate statistical analysis it was found that the metals caused perturbations to more cellular processes in the cultures grown on Bp than those grown on Sc. Al induced many changes that were indicative of increased oxidative stress as metabolites involved in DNA damage and protection, the Krebs cycle and anti-oxidant production were altered. Cu also caused metabolic changes that were indicative of similar stress, as well as appearing to disrupt other key enzymes such as fumarase. Additionally, both metals caused the accumulation of Bp degradation intermediates indicating that they interfered with Bp metabolism. Together these results provide a basic understanding of how metal toxicity specifically affects bacteria at a biochemical level during the degradation of an organic pollutant and implicate the catabolism of this carbon source as a major factor that exacerbates metal toxicity. PMID:26347721

  9. Electron optics simulation for designing carbon nanotube based field emission x-ray source

    NASA Astrophysics Data System (ADS)

    Sultana, Shabana

    In this dissertation, electron optics simulation for designing carbon nanotube (CNT) based field emission x-ray source for medical imaging applications will be presented. However, for design optimization of x-ray tubes accurate electron beam optics simulation is essential. To facilitate design of CNT x-ray sources a commercial 3D finite element software has been chosen for extensive simulation. The results show that a simplified model of uniform electron field emission from the cathode surface is not sufficient when compared to experimental measurements. This necessitated the development of a refined model to describe a macroscopic field emission CNT cathode for electron beam optics simulations. The model emulates the random distribution of CNTs and the associated variation of local field enhancement factor. The main parameter of the model has been derived empirically from the experimentally measured I-V characteristics of the CNT cathode. Simulation results based on this model agree well with experiments which include measurements of the transmission rate and focus spot size. The model provides a consistent simulation platform for optimization of electron beam optics in CNT x-ray source design. A systematic study of electron beam optics in CNT x-ray tubes led to the development of a new generation of compact x-ray source with multiple pixels. A micro focus field emission x-ray source with a variable focal spot size has been fully characterized and evaluated. It has been built and successfully integrated into micro-CT scanners which are capable of dynamic cardiac imaging of free-breathing small animals with high spatial and temporal resolutions. In addition a spatially distributed high power multi-beam x-ray source has also been designed and integrated into a stationary digital breast tomosynthesis (s-DBT) configuration. This system has the potential to reduce the total scan time to 4 seconds and yield superior image quality in breast imaging.

  10. Sources of greenhouse gases and carbon monoxide in central London (UK)

    NASA Astrophysics Data System (ADS)

    Helfter, Carole; Tremper, Anja; Zazzeri, Giulia; Barlow, Janet F.; Nemitz, Eiko

    2015-04-01

    Biosphere-atmosphere exchange of carbon dioxide (CO2) has been on the scientific agenda for several decades and new technology now also allows for high-precision, continuous monitoring of fluxes of methane (CH4) and nitrous oxide (N2O). Compared to the natural environment, flux measurements in the urban environment, which is home to over 50% of the population globally, are still rare despite high densities of anthropogenic sources of pollutants. We report on over three years of measurements atop a 192 m tower in central London (UK), Europe's largest city, which started in October 2011. Fluxes of methane, carbon monoxide (CO) and carbon dioxide are measured by eddy-covariance (EC) at the British Telecom tower (51° 31' 17.4' N 0° 8' 20.04' W). In addition to the long-term measurements, EC fluxes of nitrous oxide (N2O) were measured in February 2014. All four trace gases exhibit diurnal trends consistent with anthropogenic activities with minimum emissions at night and early afternoon maxima. Segregating emissions by wind direction reveals heterogeneous source distributions with temporal patterns and source strengths that differ between compounds. The lowest emissions for CO, CO2 and CH4 were recorded for NW winds. The highest emissions of methane were in the SE sector, in the NE for CO2 and in the W for CO. Fluxes of all 3 gases exhibited marked seasonal trends characterised by a decrease in emissions in summer (63% reduction for CO, 36% for CO2 and 22% for CH4). Monthly fluxes of CO and CO2 were linearly correlated to air temperature (R2 = 0.7 and 0.59 respectively); a weaker dependence upon temperature was also observed for CH4 (R2 = 0.31). Diurnal and seasonal emissions of CO and CO2 are mainly controlled by local fossil fuel combustion and vehicle cold starts are thought to account for 20-30% of additional emissions of CO during the winter. Fugitive emissions of CH4 from the natural gas distribution network are thought to be substantial, which is consistent

  11. Carbon monoxide exposures from propane-powered floor burnishers following addition of emissions controls

    SciTech Connect

    Demer, F.R.

    1998-11-01

    Previous published work by this author suggests that propane-powered floor burnisher use represents a potentially serious health hazard from carbon monoxide exposures, particularly for susceptible individuals. This earlier study was repeated using burnishers retrofitted with emission controls consisting of self-aspirating catalytic mufflers and computerized air/fuel monitors and alarms. Real-time carbon monoxide detectors with data-logging capabilities were placed on the burnishers in the breathing zones of operators during burnisher use. Carbon monoxide levels were recorded every 30 seconds. Ventilation and physical characteristics of the spaces of burnisher use were characterized, as were burnisher maintenance practices. Thirteen burnishing events were monitored under conditions comparable to previously published monitoring. All carbon monoxide exposures were well below even the most conservative recommended limits from the American Conference of Governmental Industrial Hygienists. Potential failures of the emission controls were also identified and included air filter blockage, spark plug malfunction, and faulty alarm function design.

  12. Novel molecular sources for dispersing boron in carbon-carbon composites. Final report, 8 September 1992-7 September 1994

    SciTech Connect

    Chen, P.S.; Stevens, W.C.

    1993-11-07

    Improving the oxidation resistance of carbon-carbon composites is key to extending the applications of this material system into higher temperature regimes. While molecularly dispersed boron, through addition of carborane, helps to provide oxidation protection to phenolic derived carbon, the moisture affinity of the boria seriously affects composite performance. Substitution of furfuryl and pitch as the resin precursors significantly improved the moisture resistance of the carbon matrix material by stabilizing the boron at low temperatures and minimizing premature boria formation. Carborane addition to a commercial furfuryl/pitch blend (Kaiser Code88A) yielded a carbon char with reduced moisture affinity and improved oxidation resistance. Mechanical properties of the Code88A matrix composites were not significantly affected by the addition of carborane. Although sample size limitations in testing detracted from the demonstration of success, data suggests that the oxidation resistance of carbon-carbons can be significantly enhanced via this approach without detriment to the physical attributes and moisture resistance of the composite.

  13. Food sources and carbon dudget of chinese prawn Penaeus chinensis

    NASA Astrophysics Data System (ADS)

    Dong, Shuang-Lin; Zhang, Shuo; Wang, Fang

    2002-03-01

    This study deals with contribution of artificial food pellet and natural food to Chinese prawn ( Penaeus orientalis) growth in a semi-intensive culture pond. The prawn carbon consumption, budget, and the effects of some factors on the budget were investigated. The results showed that 26.2% of P. orientalis growth carbon came from formulated feed at the initial culture stage (when the prawns were 0.06±0.01 g in wet weight), and was 62.5% when the prawns were 9.56±1.04 g. The remaining part of the growth carbon was derived from organic fertilizer and natural food. The highest growth rate occurred at 20×10-3 salinity. Suitable salinity for culturing Chinese prawn was (20 28)×10-3.

  14. Sources and Transformations of Carbon and Nitrogen in the Potomac River Estuary

    NASA Astrophysics Data System (ADS)

    Pennino, M. J.; Kaushal, S.; Murthy, S.

    2011-12-01

    , but more protein-like organic matter is present below the treatment plant. However, this fluorescence signal from wastewater organic matter disappears within 2-4 km downriver, indicating rapid processing of the labile organic matter within the river. Nitrate isotope data for both upriver and downriver samples show a signal from manure or sewage inputs, indicating a potential influence from animal farms upstream in the Potomac. However, only the downriver samples show evidence for denitrification. Additionally, the higher 15N isotope levels of nitrate, which are characteristic of wastewater sources, disappear by 20 km downriver. Majors rivers like the Potomac may have a huge capacity for transforming and processing large carbon and nitrogen inputs within a short distance. Greater knowledge of how land management and climate change impacts these transformations will be important in predicting changes in the amounts, forms, and stoichiometry of nutrient loads to coastal waters.

  15. Review: role of carbon sources for in vitro plant growth and development.

    PubMed

    Yaseen, Mehwish; Ahmad, Touqeer; Sablok, Gaurav; Standardi, Alvaro; Hafiz, Ishfaq Ahmad

    2013-04-01

    In vitro plant cells, tissues and organ cultures are not fully autotrophic establishing a need for carbohydrates in culture media to maintain the osmotic potential, as well as to serve as energy and carbon sources for developmental processes including shoot proliferation, root induction as well as emission, embryogenesis and organogenesis, which are highly energy demanding developmental processes in plant biology. A variety of carbon sources (both reducing and non-reducing) are used in culture media depending upon genotypes and specific stages of growth. However, sucrose is most widely used as a major transport-sugar in the phloem sap of many plants. In micropropagation systems, morphogenetic potential of plant tissues can greatly be manipulated by varying type and concentration of carbon sources. The present article reviews the past and current findings on carbon sources and their sustainable utilization for in vitro plant tissue culture to achieve better growth rate and development. PMID:23212616

  16. Quasi-steady carbon plasma source for neutral beam injector

    NASA Astrophysics Data System (ADS)

    Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y.

    2014-02-01

    Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ˜3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.

  17. Quasi-steady carbon plasma source for neutral beam injector.

    PubMed

    Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

    2014-02-01

    Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration. PMID:24593646

  18. Quasi-steady carbon plasma source for neutral beam injector

    SciTech Connect

    Koguchi, H. Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y.

    2014-02-15

    Carbon plasma is successfully sustained during 1000 s without any carrier gas in the bucket type ionization chamber with cusp magnetic field. Every several seconds, seed plasmas having ∼3 ms duration time are injected into the ionization chamber by a shunting arch plasma gun. The weakly ionized carbon plasma ejected from the shunting arch is also ionized by 2.45 GHz microwave at the electron cyclotron resonance surface and the plasma can be sustained even in the interval of gun discharges. Control of the gun discharge interval allows to keep high pressure and to sustain the plasma for long duration.

  19. Laboratory Evaluation of Selected Ways for Determining Black Carbon Source Emissions

    EPA Science Inventory

    A number of studies have been conducted which compare various methods for the determination of black carbon in the atmosphere. Relatively little attention has been paid, however, to similar measurements of black carbon from different types of emission sources. Of particular int...

  20. Soil carbon sequestration in semi-arid soil through the addition of fuel gas desulfurization gypsum (FGDG)

    NASA Astrophysics Data System (ADS)

    Han, Young-Soo; Tokunaga, Tetsu; Oh, Chamteut

    2014-05-01

    This study investigated a new strategy for increasing carbon retention in slightly alkaline soils through addition of fuel gas desulfurization gypsum (FGDG, CaSO4•2H2O). FGDG is moderately soluble and thus the FGDG amendment may be effective to reduce microbial respiration, to accelerate calcite (CaCO3) precipitation, and to promote soil organic carbon (SOC) complexation on mineral surfaces, but rates of these processes need to be understood. The effects of FGDG addition were tested in laboratory soil columns with and without FGDG-amended layers, and in greenhouse soil columns planted with switchgrass, a biofuel crop. The results of laboratory column experiments demonstrated that additions of FGDG promote soil carbon sequestration through suppressing microbial respiration to the extent of ~200 g per m2 soil per m of supplied water, and promoting calcite precipitation at similar rates. The greenhouse experiments showed that the FGDG treatments did not adversely affect biomass yield (~600 g dry biomass/m2/harvest) at the higher irrigation rate (50 cm/year), but substantially reduced recoverable biomass under the more water-limited conditions (irrigation rate = 20 cm/year). The main achievements of this study are (1) the identification of conditions in which inorganic and organic carbon sequestration is practical in semi-arid and arid soils, (2) development of a method for measuring the total carbon balance in unsaturated soil columns, and (3) the quantification of different pathways for soil carbon sequestration in response to FGDG amendments. These findings provide information for evaluating land use practices for increased soil carbon sequestration under semi-arid region biofuel crop production.

  1. Heterotrophic growth of Neochloris oleoabundans using glucose as a carbon source

    PubMed Central

    2013-01-01

    Background In comparison with phototrophic growth, heterotrophic conditions can significantly increase growth rates, final cell number and cell mass in microalgae cultures. Neochloris oleoabundans is a microalga of biotechnological interest that accumulates lipids under phototrophic and nitrogen-limited conditions. Heterotrophic flask culture experiments were conducted to identify carbon sources that can be metabolized by N. oleoabundans, and bioreactor batch and fed-batch (nitrate pulse additions) cultures supplemented with glucose were performed to study the cellular composition of the microalgae under balanced and high C/N ratios (glucose/nitrate). Results N. oleoabundans was able to grow using glucose and cellobiose as sole carbon sources under strict heterotrophic conditions. Under a balanced C/N ratio of 17 and using bioreactor batch cultures containing 3 g/L glucose, a maximal cell mass of 1.72 g/L was found, with protein being the major cell component (44% w/w). A maximal cell mass of 9.2 g/L was obtained using batch cultures at a C/N ratio of 278. Under these conditions, lipid accumulation was promoted (up to 52% w/w) through N-limitation, resulting in high lipid productivity (528.5 mg/L/day). Fed-batch cultures were performed at a C/N ratio of 278 and with nitrate pulse additions. This condition allowed a maximal cell mass of 14.2 g/L to be achieved and switched the metabolism to carbohydrate synthesis (up to 54% of dry weight), mainly in the form of starch. It was found that transmembrane transport under these conditions was dependent on a proton-motive force, indicating that glucose is transported by a symporter. Conclusions N. oleoabundans was able to grow under strict heterotrophic culture conditions with glucose or cellobiose as the only carbon source. The glucose used is transported by a symporter system. Batch cultures with a balanced C/N ratio accumulate proteins as the major cellular component; a high C/N ratio significantly increased the

  2. Antifungal activity of clotrimazole against Candida albicans depends on carbon sources, growth phase and morphology.

    PubMed

    Kasper, Lydia; Miramón, Pedro; Jablonowski, Nadja; Wisgott, Stephanie; Wilson, Duncan; Brunke, Sascha; Hube, Bernhard

    2015-07-01

    Vulvovaginal candidiasis, a superficial infection caused predominantly by the pathogenic fungus Candida albicans, is frequently treated with clotrimazole. Some drug formulations contain lactate for improved solubility. Lactate may modify C. albicans physiology and drug sensitivity by serving as a carbon source for the fungus and/or affecting local pH. Here, we explored the effects of lactate, in combination with pH changes, on C. albicans proliferation, morphology and clotrimazole sensitivity. Moreover, we determined the influence of growth phase and morphology per se on drug sensitivity. We showed that utilization of lactate as a carbon source did not promote fast fungal proliferation or filamentation. Lactate had no influence on clotrimazole-mediated killing of C. albicans in standard fungal cultivation medium but had an additive effect on the fungicidal clotrimazole action under in vitro vagina-simulative conditions. Moreover, clotrimazole-mediated killing was growth-phase and morphology dependent. Post-exponential cells were resistant to the fungicidal action of clotrimazole, whilst logarithmic cells were sensitive, and hyphae showed the highest susceptibility. Finally, we showed that treatment of pre-formed C. albicans hyphae with sublethal concentrations of clotrimazole induced a reversion to yeast-phase growth. As C. albicans hyphae are considered the pathogenic morphology during mucosal infections, these data suggest that elevated fungicidal activity of clotrimazole against hyphae plus clotrimazole-induced hyphae-to-yeast reversion may help to dampen acute vaginal infections by reducing the relative proportion of hyphae and thus shifting to a non-invasive commensal-like population. In addition, lactate as an ingredient of clotrimazole formulations may potentiate clotrimazole killing of C. albicans in the vaginal microenvironment. PMID:25976001

  3. [Utilization of carbon sources by Fusarium poae (Peck) Wollenw. Strains from different trophic groups].

    PubMed

    Kurchenko, I N; Vasilevskaia, A I; Artyshkova, L V; Nakonechnaia, L T; Iur'eva, E M

    2013-01-01

    It was shown that saprophytic (soil), endophytic and plant pathogenic strains of F. poae under cultivation conditions in the media containing carbon sources from mono- to polysaccharides had different abilities to use them and to accumulate biomass. Maltose, xylose, fructose, pectin were the most favorable carbon sources for the studied strains; less assimilated lactose, arabinose, and especially microcrystalline cellulose were less assimilated. It was found that endophytes and plant pathogens accumulated biomass equally, while soil strains had low ability for that. PMID:23516841

  4. [Spatiotemporal pattern of carbon sources and sinks in Yangtze River Delta region, China].

    PubMed

    Yi, Bai-lu; Han, Ji; Zhou, Xiang; Yang, Fang; Meng, Xing; Cao, Wu-xing; Huang, Lu-xia; Xiang, Wei-ning

    2015-04-01

    Yangtze River Delta region is the world's sixth and China's largest urban agglomeration. Its rapid and massive urbanization has also caused a series of ecological and environmental impacts. This paper accounted the inventory of carbon sources and sinks in Yangtze River Delta region during 1995-2010 and analyzed their spatiotemporal patterns. It was found that the carbon sinks increased by 9.43 million tons from 1995 to 2010, in which forest ecosystem net production in Zhejiang Province was the largest contributor. The "grain for green" policy implemented since 2003 in China played a significant role in increasing the forest area and the carbon sinks. The carbon sources increased by 327 million tons, and energy consumption and industrial processes based emissions accounted for 96% of total carbon sources in 2010. Due to the large share of manufacturing and heavy industries in economy and their dependence on the high carbon intensity energy, either the amount or the growth speed of carbon emissions in Jiangsu Province was the top one in the whole region. Moreover, because the growth speed of net carbon emissions that occurred upon the built-up land was much faster than the sprawl speed of urban built-up land, the net carbon emission intensity kept increasing in the whole region, in which Jiangsu Province demonstrated the fastest increase. PMID:26259436

  5. [Concentration and Source of Dissolved Organic Carbon in Snowpits of the Tibetan Plateau].

    PubMed

    Yan, Fang-ping; Kang, Shi-chang; Chen, Peng-fei; Bai, Jian-kun; Li, Yang; Hu, Zhao-fu; Li, Chao-liu

    2015-08-01

    Snowpit samples of three glaciers (Laohugou NO. 12 Glacier (LHG), Small Dongkemadi Glacier on Mount Tanggula (TGL) and East Ronghuk Glacier on Mount Everest (ZF)) in the Tibetan Plateau were collected. Concentrations of DOC and major ions were analyzed. The results showed that average DOC concentrations of the snowpits of LHG, TGL and ZF were (250.30 +/- 157.10), (216.92 +/- 142.82) and (152.50 +/- 56.11) microg x L(-1), respectively. DOC of TGL and ZF accounted for large parts of total values of DOC and ions. Correspondingly, DOC of LHG accounted for small part (only 5%), because LHG was located at north China and intensively influenced by natural mineral dust, which caused high concentrations of Ca2+ (the highest value could reach 5299.18 microg x L(-1)) and consequently low percentage of DOC of snowpit samples. Correlation and PCA analyses were used to study the sources of DOC. DOC was significantly correlated with Ca2+, Mg2+, K+ and SO4(2-). Additionally, PCA further indicated that the main potential source of DOC was the natural source of mineral dust. Meanwhile, anthropogenic pollutants (e.g., biomass, fossil combustion and agricultural related pollutants) could also not be ignored. Moreover, the carbon depositional fluxes of three snowpits were roughly estimated, and the values of LHG, TGL and ZF snowpits were 189.23, 132.76 and 128.44 mg (m2 x a)(-1), respectively, which played a significant role in the carbon cycle in this region and was also helpful for the study of glaciers fluctuation. PMID:26592009

  6. High-rate nitrogen removal by the Anammox process with a sufficient inorganic carbon source.

    PubMed

    Yang, Jiachun; Zhang, Li; Fukuzaki, Yasuhiro; Hira, Daisuke; Furukawa, Kenji

    2010-12-01

    This study focused on high-rate nitrogen removal by the anaerobic ammonium oxidation (Anammox) process with a sufficient inorganic carbon (IC) source. Experiments were carried out in an up-flow column Anammox reactor fed with synthetic inorganic wastewater for 110 days. The IC source was added into the influent tank in the form of bicarbonate. The results confirmed the positive impact of inorganic matter on stimulating Anammox activity. After the addition of sufficient IC, the nitrogen removal rate sharply increased from 5.2 to 11.8 kg-Nm(-3)day(-1) within only 32 days. NO(2)-N inhibition was not observed even at NO(2)-N concentrations greater than 460 mgN/L, indicating the enriched Anammox consortium adapted to high NO(2)-N concentrations. The ratio of NO(2)-N removal, NO(3)-N production and NH(4)-N removal for the reactor was correspondingly changed from 1.21:0.21:1 to 1.24:0.18:1. Simultaneously, the sludge volume index of the Anammox granules decreased markedly from 36.8 to 21.5 mL/g, which was attributed to the implementation of proper operational strategy. In addition, DNA analysis revealed that a shift from the KSU-1 strain to the KU2 strain occurred in the Anammox community. PMID:20709538

  7. Meta-analysis on Methane Mitigating Properties of Saponin-rich Sources in the Rumen: Influence of Addition Levels and Plant Sources.

    PubMed

    Jayanegara, Anuraga; Wina, Elizabeth; Takahashi, Junichi

    2014-10-01

    Saponins have been considered as promising natural substances for mitigating methane emissions from ruminants. However, studies reported that addition of saponin-rich sources often arrived at contrasting results, i.e. either it decreased methane or it did not. The aim of the present study was to assess ruminal methane emissions through a meta-analytical approach of integrating related studies from published papers which described various levels of different saponin-rich sources being added to ruminant feed. A database was constructed from published literature reporting the addition of saponin-rich sources at various levels and then monitoring ruminal methane emissions in vitro. Accordingly, levels of saponin-rich source additions as well as different saponin sources were specified in the database. Apart from methane, other related rumen fermentation parameters were also included in the database, i.e. organic matter digestibility, gas production, pH, ammonia concentration, short-chain fatty acid profiles and protozoal count. A total of 23 studies comprised of 89 data points met the inclusion criteria. The data obtained were subsequently subjected to a statistical meta-analysis based on mixed model methodology. Accordingly, different studies were treated as random effects whereas levels of saponin-rich source additions or different saponin sources were considered as fixed effects. Model statistics used were p-value and root mean square error. Results showed that an addition of increasing levels of a saponin-rich source decreased methane emission per unit of substrate incubated as well as per unit of total gas produced (p<0.05). There was a decrease in acetate proportion (linear pattern; p<0.001) and an increase in propionate proportion (linear pattern; p<0.001) with increasing levels of saponin. Log protozoal count decreased (p<0.05) at higher saponin levels. Comparing between different saponin-rich sources, all saponin sources, i.e. quillaja, tea and yucca saponins

  8. Meta-analysis on Methane Mitigating Properties of Saponin-rich Sources in the Rumen: Influence of Addition Levels and Plant Sources

    PubMed Central

    Jayanegara, Anuraga; Wina, Elizabeth; Takahashi, Junichi

    2014-01-01

    Saponins have been considered as promising natural substances for mitigating methane emissions from ruminants. However, studies reported that addition of saponin-rich sources often arrived at contrasting results, i.e. either it decreased methane or it did not. The aim of the present study was to assess ruminal methane emissions through a meta-analytical approach of integrating related studies from published papers which described various levels of different saponin-rich sources being added to ruminant feed. A database was constructed from published literature reporting the addition of saponin-rich sources at various levels and then monitoring ruminal methane emissions in vitro. Accordingly, levels of saponin-rich source additions as well as different saponin sources were specified in the database. Apart from methane, other related rumen fermentation parameters were also included in the database, i.e. organic matter digestibility, gas production, pH, ammonia concentration, short-chain fatty acid profiles and protozoal count. A total of 23 studies comprised of 89 data points met the inclusion criteria. The data obtained were subsequently subjected to a statistical meta-analysis based on mixed model methodology. Accordingly, different studies were treated as random effects whereas levels of saponin-rich source additions or different saponin sources were considered as fixed effects. Model statistics used were p-value and root mean square error. Results showed that an addition of increasing levels of a saponin-rich source decreased methane emission per unit of substrate incubated as well as per unit of total gas produced (p<0.05). There was a decrease in acetate proportion (linear pattern; p<0.001) and an increase in propionate proportion (linear pattern; p<0.001) with increasing levels of saponin. Log protozoal count decreased (p<0.05) at higher saponin levels. Comparing between different saponin-rich sources, all saponin sources, i.e. quillaja, tea and yucca saponins

  9. SUBSTITUENT EFFECTS AND ADDITIVITY IN THE CARBON-13 NUCLEAR MAGNETIC RESONANCE SPECTRA OF CHLORINATED NAPHTHALENES AND THEIR CHLORINATED NAPHTHOL METABOLITES

    EPA Science Inventory

    Carbon-13 and proton nuclear magnetic resonance spectra were obtained for 12 chlorinated naphthalenes and six chlorinated naphthols, some of which are metabolites of the naphthalenes. The validity of the use of additivity of chlorine and hydroxyl substituent effects to predict 13...

  10. Optimization of an Atmospheric Carbon Source for Extremophile Cyanobacteria

    NASA Astrophysics Data System (ADS)

    Beaubien, Courtney

    This thesis examines the use of the moisture swing resin materials employed at the Center for Negative Carbon Emissions (CNCE) in order to provide carbon dioxide from ambient air to photobioreactors containing extremophile cyanobacteria cultured at the Arizona Center for Algae Technology and Innovation (AzCATI). For this purpose, a carbon dioxide feeding device was designed, built, and tested. The results indicate how much resin should be used with a given volume of algae medium: approximately 500 grams of resin can feed 1% CO2 at about three liters per minute to a ten liter medium of the Galdieria sulphuraria 5587.1 strain for one hour (equivalent to about 0.1 grams of carbon dioxide per hour per seven grams of algae). Using the resin device, the algae grew within their normal growth range: 0.096 grams of ash-free dry weight per liter over a six hour period. Future applications in which the resin-to-algae process can be utilized are discussed.

  11. Sources and Reactivity of Terrestrial Organic Carbon to the Colville River Delta, Beaufort Sea, Alaska

    NASA Astrophysics Data System (ADS)

    Schreiner, K. M.; Bianchi, T. S.; Rosenheim, B. E.

    2014-12-01

    Terrestrial particulate organic carbon (tPOC) delivery to nearshore deltaic regions is an important mechanism of OC storage and burial, and continental margins worldwide account for approximately 90% of the carbon burial in the ocean. Increasing warming in the Arctic is leading to an acceleration of the hydrologic cycle, warming of permafrost, and broad shifts in vegetation. All of these changes are likely to affect the delivery, reactivity, and burial of tPOC in nearshore Arctic regions, making the Arctic an ideal place to study the effects of climate change on tPOC delivery. However, to date, most studies of tPOC delivery from North America to the Arctic Ocean have focused on large Arctic rivers like the Mackenzie and Yukon, and a significant portion of those watersheds lie in sub-Arctic latitudes, meaning that their tPOC delivery is likely not uniquely representative of the high Arctic tundra. Here, we focus on tPOC delivery by the Colville River, the largest North American river with a watershed that does not include sub-Arctic latitudes. Sediment samples from the river delta and nearby Simpson's Lagoon were taken in August of 2010 and subsequently fractionated by density, in order to study the delivery of both discrete and sediment-sorbed tPOC. Samples were analyzed for stable carbon isotopes, bulk radiocarbon, terrestrial biomarkers (including lignin-phenols, and other CuO reaction products), and aquatic biomarkers (algal pigments), and additionally a subset of the samples were analyzed by ramped pyrolysis-14C. Results show that tPOC delivery near the river mouth is sourced from coastal plain tundra, with additional delivery of tPOC from peat released into the lagoon from the seaward limit of the tundra by coastal erosion. Ramped pyrolysis-14C analysis also shows a clear differentiation between tPOC delivered by the river and tPOC delivered by coastal retreat in the lagoon. Additionally, a significant portion of the OC released by the Colville River is

  12. Microbiological and Mineralogical Characterization of Columbia River Basalts Prior to Supercritical Carbon Dioxide Addition

    NASA Astrophysics Data System (ADS)

    Colwell, F. S.; Fisk, M. R.; Yip, H.; Schwartz, A.; Briggs, B. R.; Spane, F.

    2009-12-01

    Deep geologic sequestration of supercritical carbon dioxide can remove excess carbon dioxide from the atmosphere but will cause profound changes to the geochemistry and microorganisms in the deep strata where it is injected. Here we report the original subsurface microbial constituents in basalt aquifers where supercritical carbon dioxide will be injected as part of the DOE Big Sky Regional Partnership field pilot investigation. Microbial cells were acquired by filtration of water from five discrete depth intervals in the Columbia River basalts during drilling of the borehole in eastern Washington state. Microbes were present in all five of the groundwater samples collected. DNA extracted from the cells was successfully amplified using 16S rRNA gene primers for bacteria, but not archaea. Terminal restriction fragment length polymorphism suggested that microbial communities in aquifers from the upper Grand Ronde basalt flows (518 to 553 m) were similar to each other, but distinct from those present in groundwater from the shallower, overlying Wanapum and deeper Grand Ronde basalt flows. Quantitative polymerase chain reaction directed at the 16S rRNA gene indicated that the aquifers had approximately 10,000 cells per ml. To date, our analysis demonstrates the presence of diverse microbial communities at and above the depths where a limited field test carbon dioxide injection (ca. 1,000 metric tons) is planned for early in 2010. A variety of secondary mineral assemblages (mainly clay minerals, silicates and carbonates) have been observed in thin section, and X-ray diffraction examination of the basalt cuttings from the pilot characterization borehole. This pre-injection study supports our inquiry of how indigenous microbial communities may be altered by supercritical carbon dioxide injection, and possible processes that may increase basalt reaction/weathering and re-precipitation of carbonate minerals. Microbial communities that become established after the carbon

  13. [Carbon source metabolic diversity of soil microbial community under different climate types in the area affected by Wenchuan earthquake].

    PubMed

    Zhang, Guang-Shuai; Lin, Yong-Ming; Ma, Rui-Feng; Deng, Hao-Jun; Du, Kun; Wu, Cheng-Zhen; Hong, Wei

    2015-02-01

    The MS8.0 Wenchuan earthquake in 2008 led to huge damage to land covers in northwest Sichuan, one of the critical fragile eco-regions in China which can be divided into Semi-arid dry hot climate zone (SDHC) and Subtropical humid monsoon climate zone (SHMC). Using the method of Bilog-ECO-microplate technique, this paper aimed to determine the functional diversity of soil microbial community in the earthquake-affected areas which can be divided into undamaged area (U), recover area (R) and damaged area without recovery (D) under different climate types, in order to provide scientific basis for ecological recovery. The results indicated that the average-well-color-development (AWCD) in undamaged area and recovery area showed SDHC > SHMC, which was contrary to the AWCD in the damaged area without recovery. The AWCD of damaged area without recovery was the lowest in both climate zones. The number of carbon source utilization types of soil microbial in SHMC zone was significantly higher than that in SDHC zone. The carbon source utilization types in both climate zones presented a trend of recover area > undamaged area > damaged area without recovery. The carbon source metabolic diversity characteristic of soil microbial community was significantly different in different climate zones. The diversity index and evenness index both showed a ranking of undamaged area > recover area > damaged area without recovery. In addition, the recovery area had the highest richness index. The soil microbial carbon sources metabolism characteristic was affected by soil nutrient, aboveground vegetation biomass and vegetation coverage to some extent. In conclusion, earthquake and its secondary disasters influenced the carbon source metabolic diversity characteristic of soil microbial community mainly through the change of aboveground vegetation and soil environmental factors. PMID:26031097

  14. Changing sources and sinks of carbon in boreal ecosystems of Interior Alaska: Current and future perspectives

    NASA Astrophysics Data System (ADS)

    Douglas, T. A.; Jones, M.; Hiemstra, C. A.

    2012-12-01

    Future climate scenarios predict a roughly 5°C increase in mean annual air temperatures for the Alaskan Interior over the next 80 years. Increasing temperatures and greater frequency and severity of climate-induced disturbances such as wildfires will be enough to initiate permafrost degradation in many areas of Alaska, leading to major changes in surface hydrology and ecosystem structure and function. This, in turn, is expected to alter the current inventories of carbon sources and sinks in the region and provide a management challenge for carbon itemization efforts. To assist land managers in adapting and planning for potential changes in Interior Alaska carbon cycling we synthesize information on climate, ecosystem processes, vegetation, and soil, permafrost, and hydrologic regimes in Interior Alaska. Our goal is to provide an assessment of the current and likely future regime of Interior Alaska carbon sources and sinks. For our carbon assessment we: 1) synthesize the most recent results from numerous studies on the carbon cycle with a focus on research from the Alaskan boreal biome, 2) assemble a summary of estimates of carbon sources in soil and vegetation in Interior Alaska, 3) categorize carbon sources and sinks for predominant Interior Alaska ecosystems, and 4) identify expected changes in sources and sinks with climate change and human activities. This information is used to provide recommendations on potential actions land managers can take to minimize carbon export from the boreal forest. Though the results from our project are geared primarily toward policy makers and land managers we also provide recommendations for filling research gaps that currently present uncertainty in our understanding of the carbon cycle in boreal forest ecosystems of Interior Alaska.

  15. Dynamic balancing of isoprene carbon sources reflects photosynthetic and photorespiratory responses to temperature stress.

    PubMed

    Jardine, Kolby; Chambers, Jeffrey; Alves, Eliane G; Teixeira, Andrea; Garcia, Sabrina; Holm, Jennifer; Higuchi, Niro; Manzi, Antonio; Abrell, Leif; Fuentes, Jose D; Nielsen, Lars K; Torn, Margaret S; Vickers, Claudia E

    2014-12-01

    The volatile gas isoprene is emitted in teragrams per annum quantities from the terrestrial biosphere and exerts a large effect on atmospheric chemistry. Isoprene is made primarily from recently fixed photosynthate; however, alternate carbon sources play an important role, particularly when photosynthate is limiting. We examined the relative contribution of these alternate carbon sources under changes in light and temperature, the two environmental conditions that have the strongest influence over isoprene emission. Using a novel real-time analytical approach that allowed us to examine dynamic changes in carbon sources, we observed that relative contributions do not change as a function of light intensity. We found that the classical uncoupling of isoprene emission from net photosynthesis at elevated leaf temperatures is associated with an increased contribution of alternate carbon. We also observed a rapid compensatory response where alternate carbon sources compensated for transient decreases in recently fixed carbon during thermal ramping, thereby maintaining overall increases in isoprene production rates at high temperatures. Photorespiration is known to contribute to the decline in net photosynthesis at high leaf temperatures. A reduction in the temperature at which the contribution of alternate carbon sources increased was observed under photorespiratory conditions, while photosynthetic conditions increased this temperature. Feeding [2-(13)C]glycine (a photorespiratory intermediate) stimulated emissions of [(13)C1-5]isoprene and (13)CO2, supporting the possibility that photorespiration can provide an alternate source of carbon for isoprene synthesis. Our observations have important implications for establishing improved mechanistic predictions of isoprene emissions and primary carbon metabolism, particularly under the predicted increases in future global temperatures. PMID:25318937

  16. Additional development of large diameter carbon monofilament. [from boron, hydrogen, and methane gas mixture

    NASA Technical Reports Server (NTRS)

    Jacob, B. A.; Veltri, R. D.

    1974-01-01

    The chemical vapor process for preparing a large diameter carbon-base monofilament from a BCl3, Ch4 and H2 gas mixture with a carbon substrate fiber was studied. The effect of reactor geometry, total gas flows and deposition temperature on the tensile strength of the monofilament were investigated. It was noted that consistent results could only be obtained when the carbon substrate fiber was cleaned. The strength of the monofilament was found to depend on the highest temperature and the temperature profile of the monofilament in the reactor. The strength of monofilament produced in the dc and RF reactors were found to be similar and similar alloy compositions in the monofilament were attained when the same gas ratios were used. The tensile strength of the monofilament at 500 C was found to be 60 to 70% of the room temperature tensile strength. No degradation was noted after exposure to molten aluminum.

  17. 75 FR 74773 - Mandatory Reporting of Greenhouse Gases: Additional Sources of Fluorinated GHGs

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-01

    ... reporting rule on October 7, 2010, and it was not published until October 28, 2010, 75 FR 66434, three weeks... electronics, fluorinated GHG production, and electrical equipment use on April 12, 2009 (74 FR 16448) as part... October 30, 2009 (74 FR 56260). EPA deferred action on these source categories because EPA received...

  18. 75 FR 18651 - Mandatory Reporting of Greenhouse Gases: Additional Sources of Fluorinated GHGs

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-12

    ...EPA is revising and supplementing its initial proposed actions to require reporting of fluorinated greenhouse gas (fluorinated GHG) emissions from certain source categories. Specifically, EPA is revising and supplementing its initial proposal to require reporting of fluorinated GHG emissions from electronics manufacturing, production of fluorinated gases, and use of electrical transmission and......

  19. Estimating the seasonal carbon source-sink geography of a natural, steady-state terrestrial biosphere

    NASA Technical Reports Server (NTRS)

    Box, Elgene O.

    1988-01-01

    The estimation of the seasonal dynamics of biospheric-carbon sources and sinks to be used as an input to global atmospheric CO2 studies and models is discussed. An ecological biosphere model is given and the advantages of the model are examined. Monthly maps of estimated biospheric carbon source and sink regions and estimates of total carbon fluxes are presented for an equilibrium terrestrial biosphere. The results are compared with those from other models. It is suggested that, despite maximum variations of atmospheric CO2 in boreal latitudes, the enormous contributions of tropical wet-dry regions to global atmospheric CO2 seasonality can not be ignored.

  20. Sugars as the Source of Energized Carbon for Abiogenesis

    NASA Astrophysics Data System (ADS)

    Weber, A. L.

    2010-04-01

    Reaction of sugars with nitrite under mild conditions yielded ammonia needed for the synthesis of nitrogenous organics for abiogenesis, thereby eliminating the need for a planet-wide source of unstable ammonia for origins processes based on sugars.

  1. Carbon sources of natural cyanamide in Vicia villosa subsp. varia.

    PubMed

    Kamo, Tsunashi; Kasahara, Ryohei; Abe, Shun; Hirota, Mitsuru; Sugano, Mami; Yamaya, Hiroko; Hiradate, Syuntaro; Fujii, Yoshiharu

    2010-10-01

    The ¹³C labels of [¹³C]carbon dioxide and D-[¹³C₆]glucose were incorporated into cyanamide (NH₂CN) when they were administered to Vicia villosa subsp. varia shoots. In contrast, the administration of sodium [2,3-¹³C₂]pyruvate did not affect the relative area of the [M + 1]+ ion of cyanamide in the gas chromatography-mass spectrometry analysis. [2,3-¹³C₂]pyruvate was incorporated into organic acids that are part of the citric acid cycle, such as succinate and fumarate, confirming that the shoots absorbed and metabolised it. These observations demonstrated that the carbon atom of cyanamide is derived from any of the carbohydrates that are present upstream of pyruvate in the metabolic pathway. PMID:20954091

  2. Carbon isotopomers measurement using mid-IR tunable laser sources.

    PubMed

    Weidmann, Damien; Roller, Chad B; Oppenheimer, Clive; Fried, Alan; Tittel, Frank K

    2005-12-01

    Recent developments of two mid-infrared tunable laser spectrometers dedicated to carbon isotope ratio determination are presented. First, a field deployable quantum cascade laser-based sensor is described, along with line selection strategy for (13/12)CO(2) ratio measurements. Secondly, an instrument architecture based on difference frequency generation is presented. The analyses of fundamental limitations, specifically temperature and pressure stability, and water vapor collision broadening, are detailed. PMID:16543185

  3. Could 4 degrees warming change Arctic tundra from carbon sink to carbon source?

    NASA Astrophysics Data System (ADS)

    Torn, M. S.; Abramoff, R. Z.; Chafe, O.; Curtis, J. B.; Smith, L. J.; Wullschleger, S. D.

    2015-12-01

    We have set up a controlled, active warming experiment in permafrost tundra on the North Slope of Alaska. The aim of this micro-warming experiment is to investigate the direct effect of soil warming on microbial decomposition of soil organic matter. We are testing the feasibility of small, short-term, in situ warming that can be run off batteries for distributed deployment and that preserves plant-soil relations and natural variability in wind, temperature, and precipitation. Based on preliminary results, the approach looks promising. One resistance heater cable per plot (25 cm diameter plots) was inserted vertically to 50 cm, spanning the full active layer (maximum thaw depth was 40 cm in 2014). Heaters were turned on August 1, 2015, and heated plots reached the 4ºC warming target within 1-3 days. We are measuring soil microclimate, thaw depth, CO2 and CH4 fluxes, and 14CO2, and microbial composition, as part of the DOE Next Generation Ecosystem Experiments (NGEE-Arctic). Ecosystem respiration increased immediately in the heated plots, and net ecosystem exchange under clear chambers changed from net uptake to net CO2 source in two of the four plots. CH4 flux shifted toward reduced net emissions or greater net uptake in all plots. These rapid responses demonstrate direct changes in decomposition without complications from microbial acclimation, altered community structure or changes in substrate availability. However, future Arctic tundra carbon balance will depend on both short term and long term microbial responses, as well as the links between warming, decomposition, nitrogen mineralization, and plant growth. Thus, we envision that distributed micro-warming plots could be combined with new approaches to aboveground passive warming being developed in NGEE, gradient studies, and modeling.

  4. Effect of powdered activated carbon (PAC) on MBR performance and effluent trihalomethane formation: At the initial stage of PAC addition.

    PubMed

    Gao, Yue; Ma, Defang; Yue, Qinyan; Gao, Baoyu; Huang, Xia

    2016-09-01

    In this study, the MBR was used to treat municipal wastewater for reuse. Effects of powdered activated carbon (PAC) addition on MBR system in terms of effluent water quality, trihalomethane (THM) formation and membrane organic fouling tendency of MBR sludge supernatant at the initial stage of PAC addition were investigated. Effects of chlorine dose and contact time on THM formation and speciation were also studied. PAC addition enhanced the removal of organic matters, especially aromatic components, which improved the UV254 removal rate from 34% to 83%. PAC addition greatly reduced the membrane organic fouling tendency of MBR sludge supernatant. PAC addition reduced the MBR effluent trihalomethane formation potential (THMFP) from 351.29 to 241.95μg/L, while increased THM formation reactivity by 42%. PAC addition enhanced the formation of higher toxic bromine-containing THMs. High chlorine dose and contact time resulted in higher THM formation but lower proportion of bromine-containing THMs. PMID:27318162

  5. Effects of various organic carbon sources on the growth and biochemical composition of Chlorella pyrenoidosa.

    PubMed

    Zhang, Weiguo; Zhang, Peiliang; Sun, Hao; Chen, Maozhen; Lu, Shan; Li, Pengfu

    2014-12-01

    The aim of this study was to investigate the effects of various organic carbon sources (glucose, galactose, fructose, sucrose, maltose, lactose and starch) on the growth and biochemical composition of Chlorella pyrenoidosa. Monosaccharides were found to exert stronger stimulative effects on the algal growth than disaccharides and starch. After 10-day culture, addition of 0.5-5.0 g L(-1) glucose and galactose significantly reduced the cellular protein contents by 27.7-63.7% and 22.6-60.5%, respectively, and significantly increased the carbohydrate contents by 103.2-266.5% and 91.9-240.0%, respectively. However, addition of 0.5-5.0 g L(-1) disaccharides and starch did not significantly affect the contents of lipid, protein and carbohydrate. Similar to the normal nitrogen condition, the cellular biochemical composition was not significantly affected by addition of 3.0 g L(-1) disaccharides and starch under the low nitrogen condition. Finally, the significance of this work in the biotechnological application of mixotrophic cultivation of C. pyrenoidosa was further discussed. PMID:25285759

  6. Turnover of soil carbon pools following addition of switchgrass-derived biochar to four soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The amendment of soils with biochar may improve plant growth and sequester carbon, especially in marginal soils not suitable for the majority of commodity production. While biochar can persist in soils, it is not clear whether its persistence is affected by soil type. Moreover, we know little of how...

  7. Mechanical and Electrical Properties of a Polyimide Film Significantly Enhanced by the Addition of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Meador, Michael A.

    2005-01-01

    Single-wall carbon nanotubes have been shown to possess a combination of outstanding mechanical, electrical, and thermal properties. The use of carbon nanotubes as an additive to improve the mechanical properties of polymers and/or enhance their thermal and electrical conductivity has been a topic of intense interest. Nanotube-modified polymeric materials could find a variety of applications in NASA missions including large-area antennas, solar arrays, and solar sails; radiation shielding materials for vehicles, habitats, and extravehicular activity suits; and multifunctional materials for vehicle structures and habitats. Use of these revolutionary materials could reduce vehicle weight significantly and improve vehicle performance and capabilities.

  8. How organic carbon derived from multiple sources contributes to carbon sequestration processes in a shallow coastal system?

    PubMed Central

    Watanabe, Kenta; Kuwae, Tomohiro

    2015-01-01

    Carbon captured by marine organisms helps sequester atmospheric CO2, especially in shallow coastal ecosystems, where rates of primary production and burial of organic carbon (OC) from multiple sources are high. However, linkages between the dynamics of OC derived from multiple sources and carbon sequestration are poorly understood. We investigated the origin (terrestrial, phytobenthos derived, and phytoplankton derived) of particulate OC (POC) and dissolved OC (DOC) in the water column and sedimentary OC using elemental, isotopic, and optical signatures in Furen Lagoon, Japan. Based on these data analysis, we explored how OC from multiple sources contributes to sequestration via storage in sediments, water column sequestration, and air–sea CO2 exchanges, and analyzed how the contributions vary with salinity in a shallow seagrass meadow as well. The relative contribution of terrestrial POC in the water column decreased with increasing salinity, whereas autochthonous POC increased in the salinity range 10–30. Phytoplankton-derived POC dominated the water column POC (65–95%) within this salinity range; however, it was minor in the sediments (3–29%). In contrast, terrestrial and phytobenthos-derived POC were relatively minor contributors in the water column but were major contributors in the sediments (49–78% and 19–36%, respectively), indicating that terrestrial and phytobenthos-derived POC were selectively stored in the sediments. Autochthonous DOC, part of which can contribute to long-term carbon sequestration in the water column, accounted for >25% of the total water column DOC pool in the salinity range 15–30. Autochthonous OC production decreased the concentration of dissolved inorganic carbon in the water column and thereby contributed to atmospheric CO2 uptake, except in the low-salinity zone. Our results indicate that shallow coastal ecosystems function not only as transition zones between land and ocean but also as carbon sequestration filters

  9. Subsurface Intertidal Microbes: A Cryptic Source Of Organic Carbon For Beach Ecosystems

    NASA Technical Reports Server (NTRS)

    Rothschild, Lynn J.; Giver, Lorraine J.; Alvarez, Teresa (Technical Monitor)

    1994-01-01

    Some freshwater, marine or hotspring beaches have no visible source of primary production, yet beneath the surface is an interstitial photosynthetic microbial community. To assess the significance of this source of organic carbon, we measured in situ carbon fixation rates in an intertidal marine beach through a diurnal cycle. Gross fixation for a transect (99 x 1 m) perpendicular to the shore was approx. 4041 mg C fixed/ day, or approx. 41 mg C fixed/ sq m day. In contrast, an adjacent well-established cyanobacterial (Lyngbya) mat was approx. 12 x as productive (approx. 490 mg C fixed/sq m day). Thus, subsurface sand mats may be an overlooked, yet important, endogenous source of organic carbon for intertidal ecosystems, as well as a sink in the global carbon cycle.

  10. A shift of thermokarst lakes from carbon sources to sinks during the Holocene epoch.

    PubMed

    Anthony, K M Walter; Zimov, S A; Grosse, G; Jones, M C; Anthony, P M; Chapin, F S; Finlay, J C; Mack, M C; Davydov, S; Frenzel, P; Frolking, S

    2014-07-24

    Thermokarst lakes formed across vast regions of Siberia and Alaska during the last deglaciation and are thought to be a net source of atmospheric methane and carbon dioxide during the Holocene epoch. However, the same thermokarst lakes can also sequester carbon, and it remains uncertain whether carbon uptake by thermokarst lakes can offset their greenhouse gas emissions. Here we use field observations of Siberian permafrost exposures, radiocarbon dating and spatial analyses to quantify Holocene carbon stocks and fluxes in lake sediments overlying thawed Pleistocene-aged permafrost. We find that carbon accumulation in deep thermokarst-lake sediments since the last deglaciation is about 1.6 times larger than the mass of Pleistocene-aged permafrost carbon released as greenhouse gases when the lakes first formed. Although methane and carbon dioxide emissions following thaw lead to immediate radiative warming, carbon uptake in peat-rich sediments occurs over millennial timescales. We assess thermokarst-lake carbon feedbacks to climate with an atmospheric perturbation model and find that thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5,000 years ago. High rates of Holocene carbon accumulation in 20 lake sediments (47 ± 10 grams of carbon per square metre per year; mean ± standard error) were driven by thermokarst erosion and deposition of terrestrial organic matter, by nutrient release from thawing permafrost that stimulated lake productivity and by slow decomposition in cold, anoxic lake bottoms. When lakes eventually drained, permafrost formation rapidly sequestered sediment carbon. Our estimate of about 160 petagrams of Holocene organic carbon in deep lake basins of Siberia and Alaska increases the circumpolar peat carbon pool estimate for permafrost regions by over 50 per cent (ref. 6). The carbon in perennially frozen drained lake sediments may become vulnerable to mineralization as permafrost disappears

  11. A shift of thermokarst lakes from carbon sources to sinks during the Holocene epoch

    USGS Publications Warehouse

    Walter Anthony, K. M.; Zimov, S. A.; Grosse, G.; Jones, Miriam C.; Anthony, P.; Chapin, F. S., III; Finlay, J. C.; Mack, M. C.; Davydov, S.; Frenzel, P.F.; Frolking, S.

    2014-01-01

    Thermokarst lakes formed across vast regions of Siberia and Alaska during the last deglaciation and are thought to be a net source of atmospheric methane and carbon dioxide during the Holocene epoch1,2,3,4. However, the same thermokarst lakes can also sequester carbon5, and it remains uncertain whether carbon uptake by thermokarst lakes can offset their greenhouse gas emissions. Here we use field observations of Siberian permafrost exposures, radiocarbon dating and spatial analyses to quantify Holocene carbon stocks and fluxes in lake sediments overlying thawed Pleistocene-aged permafrost. We find that carbon accumulation in deep thermokarst-lake sediments since the last deglaciation is about 1.6 times larger than the mass of Pleistocene-aged permafrost carbon released as greenhouse gases when the lakes first formed. Although methane and carbon dioxide emissions following thaw lead to immediate radiative warming, carbon uptake in peat-rich sediments occurs over millennial timescales. We assess thermokarst-lake carbon feedbacks to climate with an atmospheric perturbation model and find that thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5,000 years ago. High rates of Holocene carbon accumulation in 20 lake sediments (47±10 grams of carbon per square metre per year; mean±standard error) were driven by thermokarst erosion and deposition of terrestrial organic matter, by nutrient release from thawing permafrost that stimulated lake productivity and by slow decomposition in cold, anoxic lake bottoms. When lakes eventually drained, permafrost formation rapidly sequestered sediment carbon. Our estimate of about 160petagrams of Holocene organic carbon in deep lake basins of Siberia and Alaska increases the circumpolar peat carbon pool estimate for permafrost regions by over 50 per cent (ref. 6). The carbon in perennially frozen drained lake sediments may become vulnerable to mineralization as permafrost disappears7

  12. Soil Carbon Dynamics in a Shelterbelt in the Midwest: Sources and Spatial Variability

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shelterbelt planting in cropland may sequester carbon (C), but sources and spatial variability have not been documented. This study was conducted to assess sources and spatial variation of soil organic C (SOC) in a 35-year-old shelterbelt, and in two adjacent cultivated fields (CF) in eastern Nebras...

  13. Effect of different carbon sources on decolourisation of an industrial textile dye under alkaline-saline conditions.

    PubMed

    Ottoni, Cristiane; Lima, Luis; Santos, Cledir; Lima, Nelson

    2014-01-01

    White-rot fungal strains of Trametes versicolor and Phanerochaete chrysosporium were selected to study the decolourisation of the textile dye, Reactive Black 5, under alkaline-saline conditions. Free and immobilised T. versicolor cells showed 100 % decolourisation in the growth medium supplemented with 15 g l(-1) NaCl, pH 9.5 at 30 °C in liquid batch culture. Continuous culture experiments were performed in a fixed-bed reactor using free and immobilised T. versicolor cells and allowed 85-100 % dye decolourisation. The immobilisation conditions for the biomass and the additional supply of carbon sources improved the decolourisation performance during a long-term trial of 40 days. Lignin peroxidase, laccase and glyoxal oxidase activities were detected during the experiments. The laccase activity varied depending on carbon source utilized and glycerol-enhanced laccase activity compared to sucrose during extended growth. PMID:23982200

  14. Compact ECR ion source with permanent magnets for carbon therapy

    NASA Astrophysics Data System (ADS)

    Muramatsu, M.; Kitagawa, A.; Sakamoto, Y.; Sato, Y.; Yamada, S.; Ogawa, H.; Drentje, A. G.; Biri, S.; Yoshida, Y.

    2004-05-01

    Ion sources for the medical facilities should have the following characteristics of easy maintenance, low electric power, good stability, and long operation time without trouble (1 year or longer). For this, a 10 GHz compact electron cyclotron resonance ion source (ECRIS) with all permanent magnets was developed. The beam intensity and stability for C4+ were 280 e μA and better than 6% during 20 h with no adjustment of any source parameters. These results were acceptable for the medical requirements. Recently, many plans were proposed to construct the next generation cancer treatment facility. For such a facility we have designed an all permanent magnet ECRIS, in which a high magnetic field is chosen for increasing the beam intensity. The maximum mirror magnetic fields on the beam axis are 0.59 T at the extraction side and 0.87 T at the gas injection side, while the minimum B strength is 0.25 T. The source has a diameter of 32 cm and a length of 29.5 cm. Details of the design of this source and its background are described in this article.

  15. Iridium-Catalyzed Intramolecular Methoxy C-H Addition to Carbon-Carbon Triple Bonds: Direct Synthesis of 3-Substituted Benzofurans from o-Methoxyphenylalkynes.

    PubMed

    Torigoe, Takeru; Ohmura, Toshimichi; Suginome, Michinori

    2016-07-18

    Catalytic hydroalkylation of an alkyne with methyl ether was accomplished. Intramolecular addition of the C-H bond of a methoxy group in 1-methoxy-2-(arylethynyl)benzenes across a carbon-carbon triple bond took place efficiently either in toluene at 110 °C or in p-xylene at 135 °C in the presence of an iridium catalyst. The initial 5-exo cyclization products underwent double-bond migration during the reaction to give 3-(arylmethyl)benzofurans in high yields. PMID:27168516

  16. Carbon source quality and placement effects on soil organic carbon status

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improved management of agricultural soils has potential for sequestering carbon (C) and reducing the accumulation of atmospheric carbon dioxide. Development of management practices to increase C sequestration is dependent on improved understanding of soil processes influencing long-term storage of ...

  17. Food additives and environmental chemicals as sources of childhood behavior disorders

    SciTech Connect

    Weiss, B.

    1982-01-01

    The Feingold hypothesis postulates that many children who exhibit disturbed behavior improve on a diet devoid of certain food additives. Its validity has been examined on the basis of controlled trails. The total evidence, although not wholly consistent, nevertheless suggests that the hypothesis is, in principle, correct. Such a conclusion poses difficult problems and new issues for etiology, treatment, toxicology, and regulation.

  18. The effects of fire severity on black carbon additions to forest soils - 10 years post fire

    NASA Astrophysics Data System (ADS)

    Poore, R.; Wessman, C. A.; Buma, B.

    2013-12-01

    Wildfires play an active role in the global carbon cycle. While large amounts of carbon dioxide are released, a small fraction of the biomass consumed by the fire is only partially combusted, yielding soot and charcoal. These products, also called black carbon (BC) make up only 1-5% of the biomass burnt, yet they can have a disproportionate effect on both the atmosphere and fluxes in long-term carbon pools. This project specifically considers the fraction that is sequestered in forest soils. Black carbon is not a specific compound, and exists along a continuum ranging from partially burned biomass to pure carbon or graphite. Increasing aromaticity as the result of partial combustion means charcoal is highly resistant to oxidation. Although debated, most studies indicate a turnover time on the order of 500-1,000 years in warm, wet, aerobic soils. Charcoal may function as a long-term carbon sink, however its overall significance depends on its rate of formation and loss. At the landscape level, fire characteristics are one of the major factors controlling charcoal production. A few studies suggest that charcoal production increases with cooler, less-severe fires. However, there are many factors to tease apart, partly because of a lack of specificity in how fire severity is defined. Within this greater context, our lab has been working on a landscape-level study within Routt National Forest, north of Steamboat Springs, Colorado. In 2002, a large fire swept through a subalpine spruce, fir and lodgepole pine forest. In 2011-2013 we sampled BC pools in 44 plots across a range of fire severities from unburned to severe crown We hypothesized that charcoal stocks will be higher in areas of low severity fire as compared to high severity because of decreased re-combustion of charcoal in the organic soil and increased overall charcoal production due to lower temperatures. In each of our plots we measured charcoal on snags and coarse woody debris, sampled the entire organic

  19. Common genetic variants, acting additively, are a major source of risk for autism

    PubMed Central

    2012-01-01

    Background Autism spectrum disorders (ASD) are early onset neurodevelopmental syndromes typified by impairments in reciprocal social interaction and communication, accompanied by restricted and repetitive behaviors. While rare and especially de novo genetic variation are known to affect liability, whether common genetic polymorphism plays a substantial role is an open question and the relative contribution of genes and environment is contentious. It is probable that the relative contributions of rare and common variation, as well as environment, differs between ASD families having only a single affected individual (simplex) versus multiplex families who have two or more affected individuals. Methods By using quantitative genetics techniques and the contrast of ASD subjects to controls, we estimate what portion of liability can be explained by additive genetic effects, known as narrow-sense heritability. We evaluate relatives of ASD subjects using the same methods to evaluate the assumptions of the additive model and partition families by simplex/multiplex status to determine how heritability changes with status. Results By analyzing common variation throughout the genome, we show that common genetic polymorphism exerts substantial additive genetic effects on ASD liability and that simplex/multiplex family status has an impact on the identified composition of that risk. As a fraction of the total variation in liability, the estimated narrow-sense heritability exceeds 60% for ASD individuals from multiplex families and is approximately 40% for simplex families. By analyzing parents, unaffected siblings and alleles not transmitted from parents to their affected children, we conclude that the data for simplex ASD families follow the expectation for additive models closely. The data from multiplex families deviate somewhat from an additive model, possibly due to parental assortative mating. Conclusions Our results, when viewed in the context of results from genome

  20. BREEDING PIERCE'S DISEASE RESISTANT TABLE AND RAISIN GRAPES AND THE DEVELOPMENT OF MARKERS FOR ADDITIONAL SOURCES OF RESISTANCE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fifteen BC3 and two BC2 crosses between V. arizonica source of Pierce’s disease (PD) resistance and seedless table and raisin selections were made and produced 3,396 berries, 4,459 ovules and 1,840 embryos. Two additional seedless and two seeded crosses were made. Ten 2006 BC2 families (V. arizoni...

  1. A radio/optical reference frame. 5: Additional source positions in the mid-latitude southern hemisphere

    NASA Technical Reports Server (NTRS)

    Russell, J. L.; Reynolds, J. E.; Jauncey, D. L.; De Vegt, C.; Zacharias, N.; Ma, C.; Fey, A. L.; Johnston, K. J.; Hindsley, R.; Hughes, J. A.

    1994-01-01

    We report new accurate radio position measurements for 30 sources, preliminary positions for two sources, improved radio postions for nine additional sources which had limited previous observations, and optical positions and optical-radio differences for six of the radio sources. The Very Long Baseline Interferometry (VLBI) observations are part of the continuing effort to establish a global radio reference frame of about 400 compact, flat spectrum sources, which are evenly distributed across the sky. The observations were made using Mark III data format in four separate sessions in 1988-89 with radio telescopes at Tidbinbilla, Australia, Kauai, USA, and Kashima, Japan. We observed a total of 54 sources, including ten calibrators and three which were undetected. The 32 new source positions bring the total number in the radio reference frame catalog to 319 (172 northern and 147 southern) and fill in the zone -25 deg greater than delta greater than -45 deg which, prior to this list, had the lowest source density. The VLBI positions have an average formal precision of less than 1 mas, although unknown radio structure effects of about 1-2 mas may be present. The six new optical postion measurements are part of the program to obtain positions of the optical counterparts of the radio reference frame source and to map accurately the optical on to the radio reference frames. The optical measurements were obtained from United States Naval Observatory (USNO) Black Birch astrograph plates and source plates from the AAT, and Kitt Peak National Observatory (KPNO) 4 m, and the European Southern Observatory (ESO) Schmidt. The optical positions have an average precision of 0.07 sec, mostly due to the zero point error when adjusted to the FK5 optical frame using the IRS catalog. To date we have measured optical positions for 46 sources.

  2. Carbon sources and sinks in forest biomes of the former Soviet Union

    SciTech Connect

    Kolchugina, T.P.; Vinson, T.S.

    1993-06-01

    Net primary productivity (NPP) of Soviet forest biomes has been estimated from an equilibrium analysis at seven percent of the global terrestrial NPP, 20 percent of the world's total forest NPP, and half of boreal and temperate forest NPP. However, an equilibrium analysis does not allow the assessment of the role of forest biomes in carbon sequestration because it is based on the assumption that the annual carbon increment in forest biomes equals the amount of carbon released to the atmosphere through respiration. A non-equilibrium analysis accounts for carbon sequestration during specific stages of forest ecosystem development. Sources and sinks of carbon and the sequestration potential of forest biomes in the former Soviet Union are assessed in the present study under non-equilibrium conditions by considering (1) net ecosystem productivity of different age forest stands and their actual coverage, (2) carbon flux related to forest fires, (3) the rate of peat accumulation, and (4) anthropogenic influences.

  3. Production of targeted poly(3-hydroxyalkanoates) copolymers by glycogen accumulating organisms using acetate as sole carbon source.

    PubMed

    Dai, Yu; Yuan, Zhiguo; Jack, Kevin; Keller, Jurg

    2007-05-01

    One of the main limitations in bacterial polyhydroxyalkanoate (PHA) production with mixed cultures is the fact that primarily polyhydroxybutyrate (PHB) homopolymers are generated from acetate as the main carbon source, which is brittle and quite fragile. The incorporation of different 3-hydroxyalkanoate (HA) components into the polymers requires the addition of additional carbon sources, leading to extra costs and complexity. In this study, the production of poly(3-hydroxybutyrate (3HB)-co-3-hydroxyvalerate (3HV)-co-3-hydroxy-2-methylvalerate (3HMV)), with 7-35C-mol% of 3HV fractions from acetate as the only carbon source was achieved with the use of glycogen accumulating organisms (GAOs). An enriched GAO culture was obtained in a lab-scale reactor operated under alternating anaerobic and aerobic conditions with acetate fed at the beginning of the anaerobic period. The production of PHAs utilizing the enriched GAO culture was investigated under both aerobic and anaerobic conditions. A polymer content of 14-41% of dry cell weight was obtained. The PHA product accumulated by GAOs under anaerobic conditions contained a relatively constant proportion of non-3HB monomers (30+/-5C-mol%), irrespective of the amount of acetate assimilated. In contrast, under aerobic conditions, GAOs only produced 3HB monomers from acetate causing a gradually decreasing 3HV fraction during this aerobic feeding period. The PHAs were characterized by gel permeation chromatography (GPC) and differential scanning calorimetry (DSC). The data demonstrated that the copolymers possessed similar characteristics to those of commercially available poly(3HB-co-3HV) (PHBV) products. The PHAs produced under solely anaerobic conditions possessed lower melting points and crystallinity, higher molecular weights, and narrower molecular-weight distributions, compared to the aerobically produced polymers. This paper hence demonstrates the significant potential of GAOs to produce high quality polymers from a

  4. Effects of porous carbon additives and induced fluorine on low dielectric constant polyimide synthesized with an e-beam

    SciTech Connect

    Im, Ji Sun; Bae, Tae-Sung; Lee, Sung Kyu; Lee, Sei-Hyun; Jeong, Euigyung; Kang, Phil Hyun; Lee, Young-Seak

    2010-11-15

    We report the synthesis of a polyimide matrix with a low dielectric constant for application as an intercalation material between metal interconnections in electronic devices. Porous activated carbon was embedded in the polyimide to reduce the dielectric constant, and a thin film of the complex was obtained using the spin-coating and e-beam irradiation methods. The surface of the thin film was modified with fluorine functional groups to impart water resistance and reduce the dielectric constant further. The water resistance was significantly improved by the modification with hydrophobic fluorine groups. The dielectric constant was effectively decreased by porous activated carbon. The fluorine modification also resulted in a low dielectric constant on the polyimide surface by reducing the polar surface free energy. The dielectric constant of polyimide film decreased from 2.98 to 1.9 by effects of porous activated carbon additive and fluorine surface modification.

  5. EVALUATION OF BIOLOGICAL TREATMENT OF PHARMACEUTICAL WASTEWATER WITH PAC (POWDERED ACTIVATED CARBON) ADDITION. VOLUME 2. APPENDICES

    EPA Science Inventory

    A lack of information on applicable removal technologies for total chemical oxygen demand (TCOD) prevented promulgation of best available technology economically achievable (BAT) limitations and new source performance standards (NSPS) for TCOD for pharmaceutical manufacturing pla...

  6. EVALUATION OF BIOLOGICAL TREATMENT OF PHARMACEUTICAL WASTEWATER WITH PAC (POWDERED ACTIVATED CARBON) ADDITION. VOLUME 1

    EPA Science Inventory

    A lack of information on applicable removal technologies for total chemical oxygen demand (TCOD) prevented promulgation of best available technology economically achievable (BAT) limitations and new source performance standards (NSPS) for TCOD for pharmaceutical manufacturing pla...

  7. Fly ash addition affects microbial biomass and carbon mineralization in agricultural soils.

    PubMed

    Nayak, A K; Kumar, Anjani; Raja, R; Rao, K S; Mohanty, Sangita; Shahid, Mohammad; Tripathy, Rahul; Panda, B B; Bhattacharyya, P

    2014-02-01

    The microbial biomass carbon (MBC) and carbon mineralization of fly ash (FA) amended soil at (0 %, 1.25 %, 2.5 %, 5 %, 10 % and 20 % FA; v/v) was investigated under laboratory conditions for 120 days at 60 % soil water-holding capacity and 25 ± 1°C temperature. The results demonstrated that soil respiration and microbial activities were not suppressed up to 2.5 % FA amendment and these activities decreased significantly at 10 % and 20 % FA treatment with respect to control. Application of 10 % and 20 % FA treated soils showed a decreasing trend of soil MBC with time; and the decrease was significant throughout the period of incubation. The study concluded that application of FA up to 2.5 % can thus be safely used without affecting the soil biological activity and thereby improve nutrient cycling in agricultural soils. PMID:24362819

  8. Synergistic catalysis: highly diastereoselective benzoxazole addition to Morita-Baylis-Hillman carbonates.

    PubMed

    Ceban, Victor; Putaj, Piotr; Meazza, Marta; Pitak, Mateusz B; Coles, Simon J; Vesely, Jan; Rios, Ramon

    2014-07-18

    An expedited method has been developed for the diastereoselective synthesis of highly functionalized alkyl-azaarene systems with good yields and high diastereoselectivities (>15 : 1 dr). The methodology includes a synergistic catalysis event involving organometallic (10 mol% AgOAc) activation of an alkyl azaarene and Lewis base (10 mol% DABCO) activation of a Morita-Baylis-Hillman carbonate. The structure and relative configuration of a representative product were confirmed by X-ray analysis. PMID:24875953

  9. Source and sink carbon dynamics and carbon allocation in the Amazon basin

    NASA Astrophysics Data System (ADS)

    Doughty, Christopher E.; Metcalfe, D. B.; Girardin, C. A. J.; Amezquita, F. F.; Durand, L.; Huaraca Huasco, W.; Silva-Espejo, J. E.; Araujo-Murakami, A.; Costa, M. C.; Costa, A. C. L.; Rocha, W.; Meir, P.; Galbraith, D.; Malhi, Y.

    2015-05-01

    Changes to the carbon cycle in tropical forests could affect global climate, but predicting such changes has been previously limited by lack of field-based data. Here we show seasonal cycles of the complete carbon cycle for 14, 1 ha intensive carbon cycling plots which we separate into three regions: humid lowland, highlands, and dry lowlands. Our data highlight three trends: (1) there is differing seasonality of total net primary productivity (NPP) with the highlands and dry lowlands peaking in the dry season and the humid lowland sites peaking in the wet season, (2) seasonal reductions in wood NPP are not driven by reductions in total NPP but by carbon during the dry season being preferentially allocated toward either roots or canopy NPP, and (3) there is a temporal decoupling between total photosynthesis and total carbon usage (plant carbon expenditure). This decoupling indicates the presence of nonstructural carbohydrates which may allow growth and carbon to be allocated when it is most ecologically beneficial rather than when it is most environmentally available.

  10. Methane hydrate-bearing seeps as a source of aged dissolved organic carbon to the oceans

    USGS Publications Warehouse

    Pohlman, J.W.; Bauer, J.E.; Waite, W.F.; Osburn, C.L.; Chapman, N.R.

    2011-01-01

    Marine sediments contain about 500-10,000 Gt of methane carbon, primarily in gas hydrate. This reservoir is comparable in size to the amount of organic carbon in land biota, terrestrial soils, the atmosphere and sea water combined, but it releases relatively little methane to the ocean and atmosphere. Sedimentary microbes convert most of the dissolved methane to carbon dioxide. Here we show that a significant additional product associated with microbial methane consumption is methane-derived dissolved organic carbon. We use ??14 C and ??13 C measurements and isotopic mass-balance calculations to evaluate the contribution of methane-derived carbon to seawater dissolved organic carbon overlying gas hydrate-bearing seeps in the northeastern Pacific Ocean. We show that carbon derived from fossil methane accounts for up to 28% of the dissolved organic carbon. This methane-derived material is much older, and more depleted in 13 C, than background dissolved organic carbon. We suggest that fossil methane-derived carbon may contribute significantly to the estimated 4,000-6,000 year age of dissolved organic carbon in the deep ocean, and provide reduced organic matter and energy to deep-ocean microbial communities. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  11. Effects of experimental fuel additions on fire intensity and severity: unexpected carbon resilience of a neotropical forest.

    PubMed

    Brando, Paulo M; Oliveria-Santos, Claudinei; Rocha, Wanderley; Cury, Roberta; Coe, Michael T

    2016-07-01

    Global changes and associated droughts, heat waves, logging activities, and forest fragmentation may intensify fires in Amazonia by altering forest microclimate and fuel dynamics. To isolate the effects of fuel loads on fire behavior and fire-induced changes in forest carbon cycling, we manipulated fine fuel loads in a fire experiment located in southeast Amazonia. We predicted that a 50% increase in fine fuel loads would disproportionally increase fire intensity and severity (i.e., tree mortality and losses in carbon stocks) due to multiplicative effects of fine fuel loads on the rate of fire spread, fuel consumption, and burned area. The experiment followed a fully replicated randomized block design (N = 6) comprised of unburned control plots and burned plots that were treated with and without fine fuel additions. The fuel addition treatment significantly increased burned area (+22%) and consequently canopy openness (+10%), fine fuel combustion (+5%), and mortality of individuals ≥5 cm in diameter at breast height (dbh; +37%). Surprisingly, we observed nonsignificant effects of the fuel addition treatment on fireline intensity, and no significant differences among the three treatments for (i) mortality of large trees (≥30 cm dbh), (ii) aboveground forest carbon stocks, and (iii) soil respiration. It was also surprising that postfire tree growth and wood increment were higher in the burned plots treated with fuels than in the unburned control. These results suggest that (i) fine fuel load accumulation increases the likelihood of larger understory fires and (ii) single, low-intensity fires weakly influence carbon cycling of this primary neotropical forest, although delayed postfire mortality of large trees may lower carbon stocks over the long term. Overall, our findings indicate that increased fine fuel loads alone are unlikely to create threshold conditions for high-intensity, catastrophic fires during nondrought years. PMID:26750627

  12. Soil Organic Carbon Sources of Respired CO2 in a Mid-successional North Temperate Forest

    NASA Astrophysics Data System (ADS)

    Medina, N. L.; Hatton, P. J.; Le Moine, J.; Nadelhoffer, K. J.

    2015-12-01

    Given that soil organic matter (SOM) is the largest global terrestrial carbon (C) pool, some fractions of which have turnover times of centuries to millennia, it is critical to understand the mechanisms by which higher net primary productivity (NPP) and higher litter inputs, in the future, as predicted by some models, might alter the potentials of forest soils to serve as long-term C sinks. Here, we use a 10-year-old site in the DIRT (Detritus Input and Removal Treatments) network of litter manipulations to compare plots in a forested, northern-temperate sandy soil that were subjected to double-leaf-litter additions (DL) and both root- and leaf-litter removals (no inputs, NI) to non-manipulated controls. Previous data show that rather than increasing soil organic carbon (SOC) stocks, plots receiving doubled litter inputs lose SOC at rates similar to losses in Control soils. To trace the source of extra mineralized SOC, we analyzed field CO2 effluxes for δ13C and characterized SOC of varying degrees of organo-mineral association with sequential density fractionations. Soils in DL plots respired significantly faster (p=0.095) and proportionally more (p=0.015) than control soils over the course of July, August, and October 2014. This suggests a greater fresh litter contribution to soil efflux in DL than in Control plots after 10 years of treatment. Preliminary data show that intermediate (1.85 - 2.4 g/mL) and dense (>2.4 g/mL) fractions are relatively larger in DL than in Control soils. This suggests that the addition C from doubled litter could be more rapidly transferred into those more dense fractions, or that higher litter inputs prime the decomposition of lighter particulate SOC forms, leading to a relative increase of the dense organo-mineral associations. Using δ13C values to parameterize a multi-source mixing model, we partition the fate of both fresh litter and partially-decomposed SOC and will present on the modeled relative contributions of various

  13. Treatment of hydroponic wastewater by denitrification filters using plant prunings as the organic carbon source.

    PubMed

    Park, J B K; Craggs, R J; Sukias, J P S

    2008-05-01

    This study investigated the feasibility of using pre-treated plant liquors as organic carbon sources for the treatment of hydroponic wastewater containing high nitrate-N (>300 mg N/L). The waste plant material was pre-treated to extract organic carbon-rich liquors. When this plant liquor was used as an organic carbon source in denitrification filters at the organic carbon:nitrogen dose rate of 3C:N, nitrate removal efficiencies were >95% and final effluent nitrate concentrations were consistently <20mg N/L. However, at this dose rate, relatively high concentrations (>140 mg/L) of organic carbon (fBOD5) remained in the final effluents. Therefore, a 'compromise' organic carbon:nitrogen dose rate (2C:N) was trialled, at which nitrate removal efficiencies were maintained at >85%, final effluent nitrate concentrations were consistently below 45 mg N/L, and effluent fBOD5 concentrations were <25mg/L. This study has demonstrated that waste plant material is a suitable carbon source for the removal of nitrate from hydroponic wastewater in a denitrification filter. PMID:17714940

  14. An in situ generated carbon as integrated conductive additive for hierarchical negative plate of lead-acid battery

    NASA Astrophysics Data System (ADS)

    Saravanan, M.; Ganesan, M.; Ambalavanan, S.

    2014-04-01

    In this work, we report an in situ generated carbon from sugar as additive in the Negative Active Mass (NAM) which enhances the charge-discharge characteristics of the lead-acid cells. In situ formed sugar derived carbon (SDC) with leady oxide (LO) provides a conductive network and excellent protection against NAM irreversible lead sulfation. The effect of SDC and carbon black (CB) added negative plates are characterized by X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), galvanostatic charge-discharge, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. The results show that subtle changes in the addition of carbon to NAM led to subsequent changes on the performance during partial-state-of-charge (PSoC) operations in lead-acid cells. Furthermore, SDC added cells exhibit remarkable improvement in the rate capability, active material utilization, cycle performance and charge acceptance compared to that of the conventional CB added cells. The impact of SDC with LO at various synthesis conditions on the electrochemical performance of the negative plate is studied systematically.

  15. Human placenta and chorion: potential additional sources of hematopoietic stem cells for transplantation

    PubMed Central

    Bárcena, Alicia; Muench, Marcus O.; Kapidzic, Mirhan; Gormley, Matthew; Goldfien, Gabriel A.; Fisher, Susan J.

    2012-01-01

    Background Hematopoietic stem cell (HSC) transplantation is an essential element of medical therapy, leading to cures of previously incurable disease for hematological and non-hematological pathologies. Many patients do not find matched donors in a timely manner, which has driven efforts to find alternative pools of transplantable HSCs. The use of umbilical cord blood (UCB) as a source of transplantable HSCs began more than two decades ago. However, the use of UCB as a reliable source of HSCs for transplantation still faces crucial challenges: the number of HSCs present in a unit of UCB is usually sufficient for younger children but not for adults and the persistent delayed engraftment often seen can result in high rates of infection and mortality. Study Design and Methods We propose a new approach to a solution of these problems: a potential increase of the limited number of UCB–HSCs available by harvesting HSCs contained in the placenta and the fetal chorionic membrane available at birth. Results We investigated the presence of hematopoietic progenitors/HSC in human placenta and chorion at different gestational ages. The characterization of these cells was performed by flow cytometry and immunolocalization and their functional status was investigated by transplanting them into immunodeficient mice. Conclusion HSCs are present in extraembryonic tissues and could be banked in conjunction to the UCB-HSCs. This novel approach could have a large impact on the field of HSC banking and more crucially, on the outcome of patients undergoing this treatment by greatly improving the use of life-saving hematopoietic transplants. PMID:22074633

  16. Impacts of Additional HONO Sources on Concentrations and Deposition of NOy in the Beijing-Tianjin-Hebei Region of China

    NASA Astrophysics Data System (ADS)

    Li, Ying; An, Junling; Kajino, Mizuo; Li, Jian; Qu, Yu

    2015-04-01

    Reactive nitrogen-containing compounds (NOy) are involved in many important chemical processes in the atmosphere, including aerosol formation as well as ozone (O3) production and destruction. As NOy deposition was increasing rapidly in China during 1980s ~ 2000s, great effort is urgently needed to reduce N deposition. HONO, an important component of NOy, is a significant precursor of the hydroxyl radical (OH) that drives the formation of O3 and fine particles (PM2.5). Nevertheless, the detailed formation mechanisms of HONO and strength of its sources remain unclear. Unknown HONO sources and their potential impacts on air quality have gained extensive interests but to our current knowledge, the impact of HONO sources on regional-scale deposition of NOy has not been quantified up to date. The goal of this work is to evaluate the effects of the additional HONO sources on concentrations and deposition of individual NOy species as well as the NOy budget in the northern Chinese regions being affected by heavy pollution. Simulations of HONO contributions over Beijing-Tianjin-Hebei region (BTH) during summer and winter periods of 2007 using the fully coupled Weather Research and Forecasting /Chemistry (WRF/Chem) model are performed by including three additional HONO sources: 1) the reaction of photo-excited nitrogen dioxide (NO2*) with water vapor, 2) NO2 heterogeneous reaction at the aerosol surfaces, and 3) HONO emissions. The model results show that the three additional HONO sources produce a 20%~40% (> 100%) increase in monthly-mean OH concentrations in many urban areas in August (February), leading to a 10%~40% (10%~100%) variation in monthly-mean concentrations of NOx, nitrate and PAN, a 5%~10% (10%~40%) increase in the total dry deposition of NOy, and an enhancement of 1.4 Gg N (1.5 Gg N) in the total of dry and wet deposition of NOy over this region in August (February). These results suggest that the additional HONO sources aggravate regional-scale acid deposition

  17. A simple and clean source of low-energy atomic carbon

    SciTech Connect

    Krasnokutski, S. A.; Huisken, F.

    2014-09-15

    A carbon source emitting low-energy carbon atoms from a thin-walled, sealed tantalum tube via thermal evaporation has been constructed. The tube is made from a 0.05 mm thick tantalum foil and filled with {sup 12}C or {sup 13}C carbon powder. After being sealed, it is heated by direct electric current. The solvated carbon atoms diffuse to the outer surface of the tube and, when the temperature rises over 2200 K, the evaporation of atomic carbon from the surface of the tantalum tube is observed. As the evaporated species have low energy they are well-suited for the incorporation into liquid helium droplets by the pick-up technique. Mass analysis of the incorporated species reveals the dominant presence of atomic carbon and very low abundances of C{sub 2} and C{sub 3} molecules (<1%). This is in striking contrast to the thermal evaporation of pure carbon, where C{sub 3} molecules are found to be the dominant species in the gas phase. Due to the thermal evaporation and the absence of high-energy application required for the dissociation of C{sub 2} and C{sub 3} molecules, the present source provides carbon atoms with rather low energy.

  18. Enhanced bacterial decomposition with increasing addition of autochthonous to allochthonous carbon without any effect on bacterial community composition

    NASA Astrophysics Data System (ADS)

    Attermeyer, K.; Hornick, T.; Kayler, Z. E.; Bahr, A.; Zwirnmann, E.; Grossart, H.-P.; Premke, K.

    2014-03-01

    Dissolved organic carbon (DOC) concentrations - mainly of terrestrial origin - are increasing worldwide in inland waters. Heterotrophic bacteria are the main consumers of DOC and thus determine DOC temporal dynamics and availability for higher trophic levels. Our aim was to study bacterial carbon (C) turnover with respect to DOC quantity and chemical quality using both allochthonous and autochthonous DOC sources. We incubated a natural bacterial community with allochthonous C (13C-labeled beech leachate) and increased concentrations and pulses (intermittent occurrence of organic matter input) of autochthonous C (phytoplankton lysate). We then determined bacterial C consumption, activities, and community composition together with the C flow through bacteria using stable C isotopes. The chemical analysis of single sources revealed differences in aromaticity and low- and high-molecular-weight substance fractions (LMWS and HMWS, respectively) between allochthonous and autochthonous C sources. Both DOC sources (allochthonous and autochthonous DOC) were metabolized at a high bacterial growth efficiency (BGE) around 50%. In treatments with mixed sources, rising concentrations of added autochthonous DOC resulted in a further, significant increase in bacterial DOC consumption of up to 68% when nutrients were not limiting. This rise was accompanied by a decrease in the humic substance (HS) fraction and an increase in bacterial biomass. Changes in DOC concentration and consumption in mixed treatments did not affect bacterial community composition (BCC), but BCC differed in single vs. mixed incubations. Our study highlights that DOC quantity affects bacterial C consumption but not BCC in nutrient-rich aquatic systems. BCC shifted when a mixture of allochthonous and autochthonous C was provided simultaneously to the bacterial community. Our results indicate that chemical quality rather than source of DOC per se (allochthonous vs. autochthonous) determines bacterial DOC turnover.

  19. The effect of carbon source on microbial community structure and Cr(VI) reduction rate.

    PubMed

    Tekerlekopoulou, Athanasia G; Tsiamis, George; Dermou, Eftychia; Siozios, Stefanos; Bourtzis, Kostas; Vayenas, Dimitris V

    2010-10-15

    In the present work, the effect of the carbon source on microbial community structure in batch cultures derived from industrial sludge and hexavalent chromium reduction was studied. Experiments in aerobic batch reactors were carried out by amending industrial sludge with two different carbon sources: sodium acetate and sucrose. In each of the experiments performed, four different initial Cr(VI) concentrations of: 6, 13, 30 and 115 mg/L were tested. The change of carbon source in the batch reactor from sodium acetate to sucrose led to a 1.3-2.1 fold increase in chromium reduction rate and to a 5- to 9.5-fold increase in biomass. Analysis of the microbial structure in the batch reactor showed that the dominant communities were bacterial species (Acinetobacter lwoffii, Defluvibacter lusatiensis, Pseudoxanthomonas japonensis, Mesorhizium chacoense, and Flavobacterium suncheonense) when sodium acetate was used as carbon source and fungal strains (Trichoderma viride and Pichia jadinii), when sodium acetate was replaced by sucrose. These results indicate that the carbon source is a key parameter for microbial dynamics and enhanced chromium reduction and should be taken into account for efficient bioreactor design. PMID:20552669

  20. Source characteristics of marine oils as indicated by carbon isotopic ratios of volatile hydrocarbons

    SciTech Connect

    Chung, H.M.; Claypool, G.E.; Rooney, M.A. ); Squires, R.M. )

    1994-03-01

    Carbon isotopic ratios of volatile hydrocarbon fractions of marine oils are diagnostic of organic facies and depositional environments of source rocks. For carbonate oils, low-molecular-weight volatile hydrocarbons (< C[sub 9]) are isotopically lighter than high-molecular-weight volatile hydrocarbons (C[sub 9]-C[sub 17]). In contrast, for deltaic oils, low-molecular-weight volatile hydrocarbons are isotopically heavier than high-molecular-weight volatile hydrocarbons. Marine shale oils show patterns intermediate between carbonate and deltaic oils. This relative variation of carbon isotopic ratios among volatile hydrocarbons of oils is explained by earlier expulsion of marine oils derived from isotopically homogeneous (algal-bacterial) kerogens in rich source rocks, and secondary cracking of petroleum prior to expulsion for marine oils derived from isotopically heterogeneous (terrestrial) kerogens in lean source rocks. In basins with multiple source rocks, carbon isotopic ratios of volatile hydrocarbons are useful for determining oil-oil correlation and for inferring oil-source rock relationship. 67 refs., 5 figs., 2 tabs.

  1. Electron string ion sources for carbon ion cancer therapy accelerators.

    PubMed

    Boytsov, A Yu; Donets, D E; Donets, E D; Donets, E E; Katagiri, K; Noda, K; Ponkin, D O; Ramzdorf, A Yu; Salnikov, V V; Shutov, V B

    2015-08-01

    The type of the Electron String Ion Sources (ESIS) is considered to be the appropriate one to produce pulsed C(4+) and C(6+) ion beams for cancer therapy accelerators. In fact, the new test ESIS Krion-6T already now provides more than 10(10) C(4+) ions per pulse and about 5 × 10(9) C(6+) ions per pulse. Such ion sources could be suitable to apply at synchrotrons. It has also been found that Krion-6T can provide more than 10(11) C(6+) ions per second at the 100 Hz repetition rate, and the repetition rate can be increased at the same or larger ion output per second. This makes ESIS applicable at cyclotrons as well. ESIS can be also a suitable type of ion source to produce the (11)C radioactive ion beams. A specialized cryogenic cell was experimentally tested at the Krion-2M ESIS for pulse injection of gaseous species into the electron string. It has been shown in experiments with stable methane that the total conversion efficiency of methane molecules to C(4+) ions reached 5%÷10%. For cancer therapy with simultaneous irradiation and precise dose control (positron emission tomography) by means of (11)C, transporting to the tumor with the primary accelerated (11)C(4+) beam, this efficiency is preliminarily considered to be large enough to produce the (11)C(4+) beam from radioactive methane and to inject this beam into synchrotrons. PMID:26329182

  2. Electron string ion sources for carbon ion cancer therapy accelerators

    NASA Astrophysics Data System (ADS)

    Boytsov, A. Yu.; Donets, D. E.; Donets, E. D.; Donets, E. E.; Katagiri, K.; Noda, K.; Ponkin, D. O.; Ramzdorf, A. Yu.; Salnikov, V. V.; Shutov, V. B.

    2015-08-01

    The type of the Electron String Ion Sources (ESIS) is considered to be the appropriate one to produce pulsed C4+ and C6+ ion beams for cancer therapy accelerators. In fact, the new test ESIS Krion-6T already now provides more than 1010 C4+ ions per pulse and about 5 × 109 C6+ ions per pulse. Such ion sources could be suitable to apply at synchrotrons. It has also been found that Krion-6T can provide more than 1011 C6+ ions per second at the 100 Hz repetition rate, and the repetition rate can be increased at the same or larger ion output per second. This makes ESIS applicable at cyclotrons as well. ESIS can be also a suitable type of ion source to produce the 11C radioactive ion beams. A specialized cryogenic cell was experimentally tested at the Krion-2M ESIS for pulse injection of gaseous species into the electron string. It has been shown in experiments with stable methane that the total conversion efficiency of methane molecules to C4+ ions reached 5%÷10%. For cancer therapy with simultaneous irradiation and precise dose control (positron emission tomography) by means of 11C, transporting to the tumor with the primary accelerated 11C4+ beam, this efficiency is preliminarily considered to be large enough to produce the 11C4+ beam from radioactive methane and to inject this beam into synchrotrons.

  3. Fossil and contemporary sources of organic and elemental carbon at a rural and an urban site in the Netherlands

    NASA Astrophysics Data System (ADS)

    Dusek, U.; Monaco, M.; Weijers, E.; Röckmann, T.

    2012-04-01

    Measurement of the radioactive carbon isotope 14C in aerosols can provide a direct estimate of the contribution of fossil fuel sources to aerosol carbon. In aerosol science, measurements of 14C/12C ratios are usually reported as fraction modern (fm), relative to an oxalic acid standard that, by definition, has fm=1. The radiocarbon signature gives a clear distinction between 'modern' carbon sources (fm around 1.1-1.2 for biomass burning and around 1.05 for biogenic secondary organic aerosol) and 'fossil' carbon sources (fm =0 for primary and secondary formation from fossil fuel combustion). High volume filter samples have been collected since February 2011 at Cabauw, a rural location in the Netherlands, and additionally in May and June at two suburban locations around Rotterdam. We report measurements of fm for total carbon (TC), organic carbon (OC), water insoluble OC (WIOC) and thermally refractory carbon (RC) as a proxy for elemental carbon. The carbon fractions are isolated by combusting TC at 650 °C, OC and WIOC at 360 °C. Refractory carbon is defined as the carbon remaining on the filter after water extraction, combustion at 360 °C for 15 min and at 450 °C for 2 minutes. The method has been tested with test substances and real aerosol filters and shows little charring for water-extracted filters. First results of 7 filter samples taken from February - Mai 2011 show fm(OC) generally larger than 0.86 at the rural site, except for one case, when a strongly polluted air mass originating in Eastern Europe reached the site. This indicates a strong contribution of natural sources to OC, even in the Netherlands, a very densely populated country with one of the highest levels of aerosol pollution in Western Europe. In particular, WSOC in the rural springtime aerosol seems to originate almost entirely from contemporary sources. Refractory carbon also showed relatively high fm, generally between 0.3-0.5, except in two cases, when marine air masses reached the site

  4. Controlling the Electrostatic Discharge Ignition Sensitivity of Composite Energetic Materials Using Carbon Nanotube Additives

    SciTech Connect

    Kade H. Poper; Eric S. Collins; Michelle L. Pantoya; Michael Daniels

    2014-10-01

    Powder energetic materials are highly sensitive to electrostatic discharge (ESD) ignition. This study shows that small concentrations of carbon nanotubes (CNT) added to the highly reactive mixture of aluminum and copper oxide (Al + CuO) significantly reduces ESD ignition sensitivity. CNT act as a conduit for electric energy, bypassing energy buildup and desensitizing the mixture to ESD ignition. The lowest CNT concentration needed to desensitize ignition is 3.8 vol.% corresponding to percolation corresponding to an electrical conductivity of 0.04 S/cm. Conversely, added CNT increased Al + CuO thermal ignition sensitivity to a hot wire igniter.

  5. Mineral Carbonation Potential of CO2 from Natural and Industrial-based Alkalinity Sources

    NASA Astrophysics Data System (ADS)

    Wilcox, J.; Kirchofer, A.

    2014-12-01

    Mineral carbonation is a Carbon Capture and Storage (CSS) technology where gaseous CO2 is reacted with alkaline materials (such as silicate minerals and alkaline industrial wastes) and converted into stable and environmentally benign carbonate minerals (Metz et al., 2005). Here, we present a holistic, transparent life cycle assessment model of aqueous mineral carbonation built using a hybrid process model and economic input-output life cycle assessment approach. We compared the energy efficiency and the net CO2 storage potential of various mineral carbonation processes based on different feedstock material and process schemes on a consistent basis by determining the energy and material balance of each implementation (Kirchofer et al., 2011). In particular, we evaluated the net CO2 storage potential of aqueous mineral carbonation for serpentine, olivine, cement kiln dust, fly ash, and steel slag across a range of reaction conditions and process parameters. A preliminary systematic investigation of the tradeoffs inherent in mineral carbonation processes was conducted and guidelines for the optimization of the life-cycle energy efficiency are provided. The life-cycle assessment of aqueous mineral carbonation suggests that a variety of alkalinity sources and process configurations are capable of net CO2 reductions. The maximum carbonation efficiency, defined as mass percent of CO2 mitigated per CO2 input, was 83% for CKD at ambient temperature and pressure conditions. In order of decreasing efficiency, the maximum carbonation efficiencies for the other alkalinity sources investigated were: olivine, 66%; SS, 64%; FA, 36%; and serpentine, 13%. For natural alkalinity sources, availability is estimated based on U.S. production rates of a) lime (18 Mt/yr) or b) sand and gravel (760 Mt/yr) (USGS, 2011). The low estimate assumes the maximum sequestration efficiency of the alkalinity source obtained in the current work and the high estimate assumes a sequestration efficiency

  6. Inorganic carbon and fossil organic carbon are source of bias for quantification of sequestered carbon in mine spoil

    NASA Astrophysics Data System (ADS)

    Vindušková, Olga; Frouz, Jan

    2016-04-01

    Carbon sequestration in mine soils has been studied as a possibility to mitigate the rising atmospheric CO2 levels and to improve mine soil quality (Vindu\\vsková and Frouz, 2013). Moreover, these soils offer an unique opportunity to study soil carbon dynamics using the chronosequence approach (using a set of sites of different age on similar parent material). However, quantification of sequestered carbon in mine soils is often complicated by fossil organic carbon (e.g., from coal or kerogen) or inorganic carbon present in the spoil. We present a methodology for quantification of both of these common constituents of mine soils. Our recommendations are based on experiments done on post-mining soils in Sokolov basin, Czech Republic. Here, fossil organic carbon is present mainly as kerogen Type I and II and represents 2-6 wt.% C in these soils. Inorganic carbon in these soils is present mainly as siderite (FeCO3), calcite (CaCO3), and dolomite (CaMg(CO3)2). All of these carbonates are often found in the overburden of coal seams thus being a common constituent of post-mining soils in the world. Vindu\\vsková O, Frouz J, 2013. Soil carbon accumulation after open-cast coal and oil shale mining in Northern Hemisphere: a quantitative review. ENVIRONMENTAL EARTH SCIENCES, 69: 1685-1698. Vindu\\vsková O, Dvořáček V, Prohasková A, Frouz J. 2014. Distinguishing recent and fossil organic matter - A critical step in evaluation of post-mining soil development - using near infrared spectroscopy. ECOLOGICAL ENGINEERING. 73: 643-648. Vindu\\vsková O, Sebag D, Cailleau G, Brus J, Frouz J. 2015. Methodological comparison for quantitative analysis of fossil and recently derived carbon in mine soils with high content of aliphatic kerogen. ORGANIC GEOCHEMISTRY, 89-90:14-22.

  7. Phosphorus-carbon bond formation by lewis Acid catalyzed/mediated addition of silylphosphines.

    PubMed

    Hayashi, Minoru; Matsuura, Yutaka; Nishimura, Yasunobu; Yamasaki, Toshikazu; Imai, Yoshito; Watanabe, Yutaka

    2007-09-28

    Triethylaluminum-catalyzed/mediated addition of a silylphosphine to aldehydes and epoxides is described. Organophosphines containing a silyloxy group at the alpha- or beta-position on the alkyl substituent are successfully prepared in good yields. PMID:17784776

  8. Factors for Microbial Carbon Sources in Organic and Mineral Soils from Eastern United States Deciduous Forests

    NASA Astrophysics Data System (ADS)

    Stitt, C.; McFarlane, K. J.

    2013-12-01

    Forest soils represent a large portion of global terrestrial carbon; however, which soil carbon sources are used by soil microbes and respired as carbon dioxide (CO2) is not well known. This study will focus on characterizing microbial carbon sources from organic and mineral soils from four eastern United States deciduous forests using the unique radiocarbon tracer, 14C. Results from the dark incubation of the organic and mineral soils are heavily influenced by site characteristics when incubated at microbial optimal activity temperature. The sites with the most similarities are statically the same (p> 0.10). The sites with considerable differences in temperature, texture, and location are statically different concluding that site characteristics play a role in soil respiration.

  9. Biofuels from pyrolysis in perspective: trade-offs between energy yields and soil-carbon additions.

    PubMed

    Woolf, Dominic; Lehmann, Johannes; Fisher, Elizabeth M; Angenent, Largus T

    2014-06-01

    Coproduction of biofuels with biochar (the carbon-rich solid formed during biomass pyrolysis) can provide carbon-negative bioenergy if the biochar is sequestered in soil, where it can improve fertility and thus simultaneously address issues of food security, soil degradation, energy production, and climate change. However, increasing biochar production entails a reduction in bioenergy obtainable per unit biomass feedstock. Quantification of this trade-off for specific biochar-biofuel pathways has been hampered by lack of an accurate-yet-simple model for predicting yields, product compositions, and energy balances from biomass slow pyrolysis. An empirical model of biomass slow pyrolysis was developed and applied to several pathways for biochar coproduction with gaseous and liquid biofuels. Here, we show that biochar production reduces liquid biofuel yield by at least 21 GJ Mg(-1) C (biofuel energy sacrificed per unit mass of biochar C), with methanol synthesis giving this lowest energy penalty. For gaseous-biofuel production, the minimum energy penalty for biochar production is 33 GJ Mg(-1) C. These substitution rates correspond to a wide range of Pareto-optimal system configurations, implying considerable latitude to choose pyrolysis conditions to optimize for desired biochar properties or to modulate energy versus biochar yields in response to fluctuating price differentials for the two commodities. PMID:24787482

  10. Combined ab initio molecular dynamics and experimental studies of carbon atom addition to benzene.

    PubMed

    McKee, Michael L; Reisenauer, Hans Peter; Schreiner, Peter R

    2014-04-17

    Car-Parrinello molecular dynamics was used to explore the reactions between triplet and singlet carbon atoms with benzene. The computations reveal that, in the singlet C atom reaction, products are very exothermic where nearly every collision yields a product that is determined by the initial encounter geometry. The singlet C atom reaction does not follow the minimum energy path because the bimolecular reaction is controlled by dynamics (i.e., initial orientation of encounter). On the other hand, in a 10 K solid Ar matrix, ground state C((3)P) atoms do tend to follow RRKM kinetics. Thus, ab initio molecular dynamics (AIMD) results indicate that a significant fraction of C-H insertion occurs to form phenylcarbene whereas, in marked contrast to previous theoretical and experimental conclusions, the Ar matrix isolation studies indicate a large fraction of direct cycloheptatetraene formation, without the intermediacy of phenylcarbene. The AIMD calculations are more consistent with vaporized carbon atom experiments where labeling studies indicate the initial formation of phenylcarbene. This underlines that the availability of thermodynamic sinks can completely alter the observed reaction dynamics. PMID:24661002

  11. Electron string ion sources for carbon ion cancer therapy accelerators

    SciTech Connect

    Boytsov, A. Yu.; Donets, D. E.; Donets, E. D.; Donets, E. E.; Ponkin, D. O.; Ramzdorf, A. Yu.; Salnikov, V. V.; Shutov, V. B.; Katagiri, K.; Noda, K.

    2015-08-15

    The type of the Electron String Ion Sources (ESIS) is considered to be the appropriate one to produce pulsed C{sup 4+} and C{sup 6+} ion beams for cancer therapy accelerators. In fact, the new test ESIS Krion-6T already now provides more than 10{sup 10} C{sup 4+} ions per pulse and about 5 × 10{sup 9} C{sup 6+} ions per pulse. Such ion sources could be suitable to apply at synchrotrons. It has also been found that Krion-6T can provide more than 10{sup 11} C{sup 6+} ions per second at the 100 Hz repetition rate, and the repetition rate can be increased at the same or larger ion output per second. This makes ESIS applicable at cyclotrons as well. ESIS can be also a suitable type of ion source to produce the {sup 11}C radioactive ion beams. A specialized cryogenic cell was experimentally tested at the Krion-2M ESIS for pulse injection of gaseous species into the electron string. It has been shown in experiments with stable methane that the total conversion efficiency of methane molecules to C{sup 4+} ions reached 5%÷10%. For cancer therapy with simultaneous irradiation and precise dose control (positron emission tomography) by means of {sup 11}C, transporting to the tumor with the primary accelerated {sup 11}C{sup 4+} beam, this efficiency is preliminarily considered to be large enough to produce the {sup 11}C{sup 4+} beam from radioactive methane and to inject this beam into synchrotrons.

  12. Impacts of powdered activated carbon addition on trihalomethane formation reactivity of dissolved organic matter in membrane bioreactor effluent.

    PubMed

    Ma, Defang; Gao, Yue; Gao, Baoyu; Wang, Yan; Yue, Qinyan; Li, Qian

    2014-12-01

    Characteristics and trihalomethane (THM) formation reactivity of dissolved organic matter (DOM) in effluents from two membrane bioreactors (MBRs) with and without powdered activated carbon (PAC) addition (referred to as PAC/MBR and MBR, respectively) were examined to investigate the effects of PAC addition on THM formation of MBR effluent during chlorination. PAC addition increased the specific UV absorbance. Hydrophobic DOM especially hydrophobic acids in PAC/MBR effluent (50%) were more than MBR effluent (42%). DOM with molecular weight <1 kDa constituted 12% of PAC/MBR effluent DOM, which was less than that of MBR effluent (16%). Data obtained from excitation and emission matrix fluorescence spectroscopy revealed that PAC/MBR effluent DOM contained more simple aromatic protein, but had less fulvic acid-like and soluble microbial by-product-like. PAC addition reduced the formation of bromine-containing THMs during chlorination of effluents, but increased THM formation reactivity of effluent DOM. PMID:25150685

  13. Energy budgeting and carbon footprint of transgenic cotton-wheat production system through peanut intercropping and FYM addition.

    PubMed

    Singh, Raman Jeet; Ahlawat, I P S

    2015-05-01

    Two of the most pressing sustainability issues are the depletion of fossil energy resources and the emission of atmospheric green house gases like carbon dioxide to the atmosphere. The aim of this study was to assess energy budgeting and carbon footprint in transgenic cotton-wheat cropping system through peanut intercropping with using 25-50% substitution of recommended dose of nitrogen (RDN) of cotton through farmyard manure (FYM) along with 100% RDN through urea and control (0 N). To quantify the residual effects of previous crops and their fertility levels, a succeeding crop of wheat was grown with varying rates of nitrogen, viz. 0, 50, 100, and 150 kg ha(-1). Cotton + peanut-wheat cropping system recorded 21% higher system productivity which ultimately helped to maintain higher net energy return (22%), energy use efficiency (12%), human energy profitability (3%), energy productivity (7%), carbon outputs (20%), carbon efficiency (17%), and 11% lower carbon footprint over sole cotton-wheat cropping system. Peanut addition in cotton-wheat system increased the share of renewable energy inputs from 18 to 21%. With substitution of 25% RDN of cotton through FYM, share of renewable energy resources increased in the range of 21% which resulted into higher system productivity (4%), net energy return (5%), energy ratio (6%), human energy profitability (74%), energy productivity (6%), energy profitability (5%), and 5% lower carbon footprint over no substitution. The highest carbon footprint (0.201) was recorded under control followed by 50 % substitution of RDN through FYM (0.189). With each successive increase in N dose up to 150 kg N ha(-1) to wheat, energy productivity significantly reduced and share of renewable energy inputs decreased from 25 to 13%. Application of 100 kg N ha(-1) to wheat maintained the highest grain yield (3.71 t ha(-1)), net energy return (105,516 MJ ha(-1)), and human energy profitability (223.4) over other N doses applied to wheat

  14. Carbon Sequestration through Sustainably Sourced Algal Fertilizer: Deep Ocean Water.

    NASA Astrophysics Data System (ADS)

    Sherman, M. T.

    2014-12-01

    Drawing down carbon from the atmosphere happens in the oceans when marine plants are growing due to the use of carbon dioxide for biological processes and by raising the pH of the water. Macro- and microscopic marine photosynthesizers are limited in their growth by the availability of light and nutrients (nitrogen, phosphorous, iron, etc.) Deep ocean water (DOW), oceanic water from bellow about 1000m, is a natural medium for marine algae, which contains all (except in rare circumstances) necessary components for algal growth and represents over 90% of the volume of the ocean. The introduction of DOW to a tropical or summer sea can increase chlorophyll from near zero to 60 mg per M3 or more. The form of the utilization infrastructure for DOW can roughly be divided into two effective types; the unconstrained release and the open pond system. Unconstrained release has the advantage of having relatively low infrastructure investment and is available to any area of the ocean. The open pond system has high infrastructure costs but enables intensive use of DOW for harvesting macro- and microalgae and sustainable mariculture. It also enables greater concomitant production of DOW's other potential products such as electricity or potable water. However, unlike an unconstrained release the open pond system can capture much of the biomaterial from the water and limits the impact to the surrounding ecosystem. The Tidal Irrigation and Electrical System (TIESystem), is an open pond that is to be constructed on a continental shelf. It harnesses the tidal flux to pump DOW into the pond on the rising tide and then uses the falling tide to pump biologically rich material out of the pond. This biomaterial represents fixed CO2 and can be used for biofuel or fertilizers. The TIESystem benefits from an economy of scale that increases at a rate that is roughly equal to the relationship of the circumference of a circle (the barrier that creates the open pond) to the area of the pond

  15. Sources and sinks of carbon in boreal ecosystems of interior Alaska: a review

    USGS Publications Warehouse

    Douglas, Thomas A.; Jones, Miriam C.; Hiemstra, Christopher A.

    2014-01-01

    Boreal regions store large quantities of carbon but are increasingly vulnerable to carbon loss due to disturbance and climate warming. The boreal region, underlain by discontinuous permafrost, presents a challenging landscape for itemizing current and potential carbon sources and sinks in the boreal soil and vegetation. The roles of fire, forest succession, and the presence (or absence) of permafrost on carbon cycle, vegetation, and hydrologic processes have been the focus of multidisciplinary research in this area for the past 20 years. However, projections of a warming future climate, an increase in fire severity and extent, and the potential degradation of permafrost could lead to major landscape process changes over the next 20 to 50 years. This provides a major challenge for predicting how the interplay between land management activities and impacts of climate warming will affect carbon sources and sinks in Interior Alaska. To assist land managers in adapting and managing for potential changes in the Interior Alaska carbon cycle we developed this review paper incorporating an overview of the climate, ecosystem processes, vegetation types, and soil regimes in Interior Alaska with a focus on ramifications for the carbon cycle. Our objective is to provide a synthesis of the most current carbon storage estimates and measurements to support policy and land management decisions on how to best manage carbon sources and sinks in Interior Alaska. To support this we have surveyed relevant peer reviewed estimates of carbon stocks in aboveground and belowground biomass for Interior Alaska boreal ecosystems. We have also summarized methane and carbon dioxide fluxes from the same ecosystems. These data have been converted into the same units to facilitate comparison across ecosystem compartments. We identify potential changes in the carbon cycle with climate change and human disturbance including how compounding disturbances can affect the boreal system. Finally, we provide

  16. A NMR-Based Carbon-Type Analysis of Diesel Fuel Blends From Various Sources

    SciTech Connect

    Bays, J. Timothy; King, David L.

    2013-05-10

    In collaboration with participants of the Coordinating Research Council (CRC) Advanced Vehicle/Fuels/Lubricants (AVFL) Committee, and project AVFL-19, the characteristics of fuels from advanced and renewable sources were compared to commercial diesel fuels. The main objective of this study was to highlight similarities and differences among the fuel types, i.e. ULSD, renewables, and alternative fuels, and among fuels within the different fuel types. This report summarizes the carbon-type analysis from 1H and 13C{1H} nuclear magnetic resonance spectroscopy (NMR) of 14 diesel fuel samples. The diesel fuel samples come from diverse sources and include four commercial ultra-low sulfur diesel fuels (ULSD), one gas-to-liquid diesel fuel (GTL), six renewable diesel fuels (RD), two shale oil-derived diesel fuels, and one oil sands-derived diesel fuel. Overall, the fuels examined fall into two groups. The two shale oil-derived samples and the oil-sand-derived sample closely resemble the four commercial ultra-low sulfur diesels, with SO1 and SO2 most closely matched with ULSD1, ULSD2, and ULSD4, and OS1 most closely matched with ULSD3. As might be expected, the renewable diesel fuels, with the exception of RD3, do not resemble the ULSD fuels because of their very low aromatic content, but more closely resemble the gas-to-liquid sample (GTL) in this respect. RD3 is significantly different from the other renewable diesel fuels in that the aromatic content more closely resembles the ULSD fuels. Fused-ring aromatics are readily observable in the ULSD, SO, and OS samples, as well as RD3, and are noticeably absent in the remaining RD and GTL fuels. Finally, ULSD3 differs from the other ULSD fuels by having a significantly lower aromatic carbon content and higher cycloparaffinic carbon content. In addition to providing important comparative compositional information regarding the various diesel fuels, this report also provides important information about the capabilities of NMR

  17. Carbon Storages in Plantation Ecosystems in Sand Source Areas of North Beijing, China

    PubMed Central

    Liu, Xiuping; Zhang, Wanjun; Cao, Jiansheng; Shen, Huitao; Zeng, Xinhua; Yu, Zhiqiang; Zhao, Xin

    2013-01-01

    Afforestation is a mitigation option to reduce the increased atmospheric carbon dioxide levels as well as the predicted high possibility of climate change. In this paper, vegetation survey data, statistical database, National Forest Resource Inventory database, and allometric equations were used to estimate carbon density (carbon mass per hectare) and carbon storage, and identify the size and spatial distribution of forest carbon sinks in plantation ecosystems in sand source areas of north Beijing, China. From 2001 to the end of 2010, the forest areas increased more than 2.3 million ha, and total carbon storage in forest ecosystems was 173.02 Tg C, of which 82.80 percent was contained in soil in the top 0–100 cm layer. Younger forests have a large potential for enhancing carbon sequestration in terrestrial ecosystems than older ones. Regarding future afforestation efforts, it will be more effective to increase forest area and vegetation carbon density through selection of appropriate tree species and stand structure according to local climate and soil conditions, and application of proper forest management including land-shaping, artificial tending and fencing plantations. It would be also important to protect the organic carbon in surface soils during forest management. PMID:24349223

  18. Influence of natural and novel organic carbon sources on denitrification in forest, degraded urban, and restored streams

    EPA Science Inventory

    Organic carbon is important in regulating ecosystem function, and its source and abundance may be altered by urbanization. We investigated shifts in organic carbon quantity and quality associated with urbanization and ecosystem restoration, and its potential effects on denitrific...

  19. Alteration of belowground carbon dynamics by nitrogen addition in southern California mixed conifer forests

    SciTech Connect

    Nowinski, Nicole S.; Trumbore, Susan E.; Jimenez, Gloria; Fenn, Mark E.

    2009-04-01

    Nitrogen deposition rates in southern California are the highest in North America and have had substantial effects on ecosystem functioning. We document changes in the belowground C cycle near ponderosa pine trees experiencing experimental nitrogen (N) addition (50 and 150 kg N ha 1 a 1 as slow release urea since 1997) at two end member sites along a pollution gradient in the San Bernardino Mountains, California. Despite considerable differences in N deposition between the two sites, we observed parallel changes in microbial substrate use and soil enzyme activity with N addition. 14C measurements indicate that the mean age of C respired by the Oa horizon declined 10 15 years with N addition at both sites. N addition caused an increase in cellulolytic enzyme activity at the polluted site and a decrease in ligninolytic enzyme activity at the unpolluted site. Given the likely differences in lignin and cellulose ages, this could explain the difference in the age of microbial respiration with N addition. Measurements of fractionated soil organic matter did not show the same magnitude of changes in response to N addition as were observed for respired C. This lesser response was likely because the soils are mostly composed of C having turnover times of decades to centuries, and 9 years of N amendment were not enough to affect this material. Consequently, 14C of respired CO2 provided a more sensitive indicator of the effects of N addition than other methods. Results suggest that enhanced N deposition alone may not result in increased soil C storage in xeric ecosystems.

  20. Alteration of belowground carbon dynamics by nitrogen addition in southern California mixed conifer forests

    NASA Astrophysics Data System (ADS)

    Nowinski, Nicole S.; Trumbore, Susan E.; Jimenez, Gloria; Fenn, Mark E.

    2009-06-01

    Nitrogen deposition rates in southern California are the highest in North America and have had substantial effects on ecosystem functioning. We document changes in the belowground C cycle near ponderosa pine trees experiencing experimental nitrogen (N) addition (50 and 150 kg N ha-1 a-1 as slow release urea since 1997) at two end-member sites along a pollution gradient in the San Bernardino Mountains, California. Despite considerable differences in N deposition between the two sites, we observed parallel changes in microbial substrate use and soil enzyme activity with N addition. Δ14C measurements indicate that the mean age of C respired by the Oa horizon declined 10-15 years with N addition at both sites. N addition caused an increase in cellulolytic enzyme activity at the polluted site and a decrease in ligninolytic enzyme activity at the unpolluted site. Given the likely differences in lignin and cellulose ages, this could explain the difference in the age of microbial respiration with N addition. Measurements of fractionated soil organic matter did not show the same magnitude of changes in response to N addition as were observed for respired C. This lesser response was likely because the soils are mostly composed of C having turnover times of decades to centuries, and 9 years of N amendment were not enough to affect this material. Consequently, Δ14C of respired CO2 provided a more sensitive indicator of the effects of N addition than other methods. Results suggest that enhanced N deposition alone may not result in increased soil C storage in xeric ecosystems.

  1. Carbon Source Preference in Chemosynthetic Hot Spring Communities

    PubMed Central

    Urschel, Matthew R.; Kubo, Michael D.; Hoehler, Tori M.; Peters, John W.

    2015-01-01

    Rates of dissolved inorganic carbon (DIC), formate, and acetate mineralization and/or assimilation were determined in 13 high-temperature (>73°C) hot springs in Yellowstone National Park (YNP), Wyoming, in order to evaluate the relative importance of these substrates in supporting microbial metabolism. While 9 of the hot spring communities exhibited rates of DIC assimilation that were greater than those of formate and acetate assimilation, 2 exhibited rates of formate and/or acetate assimilation that exceeded those of DIC assimilation. Overall rates of DIC, formate, and acetate mineralization and assimilation were positively correlated with spring pH but showed little correlation with temperature. Communities sampled from hot springs with similar geochemistries generally exhibited similar rates of substrate transformation, as well as similar community compositions, as revealed by 16S rRNA gene-tagged sequencing. Amendment of microcosms with small (micromolar) amounts of formate suppressed DIC assimilation in short-term (<45-min) incubations, despite the presence of native DIC concentrations that exceeded those of added formate by 2 to 3 orders of magnitude. The concentration of added formate required to suppress DIC assimilation was similar to the affinity constant (Km) for formate transformation, as determined by community kinetic assays. These results suggest that dominant chemoautotrophs in high-temperature communities are facultatively autotrophic or mixotrophic, are adapted to fluctuating nutrient availabilities, and are capable of taking advantage of energy-rich organic substrates when they become available. PMID:25819970

  2. Carbon source preference in chemosynthetic hot spring communities.

    PubMed

    Urschel, Matthew R; Kubo, Michael D; Hoehler, Tori M; Peters, John W; Boyd, Eric S

    2015-06-01

    Rates of dissolved inorganic carbon (DIC), formate, and acetate mineralization and/or assimilation were determined in 13 high-temperature (>73 °C) hot springs in Yellowstone National Park (YNP), Wyoming, in order to evaluate the relative importance of these substrates in supporting microbial metabolism. While 9 of the hot spring communities exhibited rates of DIC assimilation that were greater than those of formate and acetate assimilation, 2 exhibited rates of formate and/or acetate assimilation that exceeded those of DIC assimilation. Overall rates of DIC, formate, and acetate mineralization and assimilation were positively correlated with spring pH but showed little correlation with temperature. Communities sampled from hot springs with similar geochemistries generally exhibited similar rates of substrate transformation, as well as similar community compositions, as revealed by 16S rRNA gene-tagged sequencing. Amendment of microcosms with small (micromolar) amounts of formate suppressed DIC assimilation in short-term (<45-min) incubations, despite the presence of native DIC concentrations that exceeded those of added formate by 2 to 3 orders of magnitude. The concentration of added formate required to suppress DIC assimilation was similar to the affinity constant (K(m)) for formate transformation, as determined by community kinetic assays. These results suggest that dominant chemoautotrophs in high-temperature communities are facultatively autotrophic or mixotrophic, are adapted to fluctuating nutrient availabilities, and are capable of taking advantage of energy-rich organic substrates when they become available. PMID:25819970

  3. Biotechnological Production of Docosahexaenoic Acid Using Aurantiochytrium limacinum: Carbon Sources Comparison And Growth Characterization

    PubMed Central

    Abad, Sergi; Turon, Xavier

    2015-01-01

    Aurantiochytrium limacinum, a marine heterotrophic protist/microalga has shown interesting yields of docosahexaenoic acid (DHA) when cultured with different carbon sources: glucose, pure and crude glycerol. A complete study in a lab-scale fermenter allowed for the characterization and comparison of the growth kinetic parameters corresponding to each carbon source. Artificial Marine Medium (AMM) with glucose, pure and crude glycerol offered similar biomass yields. The net growth rates (0.10–0.12 h−1), biomass (0.7–0.8 g cells/g Substrate) and product (0.14–0.15 g DHA/g cells) yields, as well as DHA productivity were similar using the three carbon sources. Viable potential applications to valorize crude glycerol are envisioned to avoid an environmental problem due to the excess of byproduct. PMID:26690180

  4. Optimization of VFAs and ethanol production with waste sludge used as the denitrification carbon source.

    PubMed

    Guo, Liang; Zhang, Jiawen; Yin, Li; Zhao, Yangguo; Gao, Mengchun; She, Zonglian

    2015-01-01

    An acidification metabolite such as volatile fatty acids (VFAs) and ethanol could be used as denitrification carbon sources for solving the difficult problem of carbon source shortages and low nitrogen removal efficiency. A proper control of environmental factors could be essential for obtaining the optimal contents of VFAs and ethanol. In this study, suspended solids (SS), oxidation reduction potential (ORP) and shaking rate were chosen to investigate the interactive effects on VFAs and ethanol production with waste sludge. It was indicated that T-VFA yield could be enhanced at lower ORP and shaking rate. Changing the SS, ORP and shaking rate could influence the distribution of acetic, propionic, butyric, valeric acids and ethanol. The optimal conditions for VFAs and ethanol production used as a denitrification carbon source were predicted by analyzing response surface methodology (RSM). PMID:26465305

  5. A new activated primary tank developed for recovering carbon source and its application.

    PubMed

    Jin, Pengkang; Wang, Xianbao; Zhang, Qionghua; Wang, Xiaochang; Ngo, Huu Hao; Yang, Lei

    2016-01-01

    A novel activated primary tank process (APT) was developed for recovering carbon source by fermentation and elutriation of primary sludge. The effects of solids retention time (SRT), elutriation intensity (G) and return sludge ratio (RSR) on this recovery were evaluated in a pilot scale reactor. Results indicated that SRT significantly influenced carbon source recovery, and mechanical elutriation could promote soluble COD (SCOD) and VFA yields. The optimal conditions of APT were SRT=5d, G=152s(-1) and RSR=10%, SCOD and VFA production were 57.0mg/L and 21.7mg/L. Particulate organic matter in sludge was converted into SCOD and VFAs as fermentative bacteria were significantly enriched in APT. Moreover, the APT process was applied in a wastewater treatment plant to solve the problem of insufficient carbon source. The outcomes demonstrated that influent SCOD of biological tank increased by 31.1%, which improved the efficiency of removing nitrogen and phosphorus. PMID:26562688

  6. [Effect of PLA/starch slow-release carbon source on biological denitrification].

    PubMed

    Tang, Dan-Qi; Wang, Juan; Zheng, Tian-Long; Liu, Jian-Guo; Wang, Qun-Hui

    2014-06-01

    We used polylactic acid (PLA) and starch to develop a slow-release carbon source and biofilm carrier by blending and fusing techniques for removing nitrate contamination from groundwater, investigated the changes of nitrate, nitrite concentrations and COD in denitrification process supplied by the slow-release carbon source in different mass ratios [PLA/starch (P: S) were 8:2, 7:3, 6:4, 5:5, respectively]. The experimental results demonstrated that the best mass ratio of PLA/starch was 5:5, resulting in a nitrate removal rate of more than 99%. A high denitrification performance was achieved in continuous fixed-bed reactor, the effluent nitrate concentration was below 2 mg x L(-1). These experiments provide scientific basis for the development of environmentally-friendly and controllable slow-release carbon source. PMID:25158501

  7. Biotechnological Production of Docosahexaenoic Acid Using Aurantiochytrium limacinum: Carbon Sources Comparison And Growth Characterization.

    PubMed

    Abad, Sergi; Turon, Xavier

    2015-12-01

    Aurantiochytrium limacinum, a marine heterotrophic protist/microalga has shown interesting yields of docosahexaenoic acid (DHA) when cultured with different carbon sources: glucose, pure and crude glycerol. A complete study in a lab-scale fermenter allowed for the characterization and comparison of the growth kinetic parameters corresponding to each carbon source. Artificial Marine Medium (AMM) with glucose, pure and crude glycerol offered similar biomass yields. The net growth rates (0.10-0.12 h(-1)), biomass (0.7-0.8 g cells/g Substrate) and product (0.14-0.15 g DHA/g cells) yields, as well as DHA productivity were similar using the three carbon sources. Viable potential applications to valorize crude glycerol are envisioned to avoid an environmental problem due to the excess of byproduct. PMID:26690180

  8. Carbon source-dependent regulation of the acetyl-coenzyme A synthetase-encoding gene ACS1 from Saccharomyces cerevisiae.

    PubMed

    Kratzer, S; Schüller, H J

    1995-08-01

    The yeast ACS1 gene, encoding acetyl-coenzyme A synthetase (ACS), was cloned using colony hybridization and a facA probe from Aspergillus nidulans. The complete sequence of 1.5 kb of the ACS1 upstream region was determined. Northern hybridization revealed a strong depression of ACS1 transcripts in a strain grown on the nonfermentable carbon sources, acetate or ethanol. In contrast to a previous report, delta acs1 null mutants did not exhibit a growth defect on acetate medium. Indeed, enzyme assays showed the presence of an additional constitutively expressed ACS activity in delta acs1 mutants. The carbon source-dependent expression was further investigated by the use of an ACS1::lacZ fusion gene, showing complete repression on easily fermentable sugars such as glucose, maltose, sucrose or galactose. Binding sites for the yeast general regulatory factors, Abf1p and Reb1p, together with a sequence reminiscent of the recently identified carbon source-responsive element (CSRE), could be detected in the ACS1 upstream region, presumably mediating the observed regulatory phenotype of this ACS isoenzyme. PMID:7642141

  9. Industrial wastewater as an external carbon source for optimization of nitrogen removal at the Wschod WWTP in Gdansk (Poland).

    PubMed

    Swinarski, M; Makinia, J; Czerwionka, K; Chrzanowska, M

    2009-01-01

    Carbon source alternatives for denitrification belong to the highest research area priorities as they allow to optimize N removal within the existing capacities. In particular, some food industry effluents appear to be good candidates for such alternatives due to their high C/N ratios and high content of readily biodegradable organic fraction. The aim of this study was to determine the immediate effects of dosing different types of industrial wastewater on the denitrification capability of process biomass originating from the "Wschod" WWTP in Gdansk (northern Poland). Three types of industrial wastewater (effluents from a distillery, brewery and fish-pickling factory) were tested in two kinds of batch experiments. The results of this study revealed that the investigated industrial wastewater can be a potential external carbon source to improve denitrification efficiency. The observed single nitrate utilization rates (NURs) were ranging from 2.4 to 6.0 g N/(kg VSS.h) and were comparable to the rates associated with the utilization of readily biodegradable COD in the settled wastewater. When the NURs were measured during anoxic P uptake, the P uptake rates did not appear to be adversely affected by the addition of any carbon source. PMID:19151486

  10. Special role of corn flour as an ideal carbon source for aerobic denitrification with minimized nitrous oxide emission.

    PubMed

    Zhu, Shuangyue; Zheng, Maosheng; Li, Can; Gui, Mengyao; Chen, Qian; Ni, Jinren

    2015-06-01

    Much effort has been made for reducing nitrous oxide (N2O) emission in wastewater treatment processes. This paper presents an interesting way to minimize N2O in aerobic denitrification by strain Pseudomonas stutzeri PCN-1 with help of corn flour as cheaper additional carbon source. Experimental results showed that maximal N2O accumulation by strain PCN-1 was only 0.02% of removed nitrogen if corn flour was used as sole carbon source, which was significantly reduced by 52.07-99.81% comparing with others such as succinate, glucose, acetate and citrate. Sustained release of reducing sugar from starch and continuous expression of nosZ coding for N2O reductase contributed to the special role of corn flour as the ideal carbon source for strain PCN-1. Further experiments in sequencing batch reactors (SBRs) demonstrated similarly efficient nitrogen removal with much less N2O emission due to synergy of the novel strain and activated sludge, which was then confirmed by quantitative PCR analysis. PMID:25802047

  11. Effects of Water and Nitrogen Addition on Ecosystem Carbon Exchange in a Meadow Steppe

    PubMed Central

    Wang, Yunbo; Jiang, Qi; Yang, Zhiming; Sun, Wei; Wang, Deli

    2015-01-01

    A changing precipitation regime and increasing nitrogen deposition are likely to have profound impacts on arid and semiarid ecosystem C cycling, which is often constrained by the timing and availability of water and nitrogen. However, little is known about the effects of altered precipitation and nitrogen addition on grassland ecosystem C exchange. We conducted a 3-year field experiment to assess the responses of vegetation composition, ecosystem productivity, and ecosystem C exchange to manipulative water and nitrogen addition in a meadow steppe. Nitrogen addition significantly stimulated aboveground biomass and net ecosystem CO2 exchange (NEE), which suggests that nitrogen availability is a primary limiting factor for ecosystem C cycling in the meadow steppe. Water addition had no significant impacts on either ecosystem C exchange or plant biomass, but ecosystem C fluxes showed a strong correlation with early growing season precipitation, rather than whole growing season precipitation, across the 3 experimental years. After we incorporated water addition into the calculation of precipitation regimes, we found that monthly average ecosystem C fluxes correlated more strongly with precipitation frequency than with precipitation amount. These results highlight the importance of precipitation distribution in regulating ecosystem C cycling. Overall, ecosystem C fluxes in the studied ecosystem are highly sensitive to nitrogen deposition, but less sensitive to increased precipitation. PMID:26010888

  12. Design of a Soil Science practical exercise to understand the soil carbon sequestration after biochar addition

    NASA Astrophysics Data System (ADS)

    Gascó, Gabriel; Cely, Paola; Saa-Requejo, Antonio; Mendez, Ana; Antón, Jose Manuel; Sánchez, Elena; Moratiel, Ruben; Tarquis, Ana M.

    2014-05-01

    The adaptation of the Universities to European Higher Education Area (EHEA) involves changes in the learning system. Students must obtain specific capabilities in the different degrees or masters. For example, in the degree of Agronomy at the Universidad Politécnica de Madrid (UPM, Spain), they must command Soil science, Mathematics or English. Sometimes, There is not a good communication between teachers and it causes that students do not understand the importance of the different subjects of a career. For this reason, teachers of the Soil Science and Mathematics Departments of the UPM designed a common practice to teach to the students the role of soil on the carbon sequestration. The objective of this paper is to explain the followed steps to the design of the practice. Acknowledgement to Universidad Politécnica de Madrid for the Projects in Education Innovation IE12_13-02009 and IE12_13-02012.

  13. Morphology Study of Prepared Carbon Nanotubes using Palm Oil as Carbon Source in Spray Pyrolysis Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Azira, A. A.; Rusop, M.

    2010-03-01

    Surface morphology study on the influence of starting carbon materials by using newly developed spray pyrolysis chemical vapor deposition (Spray-CVD) to produced carbon nanotubes (CNTs) is investigated. The CNTs derived from palm oil as carbon sources were synthesized in Argon gas ambient by using Spray-CVD system. The major parameters are also evaluated in order to obtain high-yield and high-quality CNTs. The prepared CNTs are examined using field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscope (HR-TEM) to determine the microstructure of nanocarbons. The FESEM investigation of the CNTs formed on the support catalysts provides evidence that palm oil can serve as a precursor materials for nanotubes formation. The high-temperature graphitization process induced by the Spray-CVD enables the hydrocarbons to act as carbon sources and changes the aromatic species into the layered graphite structure of CNTs. The palm oil of hydrocarbons not only found acts as the precursors but also enhances the production rate of CNTs.

  14. Evaluation of Natural Materials as Exogenous Carbon Sources for Biological Treatment of Low Carbon-to-Nitrogen Wastewater

    PubMed Central

    Ramírez-Godínez, Juan; Beltrán-Hernández, Icela; Álvarez-Hernández, Alejandro; Coronel-Olivares, Claudia; Contreras-López, Elizabeth; Quezada-Cruz, Maribel; Vázquez-Rodríguez, Gabriela

    2015-01-01

    In the bacterial processes involved in the mitigation of nitrogen pollution, an adequately high carbon-to-nitrogen (C : N) ratio is key to sustain denitrification. We evaluated three natural materials (woodchips, barley grains, and peanut shells) as carbon sources for low C : N wastewater. The amount of organic matter released from these materials to aqueous media was evaluated, as well as their pollution swapping potential by measuring the release of total Kjeldahl nitrogen, N-NH4+, NO2−, and NO3−, and total phosphorous. Barley grains yielded the highest amount of organic matter, which also showed to be the most easily biodegradable. Woodchips and peanut shells released carbon rather steadily and so they would not require frequent replenishment from biological reactors. These materials produced eluates with lower concentrations of nutrients than the leachates from barley grains. However, as woodchips yielded lower amounts of suspended solids, they constitute an adequate exogenous source for the biological treatment of carbon-deficient effluents. PMID:26495313

  15. North America carbon dioxide sources and sinks: magnitude, attribution, and uncertainty

    SciTech Connect

    King, Anthony W.; Hayes, Daniel J.; Huntzinger, Deborah N.; West, Tristram O.; Post, W. M.

    2012-12-01

    North America is both a source and sink of atmospheric CO2. Sources, predominately fossil-fuel combustion in the United States along with contributions from deforestation in Mexico, add CO2 to the atmosphere. Most North America ecosystems, particularly regrowing forests in the United States, are sinks for atmospheric CO2. CO2 is removed from the atmosphere in photosynthesis, converted into biomass and stored as carbon in vegetation, soil and wood products. Fossil-fuel emissions dominate the North American source-sink balance. North America is a net source of atmospheric CO2 with ecosystem sinks balancing approximately 35% of fossil-fuel CO2 emissions from North America.

  16. The effect of various carbon sources on the growth of single-celled cyanophyta

    NASA Technical Reports Server (NTRS)

    Avilov, I. A.; Sidorenkova, E. S.

    1983-01-01

    In 19 strains of unicellular blue-green algae, belonging to general Synechococcus, Synechocystis, Aphanocapsa and Aphanothece, the capacity of growth under mixotrophic conditions in mineral media with organic carbon sources (carbohydrates, polyols) was investigated. At moderate light intensity (1200 lx) and 0.5% of carbon source there was revealed: (1) Stimulation of growth; (2) Partial or complete inhibition of growth; (3) No influence of carbohydrate and polyols on the growth of some algae strains. Three physiological groups for the investigated strains have been outlined on the basis of data obtained. The possibility of using the differences revealed in classification of unicellular blue-green algae is discussed.

  17. Enhancement of Identifying Cancer Specialists through the Linkage of Medicare Claims to Additional Sources of Physician Specialty

    PubMed Central

    Pollack, Lori A; Adamache, Walter; Eheman, Christie R; Ryerson, A Blythe; Richardson, Lisa C

    2009-01-01

    Objective To examine the number of cancer specialists identified in three national datasets, the effect of combining these datasets, and the use of refinement rules to classify physicians as cancer specialists. Data Sources 1992–2003 linked Surveillance, Epidemiology, and End Results (SEER)-Medicare data and a cancer-free comparison population of Medicare beneficiaries, Unique Physician Identification Number (UPIN) Registry, and the American Medical Association (AMA) Masterfile. Study Design We compared differences in counts of cancer specialists identified in Medicare claims only with the number obtained by combining data sources and after using rules to refine specialty identification. Data Extraction We analyzed physician specialty variables provided on Medicare claims, along with the specialties obtained by linkage of unencrypted UPINs on Medicare claims to the UPIN Registry, the AMA Masterfile, and all sources combined. Principle Findings Medicare claims identified the fewest number of cancer specialists (n=11,721) compared with 19,753 who were identified when we combined all three datasets. The percentage increase identified by combining datasets varied by subspecialty (187 percent for surgical oncologists to 50 percent for radiation oncologists). Rules created to refine identification most affected the count of radiation oncologists. Conclusions Researchers should consider taking the additional effort and cost to refine classification by using additional data sources based on their study objectives. PMID:19207588

  18. Sources of Below-Ground Respired Carbon in a Northern Minnesota Ombrotrophic Spruce Bog and the Influence of Heating Manipulations.

    NASA Astrophysics Data System (ADS)

    Guilderson, T. P.; McFarlane, K. J.; McNicol, G.; Hanson, P. J.; Chanton, J.; Wilson, R.; Bosworth, R.; Singleton, M. J.

    2015-12-01

    A significant uncertainty in future land-surface carbon budgets is the response of wetlands to climate change. A related question is the future net climate (radiative) forcing impact due to ecosystem and environmental change in wetlands. Active wetlands emit both CO2 and CH4 to the atmosphere. CH4 is, over a few decades, a much more potent greenhouse gas than CO2 whereas as a consequence of a much longer atmospheric lifetime, CO2 has a longer 'tail' to its influence. Whether wetlands are a net source or sink of atmospheric carbon under future climate change will depend on the response of the ecosystem to rising temperatures and elevated CO2. The largest uncertainty in future wetland budgets, and its climate forcing, is the stability of the large belowground carbon stocks, often in the form of peat, and the partitioning of CO2 and CH4released via ecosystem respiration. We have characterized the isotopic signatures (14,13C of CO2 and CH4, D-CH4) of the respired carbon used for the production of CO2 and CH4 from the DOE Spruce and Peatland Responses Under Climatic and Environmental Change (SPRUCE) site in the Marcell Experimental Forest, which contains replicated mesocosm manipulations including above/below ground warming and elevated CO2. Deep warming (1-2 m) was initiated in July of 2014 and above ground heating will be initiated in July 2015. Comparison of the respired CO2 and CH4with recently fixed photosynthate, below-ground peat (up to 11,000 years old), and dissolved organic carbon allow us to determine the primary substrates used by the microbial community. Control and pre-perturbed plots are characterized by the consumption and respiration of recently fixed photosynthate and recent (few years to 15 yr) carbon. Although CH4 fluxes have begun to respond to deep-heating, the source of carbon remains similar in the control and perturbed plots. Respired CO2 remains consistent with being sourced from carbon only a few years old. We will present additional data

  19. Lead acid battery performance and cycle life increased through addition of discrete carbon nanotubes to both electrodes

    NASA Astrophysics Data System (ADS)

    Sugumaran, Nanjan; Everill, Paul; Swogger, Steven W.; Dubey, D. P.

    2015-04-01

    Contemporary applications are changing the failure mechanisms of lead acid batteries. Sulfation at the negative electrode, acid stratification, and dendrite formation now precede positive electrode failures such as grid corrosion and active material shedding. To attenuate these failures, carbon has been explored as a negative electrode additive to increase charge acceptance, eliminate sulfation, and extend cycle life. Frequently, however, carbon incorporation decreases paste density and hinders manufacturability. Discrete carbon nanotubes (dCNT), also known as Molecular Rebar®, are lead acid battery additives which can be stably incorporated into either electrode to increase charge acceptance and cycle life with no change to paste density and without impeding the manufacturing process. Here, full-scale automotive batteries containing dCNT in the negative electrode or both negative and positive electrodes are compared to control batteries. dCNT batteries show little change to Reserve Capacity, improved Cold Cranking, increased charge acceptance, and enhanced overall system efficiency. Life cycle tests show >60% increases when dCNT are incorporated into the negative electrode (HRPSoC/SBA) and up to 500% when incorporated into both electrodes (SBA), with water loss per cycle reduced >20%. Failure modes of cycled batteries are discussed and a hypothesis of dCNT action is introduced: the dCNT/Had Overcharge Reaction Mechanism.

  20. Carbon isotope based aerosol source apportionment in Eastern European city Vilnius

    NASA Astrophysics Data System (ADS)

    Garbaras, Andrius; Sapolaite, Justina; Garbariene, Inga; Ezerinskis, Zilvinas; Pocevicius, Matas; Krikscikas, Laurynas; Jacevicius, Sarunas; Plukis, Arturas; Remeikis, Vidmantas

    2016-04-01

    We present carbonaceous aerosol source apportionment results in Eastern European city Vilnius (capital of Lithuania) using stable carbon isotope ratio (δ13C) and radiocarbon (14C) methods. The aerosol sampling campaigns were performed in 2014-2016 winter seasons in Vilnius. PM1 particles were collected on quartz fiber filters using high volume sampler, while PM10 and size segregated aerosol particles were collected using low volume and MOUDI 128 cascade impactor respectively. δ13C values were measured with EA-IRMS system while radiocarbon analysis was performed using Single Stage Accelerator Mass Spectrometer (SSAMS). For the AMS analysis, filters (or aluminium foils from cascade impactor) were graphitized using Automated Graphitization Equipment. It was estimated that dominant carbonaceous aerosol source in Vilnius was of biogenic/biomass origin (60-90 %). Fossil fuel sources accounted for up to 23 % of total carbon fraction. Combining stable carbon and radiocarbon isotope analysis we were able to quantify the amount of coal derived aerosol particles. The contribution of coal burning emissions were up to 14 %. We will present the applicability of dual carbon (13C and 14C) isotope ratio method for the aerosol source apportionment in different regions of Europe, also the perspectives of using MOUDI cascade impactors to make source apportionment in size segregated aerosol particles.

  1. Carbon allocation, source-sink relations and plant growth: do we need to revise our carbon centric concepts?

    NASA Astrophysics Data System (ADS)

    Körner, Christian

    2014-05-01

    Since the discovery that plants 'eat air' 215 years ago, carbon supply was considered the largely unquestioned top driver of plant growth. The ease at which CO2 uptake (C source activity) can be measured, and the elegant algorithms that describe the responses of photosynthesis to light, temperature and CO2 concentration, explain why carbon driven growth and productivity became the starting point of all process based vegetation models. Most of these models, nowadays adopt other environmental drivers, such as nutrient availability, as modulating co-controls, but the carbon priority is retained. Yet, if we believe in the basic rules of stoichometry of all life, there is an inevitable need of 25-30 elements other then carbon, oxygen and hydrogen to build a healthy plant body. Plants compete for most of these elements, and their availability (except for N) is finite per unit land area. Hence, by pure plausibility, it is a highly unlikely situation that carbon plays the rate limiting role of growth under natural conditions, except in deep shade or on exceptionally fertile soils. Furthermore, water shortage and low temperature, both act directly upon tissue formation (meristems) long before photosynthetic limitations come into play. Hence, plants will incorporate C only to the extent other environmental drivers permit. In the case of nutrients and mature ecosystems, this sink control of plant growth may be masked in the short term by a tight, almost closed nutrient cycle or by widening the C to other element ratio. Because source and sink activity must match in the long term, it is not possible to identify the hierarchy of growth controls without manipulating the environment. Dry matter allocation to C rich structures and reserves may provide some stoichimetric leeway or periodic escapes from the more fundamental, long-term environmental controls of growth and productivity. I will explain why carbon centric explanations of growth are limited or arrive at plausible answers

  2. The efficiency of quartz addition on electric arc furnace (EAF) carbon steel slag stability.

    PubMed

    Mombelli, D; Mapelli, C; Barella, S; Gruttadauria, A; Le Saout, G; Garcia-Diaz, E

    2014-08-30

    Electric arc furnace slag (EAF) has the potential to be re-utilized as an alternative to stone material, however, only if it remains chemically stable on contact with water. The presence of hydraulic phases such as larnite (2CaO SiO2) could cause dangerous elements to be released into the environment, i.e. Ba, V, Cr. Chemical treatment appears to be the only way to guarantee a completely stable structure, especially for long-term applications. This study presents the efficiency of silica addition during the deslagging period. Microstructural characterization of modified slag was performed by SEM and XRD analysis. Elution tests were performed according to the EN 12457-2 standard, with the addition of silica and without, and the obtained results were compared. These results demonstrate the efficiency of the inertization process: the added silica induces the formation of gehlenite, which, even in caustic environments, does not exhibit hydraulic behaviour. PMID:25113518

  3. Diamond crystallization in a CO2-rich alkaline carbonate melt with a nitrogen additive

    NASA Astrophysics Data System (ADS)

    Khokhryakov, Alexander F.; Palyanov, Yuri N.; Kupriyanov, Igor N.; Nechaev, Denis V.

    2016-09-01

    Diamond crystallization was experimentally studied in a CO2-bearing alkaline carbonate melt with an increased content of nitrogen at pressure of 6.3 GPa and temperature of 1500 °C. The growth rate, morphology, internal structure of overgrown layers, and defect-impurity composition of newly formed diamond were investigated. The type of growth patterns on faces, internal structure, and nitrogen content were found to be controlled by both the crystallographic orientation of the growth surfaces and the structure of the original faces of diamond seed crystals. An overgrown layer has a uniform structure on the {100} plane faces of synthetic diamond and a fibrillar (fibrous) structure on the faceted surfaces of a natural diamond cube. The {111} faces have a polycentric vicinal relief with numerous twin intergrowths and micro twin lamellae. The stable form of diamond growth under experimental conditions is a curved-face hexoctahedron with small cube faces. The nitrogen impurity concentration in overgrown layers varies depending on the growth direction and surface type, from 100 to 1100 ppm.

  4. Short-term nitrogen additions can shift a coastal wetland from a sink to a source of N2O

    USGS Publications Warehouse

    Moseman-Valtierra, S.; Gonzalez, R.; Kroeger, K.D.; Tang, J.; Chao, W.C.; Crusius, J.; Bratton, J.; Green, A.; Shelton, J.

    2011-01-01

    Coastal salt marshes sequester carbon at high rates relative to other ecosystems and emit relatively little methane particularly compared to freshwater wetlands. However, fluxes of all major greenhouse gases (N2O, CH4, and CO2) need to be quantified for accurate assessment of the climatic roles of these ecosystems. Anthropogenic nitrogen inputs (via run-off, atmospheric deposition, and wastewater) impact coastal marshes. To test the hypothesis that a pulse of nitrogen loading may increase greenhouse gas emissions from salt marsh sediments, we compared N2O, CH4 and respiratory CO2 fluxes from nitrate-enriched plots in a Spartina patens marsh (receiving single additions of NaNO3 equivalent to 1.4 g N m-2) to those from control plots (receiving only artificial seawater solutions) in three short-term experiments (July 2009, April 2010, and June 2010). In July 2009, we also compared N2O and CH4 fluxes in both opaque and transparent chambers to test the influence of light on gas flux measurements. Background fluxes of N2O in July 2009 averaged -33 ??mol N2O m-2 day-1. However, within 1 h of nutrient additions, N2O fluxes were significantly greater in plots receiving nitrate additions relative to controls in July 2009. Respiratory rates and CH4 fluxes were not significantly affected. N2O fluxes were significantly higher in dark than in transparent chambers, averaging 108 and 42 ??mol N2O m-2 day-1 respectively. After 2 days, when nutrient concentrations returned to background levels, none of the greenhouse gas fluxes differed from controls. In April 2010, N2O and CH4 fluxes were not significantly affected by nitrate, possibly due to higher nitrogen demands by growing S. patens plants, but in June 2010 trends of higher N2O fluxes were again found among nitrate-enriched plots, indicating that responses to nutrient pulses may be strongest during the summer. In terms of carbon equivalents, the highest average N2O and CH4 fluxes observed, exceeded half the magnitude of typical

  5. Short-term nitrogen additions can shift a coastal wetland from a sink to a source of N 2O

    NASA Astrophysics Data System (ADS)

    Moseman-Valtierra, Serena; Gonzalez, Rosalinda; Kroeger, Kevin D.; Tang, Jianwu; Chao, Wei Chun; Crusius, John; Bratton, John; Green, Adrian; Shelton, James

    2011-08-01

    Coastal salt marshes sequester carbon at high rates relative to other ecosystems and emit relatively little methane particularly compared to freshwater wetlands. However, fluxes of all major greenhouse gases (N 2O, CH 4, and CO 2) need to be quantified for accurate assessment of the climatic roles of these ecosystems. Anthropogenic nitrogen inputs (via run-off, atmospheric deposition, and wastewater) impact coastal marshes. To test the hypothesis that a pulse of nitrogen loading may increase greenhouse gas emissions from salt marsh sediments, we compared N 2O, CH 4 and respiratory CO 2 fluxes from nitrate-enriched plots in a Spartina patens marsh (receiving single additions of NaNO 3 equivalent to 1.4 g N m -2) to those from control plots (receiving only artificial seawater solutions) in three short-term experiments (July 2009, April 2010, and June 2010). In July 2009, we also compared N 2O and CH 4 fluxes in both opaque and transparent chambers to test the influence of light on gas flux measurements. Background fluxes of N 2O in July 2009 averaged -33 μmol N 2O m -2 day -1. However, within 1 h of nutrient additions, N 2O fluxes were significantly greater in plots receiving nitrate additions relative to controls in July 2009. Respiratory rates and CH 4 fluxes were not significantly affected. N 2O fluxes were significantly higher in dark than in transparent chambers, averaging 108 and 42 μmol N 2O m -2 day -1 respectively. After 2 days, when nutrient concentrations returned to background levels, none of the greenhouse gas fluxes differed from controls. In April 2010, N 2O and CH 4 fluxes were not significantly affected by nitrate, possibly due to higher nitrogen demands by growing S. patens plants, but in June 2010 trends of higher N 2O fluxes were again found among nitrate-enriched plots, indicating that responses to nutrient pulses may be strongest during the summer. In terms of carbon equivalents, the highest average N 2O and CH 4 fluxes observed, exceeded half

  6. Hot isostatic pressing of silicon nitride with boron nitride, boron carbide, and carbon additions

    NASA Technical Reports Server (NTRS)

    Mieskowski, Diane M.; Sanders, William A.

    1989-01-01

    Si3N4 test bars containing additions of BN, B4C, and C, were hot isostatically pressed in Ta cladding at 1900 and 2050 C to 98.9 percent to 99.5 percent theoretical density. Room-temperature strength data on specimens containing 2 wt pct BN and 0.5 wt pct C were comparable to data obtained for Si3N4 sintered with Y2O3, Y2O3 and Al2O3, or ZrO2. The 1370 C strengths were less than those obtained for additions of Y2O3 or ZrO2 but greater than those obtained from a combination of Y2O3 and Al2O3. SEM fractography indicated that, as with other types of Si3N4, room-temperature strength was controlled by processing flaws. The decrease in strength at 1370 C was typical of Si3N4 having an amorphous grain-boundary phase. The primary advantage of nonoxide additions appears to be in facilitating specimen removal from the Ta cladding.

  7. Metabolic fluxes in Corynebacterium glutamicum during lysine production with sucrose as carbon source.

    PubMed

    Wittmann, Christoph; Kiefer, Patrick; Zelder, Oskar

    2004-12-01

    Metabolic fluxes in the central metabolism were determined for lysine-producing Corynebacterium glutamicum ATCC 21526 with sucrose as a carbon source, providing an insight into molasses-based industrial production processes with this organism. For this purpose, 13C metabolic flux analysis with parallel studies on [1-(13C)Fru]sucrose, [1-(13C)Glc]sucrose, and [13C6Fru]sucrose was carried out. C. glutamicum directed 27.4% of sucrose toward extracellular lysine. The strain exhibited a relatively high flux of 55.7% (normalized to an uptake flux of hexose units of 100%) through the pentose phosphate pathway (PPP). The glucose monomer of sucrose was completely channeled into the PPP. After transient efflux, the fructose residue was mainly taken up by the fructose-specific phosphotransferase system (PTS) and entered glycolysis at the level of fructose-1,6-bisphosphate. Glucose-6-phosphate isomerase operated in the gluconeogenetic direction from fructose-6-phosphate to glucose-6-phosphate and supplied additional carbon (7.2%) from the fructose part of the substrate toward the PPP. This involved supply of fructose-6-phosphate from the fructose part of sucrose either by PTS(Man) or by fructose-1,6-bisphosphatase. C. glutamicum further exhibited a high tricarboxylic acid (TCA) cycle flux of 78.2%. Isocitrate dehydrogenase therefore significantly contributed to the total NADPH supply of 190%. The demands for lysine (110%) and anabolism (32%) were lower than the supply, resulting in an apparent NADPH excess. The high TCA cycle flux and the significant secretion of dihydroxyacetone and glycerol display interesting targets to be approached by genetic engineers for optimization of the strain investigated. PMID:15574927

  8. Eutrophication and carbon sources in Chesapeake Bay over the last 2700 yr: Human impacts in context

    USGS Publications Warehouse

    Bratton, J.F.; Colman, Steven M.; Seal, R.R., II

    2003-01-01

    To compare natural variability and trends in a developed estuary with human-influenced patterns, stable isotope ratios (??13C and ??15N) were measured in sediments from five piston cores collected in Chesapeake Bay. Mixing of terrestrial and algal carbon sources primarily controls patterns of ??13Corg profiles, so this proxy shows changes in estuary productivity and in delivery of terrestrial carbon to the bay. Analyses of ??15N show periods when oxygen depletion allowed intense denitrification and nutrient recycling to develop in the seasonally stratified water column, in addition to recycling taking place in surficial sediments. These conditions produced 15N-enriched (heavy) nitrogen in algal biomass, and ultimately in sediment. A pronounced increasing trend in ??15N of +4??? started in about A.D. 1750 to 1800 at all core sites, indicating greater eutrophication in the bay and summer oxygen depletion since that time. The timing of the change correlates with the advent of widespread land clearing and tillage in the watershed, and associated increases in erosion and sedimentation. Isotope data show that the region has experienced up to 13 wet-dry cycles in the last 2700 yr. Relative sea-level rise and basin infilling have produced a net freshening trend overprinted with cyclic climatic variability. Isotope data also constrain the relative position of the spring productivity maximum in Chesapeake Bay and distinguish local anomalies from sustained changes impacting large regions of the bay. This approach to reconstructing environmental history should be generally applicable to studies of other estuaries and coastal embayments impacted by watershed development. Published by Elsevier Ltd.

  9. Eutrophication and carbon sources in Chesapeake Bay over the last 2700 yr: human impacts in context

    NASA Astrophysics Data System (ADS)

    Bratton, John F.; Colman, Steven M.; Seal, Robert R.

    2003-09-01

    To compare natural variability and trends in a developed estuary with human-influenced patterns, stable isotope ratios (δ 13C and δ 15N) were measured in sediments from five piston cores collected in Chesapeake Bay. Mixing of terrestrial and algal carbon sources primarily controls patterns of δ 13C org profiles, so this proxy shows changes in estuary productivity and in delivery of terrestrial carbon to the bay. Analyses of δ 15N show periods when oxygen depletion allowed intense denitrification and nutrient recycling to develop in the seasonally stratified water column, in addition to recycling taking place in surficial sediments. These conditions produced 15N-enriched (heavy) nitrogen in algal biomass, and ultimately in sediment. A pronounced increasing trend in δ 15N of +4‰ started in about A.D. 1750 to 1800 at all core sites, indicating greater eutrophication in the bay and summer oxygen depletion since that time. The timing of the change correlates with the advent of widespread land clearing and tillage in the watershed, and associated increases in erosion and sedimentation. Isotope data show that the region has experienced up to 13 wet-dry cycles in the last 2700 yr. Relative sea-level rise and basin infilling have produced a net freshening trend overprinted with cyclic climatic variability. Isotope data also constrain the relative position of the spring productivity maximum in Chesapeake Bay and distinguish local anomalies from sustained changes impacting large regions of the bay. This approach to reconstructing environmental history should be generally applicable to studies of other estuaries and coastal embayments impacted by watershed development.

  10. Tracking Nonpoint Source Nitrogen and Carbon in Watersheds of Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Kaushal, S.; Pennino, M. J.; Duan, S.; Blomquist, J.

    2012-12-01

    Humans have altered nitrogen and carbon cycles in rivers regionally with important impacts on coastal ecosystems. Nonpoint source nitrogen pollution is a leading contributor to coastal eutrophication and hypoxia. Shifts in sources of carbon impact downstream ecosystem metabolism and fate and transport of contaminants in coastal zones. We used a combination of stable isotopes and optical tracers to investigate fate and transport of nitrogen and carbon sources in tributaries of the largest estuary in the U.S., the Chesapeake Bay. We analyzed isotopic composition of water samples from major tributaries including the Potomac River, Susquehanna River, Patuxent River, and Choptank River during routine and storm event sampling over multiple years. A positive correlation between δ15N-NO3- and δ18O-NO3- in the Potomac River above Washington D.C. suggested denitrification or biological uptake in the watershed was removing agriculturally-derived N during summer months. In contrast, the Patuxent River in Maryland showed elevated δ15N-NO3- (5 - 12 per mil) with no relationship to δ18O-NO3- suggesting the importance of wastewater sources. From the perspective of carbon sources, there were distinct isotopic values of the δ13C-POM of particulate organic matter and fluorescence excitation emission matrices (EEMS) for rivers influenced by their dominant watershed land use. EEMS showed that there were increases in the humic and fulvic fractions of dissolved organic matter during spring floods, particularly in the Potomac River. Stable isotopic values of δ13C-POM also showed rapid depletion suggesting terrestrial carbon "pulses" in the Potomac River each spring. The δ15N-POM peaked to 10 - 15 per mil each spring suggested a potential manure source or result of biological processing within the watershed. Overall, there were considerable changes in sources and transformations of nitrogen and carbon that varied across rivers and that contribute to nitrogen and carbon loads

  11. A Carbon Nano Tube electron impact ionisation source for low-power, compact spacecraft mass spectrometers

    NASA Astrophysics Data System (ADS)

    Sheridan, S.; Bardwell, M. W.; Morse, A. D.; Morgan, G. H.

    2012-04-01

    A novel ionisation source which uses commercially available Carbon Nano Tube devices is demonstrated as a replacement for a filament based ionisation source in an ion trap mass spectrometer. The carbon nanotube ion source electron emission was characterised and exhibited typical emission of 30 ± 1.7 μA with an applied voltage differential of 300 V between the carbon nanotube tips and the extraction grid. The ion source was tested for longevity and operated under a condition of continuous emission for a period of 44 h; there was an observed reduction in emission current of 26.5% during operation. Spectra were generated by installing the ion source into a Finnigan Mat ITD700 ion trap mass spectrometer; the spectra recorded showed all of the characteristic m/z peaks from m/z 69 to m/z 219. Perfluorotributylamine spectra were collected and averaged contiguously for a period of 48 h with no significant signal loss or peak mass allocation shift. The low power requirements and low mass of this novel ionisation source are considered be of great value to future space missions where mass spectrometric technology will be employed.

  12. Hierarchy of Carbon Source Selection in Paracoccus pantotrophus: Strict Correlation between Reduction State of the Carbon Substrate and Aerobic Expression of the nap Operon

    PubMed Central

    Ellington, M. J. K.; Bhakoo, K. K.; Sawers, G.; Richardson, D. J.; Ferguson, S. J.

    2002-01-01

    Paracoccus pantotrophus can express a periplasmic nitrate reductase (Nap) during aerobic growth. A proposed role for this enzyme is the dissipation of excess redox energy during oxidative metabolism of reduced carbon substrates. To investigate the regulation of nap expression, a transcriptional fusion between the nap promoter region of P. pantotrophus and the lacZ gene was constructed. When this fusion was used, analyses showed that transcription from the nap promoter increases as the average reduction state of the carbon atoms increases. Thus, β-galactosidase activities increase as the carbon source changes in the order succinate-acetate-butyrate. This result was obtained regardless of which of the three carbon sources was used for culture of the inoculum. If two carbon sources were presented together, the β-galactosidase activity was always the same as it was when the least-reduced carbon source was added alone. This suggests that the regulation is dependent upon metabolism of the more-reduced carbon sources rather than just their presence in the medium. Analysis of culture medium by 1H nuclear magnetic resonance showed that for aerobic growth P. pantotrophus strictly selected its carbon source in the order succinate-acetate-butyrate. This was reflected by diauxic growth kinetics on medium containing mixed carbon substrates. The regulatory mechanism underpinning such a selection is unknown but is likely to be related to the mechanism which controls the transcription of the nap operon. PMID:12169601

  13. Biochemical Modulation by Carbon and Nitrogen Addition in Cultures of Dictyota menstrualis (Dictyotales, Phaeophyceae) to Generate Oil-based Bioproducts.

    PubMed

    Martins, Aline P; Yokoya, Nair S; Colepicolo, Pio

    2016-06-01

    Dictyota menstrualis (Hoyt) Schnetter, Hörning & Weber-Peukert (Dictyotales, Phaeophyceae) was studied for the production of oil-based bioproducts and co-products. Experiments were performed to evaluate the effect of carbon dioxide (CO2) concentration, under nitrogen (NO3 (-)) limiting and saturation conditions, on growth rate (GR), photosynthesis, as well as nitrate reductase (NR), carbonic anhydrase (CA), and Rubisco activities. In addition, the biochemical composition of D. menstrualis under these conditions was estimated. GR, protein content, and N content in D. menstrualis were higher in treatments containing NO3 (-), irrespective of CO2 addition. However, when CO2 was added to medium saturated with NO3 (-), values of maximum photosynthesis, Rubisco, and NR activity, as well as total soluble carbohydrates and lipids, were increased. CA activity did not vary under the different treatments. The fatty acid profile of D. menstrualis was characterized by a high content of polyunsaturated fatty acids, especially the omega-3 fatty acids, making it a possible candidate for nutraceutical use. In addition, this species presented high GR, photosynthetic rate, and fatty acid content, highlighting its economic importance and the possibility of different biotechnological applications. PMID:26945758

  14. Constraining Sources of Subducted and Recycled Carbon Along the Sunda Arc

    NASA Astrophysics Data System (ADS)

    House, B. M.; Bebout, G. E.; Hilton, D. R.; Rodriguez, B.; Plank, T. A.

    2014-12-01

    From sediment subduction rates and C contents at ODP/DSDP sites 765 and 211, we estimate the rate of C subduction along ~2000 km of the East Sunda Arc to be ~0.4 Tg C yr-1, representing a significant source of subducted volatiles [1]. However volatile recycling efficiency and the provenance of recycled volatiles in this region remain poorly understood. With new δ13C measurements of both carbonate and organic carbon from sites 211 and 765, we present the most detailed study yet of the spatial variability of subducted C and recycled CO2 provenance along the strike of the arc. Furthermore we demonstrate the importance of oceanic crustal carbonate as a C source in a subduction zone that is otherwise carbonate starved. Carbonate content throughout the sediment column decreases dramatically between site 765, approximately 250 km from the Australian continental margin, and site 211, approximately 300 km southwest of the trench and outboard of the Sunda Strait between Sumatra and Java. Continental and shelf carbonate input from the Australian margin dominates shallow deposits at site 765, but underlying pelagic sediments are thought to contribute the majority of inorganic C to the arc. The paucity of carbonate in sediments at site 211 suggests that along this segment essentially all carbonate subducted is derived from altered ocean crust, presenting an opportunity to study the effects of crustal carbonate input. While previous C provenance studies relied on globally-averaged δ13C values for organic and inorganic C in subducted sediments, we present new estimates based on measured δ13CVPDB of carbonate (average of ~2‰ in subducted sediments) and organic carbon (-22.5 to -23‰ average) along with previously published efflux data [2]. These estimates suggest that the arc-averaged ratio of carbonate to organic C subducted along the East Sunda Arc is nearly identical to the inorganic to organic C ratio represented in volcanic and hydrothermal CO2 output, suggesting that

  15. Old fronds serve as a vernal carbon source in the wintergreen fern Dryopteris intermedia (Aspleniaceae).

    PubMed

    Tessier, Jack T; Bornn, Matthew P

    2007-01-01

    Maintaining green leaves beyond the growing season has been hypothesized to benefit plants by supplying either a nutrient or a carbon source. Understanding such ecophysiological aspects of plants will help us to appreciate how a species functions in its environment and predict how it might be affected by future changes in that environment. The wintergreen fern species Dryopteris intermedia does not retranslocate nitrogen and phosphorus from old fronds in spring, but photosynthesis does take place in the old fronds during this season. To determine if carbon fixed in the old fronds is translocated to other parts of the plant, we labeled old fronds with (13)C via photosynthetic uptake and examined old fronds, new fronds, fine roots, and rhizomes for (13)C content 1 day and 1 month after labeling the old fronds. Vernally fixed carbon was translocated to the new fronds but not significantly to the below ground tissues. Old fronds in this species, therefore, serve as a carbon source for vernal growth of new fronds. This is the first study in which a fern was labeled with (13)C to track vernally fixed carbon from old fronds to the rest of the plant in a wintergreen species. Future research should examine the precise timing of this carbon movement and examine other species for a similar or contrasting strategy. PMID:21642204

  16. Deep-sea hydrocarbon seep communities: evidence for energy and nutritional carbon sources

    SciTech Connect

    Brooks, J.M.; Kennicutt, M.C. II; Fisher, C.R.; Macko, S.A.; Cole, K.; Childress, J.J.; Bidigare, R.R.; Vetter, R.D.

    1987-11-20

    Mussels, clams, and tube worms collected in the vicinity of hydrocarbon seeps on the Louisiana slope contain mostly dead carbon, indicating that dietary carbon is largely derived from seeping oil and gas. Enzyme assays, elemental sulfur analysis, and carbon dioxide fixation studies demonstrate that vestimentiferan tube worms and three clam species contain intracellular, autotrophic sulfur bacterial symbionts. Carbon isotopic ratios of 246 individual animal tissues were used to differentiate heterotrophic (delta/sup 14/C = -14 to -20 per mil), sulfur-based (delta/sup 14/C = -30 to -42 per mil), and methane-based (delta/sup 13/C = <-40 per mil) energy sources. Mussels with symbiotic methanotrophic bacteria reflect the carbon isotopic composition of the methane source. Isotopically light nitrogen and sulfur confirm the chemoautotrophic nature of the seep animals. Sulfur-based chemosynthetic animals contain isotopically light sulfur, whereas methane-based symbiotic mussels more closely reflect the heavier oceanic sulfate pool. The nitrogen requirement of some seep animals may be supported by nitrogen-fixing bacteria. Some grazing neogastropods have isotopic values characteristic of chemosynthetic animals, suggesting the transfer of carbon into the background deep-sea fauna.

  17. Can we afford to waste carbon dioxide? Carbon dioxide as a valuable source of carbon for the production of light olefins.

    PubMed

    Centi, Gabriele; Iaquaniello, Gaetano; Perathoner, Siglinda

    2011-09-19

    Concerns about climate change have increased the amount of activity on carbon capture and sequestration (CCS) as one of the solutions to the problem of rising levels of CO(2) in the troposphere, while the reuse of CO(2) (carbon capture and recycling; CCR) has only recently received more attention. CCR is focused on the possibility of using CO(2) as a cheap (or even negative-value) raw material. This Concept paper analyzes this possibility from a different perspective: In a sustainable vision, can we afford to waste CO(2) as a source of carbon in a changing world faced with a fast depletion of natural carbon sources and in need of a low-carbon, resource-efficient economy? One of the points emerging from this discussion concerns the use of CO(2) for the production of olefins (substituting into or integrating with current energy-intensive methodologies that start from oil or syngas from other fossil fuel resources) if H(2) from renewable resources were available at competitive costs. This offers an opportunity to accelerate the introduction of renewable energy into the chemical production chain, and thus to improve resource efficiency in this important manufacturing sector. PMID:21922678

  18. Biological nitrate removal using a food waste-derived carbon source in synthetic wastewater and real sewage.

    PubMed

    Zhang, Haowei; Jiang, Jianguo; Li, Menglu; Yan, Feng; Gong, Changxiu; Wang, Quan

    2016-01-15

    The production of volatile fatty acids (VFAs) from food waste to improve biological nutrient removal has drawn much attention. In this study, acidogenic liquid from food waste was used as an alternative carbon source for synthetic wastewater treatment. C/N ratios of 5 and 6 were suitable for denitrification, and the change in acidogenic liquid composition had no negative effect on denitrification. The denitrification rates using optimal carbon-to-nitrate ratios of acidogenic liquid were more than 25 mg NO3-N/(gVSS·h). At the same time, acidogenic liquid was used to improve nutrient removal from summer and winter sewage. C/N ratios of 5 and 6 were acceptable for summer sewage treatment. Total nitrogen in the final effluent was less than 7 mg/L. Two additional hours were required for winter sewage treatment, and the C/N ratio had to be >6. PMID:26547269

  19. Highly Aligned Carbon Fiber in Polymer Composite Structures via Additive Manufacturing

    DOE PAGESBeta

    Tekinalp, Halil L; Kunc, Vlastimil; Velez-Garcia, Gregorio M; Duty, Chad E; Love, Lonnie J; Naskar, Amit K; Blue, Craig A; Ozcan, Soydan

    2014-01-01

    Additive manufacturing, diverging from traditional manufacturing techniques, such as casting and machining materials, can handle complex shapes with great design flexibility without the typical waste. Although this technique has been mainly used for rapid prototyping, interest is growing in using this method to directly manufacture actual parts of complex shape. To use 3D-printing additive manufacturing in wide spread applications, the technique and the feedstock materials require improvements to meet the mechanical requirements of load-bearing components. Thus, we investigated the short fiber (0.2 mm to 0.4 mm) reinforced acrylonitrile-butadiene-styrene composites as a feedstock for 3D-printing in terms of their processibility, microstructuremore » and mechanical performance; and also provided comparison with traditional compression molded composites. The tensile strength and modulus of 3D-printed samples increased ~115% and ~700%, respectively. 3D-printer yielded samples with very high fiber orientation in printing direction (up to 91.5 %), whereas, compression molding process yielded samples with significantly less fiber orientation. Microstructure-mechanical property relationships revealed that although the relatively high porosity is observed in the 3D-printed composites as compared to those produced by the conventional compression molding technique, they both exhibited comparable tensile strength and modulus. This phenomena is explained based on the changes in fiber orientation, dispersion and void formation.« less

  20. Effect of geological carbon sources on eddy covariance measurements: analysis and possible correction approaches

    NASA Astrophysics Data System (ADS)

    Papale, D.; Rey, A.; Belelli-Marchesini, L.; Etiope, G.; Pegoraro, E.

    2013-12-01

    A recent set of studies carried out in the SE of Spain highlighted the need to consider geological carbon sources when estimating the net ecosystem carbon balance (NECB) of terrestrial ecosystems located in areas potentially affected by geofluid circulation. In this study we present the mechanisms and propose a new methodology using physical parameters of the atmospheric boundary layer to quantify the CO2 coming from deep origin. To test our approach, we compare NECB estimates with seasonal patterns of soil CO2 efflux and vegetation activity measured by satellite images (NDVI) over two-year period at this site (2007/2008). According with the eddy covariance measurements the alpha grass ecosystem was a net carbon source (93.7 and 145.0 g C m-2, for the years 2007 and 2008, respectively) particularly as a result of large amounts of carbon released over the dry period. This relevant CO2 emission (reaching up to 15 umol m-2 s-1) was however not related to ecosystem activities as confirmed by measurements of soil CO2 efflux using chambers (ca. 0.5 umol m-2 s-1) and plant productivity that was minimal during this period. A simple correction based on a linear relationship between NECB and wind speed for different stability conditions and wind sectors has been used to estimate the geological flux FGEO and subtracted it from the NECB to obtain the biological flux FBIO. We then partitioned FBIO into gross primary productivity and ecosystem respiration and proved that, after removing FGEO, ecosystem and soil respiration followed similar temporal patterns. The annual contribution of the geological component to NECB was 49.6 and 46.7 % for the year 2007 and 2008, respectively. Therefore, potential contribution of geological carbon sources should be tested and quantified in those ecosystems located in areas with potential natural emission of geologic gases to the surface. References: REY A., BELELLI MARCHESINI L., WERE A., SERRANO ORTIZ P., ETIOPE G., PAPALE D, DOMINGO F

  1. 40 CFR 458.26 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  2. 40 CFR 458.26 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  3. 40 CFR 458.46 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  4. 40 CFR 458.36 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  5. 40 CFR 458.26 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  6. 40 CFR 458.36 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  7. 40 CFR 458.46 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  8. 40 CFR 458.36 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  9. 40 CFR 458.46 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  10. 40 CFR 458.16 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  11. 40 CFR 458.16 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  12. 40 CFR 458.16 - Pretreatment standards for new sources.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... with 40 CFR part 403. In addition, the following pretreatment standard establishes the quantity or... GUIDELINES AND STANDARDS (CONTINUED) CARBON BLACK MANUFACTURING POINT SOURCE CATEGORY Carbon Black...

  13. Relative Contributions of Fossil and Contemporary Carbon sources to PM 2.5 Aerosols at Nine IMPROVE Network Sites

    SciTech Connect

    Bench, G; Fallon, S; Schichtel, B; Malm, W; McDade, C

    2006-06-26

    Particulate matter aerosols contribute to haze diminishing vistas and scenery at National Parks and Wilderness Areas within the United States. To increase understanding of the sources of carbonaceous aerosols at these settings, the total carbon loading and {sup 14}C/C ratio of PM 2.5 aerosols at nine IMPROVE (Interagency Monitoring for Protection Of Visual Environments) network sites were measured. Aerosols were collected weekly in the summer and winter at one rural site, two urban sites, five sites located in National Parks and one site located in a Wildlife Preserve. The carbon measurements together with the absence of {sup 14}C in fossil carbon materials and the known {sup 14}C/C levels in contemporary carbon materials were used to derive contemporary and fossil carbon contents of the particulate matter. Contemporary and fossil carbon aerosol loadings varied across the sites and suggest different percentages of carbon source inputs. The urban sites had the highest fossil carbon loadings that comprised around 50% of the total carbon aerosol loading. The Wildlife Preserve and National Park sites together with the rural site had much lower fossil carbon loading components. At these sites, variations in the total carbon aerosol loading were dominated by non-fossil carbon sources. This suggests that reduction of anthroprogenic sources of fossil carbon aerosols may result in little decrease in carbonaceous aerosol loading at many National Parks and rural areas.

  14. Culture medium pH influence on Gluconacetobacter physiology: Cellulose production rate and yield enhancement in presence of multiple carbon sources.

    PubMed

    Yassine, Fatima; Bassil, Nathalie; Flouty, Roula; Chokr, Ali; Samrani, Antoine El; Boiteux, Gisèle; Tahchi, Mario El

    2016-08-01

    Gluconacetobacter genera are valued for bacterial cellulose (BC) and acetic acid production. BC is produced at optimal yields in classical microbiological media that are expensive for a large scale of production. In addition, BC usage for industrial purposes is limited due to low conversion rate into cellulose and to long incubation duration. In this paper, Gluconacetobacter isolated from apple vinegar was kinetically studied to evaluate cellulose production in presence of different carbon sources. Acetic and citric acid effect on Gluconacetobacter metabolism is clarified. It was shown that Gluconacetobacter uses glucose as a primary carbon source for cells growth and products formation. Acetic acid employment as a co-carbon source in Hestrin Schramm medium showed an increase of 17% in BC yield with a moderate decrease in the crystallite size of the resulting polymer. PMID:27112876

  15. Enantioselective Synthesis of Quaternary Carbon Stereocenters: Addition of 3-Substituted Oxindoles to Vinyl Sulfone Catalyzed by Pentanidiums.

    PubMed

    Zong, Lili; Du, Shubo; Chin, Kek Foo; Wang, Chao; Tan, Choon-Hong

    2015-08-01

    A pentanidium-catalyzed highly enantioselective conjugate addition of 3-alkyloxindoles to phenyl vinyl sulfone has been demonstrated. This approach allows the construction of 3,3-dialkyl-substituted oxindole frameworks with high yield and excellent enantioselectivity (up to 99%) under simple phase-transfer conditions. A variety of oxindoles bearing all-carbon quaternary stereogenic centers were obtained in the presence of 0.25 mol% pentanidium. Meanwhile, practicality was illustrated by a gram-scale asymmetric synthesis of two 3,3-dialkyl-substituted oxindoles. The resulting adduct can be smoothly transformed to the natural product analogue in a short synthetic route. PMID:26179829

  16. Use of pyrolyzed carbon black as an additive (part 3. Air-cooled furnace slag). Final report

    SciTech Connect

    Lee, K.H.; Lovell, C.W.; Salgado, R.

    1996-11-20

    Scrap tires, generated at the rate of over 242 million each year in the United States, are recognized as one of the most significant environmental problems. Most of these scrap tires have been disposed of in landfills, stockpiles, and illegal dumps (EPA 1991). There is a need to find more useful, environmentally friendly applications for these tires. Extensive researches have been conducted in the past years on the utilization of the scrap tires. The use of scrap tires for asphalt pavement, which is complicated by the complex behavior of asphalt, has received major attention. This research aims to describe the performance of mixtures of asphalt using pyrolyzed carbon black as an additive.

  17. Enhancement of post-anoxic denitrification for biological nutrient removal: effect of different carbon sources.

    PubMed

    Chen, Hong-bo; Wang, Dong-bo; Li, Xiao-ming; Yang, Qi; Zeng, Guang-ming

    2015-04-01

    Previous research has demonstrated that post-anoxic denitrification and biological nutrient removal could be achieved in the oxic/anoxic/extended-idle wastewater treatment regime. This study further investigated the effect of different carbon sources on post-anoxic denitrification and biological nutrient removal. Acetate, propionate (volatile fatty acids (VFAs)), glucose (carbohydrate), methanol, and ethanol (alcohol) were used as the sole carbon source, respectively. The experimental results showed that VFA substrates led to an improvement in nitrogen and phosphorus removal. The total nitrogen and phosphorus removal efficiency values driven by acetate achieved 93 and 99%, respectively. In contrast, glucose present in mixed liquor deteriorated total nitrogen and phosphorus removal efficiency values to 72 and 54%. In the reactors cultured with methanol and ethanol, 66 and 63% of the total nitrogen were removed, and phosphorus removal efficiency values were 78 and 71%, respectively. The mechanism studies revealed that different carbon sources affected the transformations of intracellular polyhydroxyalkanoates (PHAs) and glycogen. PHAs are the dominant storages for microorganisms cultured with VFA substrates. Though glycogen is not the favorable energy and carbon source for polyphosphate-accumulating organisms, it can be consumed by microorganisms related to biological nitrogen removal and is able to serve as the electron donor for post-anoxic denitrification. PMID:25354439

  18. Exploring cover crops as carbon sources for anaerobic soil disinfestation in a vegetable production system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In a raised-bed plasticulture vegetable production system utilizing anaerobic soil disinfestation (ASD) in Florida field trials, pathogen, weed, and parasitic nematode control was equivalent to or better than the methyl bromide control. Molasses was used as the labile carbon source to stimulate micr...

  19. FOREST HARVESTS AND WOOD PRODUCTS: SOURCES AND SINKS OF ATMOSPHERIC CARBON DIOXIDE

    EPA Science Inventory

    Changes in the net carbon(c)sink-source balance related to a country's forest harvesting and use of wood products is an important component in making country-level inventories of greenhouse gas emissions,a current activity within many signatory nations to the UN Framework Convent...

  20. PCDD/F FORMATION RATES FROM FLY ASH AND METHANE COMBUSTION CARBON SOURCES

    EPA Science Inventory

    The abstract discusses polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD,F) from fly ash and methane combustion carbon sources. (NOTE: PCDD,Fs are formed in trace quantities in combustion processes via two primary mechanisms: de novo synthesis in which they ...

  1. Influence of carbon source amendment on effectiveness of anaerobic soil disinfestation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Anaerobic soil disinfestation (ASD; also termed biological soil disinfestation or soil reductive sterilization) is a non-chemical soil disinfestation process which includes 1) soil incorporation of a labile carbon (C) source, 2) mulching with a polyethylene film to limit gas exchange, and 3) drip ir...

  2. BACTERIOPLANKTON DYNAMICS IN PENSACOLA BAY, FL, USA: ROLE OF PHYTOPLANKTON AND DETRIAL CARBON SOURCES

    EPA Science Inventory

    Bacterioplankton Dynamics in Pensacola Bay, FL, USA: Role of Phytoplankton and Detrital Carbon Sources (Abstract). To be presented at the16th Biennial Conference of the Estuarine Research Foundation, ERF 2001: An Estuarine Odyssey, 4-8 November 2001, St. Pete Beach, FL. 1 p. (ER...

  3. Silica-Based Carbon Source Delivery for In-situ Bioremediation Enhancement

    NASA Astrophysics Data System (ADS)

    Zhong, L.; Lee, M. H.; Lee, B.; Yang, S.

    2015-12-01

    Colloidal silica aqueous suspensions undergo viscosity increasing and gelation over time under favorable geochemical conditions. This property of silica suspension can potentially be applied to deliver remedial amendments to the subsurface and establish slow release amendment sources for enhanced remediation. In this study, silica-based delivery of carbon sources for in-situ bioremediation enhancement is investigated. Sodium lactate, vegetable oil, ethanol, and molasses have been studied for the interaction with colloidal silica in aqueous suspensions. The rheological properties of the carbon source amendments and silica suspension have been investigated. The lactate-, ethanol-, and molasses-silica suspensions exhibited controllable viscosity increase and eventually became gels under favorable geochemical conditions. The gelation rate was a function of the concentration of silica, salinity, amendment, and temperature. The vegetable oil-silica suspensions increased viscosity immediately upon mixing, but did not perform gelation. The carbon source release rate from the lactate-, ethanol-, and molasses-silica gels was determined as a function of silica, salinity, amendment concentration. The microbial activity stimulation and in-situ bioremediation enhancement by the slow-released carbon from the amendment-silica gels will be demonstrated in future investigations planned in this study.

  4. Enhanced light absorption by mixed source black and brown carbon particles in UK winter

    PubMed Central

    Liu, Shang; Aiken, Allison C.; Gorkowski, Kyle; Dubey, Manvendra K.; Cappa, Christopher D.; Williams, Leah R.; Herndon, Scott C.; Massoli, Paola; Fortner, Edward C.; Chhabra, Puneet S.; Brooks, William A.; Onasch, Timothy B.; Jayne, John T.; Worsnop, Douglas R.; China, Swarup; Sharma, Noopur; Mazzoleni, Claudio; Xu, Lu; Ng, Nga L.; Liu, Dantong; Allan, James D.; Lee, James D.; Fleming, Zoë L.; Mohr, Claudia; Zotter, Peter; Szidat, Sönke; Prévôt, André S. H.

    2015-01-01

    Black carbon (BC) and light-absorbing organic carbon (brown carbon, BrC) play key roles in warming the atmosphere, but the magnitude of their effects remains highly uncertain. Theoretical modelling and laboratory experiments demonstrate that coatings on BC can enhance BC's light absorption, therefore many climate models simply assume enhanced BC absorption by a factor of ∼1.5. However, recent field observations show negligible absorption enhancement, implying models may overestimate BC's warming. Here we report direct evidence of substantial field-measured BC absorption enhancement, with the magnitude strongly depending on BC coating amount. Increases in BC coating result from a combination of changing sources and photochemical aging processes. When the influence of BrC is accounted for, observationally constrained model calculations of the BC absorption enhancement can be reconciled with the observations. We conclude that the influence of coatings on BC absorption should be treated as a source and regionally specific parameter in climate models. PMID:26419204

  5. A high precision study of the electrolyte additives vinylene carbonate, vinyl ethylene carbonate and lithium bis(oxalate)borate in LiCoO2/graphite pouch cells

    NASA Astrophysics Data System (ADS)

    Wang, David Yaohui; Sinha, N. N.; Burns, J. C.; Petibon, R.; Dahn, J. R.

    2014-12-01

    The effects of three well-known electrolyte additives, used singly or in combination, on LiCoO2/graphite pouch cells has been investigated using the ultra high precision charger (UHPC) at Dalhousie University, electrochemical impedance spectroscopy (EIS) and long term cycling Vinylene carbonate (VC), vinyl ethylene carbonate (VEC), and lithium bis(oxalato) borate (LiBOB) were chosen for study. The results show that combinations of electrolyte additives that act synergistically can be more effective than a single electrolyte additive. However, simply using 2% VC yielded cells very competitive in coulombic efficiency (CE), charge endpoint capacity slippage and charge transfer resistance (Rct). For cells with 1% LiBOB and VC (1, 2, 4 or 6%), adding VC above 2% does not increase the CE, but increases the electrode charge transfer impedances. Rct for cells containing 1% LiBOB and VEC (0.5, 1 or 4%) decreased after long term cycling (1800 h), compared to that tested after the UHPC cycling (500 h) indicating that VEC might be useful for the design of power cells. However, the opposite behaviour (increasing Rct with cycle number) was observed for the control cells or cells containing LiBOB and/or VC.

  6. Geochemistry of dissolved inorganic carbon in a Coastal Plain aquifer. 2. Modeling carbon sources, sinks, and δ13C evolution

    USGS Publications Warehouse

    McMahon, Peter B.; Chapelle, Francis H.

    1991-01-01

    Stable isotope data for dissolved inorganic carbon (DIC), carbonate shell material and cements, and microbial CO2 were combined with organic and inorganic chemical data from aquifer and confining-bed pore waters to construct geochemical reaction models along a flowpath in the Black Creek aquifer of South Carolina. Carbon-isotope fractionation between DIC and precipitating cements was treated as a Rayleigh distillation process. Organic matter oxidation was coupled to microbial fermentation and sulfate reduction. All reaction models reproduced the observed chemical and isotopic compositions of final waters. However, model 1, in which all sources of carbon and electron-acceptors were assumed to be internal to the aquifer, was invalidated owing to the large ratio of fermentation CO2 to respiration CO2 predicted by the model (5–49) compared with measured ratios (two or less). In model 2, this ratio was reduced by assuming that confining beds adjacent to the aquifer act as sources of dissolved organic carbon and sulfate. This assumption was based on measured high concentrations of dissolved organic acids and sulfate in confining-bed pore waters (60–100 μM and 100–380 μM, respectively) relative to aquifer pore waters (from less than 30 μM and 2–80 μM, respectively). Sodium was chosen as the companion ion to organic-acid and sulfate transport from confining beds because it is the predominant cation in confining-bed pore waters. As a result, excessive amounts of Na-for-Ca ion exchange and calcite precipitation (three to four times more cement than observed in the aquifer) were required by model 2 to achieve mass and isotope balance of final water. For this reason, model 2 was invalidated. Agreement between model-predicted and measured amounts of carbonate cement and ratios of fermentation CO2 to respiration CO2 were obtained in a reaction model that assumed confining beds act as sources of DIC, as well as organic acids and sulfate. This assumption was

  7. Effects of silicon, carbon and molybdenum additions on IASCC of neutron irradiated austenitic stainless steels

    NASA Astrophysics Data System (ADS)

    Nakano, J.; Miwa, Y.; Kohya, T.; Tsukada, T.

    2004-08-01

    To study the effects of minor elements on irradiation assisted stress corrosion cracking (IASCC), high purity type 304 and 316 stainless steels (SSs) were fabricated and minor elements, Si or C were added. After neutron irradiation to 3.5 × 10 25 n/m 2 ( E>1 MeV), slow strain rate tests (SSRTs) of irradiated specimens were conducted in oxygenated high purity water at 561 K. Specimen fractured surfaces were examined using a scanning electron microscope (SEM) after the SSRTs. The fraction of intergranular stress corrosion cracking (IGSCC) on the fractured surface after the SSRTs increased with neutron fluence. In high purity SS with added C, the fraction of IGSCC was the smallest in the all SSs, although irradiation hardening level was the largest of all the SSs. Addition of C suppressed the susceptibility to IGSCC.

  8. Methane-derived authigenic carbonates of mid-Cretaceous age in southern Tibet: Types of carbonate concretions, carbon sources, and formation processes

    NASA Astrophysics Data System (ADS)

    Liang, Huimin; Chen, Xi; Wang, Chengshan; Zhao, Dekun; Weissert, Helmut

    2016-01-01

    Methane-derived authigenic carbonates with distinctive structures and morphologies have been documented worldwide, but they are rarely found from ancient strata in the Eastern Tethys Ocean. The methane-derived authigenic carbonates found in southern Tibet are developed in calcareous or silty shales of mid-Cretaceous age in the Xigaze forearc basin and in the Tethyan Himalaya tectonic zone. The morphology, mineralogy, elemental geochemistry and composition of carbon and oxygen isotopes of these carbonates are studied in detail. The carbonates have nodular, tubular, and tabular morphologies. They are primarily composed of carbonate cement that binds and partly replaces host sediment grains; host siliciclastic sediments are composed mainly of quartz and plagioclase feldspar; a few foraminifers; and framboidal or subhedral to euhedral pyrite. Carbonate cements dominantly are micritic calcite, with minor contribution of dolomite. Nodular concretions are characterized by depleted δ13C values, commonly ranging from -30‰ to -5‰. The δ13C values show a gradual decrease from the periphery to the center, and the CaO, SiO2, Fe2O3, Al2O3, K2O, and TiO2 contents generally show a gradual change. These features indicate that the nodular concretions grew from an early-formed center toward the periphery, and that the carbon source of the nodular concretions was derived from a mixture of methane, methanogenic CO2, and seawater-dissolved inorganic carbon. The tubular concretions are characterized by δ13C values of -8.85‰ to -3.47‰ in the Shangba Section, and -27.37‰ to -23.85‰ in the upper Gamba Section. Unlike the nodular concretions, the tubular concretions show central conduits, which are possible pathways of methane-rich fluids, suggesting that the cementation of tubular concretions begins at the periphery and proceeds inward. Moreover, the tubular concretions show morphological similarity with the methane-derived carbonate chimneys, pipes and slabs reported in

  9. Using stable isotopes to determine sources of eroded carbon in low-order Sierra Nevada catchments

    NASA Astrophysics Data System (ADS)

    McCorkle, E. P.; Berhe, A.; Hunsaker, C. T.; Fogel, M. L.; Hart, S. C.

    2013-12-01

    Recent studies have shown that soil erosion can induce a terrestrial sink for atmospheric carbon dioxide and impose important controls on biogeochemical cycling of other essential elements. However, little information is available on the source of C eroded from different watersheds (i.e., whether most of the eroded material is comprised of litter, soil minerals from topsoil, vs. deep C eroded due to fresh channelization or scouring of stream banks). In order to identify sources of eroded carbon, we compared the C to N ratios and 13C, and 15N stable isotope concentrations of potential source materials to sediments collected in basins at the outlet of low order catchments in the western slopes of the Sierra Nevada. Potential source materials (i.e., surficial organic and mineral soil and stream bank sediments) from three landform positions (crest, back slope, toe slope) were sampled from low- and high-elevation catchments within the Kings River Experimental Watershed. The potential source materials were compared with materials collected from sediment basins at the outlet of the sampled catchments. Preliminary results indicate that the different landform positions have similar concentrations of 13C and 15N, but the stable isotope concentrations of sediments reflect a combination of sources. Further analysis will delineate which pool of carbon is the main contributor to the sediments. Determining the source of the eroded carbon in these catchments is critical for assessing the fate of the eroded C after it is laterally distributed by soil erosion to downslope depositional landforms within the same catchment, or exported out of these catchments.

  10. Kinetics and bioenergetics of Spirulina platensis cultivation by fed-batch addition of urea as nitrogen source.

    PubMed

    Sassano, Carlos E N; Carvalho, João C M; Gioielli, Luiz A; Sato, Sunao; Torre, Paolo; Converti, Attilio

    2004-03-01

    The cyanobacterium Spirulina platensis was cultivated in bench-scale miniponds on bicarbonate/carbonate solutions using urea as nitrogen source. To minimize limitation and inhibition phenomena, urea was supplied semicontinuously using exponentially increasing feeding rates. The average growth rates obtained alternately varying the total mass of urea added per unit reactor volume (275 < mT < 725 mg/L) and the total feeding time (9 < tT < 15 d) clearly evidenced nitrogen limitation for mT< 500 mg/L and excess nitrogen inhibition above this threshold. The time behavior of the specific growth rate at variable urea feeding patterns allowed estimation of the time-dependent Gibbs energy dissipation for cell growth under the actual depletion conditions of fed-batch cultivations. Comparison of the yield of growth on Gibbs energy obtained using either urea or KNO3 pointed to the preference of S. platensis for the former nitrogen source, likely owing to more favorable bioenergetic conditions. PMID:15007182

  11. Localized stem chilling alters carbon processes in the adjacent stem and in source leaves.

    PubMed

    De Schepper, Veerle; Vanhaecke, Lynn; Steppe, Kathy

    2011-11-01

    Transport phloem is no longer associated with impermeable pipes, but is instead considered as a leaky system in which loss and retrieval mechanisms occur. Local stem chilling is often used to study these phenomena. In this study, 5-cm- lengths of stems of 3-year-old oak trees (Quercus robur L.) were locally chilled for 1 week to investigate whether observations at stem and leaf level can be explained by the leakage-retrieval mechanism. The chilling experiment was repeated three times across the growing season. Measurements were made of leaf photosynthesis, carbohydrate concentrations in leaves and bark, stem growth and maximum daily stem shrinkage. Across the growing season, a feedback inhibition in leaf photosynthesis was observed, causing increased dark respiration and starch concentration. This inhibition was attributed to the total phloem resistance which locally increased due to the cold temperatures. It is hypothesized that this higher phloem resistance increased the phloem pressure above the cold block up to the source leaves, inducing feedback inhibition. In addition, an increase in radial stem growth and carbohydrate concentration was observed above the cold block, while the opposite occurred below the block. These observations indicate that net lateral leakage of carbohydrates from the phloem was enhanced above the cold block and that translocation towards regions below the block decreased. This behaviour is probably also attributable to the higher phloem resistance. The chilling effects on radial stem growth and carbohydrate concentration were significant in the middle of the growing season, while they were not at the beginning and near the end of the growing season. Furthermore, maximum daily shrinkages were larger above the cold block during all chilling experiments, indicating an increased resistance in the xylem vessels, also generated by low temperatures. In conclusion, localized stem chilling altered multiple carbon processes in the source leaves

  12. Understanding drivers of the export of dissolved organic carbon from a German headwater catchment using Generalised Additive Models

    NASA Astrophysics Data System (ADS)

    Selle, Benny; Musolff, Andreas; Tittel, Jörg

    2016-04-01

    In the literature, several causes of recently increasing concentrations of dissolved organic carbon (DOC) in headwaters across eastern North America and northern and central Europe have been debated. One likely driver of the widespread increase of DOC concentrations since the early 1990s are decreasing depositions of acid rain resulting in an increased solubility of organic carbon compounds including humic acids. Here, we tested the hypothesis if the reduced availability of nitrate stimulated the microbial reduction of ferric iron soil minerals and the mobilisation of DOC. Forested catchments are relatively unaffected by agricultural and urban nitrate inputs. In these catchments, decreasing depositions often resulted in a reduced availability of nitrate, which are preferred electron acceptors in microbial decomposition processes. As ferric iron minerals act as efficient sorbents of organic compounds in soils its reduction may cause a release of humic substances and hence an export of DOC. To test this hypothesis, time series of DOC, dissolved iron and nitrate from a forested headwater catchment in Germany were examined using Generalised Additive Models. We found that rising DOC concentrations most likely resulted from a reductive dissolution of iron(III) minerals in soils and the associated mobilisation of adsorbed organic carbon. Phosphate, which can trigger undesired algal growth and is also known to be adsorbed by particulate iron(III), was released as well.

  13. Evaluating microbial carbon sources in Athabasca oil sands tailings ponds using natural abundance stable and radiocarbon isotopes

    NASA Astrophysics Data System (ADS)

    Ahad, J. M.; Pakdel, H.

    2013-12-01

    Natural abundance stable (δ13C) and radiocarbon (Δ14C) isotopes of phospholipid fatty acids (PLFAs) were used to evaluate the carbon sources utilized by the active microbial populations in surface sediments from Athabasca oil sands tailings ponds. The absence of algal-specific PLFAs at three of the four sites investigated, in conjunction with δ13C signatures for PLFAs that were generally within ~3‰ of that reported for oil sands bitumen (~ -30‰), indicated that the microbial communities growing on petroleum constituents were dominated by aerobic heterotrophs. The Δ14C values of PLFAs ranged from -906 to -586‰ and pointed to a significant uptake of fossil carbon (up to ~90% of microbial carbon derived from petroleum), particularly in PLFAs (e.g., cy17:0 and cy19:0) often associated with petroleum hydrocarbon degrading bacteria. The comparatively higher levels of 14C in other, less specific PLFAs (e.g., 16:0) indicated the preferential uptake of younger organic matter by the general microbial population (~50-80% of microbial carbon derived from petroleum). Since the main carbon pools in tailings sediment were essentially 'radiocarbon dead' (i.e., no detectable 14C), the principal source for this modern carbon is considered to be the Athabasca River, which provides the bulk of the water used in the bitumen extraction process. The preferential uptake of the minor amount of young and presumably more biodegradable material present in systems otherwise dominated by recalcitrant petroleum constituents has important implications for remediation strategies. On the one hand, it implies that mining-related organic contaminants could persist in the environment long after tailings pond reclamation has begun. Alternatively, it may be that the young, labile organic matter provided by the Athabasca River plays an important role in stimulating or supporting the microbial utilization of petroleum carbon in oil sands tailings ponds via co-metabolism or priming processes

  14. Increased loss of soil-derived carbon in response to litter addition and temperature

    NASA Astrophysics Data System (ADS)

    Creamer, C.; Krull, E. S.; Sanderman, J.; Farrell, M.

    2013-12-01

    In order to predict the response of soil organic matter (SOM) to increasing temperatures, a mechanistic understanding of the interactions between OM quality, OM availability, and microbial community structure and function is needed. We used short-term incubations of 13C enriched (20 atom%) fresh and pre-incubated eucalyptus leaf litter in an Australian woodland soil to determine changes in allocation of C to various OM pools, as dictated by microbial activity, in response to temperature and substrate quality. The quantity and isotopic composition of microbial phospholipid fatty acids (PLFA) and dissolved organic C (DOC) were measured along with the quantity of dissolved inorganic and organic nitrogen at four destructive time points. The quantity and isotopic composition of respired CO2 was measured throughout the incubation. Although the temperature sensitivities of the two litters were similar (despite different chemical compositions), soil-C was significantly more temperature sensitive than litter-C. We also observed negative priming of soil-C in the fresh litter treatment and positive priming of soil-C in the pre-incubated litter treatment relative to the control (no litter addition). The extent of positive priming in the pre-incubated litter treatment also increased significantly with temperature. The quantity of soil-derived DOC was consistent between both litter treatments and the control, confirming that differences in soil-C availability were not controlling the observed differences in soil-C mineralization. In contrast, dissolved N was significantly higher in the pre-incubated litter treatment and increased with temperature, suggesting enhanced SOM decomposition in the pre-incubated litter treatment resulted in greater N cycling, production, or destabilization from SOM. The pre-incubated litter treatment also had greater proportions of PLFA that predominately cycled soil-derived OM (gram-positive bacteria), and increased in response to elevated temperature

  15. Microstructure and mechanical behavior of iron-40 aluminum containing carbon and boron additions

    NASA Astrophysics Data System (ADS)

    Pang, Lixin

    2000-10-01

    In this thesis, the effect of second phase particles on the microstructure and mechanical behavior of cast and extruded Fe-40 at.%Al-0.6 at.%C and Fe-40 at.%Al-0.5 at.%B-0.7 at.%C alloys was studied. A variety of heat treatments was performed to study changes in microstructure and their effect on the mechanical properties (tensile tests and Charpy impact tests at different strain rates and temperatures). In the as-extruded condition, the microstructure of Fe-40Al-0.6C consists of a B2 matrix, Fe3AlCO0.5 precipitates, and graphite; the microstructure of the Fe-40A1-0.7C-0.5B is further complicated by the presence of Fe2B precipitates, a metastable nu phase and a planar defect. The stability of these phases and defects was studied in detail. The nu precipitate was found to be metastable, and its formation is cooling-rate dependent. The planar defects lie on the {001} planes of the matrix, with a displacement vector 1/2<001>, which is parallel to the plane of the defect. In addition, there is an aluminum layer missing on the fault plane; these planar defects are thought to form as a consequence of the dissociation of <001> dislocations. The addition of C and B was shown to be beneficial to the ductility and impact toughness of the Fe-40Al alloy. This improvement is attributed to hydrogen trapping by carbides and borides in the FeAl matrix, thereby delaying environmental embrittlement kinetics. The strain rate versus ductility curves for the two alloys show different characteristics in the slow strain rate regime--whereas the ductility of the FeAlBC alloy remains at a constant level of ˜3.5%, the curve for the FeAlC alloy shows first, a decrease with strain rate and then a gradual increase in elongation.

  16. The response of soil organic matter decomposition and carbon cycling to temperature increase and nitrogen addition

    NASA Astrophysics Data System (ADS)

    Choi, I.; Kang, M.; Choi, J.

    2012-12-01

    Global warming caused by greenhouse effects has raised the worldwide air temperature by 1.4~5.8°C from the pre-industrial level. It has been known that the enhanced air temperature leads to increase the rate of soil organic matter decomposition. The enhanced soil organic matter decomposition could increase the emission of GHG (Green House Gas-mostly CO2, CH4) from the terrestrial ecosystem. GHG emission from the decomposition of soil organic matter can be affected by N deposition. N deposition of Asia has significantly grown from 1000mg N m2yr-1 to 2000mg N m2yr-1during the period of 1990s. It is expected that large area of South and East Asia will receive as large as 5000mg N m2yr-1of nitrogen in the future. Therefore, it is interesting to investigate the effects of global change factors, such as elevated temperature and N deposition on GHG emission from the terrestrial ecosystem. Growth chamber experiments were conducted under the enhanced air temperature and N addition (controlled at 10°C(30°C), 20°C(40°C) from ambient air temperature 18°C/23°C(day/night)) and GHG(CH4,CO2)was measured using gas chromatograph. Since combined changes in temperature and N deposition are sensitive to litter quantity and quality, especially C:N ratio of organic material, we select three sites with different C:N ratio (rice paddy, forest, wetland) in the southern part of Han river in Korea. Our results show that, for the case of rice paddy and forest, CO2 flux at 30°C was higher than at 40°C. However, wetland soil produces higher CO2 flux at 40°C than at 30°C. While CH4 flux was not detected at 30°C for all of three soils, only wetland soil produced CH4 flux at 40°C. Every flux under the condition of N addition was higher than that of N limitation. The GHG fluxes clearly related to the temperature, N concentration difference and soil types. Long term laboratory experiments are needed in three different soil types to determine how different soil type affects GHG by

  17. Successful implementation of biochar carbon sequestration in European soils requires additional benefits and close collaboration with the bioenergy sector

    NASA Astrophysics Data System (ADS)

    Hauggaard-Nielsen, Henrik; Müller-Stöver, Dorette; Bruun, Esben W.; Petersen, Carsten T.

    2014-05-01

    Biochar soil application has been proposed as a measure to mitigate climate change and on the same time improve soil fertility by increased soil carbon sequestration. However, while on tropical soils the beneficial effects of biochar application on crop growth often become immediately apparent, it has been shown to be more difficult to demonstrate these effects on the more fertile soils in temperate regions. Therefore and because of the lack of carbon credits for farmers, it is necessary to link biochar application to additional benefits, both related to agricultural as well as to bioenergy production. Thermal gasification of biomass is an efficient (95% energy efficiency) and flexible way (able to cope with many different and otherwise difficult-to-handle biomass fuels) to generate bioenergy, while producing a valuable by-product - gasification biochar, containing recalcitrant carbon and essential crop nutrients. The use of the residual char product in agricultural soils will add value to the technology as well as result in additional soil benefits such as providing plant nutrients and improving soil water-holding capacity while reducing leaching risks. From a soil column (30 x 130 cm) experiment with gasification straw biochar amendment to coarse sandy subsoil increased root density of barley at critical depths in the soil profile reducing the mechanical resistance was shown, increasing yields, and the soil's capacity to store plant available water. Incorporation of residuals from a bioenergy technology like gasification show great potentials to reduce subsoil constraints increasing yield potentials on poor soils. Another advantage currently not appropriately utilized is recovery of phosphorus (P). In a recent pot experiments char products originating from low-temperature gasification of various biofuels were evaluated for their suitability as P fertilizers. Wheat straw gasification biochar generally had a low P content but a high P plant availability. To improve

  18. Advanced Electron Beam Ion Sources (EBIS) for 2-nd generation carbon radiotherapy facilities

    NASA Astrophysics Data System (ADS)

    Shornikov, A.; Wenander, F.

    2016-04-01

    In this work we analyze how advanced Electron Beam Ion Sources (EBIS) can facilitate the progress of carbon therapy facilities. We will demonstrate that advanced ion sources enable operation of 2-nd generation ion beam therapy (IBT) accelerators. These new accelerator concepts with designs dedicated to IBT provide beams better suited for therapy and, are more cost efficient than contemporary IBT facilities. We will give a sort overview of the existing new IBT concepts and focus on those where ion source technology is the limiting factor. We will analyse whether this limitation can be overcome in the near future thanks to ongoing EBIS development.

  19. Mass spectrometry of refractory black carbon particles from six sources: carbon-cluster and oxygenated ions

    NASA Astrophysics Data System (ADS)

    Corbin, J. C.; Sierau, B.; Gysel, M.; Laborde, M.; Keller, A.; Kim, J.; Petzold, A.; Onasch, T. B.; Lohmann, U.; Mensah, A. A.

    2013-10-01

    We discuss the major mass spectral features of different types of refractory carbonaceous particles, ionized after laser vapourization with an Aerodyne High-Resolution Soot-Particle Aerosol Mass Spectrometer (SP-AMS). The SP-AMS was operated with a switchable 1064 nm laser and a 600 °C thermal vapourizer, yielding respective measurements of the refractory and non-refractory particle components. Six samples were investigated, all of which were composed primarily of refractory material: fuel-rich and fuel-lean propane/air diffusion-flame combustion particles; graphite-spark-generated particles; a commercial Fullerene-enriched Soot; Regal Black, a commercial carbon black; and nascent aircraft-turbine combustion particles. All samples exhibited a spectrum of carbon-cluster ions Cxn+ in their refractory mass spectrum. Smaller clusters (x<6) were found to dominate the Cxn+ distribution. For Fullerene Soot, fuel-rich-flame particles and spark-generated particles, significant Cxn+ clusters at x≫6 were present, with significant contributions from multiply-charged ions (n>1). In all six cases, the ions C1+ and C3+ contributed over 60% to the total C15 were present. When such signals were present, C1+/C3+ was close to 1. When absent, C1+/C3+ was <0.8. This ratio may therefore serve as a proxy to distinguish between the two types of spectra in atmospheric SP-AMS measurements. Significant refractory oxygenated ions such as CO+ and CO2+ were also observed for all samples. We discuss these signals in detail for Regal Black, and describe their formation via decomposition of oxygenated moieties incorporated into the refractory carbon structure. These species may be of importance in atmospheric processes such as water uptake, aging and heterogeneous chemistry.

  20. The effect of activated carbon addition on membrane bioreactor processes for wastewater treatment and reclamation - A critical review.

    PubMed

    Skouteris, George; Saroj, Devendra; Melidis, Paraschos; Hai, Faisal I; Ouki, Sabèha

    2015-06-01

    This review concentrates on the effect of activated carbon (AC) addition to membrane bioreactors (MBRs) treating wastewaters. Use of AC-assisted MBRs combines adsorption, biodegradation and membrane filtration. This can lead to advanced removal of recalcitrant pollutants and mitigation of membrane fouling. The relative contribution of adsorption and biodegradation to overall removal achieved by an AC-assisted MBR process can vary, and "biological AC" may not fully develop due to competition of target pollutants with bulk organics in wastewater. Thus periodic replenishment of spent AC is necessary. Sludge retention time (SRT) governs the frequency of spent AC withdrawal and addition of fresh AC, and is an important parameter that significantly influences the performance of AC-assisted MBRs. Of utmost importance is AC dosage because AC overdose may aggravate membrane fouling, increase sludge viscosity, impair mass transfer and reduce sludge dewaterability. PMID:25801795

  1. Effects of Silica Nanoparticle Supported Ionic Liquid as Additive on Thermal Reversibility of Human Carbonic Anhydrase II

    PubMed Central

    Fallahbagheri, Azadeh; Saboury, Ali Akbar; Ma'mani, Leila; Taghizadeh, Mohammad; Khodarahmi, Reza; Ranjbar, Samira; Bohlooli, Mousa; Shafiee, Abbas; Foroumadi, Alireza; Sheibani, Nader; Moosavi-Movahedi, Ali Akbar

    2013-01-01

    Silica nanoparticle supported imidazolium ionic liquid [SNImIL] was synthesized and utilized as a biocompatible additive for studying the thermal reversibility of human carbonic anhydrase II (HCA II). For this purpose, we prepared additive by modification of nanoparticles through the grafting of ionic liquids on the surface of nanoparticles (SNImIL). The SNImIL were fully characterized by Fourier Transform Infrared spectroscopy, scanning electron microscopy and thermo gravimetric analysis. The characterization of HCA II was investigated by various techniques including UV–Vis and ANS fluorescence spectrophotometry, differential scanning calorimetry, and docking study. SNImIL induced disaggregation, enhanced protein stability and increased thermal reversibility of HCA II by up to 42% at pH 7.75. PMID:22829053

  2. Biological sulfate reduction using gas-lift reactors fed with hydrogen and carbon dioxide as energy and carbon source

    SciTech Connect

    Houten, R.T. van; Hulshoff Pol, L.W.; Lettinga, G. . Dept. of Environmental Technology)

    1994-08-20

    Feasibility and engineering aspects of biological sulfate reduction in gas-lift reactors were studied. Hydrogen and carbon dioxide were used as energy and carbon source. Attention was paid to biofilm formation, sulfide toxicity, sulfate conversion rate optimization, and gas-liquid mass transfer limitations. Sulfate-reducing bacteria formed stable biofilms on pumice particles. Biofilm formation was not observed when basalt particles were used. However, use of basalt particles led to the formation of granules of sulfate-reducing biomass. The sulfate-reducing bacteria, grown on pumice, easily adapted to free H[sub 2]S concentrations up to 450 mg/L. Biofilm growth rate then equilibrated biomass loss rate. These high free H[sub 2]S concentrations caused reversible inhibition rather than acute toxicity. When free H[sub 2]S concentrations were kept below 450 mg/L, a maximum sulfate conversion rate of 30 g SO[sub 4][sup 2[minus

  3. Morphogenesis and Production of Enzymes by Penicillium echinulatum in Response to Different Carbon Sources

    PubMed Central

    Schneider, Willian Daniel Hahn; dos Reis, Laísa; Dillon, Aldo José Pinheiro

    2014-01-01

    The effect of different carbon sources on morphology and cellulase and xylanase production of Penicillium echinulatum was evaluated in this work. Among the six carbon sources studied, cellulose and sugar cane bagasse were the most suitable for the production of filter paper activity, endoglucanases, xylanases, and β-glucosidases. However, sucrose and glucose showed β-glucosidase activities similar to those obtained with the insoluble sources. The polyacrylamide gels proved the enzymatic activity, since different standards bands were detected in the media mentioned above. Regarding morphology, it was observed that the mycelium in a dispersed form provided the greatest enzymatic activity, possibly due to greater interaction between the substrate and hyphae. These data are important in understanding the physiology of fungi and could contribute to obtaining enzyme with potential application in the technology of second generation ethanol. PMID:24877074

  4. Morphogenesis and production of enzymes by Penicillium echinulatum in response to different carbon sources.

    PubMed

    Schneider, Willian Daniel Hahn; dos Reis, Laísa; Camassola, Marli; Dillon, Aldo José Pinheiro

    2014-01-01

    The effect of different carbon sources on morphology and cellulase and xylanase production of Penicillium echinulatum was evaluated in this work. Among the six carbon sources studied, cellulose and sugar cane bagasse were the most suitable for the production of filter paper activity, endoglucanases, xylanases, and β-glucosidases. However, sucrose and glucose showed β -glucosidase activities similar to those obtained with the insoluble sources. The polyacrylamide gels proved the enzymatic activity, since different standards bands were detected in the media mentioned above. Regarding morphology, it was observed that the mycelium in a dispersed form provided the greatest enzymatic activity, possibly due to greater interaction between the substrate and hyphae. These data are important in understanding the physiology of fungi and could contribute to obtaining enzyme with potential application in the technology of second generation ethanol. PMID:24877074

  5. Atmospheric carbonyl sulfide sources from anthropogenic activity: Implications for carbon cycle constraints

    SciTech Connect

    Campbell, Elliott; Whelan, Mary; Seibt, U.; Smith, Steven J.; Berry, Joe; Hilton, Timothy W.

    2015-04-28

    Carbonyl sulfide (COS) has recently emerged as an atmospheric tracer of gross primary production. All modeling studies of COS air-monitoring data rely on a climatological anthropogenic inventory that does not reflect present conditions or support interpretation of ice core and firn trends. Here we develop a global anthropogenic inventory for the years 1850 to 2013 based on new emission measurements and material-specific data. By applying methods from a recent regional inventory to global data, we find that the anthropogenic source is similar in magnitude to the plant sink, confounding carbon cycle applications. However, a material-specific approach results in a current anthropogenic source that is only one-third of plant uptake and is concentrated in Asia, supporting carbon cycle applications of global air-monitoring data. Furthermore, the source alone cannot explain the century-scale mixing ratio growth, which suggests that ice and firn data may provide the first global history of gross primary production.

  6. Isotopic evidence of magmatism and a sedimentary carbon source at the Endeavour hydrothermal system

    SciTech Connect

    Brown, T A; Proskurowski, G; Lilley, M D

    2004-01-07

    Stable and radiocarbon isotope measurements made on CO{sub 2} from high temperature hydrothermal vents on the Endeavour Segment of the Juan de Fuca Ridge indicate both magmatic and sedimentary sources of carbon to the hydrothermal system. The Endeavour segment is devoid of overlying sediments and has shown no observable signs of surficial magmatic activity during the {approx}20 years of ongoing studies. The appearance of isotopically heavy, radiocarbon dead CO{sub 2} after a 1999 earthquake swarm requires that this earthquake event was magmatic in origin. Evidence for a sedimentary organic carbon source suggests the presence of buried sediments at the ridge axis. These findings, which represent the first temporally coherent set of radiocarbon measurements from hydrothermal vent fluids, demonstrate the utility of radiocarbon analysis in hydrothermal studies. The existence of a sediment source at Endeavour and the occurrence of magmatic episodes illustrate the extremely complex and evolving nature of the Endeavour hydrothermal system.

  7. Biopolymers production with carbon source from the wastes of a beer brewery industry

    NASA Astrophysics Data System (ADS)

    Wong, Phoeby Ai Ling

    The main purpose of this study was to assess the potential and feasibility of malt wastes, and other food wastes, such as soy wastes, ice-cream wastes, confectionery wastes, vinegar wastes, milk waste and sesame oil, in the induction of biosynthesis of PHA, in the cellular assembly of novel PHA with improved physical and chemical properties, and in the reduction of the cost of PHA production. In the first part of the experiments, a specific culture of Alcaligenes latus DSM 1124 was selected to ferment several types of food wastes as carbon sources into biopolymers. In addition, the biopolymer production, by way of using malt waste, of microorganisms from municipal activated sludge was also investigated. In the second part, the experiments focused on the synthesis of biopolymer with a higher molecular mass via the bacterial strain, which was selected and isolated from sesame oil, identified as Staphylococcus epidermidis . Molecular weight and molecular weight distribution of PHB were studied by GPC. Molecular weight of PHB produced from various types of food wastes by Alcaligenes latus was higher than using synthetic sucrose medium as nutrient, however, it resulted in the reverse by Staphylococcus epidermidis. Thermal properties of biopolymers were studied by DSC and TG. Using malt wastes as nutrients by Alcaligenes latus gave a higher melting temperature. Using sucrose, confectionery and sesame oil as nutrients by Staphylococcus epidermidis gave higher melting temperature. Optimization was carried out for the recovery of microbial PHB from Alcaligenes latus. Results showed that molecular weight can be controlled by changing the hypochlorite concentration, the ratio of chloroform to hypochlorite solution and the extraction time. In addition, the determination of PHB content by thermogravimetric analysis method with wet cell was the first report in our study. (Abstract shortened by UMI.)

  8. The Wildland Fire Emissions Information System: Providing information for carbon cycle studies with open source geospatial tools

    NASA Astrophysics Data System (ADS)

    French, N. H.; Erickson, T.; McKenzie, D.

    2008-12-01

    A major goal of the North American Carbon Program is to resolve uncertainties in understanding and managing the carbon cycle of North America. As carbon modeling tools become more comprehensive and spatially oriented, accurate datasets to spatially quantify carbon emissions from fire are needed, and these data resources need to be accessible to users for decision-making. Under a new NASA Carbon Cycle Science project, Drs. Nancy French and Tyler Erickson, of the Michigan Technological University, Michigan Tech Research Institute (MTRI), are teaming with specialists with the USDA Forest Service Fire and Environmental Research Applications (FERA) team to provide information for mapping fire-derived carbon emissions to users. The project focus includes development of a web-based system to provide spatially resolved fire emissions estimates for North America in a user-friendly environment. The web-based Decision Support System will be based on a variety of open source technologies. The Fuel Characteristic Classification System (FCCS) raster map of fuels and MODIS-derived burned area vector maps will be processed using the Geographic Data Abstraction Library (GDAL) and OGR Simple Features Library. Tabular and spatial project data will be stored in a PostgreSQL/PostGIS, a spatially enabled relational database server. The browser-based user interface will be created using the Django web page framework to allow user input for the decision support system. The OpenLayers mapping framework will be used to provide users with interactive maps within the browser. In addition, the data products will be made available in standard open data formats such as KML, to allow for easy integration into other spatial models and data systems.

  9. A SnO2-samarium doped ceria additional anode layer in a direct carbon fuel cell

    NASA Astrophysics Data System (ADS)

    Yu, Baolong; Zhao, Yicheng; Li, Yongdan

    2016-02-01

    The role of a SnO2-samarium doped ceria (SDC) additional anode layer in a direct carbon fuel cell (DCFC) with SDC-(Li0.67Na0.33)2CO3 composite electrolyte and lithiated NiO-SDC-(Li0.67Na0.33)2CO3 composite cathode is investigated and compared with a NiO-SDC extra anode layer. Catalytic grown carbon fiber mixed with (Li0.67Na0.33)2CO3 is used as a fuel. At 750 °C, the maximum power outputs of 192 and 143 mW cm-2 are obtained by the cells with SnO2-SDC and NiO-SDC layers, respectively. In the SnO2-SDC layer, the reduction of SnO2 and the oxidation of Sn happen simultaneously during the cell operation, and the Sn/SnO2 redox cycle provides an additional route for fuel conversion. The formation of an insulating dense interlayer between the anode and electrolyte layers, which usually happens in DCFCs with metal anodes, is avoided in the cell with the SnO2-SDC layer, and the stability of the cell is improved consequently.

  10. Helicopter survey of methane and carbon dioxide sources on the Laptev Sea shelf near the Lena River Delta

    NASA Astrophysics Data System (ADS)

    Salyuk, A.; Semiletov, I.; Nesterov, V.; Shakhova, N.

    2009-04-01

    Carbon dioxide and methane have recently been recognized not only as key sources but also as great tracers of global climate change. The release of CH4 and CO2 from geological and biological sources on the Laptev Sea shelf was investigated during a flight on the helicopter Mi-8 20 September 2006 organized by POI FEB RAS. Gas concentrations were measured on the height of about 100 m over sea surface on the route more than 1200 km long and area over 40 000 km2 using Fast CH4 analyzer LosGatos DLT-100 and CO2 and H2O analyzer Li-8100 (LiCor). Vertical structure of atmosphere were investigated in 5 points with different air-sea interaction environment with maximal height up to 2 000 m in northernmost point. Our data reveal that Arctic air-sea exchange processes have a substantial impact on overlying atmospheric CH4 and CO2 composition. Enhanced concentrations of CH4 were measured along the entire helicopter route (>1.85 ppm Latitudinal mean average), reaching up to 1.97 ppm (6.5% increase) in particular areas. Some anomalies in air CH4 were spatially correlated with anomalies in distribution of dissolved CH4 in water which could be associated with fault zones and Lena River discharge. Vertical profiles of methane and carbon dioxide exhibit a significant increase near the sea surface, what prove later as a source of CH4 and CO2 into the atmosphere. Possibly massive escape both of these gases may be related additionally with already intensified autumn ocean convection. Offshore helicopter survey near the Lena River Delta show that the Laptev Sea surface is a strong source of carbon dioxide and methane into the atmosphere. Aircraft survey may be used for mapping of the methane anomalies on the shelf.

  11. Mixing Model Analysis of Suspended Sediment and Particulate Organic Carbon Sources in White Clay Creek, Pennsylvania

    NASA Astrophysics Data System (ADS)

    Karwan, D. L.; Aufdenkampe, A. K.; Aalto, R. E.; Marquard, J.; Pizzuto, J. E.; Newbold, J. D.

    2013-12-01

    Material exports from watersheds have consequences to upstream catchment elemental budgets, downstream ecosystem processes and water resources management. Despite this importance, quantifying exports of all major and trace elements associated with suspended sediments is challenging due to the highly episodic nature of that export. Constraining sediment sources using various mixing model approaches is further complicated by the diversity of potential sources. In this study, we leveraged the infrastructure of the Christina River Basin Critical Zone Observatory (CRB-CZO) to collect large volume (200 L) samples from 17 storms, including some of the biggest storms of the decade (i.e. Hurricane Irene and Sandy), and 95 potential source soils and sediments within the White Clay Creek watershed, a third-order watershed in southeastern Pennsylvania. On all samples we analyzed major and minor elements, rare earth elements, and radioisotopes in order to determine the erosional source category of stream suspended material, such that differences in the chemical composition of source materials can be used in a multivariate statistical model to predict the chemical composition of suspended sediment. For example, 137Cs is higher in surface and near-surface terrestrial soils and low in streambanks, deeper soils, road cuts, and road dust. Elemental chromium is much higher in road dust than any other source. We integrate sediment fingerprinting analyses common in geomorphological studies of mineral suspended material with biological and ecological characterizations of particulate organic carbon. Through this combination, we determine particle source, a necessary first step to calculating the amount of excess carbon that has complexed with particles during erosion and transit through the watershed. This interdisciplinary project is conducted as one of many studies in the CRB-CZO and directly contributes to the overall research focus of this CZO: to quantify the net carbon sink or

  12. Application of biogenic carbon dioxide produced by yeast with different carbon sources for attraction of mosquitoes towards adult mosquito traps.

    PubMed

    Sukumaran, D; Ponmariappan, S; Sharma, Atul K; Jha, Hemendra K; Wasu, Yogesh H; Sharma, Ajay K

    2016-04-01

    Surveillance is a prime requisite for controlling arthropod vectors like mosquitoes that transmit diseases such as malaria, dengue and chikungunya. Carbon dioxide (CO2) is one of the main cues from vertebrate breath that attracts mosquitoes towards the host. Hence, CO2 is used as an attractant during surveillance of mosquitoes either from commercial cylinders or dry ice for mosquito traps. In the present study, the biogenic carbon dioxide production was optimized with different carbon sources such as glucose, simple sugar and jaggery with and without yeast peptone dextrose (YPD) media using commercial baker's yeast. The results showed that yeast produced more biogenic CO2 with simple sugar as compared to other carbon sources. Further substrate concentration was optimized for the continuous production of biogenic CO2 for a minimum of 12 h by using 10 g of baker's yeast with 50 g of simple sugar added to 1.5 l distilled water (without YPD media) in a 2-l plastic bottle. This setup was applied in field condition along with two different mosquito traps namely Mosquito Killing System (MKS) and Biogents Sentinel (BGS) trap. Biogenic CO2 from this setup has increased the trapping efficiency of MKS by 6.48-fold for Culex quinquefasciatus, 2.62-fold for Aedes albopictus and 1.5-fold for Anopheles stephensi. In the case of BGS, the efficiency was found to be increased by 3.54-fold for Ae. albopictus, 4.33-fold for An. stephensi and 1.3-fold for Armigeres subalbatus mosquitoes. On the whole, plastic bottle setup releasing biogenic CO2 from sugar and yeast has increased the efficiency of MKS traps by 6.38-fold and 2.74-fold for BGS traps as compared to traps without biogenic CO2. The present study reveals that, among different carbon sources used, simple sugar as a substance (which is economical and readily available across the world) yielded maximum biogenic CO2 with yeast. This setup can be used as an alternative to CO2 cylinder and dry ice in any adult mosquito traps to

  13. Prairie restoration and carbon sequestration: difficulties quantifying C sources and sinks using a biometric approach.

    PubMed

    Cahill, Kimberly Nicholas; Kucharik, Christopher J; Foley, Jonathan A

    2009-12-01

    We investigated carbon cycling and ecosystem characteristics among two prairie restoration treatments established in 1987 and adjacent cropland, all part of the Conservation Reserve Program in southwestern Wisconsin, USA. We hypothesized that different plant functional groups (cool-season C3 vs. warm-season C4 grasses) between the two prairie restoration treatments would lead to differences in soil and vegetation characteristics and amount of sequestered carbon, compared to the crop system. We found significant (P < 0.05) differences between the two prairie restoration treatments in soil CO2 respiration and above- and belowground productivity, but no significant differences in long-term (approximately 16-year) carbon sequestration. We used a biometric approach aggregating short-term observations of above- and belowground productivity and CO2 respiration to estimate total net primary production (NPP) and net ecosystem production (NEP) using varied methods suggested in the literature. Net ecosystem production is important because it represents the ecosystem carbon sequestration, which is of interest to land managers and policymakers seeking or regulating credits for ecosystem carbon storage. Such a biometric approach would be attractive because it might offer the ability to rapidly assess the carbon source/sink status of an ecosystem. We concluded that large uncertainties in (1) estimating aboveground NPP, (2) determining belowground NPP, and (3) partitioning soil respiration into microbial and plant components strongly affect the magnitude, and even the sign, of NEP estimates made from aggregating its components. A comparison of these estimates across treatments could not distinguish differences in NEP, nor the absolute sign of the overall carbon balance. Longer-term quantification of carbon stocks in the soil, periodically linked to measurements of individual processes, may offer a more reliable measure of the carbon balance in grassland systems, suitable for

  14. A Carbon Source Apportionment Shift in Mexico City Atmospheric Particles During 2003-2004 as Determined with Stable Carbon Isotopes

    NASA Astrophysics Data System (ADS)

    Lopez-Veneroni, D. G.; Vega, E.

    2013-05-01

    The stable carbon isotope composition of atmospheric particles (PM2.5) was measured at La Merced (MER), a commercial site in the eastern sector, and at Xalostoc (XAL) an industrial site in the NE sector of Mexico City, during three sampling periods in autumn 2003, and spring and autumn 2004. At each site and sampling campaign particle samples were collected daily with minivol samplers during two week periods. Ancillary data included organic and elemental carbon, trace elements and ionic species. This data base was complement with air quality data from the RAMA (Automatic Atmospheric Monitoring Network). In general, particle concentrations, ionic species and some air quality species showed higher concentrations in autumn and lowest values in spring. Moreover, the concentrations of these chemical species were highest at XAL compared to MER. The stable carbon isotope composition of PM2.5 during autumn 2003 and spring 2004 had and average value of -26.04 (± 1.54) ‰ vs. PDB. Differences in the isotopic composition between the two sites were non significant. The average δ13C during these seasons were 1 ‰ lighter relative to data collected previously at these sites during 2000 and 2001, and is consistent with a predominant source of hydrocarbon combustion. In autumn 2004, however, average δ13C at XAL and MER increased to -22.8 (± 0.9) and -20.6 (± 3.1) ‰, respectively. Organic carbon concentrations during this period increased concomitantly at these sites. The shift in the isotopic composition in ambient particles suggests a predominance of soil-derived carbon during this period. The possible causes and implications of this are discussed.

  15. Spatial distribution and sources of organic carbon in the surface sediment of the Bosten Lake, China

    NASA Astrophysics Data System (ADS)

    Yu, Z. T.; Wang, X. J.; Zhang, E. L.; Zhao, C. Y.; Lan, H. Y.

    2015-08-01

    Lake sediment is an important carbon reservoir. However, little is known on the dynamics and sources of sediment organic carbon in the Bosten Lake. We collected 13 surface (0-2 cm) sediment samples in the Bosten Lake and analyzed total organic carbon (TOC), total nitrogen (TN), stable carbon isotopic composition in TOC (δ13Corg) and grain size. We found a large spatial variability in TOC content (1.8-4.4 %) and δ13Corg value (-26.77 to -23.98 ‰). Using a three end member mixing model with measured TOC : TN ratio and δ13Corg, we estimated that 54-90 % of TOC was from autochthonous sources. Higher TOC content (> 3.7 %) was found in the east and central-north sections and near the mouth of the Kaidu River, which was attributable to allochthonous, autochthonous plus allochthonous, and autochthonous sources, respectively. The lowest TOC content was found in the mid-west section, which might be a result of high kinetic energy levels. Our study indicated that the spatial distribution of sediment TOC in the Bosten Lake was influenced by multiple and complex processes.

  16. Spatial distribution and sources of organic carbon in the surface sediment of Bosten Lake, China

    NASA Astrophysics Data System (ADS)

    Yu, Z. T.; Wang, X. J.; Zhang, E. L.; Zhao, C. Y.; Liu, X. Q.

    2015-11-01

    Lake sediment is an important carbon reservoir. However, little is known on the dynamics and sources of sediment organic carbon in Bosten Lake. We collected 13 surface (0-2 cm) sediment samples in Bosten Lake and analyzed total organic carbon (TOC), total nitrogen (TN), stable carbon isotopic composition in TOC (δ13Corg), and grain size. We found a large spatial variability in TOC content (1.8-4.4 %) and δ 13Corg value (-26.77 to -23.98 ‰). Using a three-end-member mixing model with measured TOC : TN ratio and δ13Corg, we estimated that 54-90 % of TOC was from autochthonous sources. Higher TOC content (> 3.7 %) was found in the east and central-north sections and near the mouth of the Kaidu River, which was attributable to allochthonous, autochthonous plus allochthonous, and autochthonous sources, respectively. The lowest TOC content was found in the mid-west section, which might be a result of high kinetic energy levels. Our study indicated that the spatial distribution of sediment TOC in the Bosten Lake was influenced by multiple and complex processes.

  17. Denitrification using PBS as carbon source and biofilm support in a packed-bed bioreactor.

    PubMed

    Wu, Weizhong; Yang, Luhua; Wang, Jianlong

    2013-01-01

    Biodegradable polymer was used as carbon source and biofilm support for nitrate removal from aqueous solution as an attractive alternative for biological denitrification. The objective of this paper was to investigate the denitrification performance and microbial community of a packed-bed bioreactor using poly (butanediol succinate) (PBS), a biodegradable polymer, as carbon source and biofilm support. NO(3)-N concentration was determined by UV spectrophotometer. NO(2)-N concentration was assayed by hydrochloric acid naphthyl ethylenediamine spectrophotometry method. Total organic carbon (TOC) was measured using a TOC analyzer. The morphology of the samples was observed using an environmental scanning electron microscope (ESEM). The microbial community was analyzed by pyrosequencing method. The experimental results showed that an average removal efficiency of nitrate was 95 %. ESEM observation and FTIR analysis indicated the changes of PBS granules before and after microbial utilization. Pyrosequencing results showed that Betaproteobacteria predominated, and most of PBS-degrading denitrifying bacteria were assigned to the family Comamonadaceae. Denitrifying bacteria accounted for 13.02 % in total population. The PBS granules were suitable support and carbon source for denitrifying bacteria. PMID:22562343

  18. Production of thermostable invertases by Aspergillus caespitosus under submerged or solid state fermentation using agroindustrial residues as carbon source

    PubMed Central

    Alegre, Ana Cláudia Paiva; de Lourdes Teixeira de Moraes Polizeli, Maria; Terenzi, Héctor Francisco; Jorge, João Atílio; Guimarães, Luis Henrique Souza

    2009-01-01

    The filamentous fungus Aspergillus caespitosus was a good producer of intracellular and extracellular invertases under submerged (SbmF) or solid-state fermentation (SSF), using agroindustrial residues, such as wheat bran, as carbon source. The production of extracellular enzyme under SSF at 30°C, for 72h, was enhanced using SR salt solution (1:1, w/v) to humidify the substrate. The extracellular activity under SSF using wheat bran was around 5.5-fold higher than that obtained in SbmF (Khanna medium) with the same carbon source. However, the production of enzyme with wheat bran plus oat meal was 2.2-fold higher than wheat bran isolated. The enzymatic production was affected by supplementation with nitrogen and phosphate sources. The addition of glucose in SbmF and SSF promoted the decreasing of extracellular activity, but the intracellular form obtained in SbmF was enhanced 3-5-fold. The invertase produced in SSF exhibited optimum temperature at 50°C while the extra- and intracellular enzymes produced in SbmF exhibited maximal activities at 60°C. All enzymatic forms exhibited maximal activities at pH 4.0-6.0 and were stable up to 1 hour at 50°C. PMID:24031406

  19. [Carbon Source Utilization Characteristics of Soil Microbial Community for Apple Orchard with Interplanting Herbage].

    PubMed

    Du, Yi-fei; Fang, Kai-kai; Wang, Zhi-kang; Li, Hui-ke; Mao, Peng-juan; Zhang, Xiang-xu; Wang, Jing

    2015-11-01

    As soil fertility in apple orchard with clean tillage is declined continuously, interplanting herbage in orchard, which is a new orchard management model, plays an important role in improving orchard soil conditions. By using biolog micro-plate technique, this paper studied the functional diversity of soil microbial community under four species of management model in apple orchards, including clear tillage model, interplanting white clover model, interplanting small crown flower model and interplanting cocksfoot model, and the carbon source utilization characteristics of microbial community were explored, which could provide a reference for revealing driving mechanism of ecological process of orchard soil. The results showed that the functional diversity of microbial community had a significant difference among different treatments and in the order of white clover > small crown flower > cocksfoot > clear tillage. The correlation analysis showed that the average well color development (AWCD), Shannon index, Richness index and McIntosh index were all highly significantly positively correlated with soil organic carbon, total nitrogen, microbial biomass carbon, and Shannon index was significantly positively correlated with soil pH. The principal component analysis and the fingerprints of the physiological carbon metabolism of the microbial community demonstrated that grass treatments improved carbon source metabolic ability of soil microbial community, and the soil microbes with perennial legumes (White Clover and small crown flower) had a significantly higher utilization rate in carbohydrates (N-Acetyl-D-Glucosamine, D-Mannitol, β-Methyl-D-Glucoside), amino acids (Glycyl-L-Glutamic acid, L-Serine, L-Threonine) and polymers (Tween 40, Glycogen) than the soil microbes with clear tillage. It was considered that different treatments had the unique microbial community structure and peculiar carbon source utilization characteristics. PMID:26911017

  20. In silico carbon molecular beam epitaxial growth of graphene on the h-BN substrate: carbon source effect on van der Waals epitaxy.

    PubMed

    Lee, Jonghoon; Varshney, Vikas; Park, Jeongho; Farmer, Barry L; Roy, Ajit K

    2016-05-01

    Against the presumption that hexagonal boron-nitride (h-BN) should provide an ideal substrate for van der Waals (vdW) epitaxy to grow high quality graphene films, carbon molecular beam epitaxy (CMBE) techniques using solid carbon sublimation have reported relatively poor quality of the graphene. In this article, the CMBE growth of graphene on the h-BN substrate is numerically studied in order to identify the effect of the carbon source on the quality of the graphene film. The carbon molecular beam generated by the sublimation of solid carbon source materials such as graphite and glassy carbon is mostly composed of atomic carbon, carbon dimers and carbon trimers. Therefore, the graphene film growth becomes a complex process involving various deposition characteristics of a multitude of carbon entities. Based on the study of surface adsorption and film growth characteristics of these three major carbon entities comprising graphite vapour, we report that carbon trimers convey strong traits of vdW epitaxy prone to high quality graphene growth, while atomic carbon deposition is a surface-reaction limited process accompanied by strong chemisorption. The vdW epitaxial behaviour of carbon trimers is found to be substantial enough to nucleate and develop into graphene like planar films within a nanosecond of high flux growth simulation, while reactive atomic carbons tend to impair the structural integrity of the crystalline h-BN substrate upon deposition to form an amorphous interface between the substrate and the growing carbon film. The content of reactive atomic carbons in the molecular beam is suspected to be the primary cause of low quality graphene reported in the literature. A possible optimization of the molecular beam composition towards the synthesis of better quality graphene films is suggested. PMID:27108606