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Sample records for aerosol oxalic acid

  1. Water adsorption around oxalic acid aggregates: a molecular dynamics simulation of water nucleation on organic aerosols.

    PubMed

    Darvas, Maria; Picaud, Sylvain; Jedlovszky, Pál

    2011-11-28

    The phase behaviour of binary oxalic acid-water mixtures has been investigated by means of computer simulation techniques. Such mixtures play an important role in atmospheric processes, since the hydrogen bonding ability of oxalic acid molecules allows them to form aerosol particles. Water can in turn be readily adsorbed on the surface of such aerosol particles, which results in the formation of small ice grains. These grains are thus considered to be acting as cloud condensation nuclei, giving rise to the formation of ice clouds.

  2. Crystallization and immersion freezing ability of oxalic and succinic acid in multicomponent aqueous organic aerosol particles

    NASA Astrophysics Data System (ADS)

    Wagner, Robert; Höhler, Kristina; Möhler, Ottmar; Saathoff, Harald; Schnaiter, Martin

    2015-04-01

    This study reports on heterogeneous ice nucleation efficiency of immersed oxalic and succinic acid crystals in the temperature range from 245 to 215 K, as investigated with expansion cooling experiments using suspended particles. In contrast to previous laboratory work with emulsified solution droplets where the precipitation of solid inclusions required a preceding freezing/evaporation cycle, we show that immersed solids readily form by homogeneous crystallization within aqueous solution droplets of multicomponent organic mixtures, which have noneutonic compositions with an excess of oxalic or succinic acid. Whereas succinic acid crystals did not act as heterogeneous ice nuclei, immersion freezing by oxalic acid dihydrate crystals led to a reduction of the ice saturation ratio at freezing onset by 0.066-0.072 compared to homogeneous freezing, which is by a factor of 2 higher than previously reported laboratory data. These observations emphasize the importance of oxalic acid in heterogeneous ice nucleation.

  3. Atmospheric oxalic acid and related secondary organic aerosols in Qinghai Lake, a continental background site in Tibet Plateau

    NASA Astrophysics Data System (ADS)

    Meng, Jingjing; Wang, Gehui; Li, Jianjun; Cheng, Chunlei; Cao, Junji

    2013-11-01

    Summertime PM2.5 aerosols collected from Qinghai Lake (3200 m a.s.l.), a remote continental site in the northeastern part of Tibetan Plateau, were analyzed for dicarboxylic acids (C2-C11), ketocarboxylic acids and α-dicarbonyals. Oxalic acid (C2) is the dominant dicarboxylic acid in the samples, followed by malonic, succinic and azelaic acids. Total dicarboxylic acids (231 ± 119 ng m-3), ketocarboxylic acids (8.4 ± 4.3 ng m-3), and α-dicarbonyls (2.7 ± 2.1 ng m-3) at the Tibetan background site are 2-5 times less than those detected in lowland areas such as 14 Chinese megacities. Compared to those in other urban and marine areas enhancements in relative abundances of C2/total diacids and diacids-C/WSOC of the PM2.5 samples suggest that organic aerosols in the region are more oxidized due to strong solar radiation. Molecular compositions and air mass trajectories demonstrate that the above secondary organic aerosols in the Qinghai Lake atmosphere are largely derived from long-range transport. Ratios of oxalic acid, glyoxal and methylglyoxal to levoglucosan in PM2.5 aerosols emitted from household burning of yak dung, a major energy source for Tibetan in the region, are 30-400 times lower than those in the ambient air, which further indicates that primary emission from biomass burning is a negligible source of atmospheric oxalic acid and α-dicarbonyls at this background site.

  4. On the factors governing the abundance of oxalic acid in tropospheric aerosol particles

    NASA Astrophysics Data System (ADS)

    van Pinxteren, D.; Neusuess, C.; Brüggemann, E.; Gnauk, T.; Müller, K.; Herrmann, H.

    2010-12-01

    Oxalic acid is frequently observed as one of the most abundant single organic compounds in tropospheric particles. Its sources are commonly believed to be of secondary nature. In state-of-the-art multiphase chemistry models, different pathways exist, which can lead to oxalic acid as final product. Anthropogenic hydrocarbon emissions can be photochemically degraded to glyoxal and methyglyoxal, which - after partitioning into deliquescent particles or cloud droplets - are further oxidized via glyoxylic acid to oxalic acid [Herrmann et al., 2005]. A biogenic oxidation pathway starts with isoprene or monoterpene emissions and leads to glycolaldehyde and methylglyoxal via methacrolein and methylvinylketone, followed by aqueous phase oxalic acid formation [Lim et al., 2005]. As suggested by Warneck, 2003, a marine pathway might exist, starting from marine ethene emissions and leading via glycolaldehyde to oxalic acid. The aim of this study was to elucidate from field measurements the importance of each of these pathways. To this aim, oxalic acid concentrations from 144 size-resolved particle samples (5-stage Berner impactor) from different continental and coastal European sampling sites were statistically analyzed using principal component analysis (PCA). Hourly back trajectories were calculated for each sampling interval using the HYSPLIT model [Draxler and Rolph, 2003] and combined in a novel way with global land cover data to yield “residence times” of the sampled air masses above urban, agricultural, forested, and oceanic areas. These residence times served as quantitative proxies for different emission regimes (anthropogenic, biogenic, marine) in the statistical analysis. Additionally, meteorological parameters such as sunflux along the trajectories or mixing layer depth at the sampling site were retrieved from the HYSPLIT output. PCA of the continental dataset retrieved two factors that were connected to the oxalic acid concentrations. A first one showed high

  5. Characteristics and sources of formic, acetic and oxalic acids in PM 2.5 and PM 10 aerosols in Beijing, China

    NASA Astrophysics Data System (ADS)

    Wang, Ying; Zhuang, Guoshun; Chen, Shuang; An, Zhisheng; Zheng, Aihua

    2007-04-01

    Chemistry of formic, acetic and oxalic acids was studied at four sites representing the urban and rural conditions in Beijing from March 2002 to October 2003. The investigation was based on the PM 2.5 and PM 10 aerosols collected with virtual samplers. The total concentrations of these carboxylic acids averaged at 541 ng m - 3 in PM 2.5 and 615 ng m - 3 in PM 10, contributing 0.4% and 0.3% to the total mass of the aerosol, respectively. Oxalic acid was the most abundant carboxylic acids in aerosols. Formic and acetic acids displayed different seasonal variations (formic: spring < summer < autumn < winter; acetic: spring > summer > autumn > winter), and the variations of these acids were consistent among different sites in urban area. Formic and oxalic acids had a diurnal variation of nighttime < daytime. Formic and acetic acids had mass both in the fine and in the coarse modes, while oxalic acid predominated in the fine mode. The coarse mode fraction of these acids was elevated in summer. The traffic/dust/soil/vegetation emissions, coal/waste/biomass burnings, cooking and secondary formation from anthropogenic or natural gas-phase precursors could be the major sources of these acids. Acetic-to-formic acid ratio (A/F) was used to distinguish the primary sources and the secondary sources, and it indicated that the contribution of the primary sources was higher at rural site than at urban sites. A new method was developed to study the contribution of the biomass burning to these acids, which was estimated to be 30-60% for formic and oxalic acids in aerosols.

  6. A biogenic source of oxalic acid and glyoxal in marine boundary layer

    NASA Astrophysics Data System (ADS)

    Facchini, C.; Rinaldi, M.; Ceburnis, D.; O'Dowd, C.; Sciare, J.; Burrows, J. P.

    2011-12-01

    We present the results of oxalic acid aerosol measurements samples performed at Mace Head (Ireland, 53°20'N, 9°54'W) and Amsterdam Island (Indian Ocean, 37°48'S, 77°34'E), supporting the existence of a biogenic source of oxalic acid over the oceans. Aerosol oxalic acid was detected in clean marine air masses in concentrations ranging from 2.7 to 39 ng m-3, at Mace Head, and from 0.31 to 17 ng m-3, at Amsterdam Island. In both hemispheres, oxalic acid concentration showed a clear seasonal trend, with maxima in spring-summer and minima in the fall-winter period, in analogy with other marine biogenic aerosol components (e.g., MSA and amines). Oxalic acid was distributed along the whole aerosol size spectrum, with the major contribution given by the 1.0-2.0 μm size range, and by the lower accumulation mode (0.25-0.5 μm). Given the observed size distributions, marine aerosol oxalic acid can be assumed as the result of the combination of different formation processes, among which in-cloud oxidation of gaseous precursors [1] and photochemical degradation of biogenic unsaturated fatty acids [2] are likely the most important. Among aerosol oxalic acid precursors, glyoxal is the most likely candidate in the marine boundary layer, as a source of glyoxal over the oceans has recently been discovered by satellite observations [3] and confirmed by in situ measurements [4]. In support of this hypothesis, SCIAMACHY satellite retrieved glyoxal column concentrations, over the two sampling sites, resulted characterized by a clear seasonal trend, resembling the aerosol oxalic acid one. [1] Warneck, Atmospheric Environment, 37, 2423-2427, 2003. [2] Kawamura & Sakaguchi, J. Geophys. Res., 104, D3, 3501-3509, 1999. [3] Fu et al., J. Geophys. Res., 113, D15303, doi:10.1029/2007JD009505, 2008 [4] Sinreich et al., Atmos. Chem. Phys. Discuss., 10, 15075-15107, 2010.

  7. Ultrasonic degradation of oxalic acid in aqueous solutions.

    PubMed

    Dükkanci, M; Gündüz, G

    2006-09-01

    This paper describes the ultrasonic degradation of oxalic acid. The effects of ultrasonic power, H(2)O(2), NaCl, external gases on the degradation of oxalic acid were investigated. Reactor flask containing oxalic acid was immersed in the ultrasonic bath with water as the coupling fluid. Representative samples withdrawn were analysed by volumetric titration. Degradation degree of oxalic acid increased with increasing ultrasonic power. It was observed that H(2)O(2) has negative contribution on the degradation of oxalic acid and there was an optimum concentration of NaCl for enhancing the degradation degree of oxalic acid. Although bubbling nitrogen gave higher degradation than that for bubbling air, both gases (for 20 min before sonication and during sonication together) could not help to enhance the degradation of oxalic acid when compared with the degradation without gas passage. PMID:16352455

  8. Red facts: Oxalic acid. Fact sheet

    SciTech Connect

    Not Available

    1992-12-01

    All pesticides sold or used in the United States must be registered by EPA, based on scientific studies showing that they can be used without posing unreasonable risks to people or the environment. Because of advances in scientific knowledge, the law requires that pesticides which were first registered years ago be reregistered to ensure that they meet today's more stringent standards. Oxalic acid is registered for use as a disinfectant to control bacteria and germs, and as a sanitizer, in toilet bowls, urinals and bathroom premises. Oxalic acid also has many diverse, non-pesticidal, manufacturing and industrial uses including use in fabric printing and dyeing; bleaching straw hats; removing paint, varnish, rust or ink stains; and cleaning wood.

  9. The oxalic acid: 2-chloroacetamide crystallization: A new revelation

    NASA Astrophysics Data System (ADS)

    Chitra, R.; Choudhury, R. R.; Capet, Frederic; Roussel, Pascal

    2013-02-01

    The OH of COOH can acts as both donor and acceptor of hydrogen bond. OH of COOH as an acceptor was primarily observed in Oxalic acid Amide complexes. In order to further understand the packing in these complexes, oxalic acid was complexed with 2-tricholoroacetamide. This crystallization resulted in the formation of ammonium tetraoxalate dehydrate. A result similar to what was observed in complexation of oxalic acid with amide containing amino acids (asparagine and glutamine). Interestingly in all these cases, the amide bond is broken, to form the ammonium ion when trying to complex with oxalic acid.

  10. Kinetic study of oxalic acid inhibition on enzymatic browning.

    PubMed

    Son, S M; Moon, K D; Lee, C Y

    2000-06-01

    Oxalic acid has a strong antibrowning activity. The inhibitory pattern on catechol-PPO model system appeared to be competitive, with a K(i) value of 2.0 mM. When the PPO was incubated with oxalic acid, the activity was not recovered via dialysis, but the inactivated enzyme partially recovered its activity when cupric ion was added. Comparing the relative antibrowning effectiveness of oxalic acid with other common antibrowning agents, oxalic acid with I(50) value of 1.1 mM is as effective as kojic acid and more potent than cysteine and glutathione.

  11. Reregistration eligibility document (RED): Oxalic acid

    SciTech Connect

    Not Available

    1992-12-01

    EPA is directed by the Federal Insecticide, Fungicide, and Rodenticide Act as amended in 1988 (FIFRA '88) to review all pesticide products containing active ingredients initially registered before November 1, 1984, and to reregister those products that have a substantially complete data base and do not pose unreasonable adverse effects to people or the environment. This pesticide reregistration program is to be completed by the late 1990's. The Reregistration Eligibility Document (or RED) for oxalic acid discusses the scientific data and other information supporting EPA's regulatory conclusion that products containing a pesticide do not pose unreasonable risks when used as directed by Agency-approved labeling, and are eligible for reregistration.

  12. Growth Conditions To Reduce Oxalic Acid Content of Spinach

    NASA Technical Reports Server (NTRS)

    Johnson-Rutzke, Corinne

    2003-01-01

    A controlled-environment agricultural (CEA) technique to increase the nutritive value of spinach has been developed. This technique makes it possible to reduce the concentration of oxalic acid in spinach leaves. It is desirable to reduce the oxalic acid content because oxalic acid acts as an anti-nutritive calcium-binding component. More than 30 years ago, an enzyme (an oxidase) that breaks down oxalic acid into CO2 and H2O2 was discovered and found to be naturally present in spinach leaves. However, nitrate, which can also be present because of the use of common nitratebased fertilizers, inactivates the enzyme. In the CEA technique, one cuts off the supply of nitrate and keeps the spinach plants cool while providing sufficient oxygen. This technique provides the precise environment that enables the enzyme to naturally break down oxalate. The result of application of this technique is that the oxalate content is reduced by 2/3 in one week.

  13. Oxalic acid degradation by a novel fungal oxalate oxidase from Abortiporus biennis.

    PubMed

    Grąz, Marcin; Rachwał, Kamila; Zan, Radosław; Jarosz-Wilkołazka, Anna

    2016-01-01

    Oxalate oxidase was identified in mycelial extracts of a basidiomycete Abortiporus biennis strain. Intracellular enzyme activity was detected only after prior lowering of the pH value of the fungal cultures by using oxalic or hydrochloric acids. This enzyme was purified using size exclusion chromatography (Sephadex G-25) and ion-exchange chromatography (DEAE-Sepharose). This enzyme exhibited optimum activity at pH 2 when incubated at 40°C, and the optimum temperature was established at 60°C. Among the tested organic acids, this enzyme exhibited specificity only towards oxalic acid. Molecular mass was calculated as 58 kDa. The values of Km for oxalate and Vmax for the enzyme reaction were 0.015 M and 30 mmol min(-1), respectively. PMID:27337220

  14. Oxalic acid decreases calcium absorption in rats

    SciTech Connect

    Weaver, C.M.; Martin, B.R.; Ebner, J.S.; Krueger, C.A.

    1987-11-01

    Calcium absorption from salts and foods intrinsically labeled with /sup 45/Ca was determined in the rat model. Calcium bioavailability was nearly 10 times greater for low oxalate kale, CaCO/sub 3/ and CaCl/sub 2/ than from CaC/sub 2/O/sub 4/ (calcium oxalate) and spinach (high in oxalates). Extrinsic and intrinsic labeling techniques gave a similar assessment of calcium bioavailability from kale but not from spinach.

  15. High-sensitivity microchip electrophoresis determination of inorganic anions and oxalate in atmospheric aerosols with adjustable selectivity and conductivity detection.

    PubMed

    Noblitt, Scott D; Schwandner, Florian M; Hering, Susanne V; Collett, Jeffrey L; Henry, Charles S

    2009-02-27

    A sensitive and selective separation of common anionic constituents of atmospheric aerosols, sulfate, nitrate, chloride, and oxalate, is presented using microchip electrophoresis. The optimized separation is achieved in under 1 min and at low background electrolyte ionic strength (2.9 mM) by combining a metal-binding electrolyte anion (17 mM picolinic acid), a sulfate-binding electrolyte cation (19 mM HEPBS), a zwitterionic surfactant with affinity towards weakly solvated anions (19 mM N-tetradecyl,N,N-dimethyl-3-ammonio-1-propansulfonate), and operation in counter-electroosmotic flow (EOF) mode. The separation is performed at pH 4.7, permitting pH manipulation of oxalate's mobility. The majority of low-concentration organic acids are not observed at these conditions, allowing for rapid subsequent injections without the presence of interfering peaks. Because the mobilities of sulfate, nitrate, and oxalate are independently controlled, other minor constituents of aerosols can be analyzed, including nitrite, fluoride, and formate if desired using similar separation conditions. Contact conductivity detection is utilized, and the limit of detection for oxalate (S/N=3) is 180 nM without stacking. Sensitivity can be increased with field-amplified sample stacking by injecting from dilute electrolyte with a detection limit of 19 nM achieved. The high-sensitivity, counter-EOF operation, and short analysis time make this separation well-suited to continuous online monitoring of aerosol composition.

  16. Interaction of Gas Phase Oxalic Acid with Ammonia and its Atmospheric Implications

    SciTech Connect

    Peng, Xiu-Qiu; Liu, Yi-Rong; Huang, Teng; Jiang, Shuai; Huang, Wei

    2015-04-14

    Oxalic acid is believed to play an important role in the formation and growth of atmospheric organic aerosols. However, as a common organic acid, the understanding of the larger clusters formed by gas phase oxalic acid with multiple ammonia molecules is incomplete. In this work, the structural characteristics and thermodynamics of oxalic acid clusters with up to six ammonia molecules have been investigated at the PW91PW91/6-311++G(3df,3pd) level of theory. We found that oxalic acid forms relatively stable clusters with ammonia molecules, and that ionization events play a key role. The analyses of the thermodynamics and atmospheric relevance indicate that the heterodimer (H2C2O4)(NH3) shows an obvious relative concentration in the atmosphere, and thus likely participates in new particle formation. However, with increasing number of ammonia molecules, the concentration of clusters decreases gradually. Additionally, clusters of oxalic acid with ammonia molecules are predicted to form favorably in low temperature conditions and show high Rayleigh scattering intensities.

  17. Iron dissolution of dust source materials during simulated acidic processing: the effect of sulfuric, acetic, and oxalic acids.

    PubMed

    Chen, Haihan; Grassian, Vicki H

    2013-09-17

    Atmospheric organic acids potentially display different capacities in iron (Fe) mobilization from atmospheric dust compared with inorganic acids, but few measurements have been made on this comparison. We report here a laboratory investigation of Fe mobilization of coal fly ash, a representative Fe-containing anthropogenic aerosol, and Arizona test dust, a reference source material for mineral dust, in pH 2 sulfuric acid, acetic acid, and oxalic acid, respectively. The effects of pH and solar radiation on Fe dissolution have also been explored. The relative capacities of these three acids in Fe dissolution are in the order of oxalic acid > sulfuric acid > acetic acid. Oxalate forms mononuclear bidentate ligand with surface Fe and promotes Fe dissolution to the greatest extent. Photolysis of Fe-oxalate complexes further enhances Fe dissolution with the concomitant degradation of oxalate. These results suggest that ligand-promoted dissolution of Fe may play a more significant role in mobilizing Fe from atmospheric dust compared with proton-assisted processing. The role of atmospheric organic acids should be taken into account in global-biogeochemical modeling to better access dissolved atmospheric Fe deposition flux at the ocean surface.

  18. Production of oxalic acid by some fungi infected tubers.

    PubMed

    Faboya, O; Ikotun, T; Fatoki, O S

    1983-01-01

    Oxalic acid (as oxalate) was detected in four tubers commonly used for food in Nigeria-Dioscorea rotundata (White yam), Solanum tuberosum (Irish potato), Ipomoea batatas (Sweet potato), and Manihot esculenta (cassava). Whereas healthy I. batata had the highest oxalic acid content, healthy M. esculenta contained the lowest. When all tubers were artifically inoculated with four fungi-Penicillium oxalicum CURIE and THOM, Aspergillus niger VAN TIEGH, A. flavus and A. tamarii KITA, there was an increase in oxalate content/g of tuber tissue. The greatest amount of oxalate was produced by P. oxalicum in D. rotundata tuber. Consistently higher amounts of oxalate were produced by the four fungi in infected sweet potato tuber than in any other tuber and consistently lower amounts of oxalate were produced by the four fungi in Irish potato tuber. Differences in the carbohydrate type present in the tubers and in the biosynthesis pathway are thought to be responsible for variation in the production of oxalate in the different tubers by the four fungi used.

  19. Heterogeneous photochemistry of oxalic acid on Mauritanian sand and Icelandic volcanic ash.

    PubMed

    Styler, Sarah A; Donaldson, D J

    2012-08-21

    Teragram quantities of crustal and volcanic aerosol are released into the atmosphere on an annual basis. Although these substrates contain photoactive metal oxides, little is known about the role that they may play in catalyzing the heterogeneous phototransformation of semivolatile organic species. In the present study, we have investigated oxalic acid photochemistry at the surface of Fe(2)O(3), TiO(2), Mauritanian sand, and Icelandic volcanic ash in the presence and absence of oxygen using a photochemical Knudsen cell reactor. Illumination of all sample types resulted in the production of gas-phase CO(2). In the case of Mauritanian sand, the production of gas-phase CO(2) scaled with the loss of surface oxalic acid. In the absence of oxygen, the production of CO(2) by the sand and ash films scaled with the absorption spectrum of iron oxalate, which suggests that the reaction is at least in part iron-mediated. The presence of oxygen suppressed CO(2) production at the Fe(2)O(3) surface, enhanced CO(2) production at the Mauritanian sand surface, and did not have a net effect upon CO(2) production at the Icelandic ash surface. These different oxygen dependencies imply that oxalic acid photochemistry at the authentic surfaces under study was not solely iron-mediated. Experiments at the TiO(2) surface, which showed enhanced CO(2) production from oxalic acid in the presence of oxygen, suggest that Ti-mediated photochemistry played an important role. In summary, these results provide evidence that solid-phase aerosol photochemistry may influence the atmospheric lifetime of oxalic acid in arid regions, where its removal via wet deposition is insignificant.

  20. Production and degradation of oxalic acid by brown rot fungi

    SciTech Connect

    Espejo, E.; Agosin, E. )

    1991-07-01

    Our results show that all of the brown rot fungi tested produce oxalic acid in liquid as well as in semisolid cultures. Gloeophyllum trabeum, which accumulates the lowest amount of oxalic acid during decay of pine holocellulose, showed the highest polysaccharide-depolymerizing activity. Semisolid cultures inoculated with this fungus rapidly converted {sup 14}C-labeled oxalic acid to CO{sub 2} during cellulose depolymerization. The other brown rot fungi also oxidized {sup 14}C-labeled oxalic acid, although less rapidly. In contrast, semisolid cultures inoculated with the white rot fungus Coriolus versicolor did not significantly catabolize the acid and did not depolymerize the holocellulose during decay. Semisolid cultures of G. trabeum amended with desferrioxamine, a specific iron-chelating agent, were unable to lower the degree of polymerization of cellulose or to oxidize {sup 14}C-labeled oxalic acid to the extent or at the rate that control cultures did. These results suggest that both iron and oxalic acid are involved in cellulose depolymerization by brown rot fungi.

  1. Production and Degradation of Oxalic Acid by Brown Rot Fungi

    PubMed Central

    Espejo, Eduardo; Agosin, Eduardo

    1991-01-01

    Our results show that all of the brown rot fungi tested produce oxalic acid in liquid as well as in semisolid cultures. Gloeophyllum trabeum, which accumulates the lowest amount of oxalic acid during decay of pine holocellulose, showed the highest polysaccharide-depolymerizing activity. Semisolid cultures inoculated with this fungus rapidly converted 14C-labeled oxalic acid to CO2 during cellulose depolymerization. The other brown rot fungi also oxidized 14C-labeled oxalic acid, although less rapidly. In contrast, semisolid cultures inoculated with the white rot fungus Coriolus versicolor did not significantly catabolize the acid and did not depolymerize the holocellulose during decay. Semisolid cultures of G. trabeum amended with desferrioxamine, a specific iron-chelating agent, were unable to lower the degree of polymerization of cellulose or to oxidize 14C-labeled oxalic acid to the extent or at the rate that control cultures did. These results suggest that both iron and oxalic acid are involved in cellulose depolymerization by brown rot fungi. PMID:16348522

  2. Oxalic acid, epsom salt and the poison bottle.

    PubMed

    Campbell, W A

    1982-03-01

    1 During the 19th century inadequate control of the sale of poisons, widespread illiteracy, and the English addiction to self-medication contributed to the high incidence of accidental poisoning by oxalic acid mistaken for Epsom salt. 2 Chemical methods for identifying oxalic acid failed when the product was adulterated. 3 Many mechanical devices were proposed to prevent careless dispensing; designs for poison bottles of distinctive shape, colour and texture appeared regularly for 40 years. PMID:6757103

  3. Means for reducing oxalic acid to a product

    SciTech Connect

    Morduchowitz, A.; Sammells, A.F.

    1988-12-06

    This patent describes an apparatus for reducing oxalic acid to a product comprising: a cell including a separator for separating the cell into two chambers, a catholyte chamber and an anolyte chamber, each chamber having an inlet and an outlet; a porous anode arranged within the anolyte section in a manner so that an electrolyte entering through the inlet of the anolyte section will pass through the anode and exit through the outlet of the anolyte section; means for providing an electrolyte to the inlet of the anolyte chamber in a manner so that it will exit through the outlet of the anolyte chamber; means for providing a mixture of oxalic acid and an electrolyte to the inlet of the catholyte chamber; porous cathode means located in the catholyte chamber for reducing the oxalic acid in the oxalic acid-electrolyte mixture to the product within the cathode means when a d.c. voltage provided across the anode and the cathode means, the product exiting the cell by way of the catholyte chamber's outlet; and means for providing a d.c. voltage across the cathode means and the anode so as to cooperate in the reduction of the oxalic acid; and in which the cathode means includes a porous cathode having discrete sites of platinum and mercury as catalysts and the product is ethylene glycol.

  4. Oxalic acid adsorption states on the clean Cu(110) surface

    NASA Astrophysics Data System (ADS)

    Fortuna, Sara

    2016-11-01

    Carboxylic acids are known to assume a variety of configurations on metallic surfaces. In particular oxalic acid on the Cu(110) surface has been proposed to assume a number of upright configurations. Here we explore with DFT calculations the possible structures that oxalic acid can form on copper 110 at different protonation states, with particular attention at the possibility of forming structures composed of vertically standing molecules. In its fully protonated form it is capable of anchoring itself on the surface thanks to one of its hydrogen-free oxygens. We show the monodeprotonated upright molecule with two oxygens anchoring it on the surface to be the lowest energy conformation of a single oxalic molecules on the Cu(110) surface. We further show that it is possible for this configuration to form dense hexagonally arranged patterns in the unlikely scenario in which adatoms are not involved.

  5. The abiotic degradation of soil organic matter to oxalic acid

    NASA Astrophysics Data System (ADS)

    Studenroth, Sabine; Huber, Stefan; Schöler, H. F.

    2010-05-01

    The abiotic degradation of soil organic matter to volatile organic compounds was studied intensely over the last years (Keppler et al., 2000; Huber et al., 2009). It was shown that soil organic matter is oxidised due to the presence of iron (III), hydrogen peroxide and chloride and thereby produces diverse alkyl halides, which are emitted into the atmosphere. The formation of polar halogenated compounds like chlorinated acetic acids which are relevant toxic environmental substances was also found in soils and sediments (Kilian et al., 2002). The investigation of the formation of other polar halogenated and non-halogenated compounds like diverse mono- and dicarboxylic acids is going to attain more and more importance. Due to its high acidity oxalic acid might have impacts on the environment e.g., nutrient leaching, plant diseases and negative influence on microbial growth. In this study, the abiotic formation of oxalic acid in soil is examined. For a better understanding of natural degradation processes mechanistic studies were conducted using the model compound catechol as representative for structural elements of the humic substances and its reaction with iron (III) and hydrogen peroxide. Iron is one of the most abundant elements on earth and hydrogen peroxide is produced by bacteria or through incomplete reduction of oxygen. To find suitable parameters for an optimal reaction and a qualitative and quantitative analysis method the following reaction parameters are varied: concentration of iron (III) and hydrogen peroxide, time dependence, pH-value and influence of chloride. Analysis of oxalic acid was performed employing an ion chromatograph equipped with a conductivity detector. The time dependent reaction shows a relatively fast formation of oxalic acid, the optimum yield is achieved after 60 minutes. Compared to the concentration of catechol an excess of hydrogen peroxide as well as a low concentration of iron (III) are required. In absence of chloride the

  6. Organic acids in continental background aerosols

    NASA Astrophysics Data System (ADS)

    Limbeck, Andreas; Puxbaum, Hans

    With a newly developed method aerosol samples from three distinctly different continental sites were analyzed: an urban site (Vienna), a savanna site in South Africa (Nylsvley Nature Reserve, NNR) and a free tropospheric continental background site (Sonnblick Observatory, SBO). In all samples a range of monocarboxylic acids (MCAs) and dicarboxylic acids (DCAs) has been identified and quantified. The three most abundant MCAs in Vienna were the C18, C16 and C14 acids with concentrations of 66, 45 and 36 ng m -3, respectively. At the mid tropospheric background site (SBO) the three most abundant MCAs were the C18, C16 and C12 acid. For the DCAs at all three sites oxalic, malonic and succinic acid were the dominant compounds. For some individual compounds an information about the sources could be obtained. For example the determined unsaturated MCAs in South Africa appear to result from biogenic sources whereas in Vienna those acids are considered to be derived from combustion processes. Oxalic and glyoxalic acid appear to have a free tropospheric air chemical source. The relative high amounts at SBO in comparison to Vienna can only be explained by secondary formation of oxalic acid in the atmosphere.

  7. Solubility of the Sodium and Ammonium Salts of Oxalic Acid in Water with Ammonium Sulfate.

    PubMed

    Buttke, Lukas G; Schueller, Justin R; Pearson, Christian S; Beyer, Keith D

    2016-08-18

    The solubility of the sodium and ammonium salts of oxalic acid in water with ammonium sulfate present has been studied using differential scanning calorimetry, X-ray crystallography, and infrared spectroscopy. The crystals that form from aqueous mixtures of ammonium sulfate/sodium hydrogen oxalate were determined to be sodium hydrogen oxalate monohydrate under low ammonium sulfate conditions and ammonium hydrogen oxalate hemihydrate under high ammonium sulfate conditions. Crystals from aqueous mixtures of ammonium sulfate/sodium oxalate were determined to be ammonium oxalate monohydrate under moderate to high ammonium sulfate concentrations and sodium oxalate under low ammonium sulfate concentrations. It was also found that ammonium sulfate enhances the solubility of the sodium oxalate salts (salting in effect) and decreases the solubility of the ammonium oxalate salts (salting out effect). In addition, a partial phase diagram for the ammonium hydrogen oxalate/water system was determined.

  8. Solubility of the Sodium and Ammonium Salts of Oxalic Acid in Water with Ammonium Sulfate.

    PubMed

    Buttke, Lukas G; Schueller, Justin R; Pearson, Christian S; Beyer, Keith D

    2016-08-18

    The solubility of the sodium and ammonium salts of oxalic acid in water with ammonium sulfate present has been studied using differential scanning calorimetry, X-ray crystallography, and infrared spectroscopy. The crystals that form from aqueous mixtures of ammonium sulfate/sodium hydrogen oxalate were determined to be sodium hydrogen oxalate monohydrate under low ammonium sulfate conditions and ammonium hydrogen oxalate hemihydrate under high ammonium sulfate conditions. Crystals from aqueous mixtures of ammonium sulfate/sodium oxalate were determined to be ammonium oxalate monohydrate under moderate to high ammonium sulfate concentrations and sodium oxalate under low ammonium sulfate concentrations. It was also found that ammonium sulfate enhances the solubility of the sodium oxalate salts (salting in effect) and decreases the solubility of the ammonium oxalate salts (salting out effect). In addition, a partial phase diagram for the ammonium hydrogen oxalate/water system was determined. PMID:27482644

  9. GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

    SciTech Connect

    Pierce, R.

    2012-02-22

    HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into the H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. For 6 M HNO{sub 3}, 10.5 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2 g/L and 0.25 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}.

  10. Oxalic acid production by citric acid-producing Aspergillus niger overexpressing the oxaloacetate hydrolase gene oahA.

    PubMed

    Kobayashi, Keiichi; Hattori, Takasumi; Honda, Yuki; Kirimura, Kohtaro

    2014-05-01

    The filamentous fungus Aspergillus niger is used worldwide in the industrial production of citric acid. However, under specific cultivation conditions, citric acid-producing strains of A. niger accumulate oxalic acid as a by-product. Oxalic acid is used as a chelator, detergent, or tanning agent. Here, we sought to develop oxalic acid hyperproducers using A. niger as a host. To generate oxalic acid hyperproducers by metabolic engineering, transformants overexpressing the oahA gene, encoding oxaloacetate hydrolase (OAH; EC 3.7.1.1), were constructed in citric acid-producing A. niger WU-2223L as a host. The oxalic acid production capacity of this strain was examined by cultivation of EOAH-1 under conditions appropriate for oxalic acid production with 30 g/l glucose as a carbon source. Under all the cultivation conditions tested, the amount of oxalic acid produced by EOAH-1, a representative oahA-overexpressing transformant, exceeded that produced by A. niger WU-2223L. A. niger WU-2223L and EOAH-1 produced 15.6 and 28.9 g/l oxalic acid, respectively, during the 12-day cultivation period. The yield of oxalic acid for EOAH-1 was 64.2 % of the maximum theoretical yield. Our method for oxalic acid production gave the highest yield of any study reported to date. Therefore, we succeeded in generating oxalic acid hyperproducers by overexpressing a single gene, i.e., oahA, in citric acid-producing A. niger as a host.

  11. GADOLINIUM OXALATE SOLUBILITY MEASUREMENTS IN NITRIC ACID SOLUTIONS

    SciTech Connect

    Pierce, R. A.

    2012-03-12

    HB-Line will begin processing Pu solutions during FY2012 that will involve the recovery of Pu using oxalate precipitation and filtration. After the precipitation and filtration processes, the filtrate solution will be transferred from HB-Line to H-Canyon. The presence of excess oxalate and unfiltered Pu oxalate solids in these solutions create a criticality safety issue if they are sent to H-Canyon without controls in H-Canyon. One approach involves H-Canyon receiving the filtrate solution into a tank that is poisoned with soluble gadolinium (Gd). Decomposition of the oxalate will occur within a subsequent H-Canyon vessel. The receipt of excess oxalate into the H-Canyon receipt tanks has the potential to precipitate a portion of the Gd poison in the receipt tanks. Because the amount of Gd in solution determines the maximum amount of Pu solids that H-Canyon can receive, H-Canyon Engineering requested that SRNL determine the solubility of Gd in aqueous solutions of 4-10 M nitric acid (HNO{sub 3}), 4-12 g/L Gd, and 0.15-0.25 M oxalic acid (H{sub 2}C{sub 2}O{sub 4}) at 25 °C. The target soluble Gd concentration is 6 g/L. The data indicate that the target can be achieved above 6 M HNO{sub 3} and below 0.25 M H{sub 2}C{sub 2}O{sub 4}. At 25 °C, for 6 M HNO{sub 3}, 11 g/L and 7 g/L Gd are soluble in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. In 4 M HNO{sub 3}, the Gd solubility drops significantly to 2.5 g/L and 0.8 g/L in 0.15 M and 0.25 M H{sub 2}C{sub 2}O{sub 4}, respectively. The solubility of Gd at 8-10 M HNO{sub 3} exceeds the solubility at 6 M HNO{sub 3}. The data for 4 M HNO{sub 3} showed good agreement with data in the literature. To achieve a target of 6 g/L soluble Gd in solution in the presence of 0.15-0.25 M oxalate, the HNO{sub 3} concentration must be maintained at or above 6 M HNO{sub 3}. The solubility of Gd in 4 M HNO{sub 3} with 0.15 M oxalate at 10 °C is about 1.5 g/L. For 6 M HNO{sub 3} with 0.15 M oxalate, the solubility of Gd at 10

  12. Aircraft observations of water-soluble dicarboxylic acids in the aerosols over China

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Lin; Kawamura, Kimitaka; Qing Fu, Ping; Boreddy, Suresh K. R.; Watanabe, Tomomi; Hatakeyama, Shiro; Takami, Akinori; Wang, Wei

    2016-05-01

    Vertical profiles of dicarboxylic acids, related organic compounds and secondary organic aerosol (SOA) tracer compounds in particle phase have not yet been simultaneously explored in East Asia, although there is growing evidence that aqueous-phase oxidation of volatile organic compounds may be responsible for the elevated organic aerosols (OA) in the troposphere. Here, we found consistently good correlation of oxalic acid, the most abundant individual organic compounds in aerosols globally, with its precursors as well as biogenic-derived SOA compounds in Chinese tropospheric aerosols by aircraft measurements. Anthropogenically derived dicarboxylic acids (i.e., C5 and C6 diacids) at high altitudes were 4-20 times higher than those from surface measurements and even occasionally dominant over oxalic acid at altitudes higher than 2 km, which is in contrast to the predominance of oxalic acid previously reported globally including the tropospheric and surface aerosols. This indicates an enhancement of tropospheric SOA formation from anthropogenic precursors. Furthermore, oxalic acid-to-sulfate ratio maximized at altitudes of ˜ 2 km, explaining aqueous-phase SOA production that was supported by good correlations with predicted liquid water content, organic carbon and biogenic SOA tracers. These results demonstrate that elevated oxalic acid and related SOA compounds from both the anthropogenic and biogenic sources may substantially contribute to tropospheric OA burden over polluted regions of China, implying aerosol-associated climate effects and intercontinental transport.

  13. Crystal structure of di­methyl­ammonium hydrogen oxalate hemi(oxalic acid)

    PubMed Central

    Diallo, Waly; Gueye, Ndongo; Crochet, Aurélien; Plasseraud, Laurent; Cattey, Hélène

    2015-01-01

    Single crystals of the title salt, Me2NH2 +·HC2O4 −·0.5H2C2O4, were isolated as a side product from the reaction involving Me2NH, H2C2O4 and Sn(n-Bu)3Cl in a 1:2 ratio in methanol or by the reaction of the (Me2NH2)2C2O4 salt and Sn(CH3)3Cl in a 2:1 ratio in ethanol. The asymmetric unit comprises a di­methyl­ammonium cation (Me2NH2 +), an hydrogenoxalate anion (HC2O4 −), and half a mol­ecule of oxalic acid (H2C2O4) situated about an inversion center. From a supra­molecular point of view, the three components inter­act together via hydrogen bonding. The Me2NH2 + cations and the HC2O4 − anions are in close proximity through bifurcated N—H⋯(O,O) hydrogen bonds, while the HC2O4 − anions are organized into infinite chains via O—H⋯O hydrogen bonds, propagating along the a-axis direction. In addition, the oxalic acid (H2C2O4) mol­ecules play the role of connectors between these chains. Both the carbonyl and hydroxyl groups of each diacid are involved in four inter­molecular inter­actions with two Me2NH2 + and two HC2O4 − ions of four distinct polymeric chains, via two N—H⋯O and two O—H⋯O hydrogen bonds, respectively. The resulting mol­ecular assembly can be viewed as a two-dimensional bilayer-like arrangement lying parallel to (010), and reinforced by a C—H⋯O hydrogen bond. PMID:25995858

  14. Crystal structure of di-methyl-ammonium hydrogen oxalate hemi(oxalic acid).

    PubMed

    Diallo, Waly; Gueye, Ndongo; Crochet, Aurélien; Plasseraud, Laurent; Cattey, Hélène

    2015-05-01

    Single crystals of the title salt, Me2NH2 (+)·HC2O4 (-)·0.5H2C2O4, were isolated as a side product from the reaction involving Me2NH, H2C2O4 and Sn(n-Bu)3Cl in a 1:2 ratio in methanol or by the reaction of the (Me2NH2)2C2O4 salt and Sn(CH3)3Cl in a 2:1 ratio in ethanol. The asymmetric unit comprises a di-methyl-ammonium cation (Me2NH2 (+)), an hydrogenoxalate anion (HC2O4 (-)), and half a mol-ecule of oxalic acid (H2C2O4) situated about an inversion center. From a supra-molecular point of view, the three components inter-act together via hydrogen bonding. The Me2NH2 (+) cations and the HC2O4 (-) anions are in close proximity through bifurcated N-H⋯(O,O) hydrogen bonds, while the HC2O4 (-) anions are organized into infinite chains via O-H⋯O hydrogen bonds, propagating along the a-axis direction. In addition, the oxalic acid (H2C2O4) mol-ecules play the role of connectors between these chains. Both the carbonyl and hydroxyl groups of each diacid are involved in four inter-molecular inter-actions with two Me2NH2 (+) and two HC2O4 (-) ions of four distinct polymeric chains, via two N-H⋯O and two O-H⋯O hydrogen bonds, respectively. The resulting mol-ecular assembly can be viewed as a two-dimensional bilayer-like arrangement lying parallel to (010), and reinforced by a C-H⋯O hydrogen bond.

  15. Exposures to acidic aerosols.

    PubMed

    Spengler, J D; Keeler, G J; Koutrakis, P; Ryan, P B; Raizenne, M; Franklin, C A

    1989-02-01

    Ambient monitoring of acid aerosols in four U.S. cities and in a rural region of southern Ontario clearly show distinct periods of strong acidity. Measurements made in Kingston, TN, and Steubenville, OH, resulted in 24-hr H+ ion concentrations exceeding 100 nmole/m3 more than 10 times during summer months. Periods of elevated acidic aerosols occur less frequently in winter months. The H+ determined during episodic conditions in southern Ontario indicates that respiratory tract deposition can exceed the effects level reported in clinical studies. Observed 12-hr H+ concentrations exceeded 550 nmole/m3 (approximately 27 micrograms/m3 H2SO4). The maximum estimated 1-hr concentration exceeded 1500 nmole/m3 for H+ ions. At these concentrations, an active child might receive more than 2000 nmole of H+ ion in 12 hr and in excess of 900 nmole during the hour when H2SO4 exceeded 50 micrograms/m3.

  16. Oxalic acid-mediated stress responses in Brassica napus L.

    PubMed

    Liang, Yue; Strelkov, Stephen E; Kav, Nat N V

    2009-06-01

    Oxalic acid (OA) occurs extensively in nature and plays diverse roles, especially in pathogenic processes involving various plant pathogens. However, proteome changes and modifications of signaling and oxidative network of plants in response to OA are not well understood. In order to investigate the responses of Brassica napus toward OA, a proteome analysis was conducted employing 2-DE with MS/MS. A total of 37 proteins were identified as responding to OA stress, of which 13 were up-regulated and 24 were down-regulated. These proteins were categorized into several functional groups including protein processing, RNA processing, photosynthesis, signal transduction, stress response, and redox homeostasis. Investigation of the effect of OA on phytohormone signaling and oxidative responses revealed that jasmonic acid-, ethylene-, and abscisic acid-mediated signaling pathways appear to increase at later time points, whereas those pathways mediated by salicylic acid appear to be suppressed. Moreover, the activities of the antioxidant enzymes catalase, peroxidase, superoxide dismutase and oxalic acid oxidase, but not NADPH oxidase, were suppressed by OA stress. Our findings are discussed within the context of the proposed role(s) of OA during infection by Sclerotinia sclerotiorum and subsequent disease progression. PMID:19526549

  17. Oxalic Acid Has an Additional, Detoxifying Function in Sclerotinia sclerotiorum Pathogenesis

    PubMed Central

    Heller, Annerose; Witt-Geiges, Tanja

    2013-01-01

    The mechanism of the diseases caused by the necrotroph plant pathogen Sclerotinia sclerotiorum is not well understood. To investigate the role of oxalic acid during infection high resolution, light-, scanning-, transmission electron microscopy and various histochemical staining methods were used. Our inoculation method allowed us to follow degradation of host plant tissue around single hyphae and to observe the reaction of host cells in direct contact with single invading hyphae. After penetration the outer epidermal cell wall matrix appeared degraded around subcuticular hyphae (12-24 hpi). Calcium oxalate crystals were detected in advanced (36-48 hpi) and late (72 hpi) infection stages, but not in early stages. In early infection stages, surprisingly, no toxic effect of oxalic acid eventually secreted by S. sclerotiorum was observed. As oxalic acid is a common metabolite in plants, we propose that attacked host cells are able to metabolize oxalic acid in the early infection stage and translocate it to their vacuoles where it is stored as calcium oxalate. The effects, observed on healthy tissue upon external application of oxalic acid to non-infected, living tissue and cell wall degradation of dead host cells starting at the inner side of the walls support this idea. The results indicate that oxalic acid concentrations in the early stage of infection stay below the toxic level. In plant and fungi oxalic acid/calcium oxalate plays an important role in calcium regulation. Oxalic acid likely could quench calcium ions released during cell wall breakdown to protect growing hyphae from toxic calcium concentrations in the infection area. As calcium antimonate-precipitates were found in vesicles of young hyphae, we propose that calcium is translocated to the older parts of hyphae and detoxified by building non-toxic, stable oxalate crystals. We propose an infection model where oxalic acid plays a detoxifying role in late infection stages. PMID:23951305

  18. On the source of organic acid aerosol layers above clouds.

    PubMed

    Sorooshian, Armin; Lu, Miao-Ling; Brechtel, Fred J; Jonsson, Haflidi; Feingold, Graham; Flagan, Richard C; Seinfeld, John H

    2007-07-01

    During the July 2005 Marine Stratus/Stratocumulus Experiment (MASE) and the August-September 2006 Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS), the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter probed aerosols and cumulus clouds in the eastern Pacific Ocean off the coast of northern California and in southeastern Texas, respectively. An on-board particle-into-liquid sampler (PILS) quantified inorganic and organic acid species with < or = 5-min time resolution. Ubiquitous organic aerosol layers above cloud with enhanced organic acid levels were observed in both locations. The data suggest that aqueous-phase reactions to produce organic acids, mainly oxalic acid, followed by droplet evaporation is a source of elevated organic acid aerosol levels above cloud. Oxalic acid is observed to be produced more efficiently relative to sulfate as the cloud liquid water content increases, corresponding to larger and less acidic droplets. As derived from large eddy simulations of stratocumulus underthe conditions of MASE, both Lagrangian trajectory analysis and diurnal cloudtop evolution provide evidence that a significant fraction of the aerosol mass concentration above cloud can be accounted for by evaporated droplet residual particles. Methanesulfonate data suggest that entrainment of free tropospheric aerosol can also be a source of organic acids above boundary layer clouds.

  19. The oxalic acid biosynthetic activity of Burkholderia mallei is encoded by a single locus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although it is known that oxalic acid provides a selective advantage to the secreting microbe, our understanding of how this acid is biosynthesized remains incomplete. This study reports the identification, cloning, and partial characterization of the oxalic acid biosynthetic enzyme from the animal ...

  20. Effect of oxalic acid on Nosema ceranae infection.

    PubMed

    Nanetti, Antonio; Rodriguez-García, Cristina; Meana, Aránzazu; Martín-Hernández, Raquel; Higes, Mariano

    2015-10-01

    Nosema ceranae is a honey bee pathogen parasitizing the ventricular epithelium and potentially causing colony death. The effect of 0.25 M oxalic acid solution administered to the bees in the form of sugar syrup was determined in laboratory and field trials. The spore numbers in an 8-day laboratory experiment were significantly lower when AO was administered (treated: 11.86 ± 0.94 s.e. × 10^6; untreated: 30.64 ± 0.31 s.e.x10^6). When administered in autumn to free flying colonies twice, 3 weeks apart, the infection prevalence decreased in young (relative reduction of 53.8% ± 6.5 s.e.) and old bees (relative reduction of 44.4% ± 6.0 s.e.). Meanwhile increased prevalence in all the controls was detected (young and old bees: relative increase of 45.7% ± 22.8 s.e. and 10.2% ± 5.9 s.e., respectively). While all the treated colonies overwintered correctly, the untreated ones did not (3 out of 5 were dead). In the absence of commercial products approved in several countries to control nosemosis, oxalic acid syrup appears promising in the development of alternative management strategies.

  1. Effect of oxalic acid on Nosema ceranae infection.

    PubMed

    Nanetti, Antonio; Rodriguez-García, Cristina; Meana, Aránzazu; Martín-Hernández, Raquel; Higes, Mariano

    2015-10-01

    Nosema ceranae is a honey bee pathogen parasitizing the ventricular epithelium and potentially causing colony death. The effect of 0.25 M oxalic acid solution administered to the bees in the form of sugar syrup was determined in laboratory and field trials. The spore numbers in an 8-day laboratory experiment were significantly lower when AO was administered (treated: 11.86 ± 0.94 s.e. × 10^6; untreated: 30.64 ± 0.31 s.e.x10^6). When administered in autumn to free flying colonies twice, 3 weeks apart, the infection prevalence decreased in young (relative reduction of 53.8% ± 6.5 s.e.) and old bees (relative reduction of 44.4% ± 6.0 s.e.). Meanwhile increased prevalence in all the controls was detected (young and old bees: relative increase of 45.7% ± 22.8 s.e. and 10.2% ± 5.9 s.e., respectively). While all the treated colonies overwintered correctly, the untreated ones did not (3 out of 5 were dead). In the absence of commercial products approved in several countries to control nosemosis, oxalic acid syrup appears promising in the development of alternative management strategies. PMID:26412538

  2. Pseudomonas fluorescens ATCC 13525 Containing an Artificial Oxalate Operon and Vitreoscilla Hemoglobin Secretes Oxalic Acid and Solubilizes Rock Phosphate in Acidic Alfisols

    PubMed Central

    Archana, G.; Naresh Kumar, G.

    2014-01-01

    Oxalate secretion was achieved in Pseudomonas fluorescens ATCC 13525 by incorporation of genes encoding Aspergillus niger oxaloacetate acetyl hydrolase (oah), Fomitopsis plaustris oxalate transporter (FpOAR) and Vitreoscilla hemoglobin (vgb) in various combinations. Pf (pKCN2) transformant containing oah alone accumulated 19 mM oxalic acid intracellularly but secreted 1.2 mM. However, in the presence of an artificial oxalate operon containing oah and FpOAR genes in plasmid pKCN4, Pf (pKCN4) secreted 13.6 mM oxalate in the medium while 3.6 mM remained inside. This transformant solubilized 509 μM of phosphorus from rock phosphate in alfisol which is 4.5 fold higher than the Pf (pKCN2) transformant. Genomic integrants of P. fluorescens (Pf int1 and Pf int2) containing artificial oxalate operon (plac-FpOAR-oah) and artificial oxalate gene cluster (plac-FpOAR-oah, vgb, egfp) secreted 4.8 mM and 5.4 mM oxalic acid, released 329 μM and 351 μM P, respectively, in alfisol. The integrants showed enhanced root colonization, improved growth and increased P content of Vigna radiata plants. This study demonstrates oxalic acid secretion in P. fluorescens by incorporation of an artificial operon constituted of genes for oxalate synthesis and transport, which imparts mineral phosphate solubilizing ability to the organism leading to enhanced growth and P content of V. radiata in alfisol soil. PMID:24705024

  3. Synthesis of Oxalic Acid by Enzymes from Lettuce Leaves

    PubMed Central

    Davies, David D.; Asker, Hassan

    1983-01-01

    A rapid purification of lactate dehydrogenase and glycolate oxidase from lettuce (Lactuca sativa) leaves is described. The kinetics of both enzymes are reported in relation to their possible roles in the production of oxalate. Lettuce lactate dehydrogenase behaves like mammalian dehydrogenase, catalyzing the dismutation of glyoxylate to glycolate and oxalate. A model is proposed in which glycolate oxidase in the peroxisomes and lactate dehydrogenase in the cytosol are involved in the production of oxalate. The effect of pH on the balance between oxalate and glycolate produced from glyoxylate suggests that in leaves lactate dehydrogenase may function as part of an oxalate-based biochemical, pH-stat. PMID:16662946

  4. Oxalic acid biosynthesis is encoded by an operon in Burkholderia glumae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although the biosynthesis of oxalic acid is known to occur in a number of bacteria, the mechanism(s) regulating its production remains largely unknown. To date, there is no report on the identification of an oxalic acid biosynthetic pathway gene from bacteria. In an attempt to identify such a gene...

  5. Effect of oxalic acid treatment on sediment arsenic concentrations and lability under reducing conditions.

    PubMed

    Sun, Jing; Bostick, Benjamin C; Mailloux, Brian J; Ross, James M; Chillrud, Steven N

    2016-07-01

    Oxalic acid enhances arsenic (As) mobilization by dissolving As host minerals and competing for sorption sites. Oxalic acid amendments thus could potentially improve the efficiency of widely used pump-and-treat (P&T) remediation. This study investigates the effectiveness of oxalic acid on As mobilization from contaminated sediments with different As input sources and redox conditions, and examines whether residual sediment As after oxalic acid treatment can still be reductively mobilized. Batch extraction, column, and microcosm experiments were performed in the laboratory using sediments from the Dover Municipal Landfill and the Vineland Chemical Company Superfund sites. Oxalic acid mobilized As from both Dover and Vineland sediments, although the efficiency rates were different. The residual As in both Dover and Vineland sediments after oxalic acid treatment was less vulnerable to microbial reduction than before the treatment. Oxalic acid could thus improve the efficiency of P&T. X-ray absorption spectroscopy analysis indicated that the Vineland sediment samples still contained reactive Fe(III) minerals after oxalic acid treatment, and thus released more As into solution under reducing conditions than the treated Dover samples. Therefore, the efficacy of enhanced P&T must consider sediment Fe mineralogy when evaluating its overall potential for remediating groundwater As.

  6. High abundances of oxalic, azelaic, and glyoxylic acids and methylglyoxal in the open ocean with high biological activity: Implication for secondary OA formation from isoprene

    NASA Astrophysics Data System (ADS)

    Bikkina, Srinivas; Kawamura, Kimitaka; Miyazaki, Yuzo; Fu, Pingqing

    2014-05-01

    Atmospheric dicarboxylic acids (DCA) are a ubiquitous water-soluble component of secondary organic aerosols (SOA), which can act as cloud condensation nuclei (CCN), affecting the Earth's climate. Despite the high abundances of oxalic acid and related compounds in the marine aerosols, there is no consensus on what controls their distributions over the open ocean. Marine biological productivity could play a role in the production of DCA, but there is no substantial evidence to support this hypothesis. Here we present latitudinal distributions of DCA, oxoacids and α-dicarbonyls in the marine aerosols from the remote Pacific. Their concentrations were found several times higher in more biologically influenced aerosols (MBA) than less biologically influenced aerosols. We propose isoprene and unsaturated fatty acids as sources of DCA as inferred from significantly higher abundances of isoprene-SOA tracers and azelaic acid in MBA. These results have implications toward the reassessment of climate forcing feedbacks of marine-derived SOA.

  7. EFFECTIVENESS OF USING DILUTE OXALIC ACID TO DISSOLVEHIGH LEVEL WASTE IRON BASED SLUDGE SIMULANT

    SciTech Connect

    Ketusky, E

    2008-07-11

    At the Savannah River Site (SRS), near Aiken South Carolina, there is a crucial need to remove residual quantities of highly radioactive iron-based sludge from large select underground storage tanks (e.g., 19,000 liters of sludge per tank), in order to support tank closure. The use of oxalic acid is planned to dissolve the residual sludge, hence, helping in the removal. Based on rigorous testing, primarily using 4 and 8 wt% oxalic acid solutions, it was concluded that the more concentrated the acid, the greater the amount of residual sludge that would be dissolved; hence, a baseline technology on using 8 wt% oxalic acid was developed. In stark contrast to the baseline technology, reports from other industries suggest that the dissolution will most effectively occur at 1 wt% oxalic acid (i.e., maintaining the pH near 2). The driver for using less oxalic acid is that less (i.e., moles) would decrease the severity of the downstream impacts (i.e., required oxalate solids removal efforts). To determine the initial feasibility of using 1 wt% acid to dissolve > 90% of the sludge solids, about 19,000 liters of representative sludge was modeled using about 530,000 liters of 0 to 8 wt% oxalic acid solutions. With the chemical thermodynamic equilibrium based software results showing that 1 wt% oxalic acid could theoretically work, simulant dissolution testing was initiated. For the dissolution testing, existing simulant was obtained, and an approximate 20 liter test rig was built. Multiple batch dissolutions of both wet and air-dried simulant were performed. Overall, the testing showed that dilute oxalic acid dissolved a greater fraction of the stimulant and resulted in a significantly larger acid effectiveness (i.e., grams of sludge dissolved/mole of acid) than the baseline technology. With the potential effectiveness confirmed via simulant testing, additional testing, including radioactive sludge testing, is planned.

  8. Availability to rats of iron from spinach: Effects of oxalic acid.

    PubMed

    Van Campen, D R; Welch, R M

    1980-08-01

    The availability to rats of iron from two varieties of spinach was determined. Also, the absorption of Fe was compared between FeCl3 and Fe-oxalate and the effects of adding 0.75% oxalate to the diet were determined. Absorption of iron from both varieties of spinach was comparable to that from FeCl3 and the iron was equally available from Fe-oxalate and FeCl3. The addition of 0.75% oxalic acid to the diet did not depress iron absorption and, if anything, appeared to enhance iron utilization by rats.

  9. Determination of trace amount of oxalic acid with zirconium(IV)-(DBS-arsenazo) by spectrophotometry

    NASA Astrophysics Data System (ADS)

    Zhai, Qing-Zhou

    2008-11-01

    A novel method is proposed for the determination of trace amount of oxalic acid in the present article. In 1.0 M hydrochloric acid medium, oxalic acid can react with the zirconium(IV) in Zr(IV)-(DBS-arsenazo) complex and replaces the DBS-arsenazo to produce a hyperchromic effect at 520 nm. The hyperchromic degree is proportional to the concentration of the oxalic acid added over a defined range. Based on this property, a new method for the spectrophotometric determination of trace oxalic acid was developed. Beer's law is held over the concentration range of 9.0 × 10 -6 to 5.0 × 10 -4 M for oxalic acid with a correlation coefficient of 0.9995. The apparent molar absorptivity of the method is ɛ520 nm = 1.16 × 10 3 L mol -1 cm -1 and the detection limit for oxalic acid is 0.815 μg/mL. The developed method was directly applied to the determination of oxalic acid in tomato samples with satisfactory results.

  10. [Catalytic ozonation by ceramic honeycomb for the degradation of oxalic acid in aqueous solution].

    PubMed

    Zhao, Lei; Sun, Zhi-Zhong; Ma, Jun

    2007-11-01

    Comparative experiments for the degradation of oxalic acid in aqueous solution were carried out in the three processes of ozonation alone, ceramic honeycomb-catalyzed ozonation and ceramic honeycomb adsorption. The results show that the degradation rates of oxalic acid in the ceramic honeycomb-catalyzed ozonation, ozonation alone and ceramic honeycomb adsorption systems are 37.6%, 2.2% and 0.4%, and the presence of ceramic honeycomb catalyst significantly improves the degradation rate of oxalic acid compared to the results from non-catalytic ozonation and adsorption. With the addition of tert-butanol, the degradation rates of oxalic acid in catalytic ozonation system decrease by 24.1%, 29.0% and 30.1%, respectively, at the concentration of 5, 10 and 15 mg x L(-1). This phenomenon indicates that ceramic honeycomb-catalyzed ozonation for the degradation of oxalic acid in aqueous solution follows the mechanism of *OH oxidation, namely the heterogeneous surface of catalyst enhances the initiation of *OH. The results of TOC analysis demonstrate that the process of ceramic honeycomb-catalyzed ozonation can achieve the complete mineralization level without the formation of intermediary degradation products. The experimental results suggest that the reaction temperature has positive relationship with the degradation rate of oxalic acid. The degradation rates of oxalic acid in the ceramic honeycomb-catalyzed ozonation system are 16.4%, 37.6%, 61.3% and 68.2%, at the respective reaction temperature of 10, 20, 30 and 40 degrees C.

  11. Enhanced Nitrogen Availability in Karst Ecosystems by Oxalic Acid Release in the Rhizosphere.

    PubMed

    Pan, Fujing; Liang, Yueming; Zhang, Wei; Zhao, Jie; Wang, Kelin

    2016-01-01

    In karst ecosystems, a high level of CaCO3 enhances the stabilization of soil organic matter (SOM) and causes nitrogen (N) and/or phosphorus (P) limitation in plants. Oxalic acid has been suggested to be involved in the nutrient-acquisition strategy of plants because its addition can temporarily relieve nutrient limitation. Therefore, understanding how oxalic acid drives N availability may help support successful vegetation restoration in the karst ecosystems of southwest China. We tested a model suggested by Clarholm et al. (2015) where oxalate reacts with Ca bridges in SOM, thus exposing previously protected areas to enzymatic attacks in a way that releases N for local uptake. We studied the effects of oxalic acid, microbial biomass carbon (MBC), and β-1,4-N-acetylglucosaminidase (NAG) on potential N mineralization rates in rhizosphere soils of four plant species (two shrubs and two trees) in karst areas. The results showed that rhizosphere soils of shrubs grown on formerly deforested land had significantly lower oxalic acid concentrations and NAG activity than that of trees in a 200-year-old forest. The levels of MBC in rhizosphere soils of shrubs were significantly lower than those of trees in the growing season, but the measure of shrubs and trees were similar in the non-growing season; the potential N mineralization rates showed a reverse pattern. Positive relationships were found among oxalic acid, MBC, NAG activity, and potential N mineralization rates for both shrubs and trees. This indicated that oxalic acid, microbes, and NAG may enhance N availability for acquisition by plants. Path analysis showed that oxalic acid enhanced potential N mineralization rates indirectly through inducing microbes and NAG activities. We found that the exudation of oxalic acid clearly provides an important mechanism that allows plants to enhance nutrient acquisition in karst ecosystems.

  12. Enhanced Nitrogen Availability in Karst Ecosystems by Oxalic Acid Release in the Rhizosphere

    PubMed Central

    Pan, Fujing; Liang, Yueming; Zhang, Wei; Zhao, Jie; Wang, Kelin

    2016-01-01

    In karst ecosystems, a high level of CaCO3 enhances the stabilization of soil organic matter (SOM) and causes nitrogen (N) and/or phosphorus (P) limitation in plants. Oxalic acid has been suggested to be involved in the nutrient-acquisition strategy of plants because its addition can temporarily relieve nutrient limitation. Therefore, understanding how oxalic acid drives N availability may help support successful vegetation restoration in the karst ecosystems of southwest China. We tested a model suggested by Clarholm et al. (2015) where oxalate reacts with Ca bridges in SOM, thus exposing previously protected areas to enzymatic attacks in a way that releases N for local uptake. We studied the effects of oxalic acid, microbial biomass carbon (MBC), and β-1,4-N-acetylglucosaminidase (NAG) on potential N mineralization rates in rhizosphere soils of four plant species (two shrubs and two trees) in karst areas. The results showed that rhizosphere soils of shrubs grown on formerly deforested land had significantly lower oxalic acid concentrations and NAG activity than that of trees in a 200-year-old forest. The levels of MBC in rhizosphere soils of shrubs were significantly lower than those of trees in the growing season, but the measure of shrubs and trees were similar in the non-growing season; the potential N mineralization rates showed a reverse pattern. Positive relationships were found among oxalic acid, MBC, NAG activity, and potential N mineralization rates for both shrubs and trees. This indicated that oxalic acid, microbes, and NAG may enhance N availability for acquisition by plants. Path analysis showed that oxalic acid enhanced potential N mineralization rates indirectly through inducing microbes and NAG activities. We found that the exudation of oxalic acid clearly provides an important mechanism that allows plants to enhance nutrient acquisition in karst ecosystems. PMID:27252713

  13. Enhanced Nitrogen Availability in Karst Ecosystems by Oxalic Acid Release in the Rhizosphere.

    PubMed

    Pan, Fujing; Liang, Yueming; Zhang, Wei; Zhao, Jie; Wang, Kelin

    2016-01-01

    In karst ecosystems, a high level of CaCO3 enhances the stabilization of soil organic matter (SOM) and causes nitrogen (N) and/or phosphorus (P) limitation in plants. Oxalic acid has been suggested to be involved in the nutrient-acquisition strategy of plants because its addition can temporarily relieve nutrient limitation. Therefore, understanding how oxalic acid drives N availability may help support successful vegetation restoration in the karst ecosystems of southwest China. We tested a model suggested by Clarholm et al. (2015) where oxalate reacts with Ca bridges in SOM, thus exposing previously protected areas to enzymatic attacks in a way that releases N for local uptake. We studied the effects of oxalic acid, microbial biomass carbon (MBC), and β-1,4-N-acetylglucosaminidase (NAG) on potential N mineralization rates in rhizosphere soils of four plant species (two shrubs and two trees) in karst areas. The results showed that rhizosphere soils of shrubs grown on formerly deforested land had significantly lower oxalic acid concentrations and NAG activity than that of trees in a 200-year-old forest. The levels of MBC in rhizosphere soils of shrubs were significantly lower than those of trees in the growing season, but the measure of shrubs and trees were similar in the non-growing season; the potential N mineralization rates showed a reverse pattern. Positive relationships were found among oxalic acid, MBC, NAG activity, and potential N mineralization rates for both shrubs and trees. This indicated that oxalic acid, microbes, and NAG may enhance N availability for acquisition by plants. Path analysis showed that oxalic acid enhanced potential N mineralization rates indirectly through inducing microbes and NAG activities. We found that the exudation of oxalic acid clearly provides an important mechanism that allows plants to enhance nutrient acquisition in karst ecosystems. PMID:27252713

  14. The influence of dicarboxylic acids: Oxalic acid and tartaric acid on the compressive strength of glass ionomer cements

    NASA Astrophysics Data System (ADS)

    Permana, Ahmadi Jaya; Setyawati, Harsasi; Hamami, Murwani, Irmina Kris

    2016-03-01

    Glass ionomer cement (GIC) has limitation on the mechanical properties especially compressive strength. The change of compressive strength of GIC by adding oxalic acid and tartaric acid has been investigated. Oxalic acid and tartaric acid was added to the liquid components at concentrations of 0 - 15% (w/w). Powder component of GIC was made from optimum experimental powder glass SiO2-Al2O3-CaF2. GIC was characterized by compressive strength test, SEM-EDX and FTIR. The addition of tartaric acid to GIC has greater improvement than addition of oxalic acid. The addition of tartaric acid at 10 % (w/w) to GIC has greatest value of compressive strength.

  15. Acute renal failure and metabolic acidosis due to oxalic acid intoxication: a case report.

    PubMed

    Yamamoto, Rie; Morita, Seiji; Aoki, Hiromichi; Nakagawa, Yoshihide; Yamamoto, Isotoshi; Inokuchi, Sadaki

    2011-12-01

    Most of the reports of oxalic acid intoxication are in cases of ethylene glycol intoxication. These symptoms are known to be central nerve system manifestations, cardiopulmonary manifestations and acute renal failure. There have been only a few reports of direct oxalic acid intoxication. However, there have been a few recent reports of oxalic acid intoxication due to the ingestion of star fruit and ascorbic acid. We herein report the case of a patient with acute renal failure and metabolic acidosis caused directly by consumption of oxalic acid. During the initial examination by the physician at our hospital, the patient presented with tachypnea, a precordinal burning sensation, nausea and metabolic acidosis. After admission, the patient developed renal failure and anion gap high metabolic acidosis, but did not develop any CNS or cardio-pulmonary manifestations in the clinical course. The patient benefitted symptomatically from hemodialysis.

  16. Role of Oxalic Acid Overexcretion in Transformations of Toxic Metal Minerals by Beauveria caledonica

    PubMed Central

    Fomina, M.; Hillier, S.; Charnock, J. M.; Melville, K.; Alexander, I. J.; Gadd, G. M.

    2005-01-01

    The fungus Beauveria caledonica was highly tolerant to toxic metals and solubilized cadmium, copper, lead, and zinc minerals, converting them into oxalates. This fungus was found to overexcrete organic acids with strong metal-chelating properties (oxalic and citric acids), suggesting that a ligand-promoted mechanism was the main mechanism of mineral dissolution. Our data also suggested that oxalic acid was the main mineral-transforming agent. Cadmium, copper, and zinc oxalates were precipitated by the fungus in the local environment and also in association with the mycelium. The presence of toxic metal minerals often led to the formation of mycelial cords, and in the presence of copper-containing minerals, these cords exhibited enhanced excretion of oxalic acid, which resulted in considerable encrustation of the cords by copper oxalate hydrate (moolooite). It was found that B. caledonica hyphae and cords were covered by a thick hydrated mucilaginous sheath which provided a microenvironment for chemical reactions, crystal deposition, and growth. Cryo-scanning electron microscopy revealed that mycogenic metal oxalates overgrew parental fungal hyphae, leaving a labyrinth of fungal tunnels within the newly formed mineral matter. X-ray absorption spectroscopy revealed that oxygen ligands played a major role in metal coordination within the fungal biomass during the accumulation of mobilized toxic metals by B. caledonica mycelium; these ligands were carboxylic groups in copper phosphate-containing medium and phosphate groups in pyromorphite-containing medium. PMID:15640211

  17. Production of citric and oxalic acids and solubilization of calcium phosphate by Penicillium bilaii.

    PubMed Central

    Cunningham, J E; Kuiack, C

    1992-01-01

    An isolate of Penicillium bilaii previously reported to solubilize mineral phosphates and enhance plant uptake of phosphate was studied. Using agar media with calcium phosphate and the pH indicator alizarin red S, the influence of the medium composition on phosphate solubility and medium acidification was recorded. The major acidic metabolites produced by P. bilaii in a sucrose nitrate liquid medium were found to be oxalic acid and citric acid. Citric acid production was promoted under nitrogen-limited conditions, while oxalic acid production was promoted under carbon-limited conditions. Citric acid was produced in both growth and stationary phases, but oxalic acid production occurred only in stationary phase. When submerged cultures which normally produce acid were induced to sporulate, the culture medium shifted toward alkaline rather than acid reaction with growth. PMID:1622211

  18. Study on Dicarboxylic Acids in Aerosol Samples with Capillary Electrophoresis

    PubMed Central

    Adler, Heidi; Sirén, Heli

    2014-01-01

    The research was performed to study the simultaneous detection of a homologous series of α, ω-dicarboxylic acids (C2–C10), oxalic, malonic, succinic, glutaric, adipic, pimelic, suberic, azelaic, and sebacic acids, with capillary electrophoresis using indirect UV detection. Good separation efficiency in 2,6-pyridinedicarboxylic acid as background electrolyte modified with myristyl trimethyl ammonium bromide was obtained. The dicarboxylic acids were ionised and separated within five minutes. For the study, authentic samples were collected onto dry cellulose membrane filters of a cascade impactor (12 stages) from outdoor spring aerosols in an urban area. Hot water and ultrasonication extraction methods were used to isolate the acids from membrane filters. Due to the low concentrations of acids in the aerosols, the extracts were concentrated with solid-phase extraction (SPE) before determination. The enrichment of the carboxylic acids was between 86 and 134% with sample pretreatment followed by 100-time increase by preparation of the sample to 50 μL. Inaccuracy was optimised for all the sample processing steps. The aerosols contained dicarboxylic acids C2–C10. Then, mostly they contained C2, C5, and C10. Only one sample contained succinic acid. In the study, the concentrations of the acids in aerosols were lower than 10 ng/m3. PMID:24729915

  19. Determination of water-soluble forms of oxalic and formic acids in soils by ion chromatography

    NASA Astrophysics Data System (ADS)

    Karicheva, E.; Guseva, N.; Kambalina, M.

    2016-03-01

    Carboxylic acids (CA) play an important role in the chemical composition origin of soils and migration of elements. The content of these acids and their salts is one of the important characteristics for agrochemical, ecological, ameliorative and hygienic assessment of soils. The aim of the article is to determine water-soluble forms of same carboxylic acids — (oxalic and formic acids) in soils by ion chromatography with gradient elution. For the separation and determination of water-soluble carboxylic acids we used reagent-free gradient elution ion-exchange chromatography ICS-2000 (Dionex, USA), the model solutions of oxalate and formate ions, and leachates from soils of the Kola Peninsula. The optimal gradient program was established for separation and detection of oxalate and formate ions in water solutions by ion chromatography. A stability indicating method was developed for the simultaneous determination of water-soluble organic acids in soils. The method has shown high detection limits such as 0.03 mg/L for oxalate ion and 0.02 mg/L for formate ion. High signal reproducibility was achieved in wide range of intensities which correspond to the following ion concentrations: from 0.04 mg/g to 10 mg/L (formate), from 0.1 mg/g to 25 mg/L (oxalate). The concentration of formate and oxalate ions in soil samples is from 0.04 to 0.9 mg/L and 0.45 to 17 mg/L respectively.

  20. Acetate induced enhancement of photocatalytic hydrogen peroxide production from oxalic acid and dioxygen.

    PubMed

    Yamada, Yusuke; Nomura, Akifumi; Miyahigashi, Takamitsu; Ohkubo, Kei; Fukuzumi, Shunichi

    2013-05-01

    The addition of acetate ion to an O2-saturated mixed solution of acetonitrile and water containing oxalic acid as a reductant and 2-phenyl-4-(1-naphthyl)quinolinium ion (QuPh(+)-NA) as a photocatalyst dramatically enhanced the turnover number of hydrogen peroxide (H2O2) production. In this photocatalytic H2O2 production, a base is required to facilitate deprotonation of oxalic acid forming oxalate dianion, which acts as an actual electron donor, whereas a Brønsted acid is also necessary to protonate O2(•-) for production of H2O2 by disproportionation. The addition of acetate ion to a reaction solution facilitates both the deprotonation of oxalic acid and the protonation of O2(•-) owing to a pH buffer effect. The quantum yield of the photocatalytic H2O2 production under photoirradiation (λ = 334 nm) of an O2-saturated acetonitrile-water mixed solution containing acetate ion, oxalic acid and QuPh(+)-NA was determined to be as high as 0.34, which is more than double the quantum yield obtained by using oxalate salt as an electron donor without acetate ion (0.14). In addition, the turnover number of QuPh(+)-NA reached more than 340. The reaction mechanism and the effect of solvent composition on the photocatalytic H2O2 production were scrutinized by using nanosecond laser flash photolysis.

  1. REMOVING SLUDGE HEELS FROM SAVANNAH RIVER SITE WASTE TANKS BY OXALIC ACID DISSOLUTION

    SciTech Connect

    Poirier, M; David Herman, D; Fernando Fondeur, F; John Pareizs, J; Michael Hay, M; Bruce Wiersma, B; Kim Crapse, K; Thomas Peters, T; Samuel Fink, S; Donald Thaxton, D

    2009-03-01

    The Savannah River Site (SRS) will remove sludge as part of waste tank closure operations. Typically the bulk sludge is removed by mixing it with supernate to produce a slurry, and transporting the slurry to a downstream tank for processing. Experience shows that a residual heel may remain in the tank that cannot be removed by this conventional technique. In the past, SRS used oxalic acid solutions to disperse or dissolve the sludge heel to complete the waste removal. To better understand the actual conditions of oxalic acid cleaning of waste from carbon steel tanks, the authors developed and conducted an experimental program to determine its effectiveness in dissolving sludge, the hydrogen generation rate, the generation rate of other gases, the carbon steel corrosion rate, the impact of mixing on chemical cleaning, the impact of temperature, and the types of precipitates formed during the neutralization process. The test samples included actual SRS sludge and simulated SRS sludge. The authors performed the simulated waste tests at 25, 50, and 75 C by adding 8 wt % oxalic acid to the sludge over seven days. They conducted the actual waste tests at 50 and 75 C by adding 8 wt % oxalic acid to the sludge as a single batch. Following the testing, SRS conducted chemical cleaning with oxalic acid in two waste tanks. In Tank 5F, the oxalic acid (8 wt %) addition occurred over seven days, followed by inhibited water to ensure the tank contained enough liquid to operate the mixer pumps. The tank temperature during oxalic acid addition and dissolution was approximately 45 C. The authors analyzed samples from the chemical cleaning process and compared it with test data. The conclusions from the work are: (1) Oxalic acid addition proved effective in dissolving sludge heels in the simulant demonstration, the actual waste demonstration, and in SRS Tank 5F. (2) The oxalic acid dissolved {approx} 100% of the uranium, {approx} 100% of the iron, and {approx} 40% of the manganese

  2. Biological Control of Meloidogyne incognita by Aspergillus niger F22 Producing Oxalic Acid.

    PubMed

    Jang, Ja Yeong; Choi, Yong Ho; Shin, Teak Soo; Kim, Tae Hoon; Shin, Kee-Sun; Park, Hae Woong; Kim, Young Ho; Kim, Hun; Choi, Gyung Ja; Jang, Kyoung Soo; Cha, Byeongjin; Kim, In Seon; Myung, Eul Jae; Kim, Jin-Cheol

    2016-01-01

    Restricted usage of chemical nematicides has led to development of environmentally safe alternatives. A culture filtrate of Aspergillus niger F22 was highly active against Meloidogyne incognita with marked mortality of second-stage juveniles (J2s) and inhibition of egg hatching. The nematicidal component was identified as oxalic acid by organic acid analysis and gas chromatography-mass spectroscopy (GC-MS). Exposure to 2 mmol/L oxalic acid resulted in 100% juvenile mortality at 1 day after treatment and suppressed egg hatching by 95.6% at 7 days after treatment. Oxalic acid showed similar nematicidal activity against M. hapla, but was not highly toxic to Bursaphelenchus xylophilus. The fungus was incubated on solid medium and dried culture was used for preparation of a wettable powder-type (WP) formulation as an active ingredient. Two WP formulations, F22-WP10 (ai 10%) and oxalic acid-WP8 (ai 8%), were prepared using F22 solid culture and oxalic acid. In a field naturally infested with M. incognita, application of a mixture of F22-WP10 + oxalic acid-WP8 at 1,000- and 500-fold dilutions significantly reduced gall formation on the roots of watermelon plants by 58.8 and 70.7%, respectively, compared to the non-treated control. The disease control efficacy of the mixture of F22-WP10 + oxalic acid-WP8 was significantly higher than that of a chemical nematicide, Sunchungtan (ai 30% fosthiazate). These results suggest that A. niger F22 can be used as a microbial nematicide for the control of root-knot nematode disease. PMID:27258452

  3. Biological Control of Meloidogyne incognita by Aspergillus niger F22 Producing Oxalic Acid

    PubMed Central

    Jang, Ja Yeong; Choi, Yong Ho; Shin, Teak Soo; Kim, Tae Hoon; Shin, Kee-Sun; Park, Hae Woong; Kim, Young Ho; Kim, Hun; Choi, Gyung Ja; Jang, Kyoung Soo; Cha, Byeongjin; Kim, In Seon; Myung, Eul Jae

    2016-01-01

    Restricted usage of chemical nematicides has led to development of environmentally safe alternatives. A culture filtrate of Aspergillus niger F22 was highly active against Meloidogyne incognita with marked mortality of second-stage juveniles (J2s) and inhibition of egg hatching. The nematicidal component was identified as oxalic acid by organic acid analysis and gas chromatography-mass spectroscopy (GC-MS). Exposure to 2 mmol/L oxalic acid resulted in 100% juvenile mortality at 1 day after treatment and suppressed egg hatching by 95.6% at 7 days after treatment. Oxalic acid showed similar nematicidal activity against M. hapla, but was not highly toxic to Bursaphelenchus xylophilus. The fungus was incubated on solid medium and dried culture was used for preparation of a wettable powder-type (WP) formulation as an active ingredient. Two WP formulations, F22-WP10 (ai 10%) and oxalic acid-WP8 (ai 8%), were prepared using F22 solid culture and oxalic acid. In a field naturally infested with M. incognita, application of a mixture of F22-WP10 + oxalic acid-WP8 at 1,000- and 500-fold dilutions significantly reduced gall formation on the roots of watermelon plants by 58.8 and 70.7%, respectively, compared to the non-treated control. The disease control efficacy of the mixture of F22-WP10 + oxalic acid-WP8 was significantly higher than that of a chemical nematicide, Sunchungtan (ai 30% fosthiazate). These results suggest that A. niger F22 can be used as a microbial nematicide for the control of root-knot nematode disease. PMID:27258452

  4. Biological Control of Meloidogyne incognita by Aspergillus niger F22 Producing Oxalic Acid.

    PubMed

    Jang, Ja Yeong; Choi, Yong Ho; Shin, Teak Soo; Kim, Tae Hoon; Shin, Kee-Sun; Park, Hae Woong; Kim, Young Ho; Kim, Hun; Choi, Gyung Ja; Jang, Kyoung Soo; Cha, Byeongjin; Kim, In Seon; Myung, Eul Jae; Kim, Jin-Cheol

    2016-01-01

    Restricted usage of chemical nematicides has led to development of environmentally safe alternatives. A culture filtrate of Aspergillus niger F22 was highly active against Meloidogyne incognita with marked mortality of second-stage juveniles (J2s) and inhibition of egg hatching. The nematicidal component was identified as oxalic acid by organic acid analysis and gas chromatography-mass spectroscopy (GC-MS). Exposure to 2 mmol/L oxalic acid resulted in 100% juvenile mortality at 1 day after treatment and suppressed egg hatching by 95.6% at 7 days after treatment. Oxalic acid showed similar nematicidal activity against M. hapla, but was not highly toxic to Bursaphelenchus xylophilus. The fungus was incubated on solid medium and dried culture was used for preparation of a wettable powder-type (WP) formulation as an active ingredient. Two WP formulations, F22-WP10 (ai 10%) and oxalic acid-WP8 (ai 8%), were prepared using F22 solid culture and oxalic acid. In a field naturally infested with M. incognita, application of a mixture of F22-WP10 + oxalic acid-WP8 at 1,000- and 500-fold dilutions significantly reduced gall formation on the roots of watermelon plants by 58.8 and 70.7%, respectively, compared to the non-treated control. The disease control efficacy of the mixture of F22-WP10 + oxalic acid-WP8 was significantly higher than that of a chemical nematicide, Sunchungtan (ai 30% fosthiazate). These results suggest that A. niger F22 can be used as a microbial nematicide for the control of root-knot nematode disease.

  5. Comparison of sulfuric and oxalic acid anodizing for preparation of thermal control coatings for spacecraft

    NASA Technical Reports Server (NTRS)

    Le, Huong G.; Watcher, John M.; Smith, Charles A.

    1988-01-01

    The development of thermal control surfaces, which maintain stable solar absorptivity and infrared emissivity over long periods, is challenging due to severe conditions in low-Earth orbit (LEO). Some candidate coatings are second-surface silver-coated Teflon; second-surface, silvered optical solar reflectors made of glass or quartz; and anodized aluminum. Sulfuric acid anodized and oxalic acid anodized aluminum was evaluated under simulated LEO conditions. Oxalic acid anodizing shows promise of greater stability in LEO over long missions, such as the 30 years planned for the Space Station. However, sulfuric acid anodizing shows lower solar absorptivity.

  6. Corrosion Behavior of Alloy 22 in Oxalic Acid and Sodium Chloride Solutions

    SciTech Connect

    Day, S D; Whalen, M T; King, K J; Hust, G A; Wong, L L; Estill, J C; Rebak, R B

    2003-06-24

    Nickel based Alloy 22 (NO6022) is extensively used in aggressive industrial applications, especially due to its resistance to localized corrosion and stress corrosion cracking in high chloride environments. The purpose of this work was to characterize the anodic behavior of Alloy 22 in oxalic acid solution and to compare its behavior to sodium chloride (NaCl) solutions. Standard electrochemical tests such as polarization resistance and cyclic polarization were used. Results show that the corrosion rate of Alloy 22 in oxalic acid solutions increased rapidly as the temperature and the acid concentration increased. Extrapolation studies show that even at a concentration of 10{sup -4}M oxalic acid, the corrosion rate of Alloy 22 would be higher in oxalic acid than in 1 M NaCl solution. Alloy 22 was not susceptible to localized corrosion in oxalic acid solutions. Cyclic polarization tests in 1 M NaCl showed that Alloy 22 was susceptible to crevice corrosion at 90 C but was not susceptible at 60 C.

  7. Fungal production of citric and oxalic acid: importance in metal speciation, physiology and biogeochemical processes.

    PubMed

    Gadd, G M

    1999-01-01

    The production of organic acids by fungi has profound implications for metal speciation, physiology and biogeochemical cycles. Biosynthesis of oxalic acid from glucose occurs by hydrolysis of oxaloacetate to oxalate and acetate catalysed by cytosolic oxaloacetase, whereas on citric acid, oxalate production occurs by means of glyoxylate oxidation. Citric acid is an intermediate in the tricarboxylic acid cycle, with metals greatly influencing biosynthesis: growth limiting concentrations of Mn, Fe and Zn are important for high yields. The metal-complexing properties of these organic acids assist both essential metal and anionic (e.g. phosphate) nutrition of fungi, other microbes and plants, and determine metal speciation and mobility in the environment, including transfer between terrestrial and aquatic habitats, biocorrosion and weathering. Metal solubilization processes are also of potential for metal recovery and reclamation from contaminated solid wastes, soils and low-grade ores. Such 'heterotrophic leaching' can occur by several mechanisms but organic acids occupy a central position in the overall process, supplying both protons and a metal-complexing organic acid anion. Most simple metal oxalates [except those of alkali metals, Fe(III) and Al] are sparingly soluble and precipitate as crystalline or amorphous solids. Calcium oxalate is the most important manifestation of this in the environment and, in a variety of crystalline structures, is ubiquitously associated with free-living, plant symbiotic and pathogenic fungi. The main forms are the monohydrate (whewellite) and the dihydrate (weddelite) and their formation is of significance in biomineralization, since they affect nutritional heterogeneity in soil, especially Ca, P, K and Al cycling. The formation of insoluble toxic metal oxalates, e.g. of Cu, may confer tolerance and ensure survival in contaminated environments. In semi-arid environments, calcium oxalate formation is important in the formation and

  8. The effect of oxalic and itaconic acids on threo-Ds-isocitric acid production from rapeseed oil by Yarrowia lipolytica.

    PubMed

    Kamzolova, Svetlana V; Allayarov, Ramil K; Lunina, Julia N; Morgunov, Igor G

    2016-04-01

    The effect of oxalic and itaconic acids, the inhibitors of the isocitrate lyase, on the production of isocitric acid by the wild strain Yarrowia lipolytica VKM Y-2373 grown in the medium containing rapeseed oil was studied. In the presence of oxalic and itaconic acids, strain Y. lipolytica accumulated in the medium isocitric acid (70.0 and 82.7 g/L, respectively) and citric acid (23.0 and 18.4 g/L, respectively). In control experiment, when the inhibitors were not added to the medium, the strain accumulated isocitric and citric acids at concentrations of 62.0 and 28.0 g/L, respectively. Thus, the use of the oxalic and itaconic acids as additives to the medium is a simple and convenient method of isocitric acid production with a minimum content of citric acid.

  9. The adsorption and photo-degradation of oxalic acid at the TiO2 surface.

    NASA Astrophysics Data System (ADS)

    Mendive, Cecilia; Blesa, Miguel; Bahnemann, Detlef

    2006-03-01

    Oxalic acid is the simplest model compound to study the heterogeneous photocatalytic oxidation of pollutants on TiO2 containing more than one carboxylate group. We have carried out a study of a system of an oxalic acid solution in contact with a thin film of TiO2 particles employing ATR - FTIR in combination with quantum chemical calculations. Thus, possible adsorption structures have been identified and molecular dynamic simulations have been used to compare their predictions with the experimental data. It was found that the adsorption of oxalic acid on TiO2 in the dark can be explained in terms of two surface complexation modes for the anatase phase and only one surface complexation mode for the rutile phase. We have found that under illumination one of the complexes on the anatase phase preferably undergoes photo-degradation. At the same time water molecules are desorbed from the TiO2 surface by a thermal mechanism induced by the absorption of photons. Both processes favor the adsorption of more molecules of oxalic acid at the TiO2 surface which is thus enriched in the second complexation mode. A similar mechanism was found to occur on the rutile phase. The only complexation mode appears not to be photo-sensitive but the TiO2 surface is enriched in oxalic acid under illumination due to the replacement of photo-desorbed water molecules.

  10. Dissolution of Simulated and Radioactive Savannah River Site High-Level Waste Sludges with Oxalic Acid & Citric Acid Solutions

    SciTech Connect

    STALLINGS, MARY

    2004-07-08

    This report presents findings from tests investigating the dissolution of simulated and radioactive Savannah River Site sludges with 4 per cent oxalic acid and mixtures of oxalic and citric acid previously recommended by a Russian team from the Khlopin Radium Institute and the Mining and Chemical Combine (MCC). Testing also included characterization of the simulated and radioactive waste sludges. Testing results showed the following: Dissolution of simulated HM and PUREX sludges with oxalic and citric acid mixtures at SRTC confirmed general trends reported previously by Russian testing. Unlike the previous Russian testing six sequential contacts of a mixture of oxalic acid citric acids at a 2:1 ratio (v/w) of acid to sludge did not produce complete dissolution of simulated HM and PUREX sludges. We observed that increased sludge dissolution occurred at a higher acid to sludge ratio, 50:1 (v/w), compared to the recommended ratio of 2:1 (v/w). We observed much lower dissolution of aluminum in a simulated HM sludge by sodium hydroxide leaching. We attribute the low aluminum dissolution in caustic to the high fraction of boehmite present in the simulated sludge. Dissolution of HLW sludges with 4 per cent oxalic acid and oxalic/citric acid followed general trends observed with simulated sludges. The limited testing suggests that a mixture of oxalic and citric acids is more efficient for dissolving HM and PUREX sludges and provides a more homogeneous dissolution of HM sludge than oxalic acid alone. Dissolution of HLW sludges in oxalic and oxalic/citric acid mixtures produced residual sludge solids that measured at higher neutron poison to equivalent 235U weight ratios than that in the untreated sludge solids. This finding suggests that residual solids do not present an increased nuclear criticality safety risk. Generally the neutron poison to equivalent 235U weight ratios of the acid solutions containing dissolved sludge components are lower than those in the untreated

  11. SAVANNAH RIVER SITE TANK CLEANING: CORROSION RATE FOR ONE VERSUS EIGHT PERCENT OXALIC ACID SOLUTION

    SciTech Connect

    Ketusky, E.; Subramanian, K.

    2011-01-20

    Until recently, the use of oxalic acid for chemically cleaning the Savannah River Site (SRS) radioactive waste tanks focused on using concentrated 4 and 8-wt% solutions. Recent testing and research on applicable dissolution mechanisms have concluded that under appropriate conditions, dilute solutions of oxalic acid (i.e., 1-wt%) may be more effective. Based on the need to maximize cleaning effectiveness, coupled with the need to minimize downstream impacts, SRS is now developing plans for using a 1-wt% oxalic acid solution. A technology gap associated with using a 1-wt% oxalic acid solution was a dearth of suitable corrosion data. Assuming oxalic acid's passivation of carbon steel was proportional to the free oxalate concentration, the general corrosion rate (CR) from a 1-wt% solution may not be bound by those from 8-wt%. Therefore, after developing the test strategy and plan, the corrosion testing was performed. Starting with the envisioned process specific baseline solvent, a 1-wt% oxalic acid solution, with sludge (limited to Purex type sludge-simulant for this initial effort) at 75 C and agitated, the corrosion rate (CR) was determined from the measured weight loss of the exposed coupon. Environmental variations tested were: (a) Inclusion of sludge in the test vessel or assuming a pure oxalic acid solution; (b) acid solution temperature maintained at 75 or 45 C; and (c) agitation of the acid solution or stagnant. Application of select electrochemical testing (EC) explored the impact of each variation on the passivation mechanisms and confirmed the CR. The 1-wt% results were then compared to those from the 8-wt%. The immersion coupons showed that the maximum time averaged CR for a 1-wt% solution with sludge was less than 25-mils/yr for all conditions. For an agitated 8-wt% solution with sludge, the maximum time averaged CR was about 30-mils/yr at 50 C, and 86-mils/yr at 75 C. Both the 1-wt% and the 8-wt% testing demonstrated that if the sludge was removed from

  12. Electrochemical Oxidation and Determination of Oxalic Acid at an Exfoliated Graphite-Polystyrene Composite Electrode

    PubMed Central

    Manea, Florica; Radovan, Ciprian; Corb, Ioana; Pop, Aniela; Burtica, Georgeta; Malchev, Plamen; Picken, Stephen; Schoonman, Joop

    2007-01-01

    An exfoliated graphite-polystyrene composite electrode was evaluated as an alternative electrode in the oxidation and the determination of oxalic acid in 0.1 M Na2SO4 supporting electrolyte. Using CV, LSV, CA procedures, linear dependences I vs. C were obtained in the concentrations range of oxalic acid between 0.5 to 3 mM, with LOD =0.05 mM, and recovery degree of 98%, without need of surface renewing between successive runs. The accuracy of the methods was evaluated as excellent comparing the detection results with that obtained using conventional KMnO4 titration method. In addition, the apparent diffusion coefficient of oxalic acid D was found to be around 2.89 · 10-8 cm2·s-1 by CA and CV.

  13. In Situ Investigation of a Self-Accelerated Cocrystal Formation by Grinding Pyrazinamide with Oxalic Acid.

    PubMed

    Kulla, Hannes; Greiser, Sebastian; Benemann, Sigrid; Rademann, Klaus; Emmerling, Franziska

    2016-01-01

    A new cocrystal of pyrazinamide with oxalic acid was prepared mechanochemically and characterized by PXRD, Raman spectroscopy, solid-state NMR spectroscopy, DTA-TG, and SEM. Based on powder X-ray diffraction data the structure was solved. The formation pathway of the reaction was studied in situ using combined synchrotron PXRD and Raman spectroscopy. Using oxalic acid dihydrate the initially neat grinding turned into a rapid self-accelerated liquid-assisted grinding process by the release of crystallization water. Under these conditions, the cocrystal was formed directly within two minutes. PMID:27428942

  14. Fatty acids on continental sulfate aerosol particles

    NASA Astrophysics Data System (ADS)

    Tervahattu, H.; Juhanoja, J.; Vaida, V.; Tuck, A. F.; Niemi, J. V.; Kupiainen, K.; Kulmala, M.; VehkamäKi, H.

    2005-03-01

    Surface analyses of atmospheric aerosols from different continental sources, such as forest fires and coal and straw burning, show that organic surfactants are found on such aerosols. The predominant organic species detected by time-of-flight secondary ion mass spectrometry on the sulfate aerosols are fatty acids of different carbon chain length up to the C32 acid. These observations are consistent with literature accounts of functional group analysis of bulk samples, but this is the first direct evidence of fatty acid films on the surface of sulfate aerosols. Surface analysis leads to the conclusion that fatty acid films on continental aerosols may be more common than has been previously suggested.

  15. A feasibility study on the multistage process for the oxalic acid pretreatment of a lignocellulosic biomass using electrodialysis.

    PubMed

    Lee, Hong-Joo; Ahn, Sung Ju; Seo, Young-Jun; Lee, Jae-Won

    2013-02-01

    The present study investigated the feasibility of the recovery and reuse oxalic acid in a multistage process for the pretreatment of a lignocellulosic biomass. Electrodialysis (ED), an electrochemical process using ion exchange membranes, was used to recover and reuse oxalic acid in the multistage process. The ED optimal condition for recover oxalic acid was potential of 10V and pH 2.2 in synthetic solutions. The recovery efficiency of oxalic acid from hydrolysates reached 100% at potential of 10V. The power consumption to treat 1mol of oxalic acid was estimated to be 41.0wh. At the same time, ethanol production increased up to 19g/L in the ED-treated hydrolysate, corresponding to ethanol productivity of 0.27g/L/h. It was clearly shown that bioethanol fermentation efficiency increased using the ED process, due to a small loss of fermentable sugar and a significantly high removal of inhibitory chemicals. PMID:23306131

  16. Response to oxalic acid as a resistance assay for Sclerotinia minor in peanut

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Response to oxalic acid was evaluated as a potential assay for screening peanut breeding lines for resistance to Sclerotinia blight caused by Sclerotinia minor. Detached stems of seven Spanish- and six runner-type peanut cultivars and advanced breeding lines, varying in resistance to Sclerotinia bl...

  17. [Catalytic ozonation of oxalic acid in water with Pt/graphite catalyst].

    PubMed

    Liu, Zheng-Qian; Ma, Jun; Zhao, Lei

    2007-06-01

    Pt/graphite catalyst was prepared by incipient wetness impregnation using H2PtCl6 x 6H2O as precursor substance. The removal efficiencies of oxalic acid by Pt/graphite, graphite catalyzed ozonation and ozonation alone were compared. It was found that the removal efficiency of oxalic acid in ozonation alone, graphite and Pt/graphite catalyzed ozonation was 3.0%, 47.6% and 99.3% respectively under the present experimental conditions. Results showed that loading of Pt could significantly increase the catalytic activity of graphite. Taking oxalic acid degradation efficiency as indication, the preparation conditions of Pt/graphite were optimized. The pretreatment of graphite had no favor to improve the activity of Pt/graphite catalyst. The optimal preparation conditions of Pt/graphite catalyst are as follow: impregnant, distilled water; impregnation time, 24 h; the loading amount of Pt, 1.0%; reduction temperature, 35 degrees C. The Pt/graphite catalyst was used for five times with no significant decrease of its activity and more than 90% oxalic acid removal was obtained. PMID:17674732

  18. Alleviation of chilling injury in tomato fruit by exogenous application of oxalic acid.

    PubMed

    Li, Peiyan; Yin, Fei; Song, Lijun; Zheng, Xiaolin

    2016-07-01

    The effects of oxalic acid on the development of chilling injury (CI), energy metabolism and lycopene metabolism in tomato fruit (Solanum lycopersicum L.) were investigated. Mature green tomatoes were dipped in 10mmoll(-1) oxalic acid (OA) solution for 10min at 25°C. Tomatoes were subsequently stored at 4±0.5°C for 20days before being transferred to 25°C for 12days. Oxalic acid treatment apparently alleviated CI development and membrane damage; maintained higher levels of ATP and ADP; increased activities of succinic dehydrogenase (SDH), Ca(2+)-adenosine triphosphatase (Ca(2+)-ATPase) and H(+)-adenosine triphosphatase (H(+)-ATPase); and elevated lycopene accumulation associated with the upregulation of PSY1 and ZDS expression in tomatoes during a period at room temperature following exposure to chilling stress. Thus, oxalic acid treatment benefited the control of CI and the maintenance of fruit quality in tomatoes stored for long periods (approximately 32days). PMID:26920276

  19. YfdW and YfdU are required for oxalate-induced acid tolerance in Escherichia coli K-12.

    PubMed

    Fontenot, Elise M; Ezelle, Karen E; Gabreski, Lauren N; Giglio, Eleanor R; McAfee, John M; Mills, Alexandria C; Qureshi, Maryam N; Salmon, Kristin M; Toyota, Cory G

    2013-04-01

    Escherichia coli has several mechanisms for surviving low-pH stress. We report that oxalic acid, a small-chain organic acid (SCOA), induces a moderate acid tolerance response (ATR) in two ways. Adaptation of E. coli K-12 at pH 5.5 with 50 mM oxalate and inclusion of 25 mM oxalate in pH 3.0 minimal challenge medium separately conferred protection, with 67% ± 7% and 87% ± 17% survival after 2 h, respectively. The combination of oxalate adaptation and oxalate supplementation in the challenge medium resulted in increased survival over adaptation or oxalate in the challenge medium alone. The enzymes YfdW, a formyl coenzyme A (CoA) transferase, and YfdU, an oxalyl-CoA decarboxylase, are required for the adaptation effect but not during challenge. Unlike other SCOAs, this oxalate ATR is not a part of the RpoS regulon but appears to be linked to the signal protein GadE. We theorize that this oxalate ATR could enhance the pathogenesis of virulent E. coli consumed with oxalate-containing foods like spinach.

  20. YfdW and YfdU Are Required for Oxalate-Induced Acid Tolerance in Escherichia coli K-12

    PubMed Central

    Fontenot, Elise M.; Ezelle, Karen E.; Gabreski, Lauren N.; Giglio, Eleanor R.; McAfee, John M.; Mills, Alexandria C.; Qureshi, Maryam N.; Salmon, Kristin M.

    2013-01-01

    Escherichia coli has several mechanisms for surviving low-pH stress. We report that oxalic acid, a small-chain organic acid (SCOA), induces a moderate acid tolerance response (ATR) in two ways. Adaptation of E. coli K-12 at pH 5.5 with 50 mM oxalate and inclusion of 25 mM oxalate in pH 3.0 minimal challenge medium separately conferred protection, with 67% ± 7% and 87% ± 17% survival after 2 h, respectively. The combination of oxalate adaptation and oxalate supplementation in the challenge medium resulted in increased survival over adaptation or oxalate in the challenge medium alone. The enzymes YfdW, a formyl coenzyme A (CoA) transferase, and YfdU, an oxalyl-CoA decarboxylase, are required for the adaptation effect but not during challenge. Unlike other SCOAs, this oxalate ATR is not a part of the RpoS regulon but appears to be linked to the signal protein GadE. We theorize that this oxalate ATR could enhance the pathogenesis of virulent E. coli consumed with oxalate-containing foods like spinach. PMID:23335415

  1. Longitudinal distributions of dicarboxylic acids, ω-oxoacids, pyruvic acid, α-dicarbonyls, and fatty acids in the marine aerosols from the central Pacific including equatorial upwelling

    NASA Astrophysics Data System (ADS)

    Hoque, Mir Md. Mozammal; Kawamura, Kimitaka

    2016-03-01

    Remote marine aerosol samples (total suspended particles) were collected during a cruise in the central Pacific from Japan to Mexico (1°59'N-35°N and 171°54'E-90°58'W). The aerosol samples were analyzed for dicarboxylic acids (C2-C11), ω-oxoacids, pyruvic acid, α-dicarbonyls, and fatty acids as well as organic and elemental carbon, water-soluble organic carbon, and total nitrogen (WSTN). During the study, diacids were the most abundant compound class followed by fatty acids, ω-oxoacids, and α-dicarbonyls. Molecular compositions of diacids showed a predominance of oxalic (C2) acid followed by malonic (C3) and succinic (C4) acids. Oxalic acid comprises 74% of total diacids. This result suggests that photochemical production of oxalic acid is significant over the central Pacific. Spatial distributions of diacids, ω-oxoacids, pyruvic acid, α-dicarbonyls, and fatty acids together with total carbon and WSTN showed higher abundances in the eastern equatorial Pacific where the upwelling of high-nutrient waters followed by high biological productivity is common, indicating that their in situ production is important in the warmer central Pacific through photochemical oxidation from their gaseous and particulate precursors. This study demonstrates that there is a strong linkage in biogeochemical cycles of carbon in the sea-air interface via ocean upwelling, phytoplankton productivity, sea-to-air emissions of organic matter, and formation of secondary organic aerosols in the eastern equatorial Pacific.

  2. Spectra investigation on surface characteristics of graphene oxide nanosheets treated with tartaric, malic and oxalic acids.

    PubMed

    Teng, Xiyao; Yan, Manqing; Bi, Hong

    2014-01-24

    The surface characteristics of graphene oxide nanosheets (GO) treated respectively with tartaric acid, malic acid and oxalic acid, have been investigated by mainly using optical spectroscopic methods including Fourier transform infrared spectroscopy (FT-IR), Ultraviolet-visible (UV-Vis) absorption and Raman spectroscopy. Additionally, the electrochemical property of the products has also been studied. The data revealed that oxygen-containing groups such as OH, COOH and CO on the GO surface have been almost removed and thus reduced graphene oxide nanosheets (RGN) were obtained. Interestingly, the number of sp(2) domains of RGN increases as treated by tartaric acidacid acid whereas the steric hindrance (SH) decreases and the ionization constant (IC) differs among these three acids. Furthermore, the specific capacitances (Cs) of GO have been greatly promoted from 2.4 F g(-1) to 100.8, 112.4, and 147 F g(-1) after treated with tartaric, malic and oxalic acids, respectively. This finding agrees well with the spectra result of the tendency of surface conjugated degree alteration. We claim that the difference in both SH and IC among these acids is the main reason for the diverse surface characteristics as well as the improved Cs of the RGN.

  3. Immobilization of lead in anthropogenic contaminated soils using phosphates with/without oxalic acid.

    PubMed

    Su, Xiaojuan; Zhu, Jun; Fu, Qingling; Zuo, Jichao; Liu, Yonghong; Hu, Hongqing

    2015-02-01

    Understanding the effects of oxalic acid (OA) on the immobilization of Pb(II) in contaminated soils by phosphate materials, has considerable benefits for risk assessment and remediation strategies for the soil. A series of phosphate amendments with/without oxalic acid were applied to two anthropogenic contaminated soils. We investigated the immobilization of Pb(II) by KH2PO4, phosphate rock (PR), activated phosphate rock (APR) and synthetic hydroxyapatite (HAP) at different phosphate:Pb (P:Pb) molar ratios (0, 0.6, 2.0 and 4.0) in the presence/absence of 50 mmol oxalic acid/kg soil, respectively. The effects of treatments were evaluated using single extraction with deionized water or CaCl2, Community Bureau of Reference (BCR) sequential extraction and toxicity characteristic leaching procedure (TCLP) methods. Our results showed that the concentration of water extractable, exchangeable and TCLP-Pb all decreased with incubation time. The concentration of water-extractable Pb after 120 days was reduced by 100% when soils were amended with APR, HAP and HAP+OA, and the TCLP-Pb was <5 mg/L for the red soil at P:Pb molar ratio 4.0. Water-soluble Pb could not be detected and the TCLP-Pb was <5 mg/L at all treatments applied to the yellow-brown soil. BCR results indicated that APR was most effective, although a slight enhancement of water-soluble phosphate was detected at the P:Pb molar ratio 4.0 at the beginning of incubation. Oxalic acid activated phosphates, and so mixing insoluble phosphates with oxalic acid may be a useful strategy to improve their effectiveness in reducing Pb bioavailability.

  4. In Situ Oxalic Acid Injection to Accelerate Arsenic Remediation at a Superfund Site in New Jersey

    PubMed Central

    Wovkulich, Karen; Stute, Martin; Mailloux, Brian J.; Keimowitz, Alison R.; Ross, James; Bostick, Benjamin; Sun, Jing; Chillrud, Steven N.

    2015-01-01

    Arsenic is a prevalent contaminant at a large number of US Superfund sites; establishing techniques that accelerate As remediation could benefit many sites. Hundreds of tons of As were released into the environment by the Vineland Chemical Co. in southern New Jersey during its manufacturing lifetime (1949–1994), resulting in extensive contamination of surface and subsurface soils and sediments, groundwater, and the downstream watershed. Despite substantial intervention at this Superfund site, sufficient aquifer cleanup could require many decades if based on traditional pump and treat technologies only. Laboratory column experiments have suggested that oxalic acid addition to contaminated aquifer solids could promote significant As release from the solid phase. To evaluate the potential of chemical additions to increase As release in situ and boost treatment efficiency, a forced gradient pilot scale study was conducted on the Vineland site. During spring/summer 2009, oxalic acid and bromide tracer were injected into a small portion (~50 m2) of the site for 3 months. Groundwater samples indicate that introduction of oxalic acid led to increased As release. Between 2.9 and 3.6 kg of As were removed from the sampled wells as a result of the oxalic acid treatment during the 3-month injection. A comparison of As concentrations on sediment cores collected before and after treatment and analyzed using X-ray fluorescence spectroscopy suggested reduction in As concentrations of ~36% (median difference) to 48% (mean difference). While further study is necessary, the addition of oxalic acid shows potential for accelerating treatment of a highly contaminated site and decreasing the As remediation time-scale. PMID:25598701

  5. Correlation between the production of exopolysaccharides and oxalic acid secretion by Ganoderma applanatum and Tyromyces palustris.

    PubMed

    Osińska-Jaroszuk, Monika; Wlizło, Kamila; Szałapata, Katarzyna; Jarosz-Wilkołazka, Anna

    2014-12-01

    The secretion of exopolysaccharides and oxalic acid in cultures of a white rot Ganoderma applanatum strain and a brown rot Tyromyces palustris strain were tested in terms of culture time, pH range, and temperature. The high yield of exopolysaccharides (EPS) required a moderate temperature of 28 °C for G. applanatum and 20 °C for T. palustris. G. applanatum and T. palustris accumulated more EPS when the concentration of the carbon source (maltose for G. applanatum and fructose for T. palustris) was 30 g/L. The results indicate that the production of oxalic acid by G. applanatum is correlated with the initial pH value of the culture medium and the concentration of oxalic acid increased to 1.66 ± 0.2 mM at the initial pH of 6.5 during the fungal growth. During the growth of T. palustris, the reduction of the initial pH value of the growing medium lowered the oxalic acid concentration from 7.7 ± 0.6 mM at pH 6.0 to 1.99 ± 0.2 mM at pH 3.5. T. palustris accumulated considerably more oxalic acid than G. applanatum and its presence did not affect significantly the production of exopolysaccharides. We also observed that the maximum amounts of exopolysaccharides secreted during cultivation of G. applanatum and T. palustris were 45.8 ± 1.2 and 19.1 ± 1.2 g/L, respectively.

  6. Evaluation Of Sludge Heel Dissolution Efficiency With Oxalic Acid Cleaning At Savannah River Site

    SciTech Connect

    Sudduth, Christie; Vitali, Jason; Keefer, Mark

    2014-01-08

    The chemical cleaning process baseline strategy at the Savannah River Site was revised to improve efficiency during future execution of the process based on lessons learned during previous bulk oxalic acid cleaning activities and to account for operational constraints imposed by safety basis requirements. These improvements were also intended to transcend the difficulties that arise from waste removal in higher rheological yield stress sludge tanks. Tank 12 implemented this improved strategy and the bulk oxalic acid cleaning efforts concluded in July 2013. The Tank 12 radiological removal results were similar to previous bulk oxalic acid cleaning campaigns despite the fact that Tank 12 contained higher rheological yield stress sludge that would make removal more difficult than the sludge treated in previous cleaning campaigns. No appreciable oxalate precipitation occurred during the cleaning process in Tank 12 compared to previous campaigns, which aided in the net volume reduction of 75-80%. Overall, the controls established for Tank 12 provide a template for an improved cleaning process.

  7. Dilute oxalic acid pretreatment for high total sugar recovery in pretreatment and subsequent enzymatic hydrolysis.

    PubMed

    Qing, Qing; Huang, Meizi; He, Yucai; Wang, Liqun; Zhang, Yue

    2015-12-01

    Oxalic acid was evaluated as an alternative reagent to mineral inorganic acid in pretreatment of corncob to achieve high xylose yield in addition to highly digestible solid residue. A quadratic polynomial model of xylose formation was developed for optimization of pretreatment process by the response surface methodology based on the impact factors of pretreatment temperature, reaction time, acid concentration, and solid-to-liquid ratio. The highest xylose yield was 94.3 % that was obtained under the pretreatment condition of 140 °C for 40 min with 0.5 wt% oxalic acid at a solid loading of 7.5 %. Under these conditions, the xylose yield results of verification experiments were very close to the model prediction, which indicated that the model was applicable. The solid residue generated under this condition also demonstrated a satisfactory enzymatic digestibility and fermentability. PMID:26494137

  8. An ATP and Oxalate Generating Variant Tricarboxylic Acid Cycle Counters Aluminum Toxicity in Pseudomonas fluorescens

    PubMed Central

    Singh, Ranji; Lemire, Joseph; Mailloux, Ryan J.; Chénier, Daniel; Hamel, Robert; Appanna, Vasu D.

    2009-01-01

    Although the tricarboxylic acid (TCA) cycle is essential in almost all aerobic organisms, its precise modulation and integration in global cellular metabolism is not fully understood. Here, we report on an alternative TCA cycle uniquely aimed at generating ATP and oxalate, two metabolites critical for the survival of Pseudomonas fluorescens. The upregulation of isocitrate lyase (ICL) and acylating glyoxylate dehydrogenase (AGODH) led to the enhanced synthesis of oxalate, a dicarboxylic acid involved in the immobilization of aluminum (Al). The increased activity of succinyl-CoA synthetase (SCS) and oxalate CoA-transferase (OCT) in the Al-stressed cells afforded an effective route to ATP synthesis from oxalyl-CoA via substrate level phosphorylation. This modified TCA cycle with diminished efficacy in NADH production and decreased CO2-evolving capacity, orchestrates the synthesis of oxalate, NADPH, and ATP, ingredients pivotal to the survival of P. fluorescens in an Al environment. The channeling of succinyl-CoA towards ATP formation may be an important function of the TCA cycle during anaerobiosis, Fe starvation and O2-limited conditions. PMID:19809498

  9. Size distributions of nano/micron dicarboxylic acids and inorganic ions in suburban PM episode and non-episodic aerosol

    NASA Astrophysics Data System (ADS)

    Hsieh, Li-Ying; Kuo, Su-Ching; Chen, Chien-Lung; Tsai, Ying I.

    The distribution of nano/micron dicarboxylic acids and inorganic ions in size-segregated suburban aerosol of southern Taiwan was studied for a PM episode and a non-episodic pollution period, revealing for the first time the distribution of these nanoscale particles in suburban aerosols. Inorganic species, especially nitrate, were present in higher concentrations during the PM episode. A combination of gas-to-nuclei conversion of nitrate particles and accumulation of secondary photochemical products originating from traffic-related emissions was likely a crucial cause of the PM episode. Sulfate, ammonium, and oxalic acid were the dominant anion, cation, and dicarboxylic acid, respectively, accounting for a minimum of 49% of the total anion, cation or dicarboxylic acid mass. Peak concentrations of these species occurred at 0.54 μm in the droplet mode during both non-episodic and PM episode periods, indicating an association with cloud-processed particles. On average, sulfate concentration was 16-17 times that of oxalic acid. Oxalic acid was nevertheless the most abundant dicarboxylic acid during both periods, followed by succinic, malonic, maleic, malic and tartaric acid. The mass median aerodynamic diameter (MMAD) of oxalic acid was 0.77 μm with a bi-modal presence at 0.54 μm and 18 nm during non-episodic pollution and an MMAD of 0.67 μm with mono-modal presence at 0.54 μm in PM episode aerosol. The concomitant formation of malonic acid and oxalic acid was attributed to in-cloud processes. During the PM episode in the 5-100 nm nanoscale range, an oxalic acid/sulfate mass ratio of 40.2-82.3% suggested a stronger formation potential for oxalic acid than for sulfate in the nuclei mode. For total cations (TC), total inorganic anions (TIA) and total dicarboxylic acids (TDA), major contributing particles were in the droplet mode, with least in the nuclei mode. The ratio of TDA to TIA in the nuclei mode increased greatly from 8.40% during the non-episodic pollution

  10. IN-SITU MONITORING OF CORROSION DURING A LABORATORY SIMULATION OF OXALIC ACID CHEMICAL CLEANING

    SciTech Connect

    Wiersma, B; John Mickalonis, J; Michael Poirier, M; John Pareizs, J; David Herman, D; David Beam, D; Samuel Fink, S; Fernando Fondeur, F

    2007-10-08

    The Savannah River Site (SRS) will disperse or dissolve precipitated metal oxides as part of radioactive waste tank closure operations. Previously SRS used oxalic acid to accomplish this task. To better understand the conditions of oxalic acid cleaning of the carbon steel waste tanks, laboratory simulations of the process were conducted to determine the corrosion rate of carbon steel and the generation of gases such as hydrogen and carbon dioxide. Open circuit potential measurements, linear polarization measurements, and coupon immersion tests were performed in-situ to determine the corrosion behavior of carbon steel during the demonstration. Vapor samples were analyzed continuously to determine the constituents of the phase. The combined results from these measurements indicated that in aerated environments, such as the tank, that the corrosion rates are manageable for short contact times and will facilitate prediction and control of the hydrogen generation rate during operations.

  11. ELECTROCHEMICAL STUDIES ON THE CORROSION OF CARBON STEEL IN OXALIC ACID CLEANING SOLUTIONS

    SciTech Connect

    Wiersma, B; John Mickalonis, J

    2007-10-08

    The Savannah River Site (SRS) will disperse or dissolve precipitated metal oxides as part of radioactive waste tank closure operations. Previously SRS has utilized oxalic acid to accomplish this task. Since the waste tanks are constructed of carbon steel, a significant amount of corrosion may occur. Although the total amount of corrosion may be insignificant for a short contact time, a significant amount of hydrogen may be generated due to the corrosion reaction. Linear polarization resistance and anodic/cathodic polarization tests were performed to investigate the corrosion behavior during the process. The effect of process variables such as temperature, agitation, aeration, sample orientation, light as well as surface finish on the corrosion behavior were evaluated. The results of the tests provided insight into the corrosion mechanism for the iron-oxalic acid system.

  12. Oxidation of ferrocene by thiocyanic acid in the presence of ammonium oxalate

    NASA Astrophysics Data System (ADS)

    Ruslin, Farah bt; Yamin, Bohari M.

    2014-09-01

    A flake-like crystalline salt was obtained from the reaction of ferrocene, oxalic acid and ammonium thiocyanate in ethanol The elemental analysis and spectroscopic data were in agreement with the preliminary X-ray molecular structure. The compound consists of four ferrocenium moieties and a counter anion consisting of two (tetraisothiocyanato)iron(III) linked by an oxalato bridging group in such a way that both iron central atoms adopt octahedral geometries.

  13. Oxidation of ferrocene by thiocyanic acid in the presence of ammonium oxalate

    SciTech Connect

    Ruslin, Farah bt; Yamin, Bohari M.

    2014-09-03

    A flake-like crystalline salt was obtained from the reaction of ferrocene, oxalic acid and ammonium thiocyanate in ethanol The elemental analysis and spectroscopic data were in agreement with the preliminary X-ray molecular structure. The compound consists of four ferrocenium moieties and a counter anion consisting of two (tetraisothiocyanato)iron(III) linked by an oxalato bridging group in such a way that both iron central atoms adopt octahedral geometries.

  14. Removal of oxalic acid, oxamic acid and aniline by a combined photolysis and ozonation process.

    PubMed

    Orge, C A; Faria, J L; Pereira, M F R

    2015-01-01

    Aniline (ANL), an aromatic amine, oxalic acid (OXA) and oxamic acid (OMA), short-chain carboxylic acids, were chosen as model organic pollutants for testing the combined effect of neat photolysis and ozonation in the treatment of aqueous effluents. In order to better understand the results, single ozonation and neat photolysis were also carried out. OXA has a high refractory character relatively to single ozonation and neat photolysis only accounted for 26% conversion of OXA after 2 h of reaction. On the other hand, OXA complete degradation was observed in less than an hour when ozone and light were used simultaneously. Despite OMA, a compound never studied before by a combined ozonation and photolysis treatment, being highly refractory to oxidation, more than 50% was removed by photo-ozonation after 3 h of reaction. In the case of ANL, both single ozonation and photo-ozonation resulted in 100% removal in a short reaction period due to the high reactivity of ozone to attack this type of molecules; however, only the combined method leads to efficient mineralization (89%) after 3 h of reaction. A significant synergetic effect was observed in the degradation of the selected contaminants by the simultaneous use of ozone and light, since the mineralization rate of combined method is higher than the sum of the mineralization rates of the individual treatments. The promising results observed in the degradation of the selected contaminants are paving the way to the application of photo-ozonation in the treatment of wastewater containing this type of pollutants.

  15. Optical properties in the UV and visible spectral region of organic acids relevant to tropospheric aerosols

    NASA Astrophysics Data System (ADS)

    Lund Myhre, C. E.; Nielsen, C. J.

    2004-09-01

    Refractive and absorption indices in the UV and visible region of selected aqueous organic acids relevant to tropospheric aerosols are reported. The acids investigated are the aliphatic dicarboxylic acids oxalic, malonic, tartronic, succinic and glutaric acid. In addition we report data for pyruvic, pinonic, benzoic and phthalic acid. To cover a wide range of conditions we have investigated the aqueous organic acids at different concentrations spanning from highly diluted samples to concentrations close to saturation. The density of the investigated samples is reported and a parameterisation of the absorption and refractive index that allows the calculation of the optical constants of mixed aqueous organic acids at different concentrations is presented. The single scattering albedo is calculated for two size distributions using measured and a synthetic set of optical constants. The results show that tropospheric aerosols consisting of only these organic acids and water have a pure scattering effect.

  16. Optical properties in the UV and visible spectral region of organic acids relevant to tropospheric aerosols

    NASA Astrophysics Data System (ADS)

    Lund Myhre, C. E.; Nielsen, C. J.

    2004-06-01

    Refractive and absorption indices in the UV and visible region of selected aqueous organic acids relevant to tropospheric aerosols are reported. The acids investigated are the aliphatic dicarboxylic acids oxalic, malonic, tartronic, succinic and glutaric acid. In addition we report data for pyruvic, pinonic, benzoic and phthalic acid. To cover a wide range of conditions we have investigated the aqueous organic acids at different concentrations spanning from highly diluted samples to concentrations close to saturation. The density of the investigated samples is reported and a parameterisation of the absorption and refractive index that allows the calculation of the optical constants of mixed aqueous organic acids at different concentrations is presented. The single scattering albedo is calculated for two size distributions using measured and a synthetic set of optical constants. The results show that tropospheric aerosols consisting of only these organic acids and water have a pure scattering effect.

  17. Field assessment of yeast- and oxalic Acid-generated carbon dioxide for mosquito surveillance.

    PubMed

    Harwood, James F; Richardson, Alec G; Wright, Jennifer A; Obenauer, Peter J

    2014-12-01

    Carbon dioxide (CO2) sources improve the efficacy of mosquito traps. However, traditional CO2 sources (dry ice or compressed gas) may be difficult to acquire for vector surveillance during military contingency operations. For this reason, a new and convenient source of CO2 is required. Two novel CO2 generators were evaluated in order to address this capability gap: 1) an electrolyzer that converts solid oxalic acid into CO2 gas, and 2) CO2 produced by yeast as it metabolizes sugar. The flow rate and CO2 concentration produced by each generator were measured, and each generator's ability to attract mosquitoes to BG-Sentinel™ traps during day surveillance and to Centers for Disease Control and Prevention light traps with incandescent bulbs during night surveillance was compared to dry ice and compressed gas in Jacksonville, FL. The electrolyzed oxalic acid only slightly increased the number of mosquitoes captured compared to unbaited traps. Based on the modest increase in mosquito collection for traps paired with the oxalic acid, it is not a suitable stand-in for either of the 2 traditional CO2 sources. Conversely, the yeast-generated CO2 resulted in collections with mosquito abundance and species richness more closely resembling those of the traditional CO2 sources, despite achieving a lower CO2 flow rate. Therefore, if dry ice or compressed gas cannot be acquired for vector surveillance, yeast-generated CO2 can significantly improve trap capability. PMID:25843133

  18. Evidence of Polaron Excitations in Low Temperature Raman Spectra of Oxalic Acid Dihydrate.

    PubMed

    Mohaček-Grošev, Vlasta; Grdadolnik, Jože; Hadži, Dušan

    2016-05-12

    Low temperature Raman spectra of oxalic acid dihydrate (8-300 K) for both the polycrystalline and single crystal phase show strong variation with temperature in the interval from 1200 to 2000 cm(-1). Previous low temperature diffraction studies all confirmed the stability of the crystal P21/n phase with no indications of any phase transition, reporting the existence of a strong hydrogen bond between the oxalic acid and a water molecule. A new group of Raman bands in the 1200-1300 cm(-1) interval below 90 K is observed, caused by possible loss of the center of inversion. This in turn could originate either due to disorder in hydroxyl proton positions or due to proton transfer from carboxylic group to water molecule. The hypothesis of proton transfer is further supported by the emergence of new bands centered at 1600 and 1813 cm(-1), which can be explained with vibrations of H3O(+) ions. The broad band at 1600 cm(-1) looses intensity, while the band at 1813 cm(-1) gains intensity on cooling. The agreement between quantum calculations of vibrational spectra and experimentally observed Raman bands of hydronium ions in oxalic acid sesquihydrate crystal corroborates this hypothesis. PMID:27093217

  19. Oxalate catabolism in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oxalic acid is found in most plant species and can serve beneficial roles that protect the plant from a variety of environmental stresses. Excessive amounts of oxalate, however, can be detrimental to plant health. Thus, careful coordination of oxalate metabolism is needed. Despite the important impa...

  20. Effects of precursor concentration and acidic sulfate in aqueous glyoxal-OH radical oxidation and implications for secondary organic aerosol.

    PubMed

    Tan, Yi; Perri, Mark J; Seitzinger, Sybil P; Turpin, Barbara J

    2009-11-01

    Previous experiments demonstrated that aqueous OH radical oxidation of glyoxal yields low-volatility compounds. When this chemistry takes place in clouds and fogs, followed by droplet evaporation (or if it occurs in aerosol water), the products are expected to remain partially in the particle phase, forming secondary organic aerosol (SOA). Acidic sulfate exists ubiquitously in atmospheric water and has been shown to enhance SOA formation through aerosol phase reactions. In this work, we investigate how starting concentrations of glyoxal (30-3000 microM) and the presence of acidic sulfate (0-840 microM) affect product formation in the aqueous reaction between glyoxal and OH radical. The oxalic acid yield decreased with increasing precursor concentrations, and the presence of sulfuric acid did not alter oxalic acid concentrations significantly. A dilute aqueous chemistry model successfully reproduced oxalic acid concentrations, when the experiment was performed at cloud-relevant concentrations (glyoxal <300 microM), but predictions deviated from measurements at increasing concentrations. Results elucidate similarities and differences in aqueous glyoxal chemistry in clouds and in wet aerosols. They validate for the first time the accuracy of model predictions at cloud-relevant concentrations. These results suggest that cloud processing of glyoxal could be an important source of SOA. PMID:19924930

  1. Effects of precursor concentration and acidic sulfate in aqueous glyoxal-OH radical oxidation and implications for secondary organic aerosol.

    PubMed

    Tan, Yi; Perri, Mark J; Seitzinger, Sybil P; Turpin, Barbara J

    2009-11-01

    Previous experiments demonstrated that aqueous OH radical oxidation of glyoxal yields low-volatility compounds. When this chemistry takes place in clouds and fogs, followed by droplet evaporation (or if it occurs in aerosol water), the products are expected to remain partially in the particle phase, forming secondary organic aerosol (SOA). Acidic sulfate exists ubiquitously in atmospheric water and has been shown to enhance SOA formation through aerosol phase reactions. In this work, we investigate how starting concentrations of glyoxal (30-3000 microM) and the presence of acidic sulfate (0-840 microM) affect product formation in the aqueous reaction between glyoxal and OH radical. The oxalic acid yield decreased with increasing precursor concentrations, and the presence of sulfuric acid did not alter oxalic acid concentrations significantly. A dilute aqueous chemistry model successfully reproduced oxalic acid concentrations, when the experiment was performed at cloud-relevant concentrations (glyoxal <300 microM), but predictions deviated from measurements at increasing concentrations. Results elucidate similarities and differences in aqueous glyoxal chemistry in clouds and in wet aerosols. They validate for the first time the accuracy of model predictions at cloud-relevant concentrations. These results suggest that cloud processing of glyoxal could be an important source of SOA.

  2. Stable carbon isotopic compositions of low-molecular-weight dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, and fatty acids: Implications for atmospheric processing of organic aerosols

    NASA Astrophysics Data System (ADS)

    Zhang, Yan-Lin; Kawamura, Kimitaka; Cao, Fang; Lee, Meehye

    2016-04-01

    Stable carbon isotopic compositions (δ13C) were measured for 23 individual organic species including 9 dicarboxylic acids, 7 oxocarboxylic acids, 1 tricarboxylic acid, 2 α-dicarbonyls, and 4 fatty acids in the aerosols from Gosan background site in East Asia. δ13C values of particle phase glyoxal and methylglyoxal are significantly larger than those previously reported for isoprene and other precursors. The values are consistently less negative in oxalic acid (C2, average -14.1‰), glyoxylic acid (-13.8‰), pyruvic acid (-19.4‰), glyoxal (-13.5‰), and methylglyoxal (-18.6‰) compared to other organic species (e.g., palmitic acid, -26.3‰), which can be explained by the kinetic isotope effects during atmospheric oxidation of pre-aged precursors (e.g., isoprene) and the subsequent gas-particle partitioning after the evaporation of clouds or wet aerosols. The δ13C values of C2 is positively correlated with C2 to organic carbon ratio, indicating that photochemical production of C2 is more pronounced than its degradation during long-range atmospheric transport. The isotopic results also suggest that aqueous phase oxidation of glyoxal and methylglyoxal is a major formation process of oxalic acid via the intermediates such as glyoxylic acid and pyruvic acid. This study provides evidence that organic aerosols are intensively photochemically aged in the western North Pacific rim.

  3. [EXPERIENCE OF USE OF BLEMAREN® IN THE TREATMENT OF PATIENTS IN URIC ACID AND CALCIUM OXALATE UROLITHIASIS].

    PubMed

    Konstantinova, O V; Yanenko, E K

    2015-01-01

    154 patients with urolithiasis were under outpatient observation for 2-8 years. Among them there were 76 women and 78 men aged 21-66 years, of which 46 patients with uric acid urolithiasis, and 88--with calcium oxalate urolithiasis. Treatment of patients was carried out systematically, depending on their condition. Indications for the application of Blemaren® included the presence of uric acid stones, uric acid and/or oxalate crystalluria. The duration of treatment was 6.1 months. The dosage of the drug varied from 6 to 18 g per day and was selected individually, depending on the purpose of the appointment of Blemaren®. Reduction of the urine pH to 6.2- 6.8-7.2 was the criterion for properly selected dose. To dissolve uric acid stones in the presence of hyperuricemia and/or hyperuricuria, Blemaren® was administered in combination with allopurinol at a dose of 0.1 g 3-4 times a day. Besides pharmacotherapy, treatment included diet therapy. It was found that the morning urine pH in urate urolithiasis is sustainable and has a range of 5.0-6.0, in 80.4% of cases--range of 5.0-5.5. In calcium oxalate urolithiasis this parameter is also stable and has a range of 5.0-6.7, in 82.9% of cases--range of 5.5-6.0. Optimal urine pH to eliminate uric acid and oxalate crystalluria in patients with uric acid and calcium oxalate urolithiasis is the interval of 6.2-6.4. It was shown that Blemaren® is a highly effective agent for treatment and prevention of uric acid and calcium oxalate crystalluria in calcium oxalate and uric acid urolithiasis. Further, its effectiveness in dissolving of uric acid stones in the absence of an infectious inflammatory process is 82.3%. PMID:26859932

  4. Stable carbon isotopic compositions of low-molecular-weight dicarboxylic acids, oxocarboxylic acids, α-dicarbonyls, and fatty acids: implications for atmospheric processing of organic aerosols

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Kawamura, K.; Cao, F.; Lee, M.

    2015-12-01

    Stable carbon isotopic compositions (δ13C) were measured for 23 individual organic species including 9 dicarboxylic acids, 7 oxocarboxylic acids, 1 tricarboxylic acid, 2 α-dicarbonyls and 4 fatty acids in the aerosols from Gosan background site in East Asia. δ13C of particle-phase glyoxal and methylglyoxal are significantly higher than those previously reported for isoprene and other precursors, associated with isotope fractionation during atmospheric oxidation. 13C is consistently more enriched for oxalic acid (C2), glyoxylic acid, pyruvic acid, glyoxal and methylglyoxal compared to other organic compounds identified, which can be explained by the kinetic isotope effects during aqueous-phase processing and the subsequent gas-particle partitioning after clouds or wet aerosols evaporation δ13C of C2 is positively correlated with C2 and organic carbon ratio, indicating that a photochemical production of C2 is more pronounced than its degradation process during long-range transport. The 13C results also suggest that aqueous-phase oxidation of glyoxal and methylglyoxal is major formation process of oxalic acid production via the major intermediates glyoxylic acid and pyruvic acid. This study provides evidence that organic aerosols are intensively photo-chemically aged in this region.

  5. Evaluation of an acid ammonium oxalate extraction to determine fluoride resident concentrations in soils.

    PubMed

    Bégin, Louis; Fortin, Josée

    2003-01-01

    Fluoride depositions near aluminum smelters and other fluoride-emitting plants can lead to fluoride accumulation in soils, which constitutes a risk for ground water contamination. This study was conducted to investigate the capacity of a 0.2 M acid ammonium oxalate solution to selectively and quantitatively extract fluoride accumulated in soils. The recovery of fluoride added to three soils was evaluated following 7- to 28-d incubations. Oxalate extraction was also compared with a total fluoride extraction method, using oxalate-extractable fluoride (Fox) and total fluoride (Ftot) accumulation profiles derived from column percolation experiments. To determine low-level fluoride concentrations without interference from high Al and Fe concentrations, an adapted ion chromatography method was used. Following soil incubations, oxalate extracted 42 to 86% of added fluoride. Recovery varied between soils and, in one soil, increased with added fluoride concentration. Recovery was unaffected by incubation time. Maximum recovery was obtained in a soil high in amorphous Fe and Al, low in clay, and free of carbonate. Lower recoveries were obtained in soils with higher clay or carbonate contents. Only 4 to 8% of Ftot was extracted in untreated samples using Fox, which suggests a high selectivity of this method for added fluoride. In percolation experiments, the use of Fox reduced considerably the background noise associated with Ftot for the evaluation of fluoride accumulation profiles. Because of its high selectivity and despite incomplete fluoride recovery, the use of Fox to determine fluoride resident concentrations in soils may improve environmental monitoring of fluoride accumulation and movement in contaminated soils.

  6. The Relationship between Serum Oxalic Acid, Central Hemodynamic Parameters and Colonization by Oxalobacter formigenes in Hemodialysis Patients

    PubMed Central

    Gulhan, Baris; Turkmen, Kultigin; Aydin, Merve; Gunay, Murat; Cıkman, Aytekin; Kara, Murat

    2015-01-01

    Background/Objective Elevated pulse wave velocity (PWV) and central aortic blood pressures are independent predictors of increased cardiovascular morbidity and mortality in hemodialysis (HD) patients. Oxalic acid is a uremic retention molecule that is extensively studied in the pathogenesis of calcium oxalate stones. Oxalobacter formigenes, a member of the colon microbiota, has important roles in oxalate homeostasis. Data regarding the colonization by and the exact role of O. formigenes in the pathogenesis of oxalic acid metabolism in HD patients are scant. Hence, we aimed to determine the relationship between fecal O. formigenes colonization, serum oxalic acid and hemodynamic parameters in HD patients with regard to the colo-reno-cardiac axis. Methods Fifty HD patients were enrolled in this study. PWV and central aortic systolic (cASBP) and diastolic blood pressures (cADBP) were measured with a Mobil-O-Graph (I.E.M. GmbH, Stolberg, Germany). Serum oxalic acid levels were assessed by ELISA, and fecal O. formigenes DNA levels were isolated and measured by real-time PCR. Results Isolation of fecal O. formigenes was found in only 2 HD patients. One of them had 113,609 copies/ml, the other one had 1,056 copies/ml. Serum oxalic acid levels were found to be positively correlated with PWV (r = 0.29, p = 0.03), cASBP (r = 0.33, p = 0.001) and cADBP (r = 0.42, p = 0.002) and negatively correlated with LDL (r = −0.30, p = 0.03). In multivariate linear regression analysis, PWV was independently predicted by oxalic acid, glucose and triglyceride. Conclusions This is the first study that demonstrates the absence of O. formigenes as well as a relation between serum oxalic acid and cASBP, cADBP and PWV in HD patients. Replacement of O. formigenes with pre- and probiotics might decrease serum oxalic acid levels and improve cardiovascular outcomes in HD patients. PMID:26195968

  7. DEPOSITION TANK CORROSION TESTING FOR ENHANCED CHEMICAL CLEANING POST OXALIC ACID DESTRUCTION

    SciTech Connect

    Mickalonis, J.

    2011-08-29

    An Enhanced Chemical Cleaning (ECC) process is being developed to aid in the high level waste tank closure at the Savannah River Site. The ECC process uses an advanced oxidation process (AOP) to destroy the oxalic acid that is used to remove residual sludge from a waste tank prior to closure. The AOP process treats the dissolved sludge with ozone to decompose the oxalic acid through reactions with hydroxyl radicals. The effluent from this oxalic acid decomposition is to be sent to a Type III waste tank and may be corrosive to these tanks. As part of the hazardous simulant testing that was conducted at the ECC vendor location, corrosion testing was conducted to determine the general corrosion rate for the deposition tank and to assess the susceptibility to localized corrosion, especially pitting. Both of these factors impact the calculation of hydrogen gas generation and the structural integrity of the tanks, which are considered safety class functions. The testing consisted of immersion and electrochemical testing of A537 carbon steel, the material of construction of Type III tanks, and 304L stainless steel, the material of construction for transfer piping. Tests were conducted in solutions removed from the destruction loop of the prototype ECC set up. Hazardous simulants, which were manufactured at SRNL, were used as representative sludges for F-area and H-area waste tanks. Oxalic acid concentrations of 1 and 2.5% were used to dissolve the sludge as a feed to the ECC process. Test solutions included the uninhibited effluent, as well as the effluent treated for corrosion control. The corrosion control options included mixing with an inhibited supernate and the addition of hydroxide. Evaporation of the uninhibited effluent was also tested since it may have a positive impact on reducing corrosion. All corrosion testing was conducted at 50 C. The uninhibited effluent was found to increase the corrosion rate by an order of magnitude from less than 1 mil per year (mpy

  8. Adsorption and oxidation of oxalic acid on anatase TiO2 (001) surface: A density functional theory study.

    PubMed

    Sun, Tao; Wang, Yun; Zhang, Haimin; Liu, Porun; Zhao, Huijun

    2015-09-15

    Anatase TiO2 (001) surfaces have attracted great interest for photo-degradation of organic species recently due to their high reactivity. In this work, adsorption properties and oxidation mechanisms of oxalic acid on the anatase TiO2 (001) surface have been theoretically investigated using the first-principles density functional theory. Various possible adsorption configurations are considered by diversifying the connectivity of carboxylic groups with the surface. It is found that the adsorption of oxalic acid on the anatase (001) surface prefer the dissociative states. A novel double-bidentate configuration has been found due to the structural match between oxalic acid and the (001) surface. More charge is transferred from the adsorbed oxalic acid to the surface with the double-bidentate configuration when comparing with other adsorption structures. Thus, there is a positive correlation relationship between the transferred charge amount and the interfacial bond numbers when oxalic acid adsorbs on the anatase TiO2 (001) surface. The adsorption energies with dispersion corrections have demonstrated that the van der Waals interactions play an important role in the adsorption, especially when adsorbates are close to the surface.

  9. Polyacrylonitrile/manganese acetate composite nanofibers and their catalysis performance on chromium (VI) reduction by oxalic acid.

    PubMed

    Zhang, Chengcheng; Li, Xiang; Bian, Xiujie; Zheng, Tian; Wang, Ce

    2012-08-30

    Polyacrylonitrile(PAN)/manganese acetate(Mn(CH(3)COO)(2)) composite nanofibers have been fabricated by electrospinning, a simple and effective technology. The obtained composite nanofibers were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectrometer (FT-IR). The composite nanofibers are amorphous in structure, continuous, even and smooth. At the same time, the reduction performance of Cr(VI) by oxalic acid in the presence of the composite nanofibers is also investigated. The results indicate that the composite nanofibers have exhibited excellent catalysis performance for Cr(VI) reduction from a Cr(2)O(7)(2-)-containing solution by oxalic acid. And the critical parameters, such as the catalyst dosage, oxalic acid content, chromium concentration, the pH value of the reaction solution and light have important impact on the reduction process. Under the simulated solar light irradiation, after only 60 min, 1.2mM initial Cr(VI) solution was reduced absolutely in the presence of PAN/Mn(CH(3)COO)(2) composite nanofibers containing 17.5 wt.% Mn(CH(3)COO)(2) by 0.3 mL 0.5M oxalic acid. In light, the reduction of Cr(VI) by oxalic acid is markedly accelerated. PMID:22709851

  10. CORROSION TESTING OF CARBON STEEL IN OXALIC ACID CHEMICAL CLEANING SOLUTIONS

    SciTech Connect

    Wiersma, B.; Mickalonis, J.; Subramanian, K.; Ketusky, E.

    2011-10-14

    Radioactive liquid waste has been stored in underground carbon steel tanks for nearly 60 years at the Savannah River Site. The site is currently in the process of removing the waste from these tanks in order to place it into vitrified, stable state for longer term storage. The last stage in the removal sequence is a chemical cleaning step that breaks up and dissolves metal oxide solids that cannot be easily pumped out of the tank. Oxalic acid has been selected for this purpose because it is an effective chelating agent for the solids and is not as corrosive as other acids. Electrochemical and immersion studies were conducted to investigate the corrosion behavior of carbon steel in simulated chemical cleaning environments. The effects of temperature, agitation, and the presence of sludge solids in the oxalic acid on the corrosion rate and the likelihood of hydrogen evolution were determined. The testing showed that the corrosion rates decreased significantly in the presence of the sludge solids. Corrosion rates increased with agitation, however, the changes were less noticeable.

  11. Seasonal characteristics of oxalic acid and related SOA in the free troposphere of Mt. Hua, central China: implications for sources and formation mechanisms.

    PubMed

    Meng, Jingjing; Wang, Gehui; Li, Jianjun; Cheng, Chunlei; Ren, Yanqin; Huang, Yao; Cheng, Yuting; Cao, Junji; Zhang, Ting

    2014-09-15

    PM10 aerosols from the summit of Mt. Hua (2060 m a.s.l) in central China during the winter and summer of 2009 were analyzed for dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls. Molecular composition of dicarboxylic acids (C2-C11) in the free tropospheric aerosols reveals that oxalic acid (C2, 399 ± 261 ng m(-3) in winter and 522 ± 261 ng m(-3) in summer) is the most abundant species in both seasons, followed by malonic (C3) and succinic (C4) acids, being consistent with that on ground levels. Most of the diacids are more abundant in summer than in winter, but adipic (C6) and phthalic (Ph) acids are twice lower in summer, suggesting more significant impact of anthropogenic pollution on the wintertime alpine atmosphere. Moreover, glyoxal (Gly) and methylglyoxal (mGly) are also lower in summer (12 ± 6.1 ng m(-3)) than in winter (22 ± 13 ng m(-3)). As both dicarbonyls are a major precursor of C2, their seasonal variation patterns, which are opposite to those of the diacids, indicate that the mountain troposphere is more oxidative in summer. C2 showed strong linear correlations with levoglucosan in winter and oxidation products of isoprene and monoterpene in summer. PCA analysis further suggested that the wintertime C2 and related SOA in the Mt. Hua troposphere mostly originate from photochemical oxidations of anthropogenic pollutants emitted from biofuel and coal combustion in lowland regions. On contrast, the summertime C2 and related SOA mostly originate from further oxidation of the mountainous isoprene and monoterpene oxidation products. The AIM model calculation results showed that oxalic acid concentration well correlated with particle acidity (R(2)=0.60) but not correlated with particle liquid water content, indicating that particle acidity favors the organic acid formation because aqueous-phase C2 production is the primary mechanism of C2 formation in ambient aerosols and is driven by acid-catalyzed oxidation. PMID:24925591

  12. Molecular distributions and isotopic compositions of marine aerosols over the western North Atlantic: Dicarboxylic acids, ketoacids, α-dicarbonyls (glyoxal and methylglyoxal), fatty acids, sugars, and SOA tracers

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Ono, K.; Tachibana, E.; Quinn, P.; Bates, T. S.

    2013-12-01

    Marine aerosols were collected over the western North Atlantic from off the coast of Boston to Bermuda during the WACS (Western Atlantic Climate Study) cruise of R/V Ronald H. Brown in August 2012 using a high volume air sampler and pre-combusted quartz fiber filters. Aerosol filter samples (n=5) were analyzed for OC/EC, major inorganic ions, low molecular weight dicarboxylic acids and various secondary organic aerosol (SOA) tracers using carbon analyzer, ion chromatograph, GC/FID and GC/MS, respectively. Homologous series (C2-C12) of dicarboxylic acids (31-335 ng m-3) were detected with a predominance of oxalic acid. Total carbon and nitrogen and their stable isotope ratios were determined as well as stable carbon isotopic compositions of individual diacids using IRMS. Diacids were found to be the most abundant compound class followed by monoterpene-SOA tracers > isoprene-SOA tracers > sugar compounds > ketoacids > fatty alcohols > fatty acids > α-dicarbonyls > aromatic acids > n-alkanes. The concentrations of these compounds were higher in the coastal site and decreased in the open ocean. However, diacids stayed relatively high even in the remote ocean. Interestingly, contributions of oxalic acid to total aerosol carbon increased from the coast (2.3%) to the remote ocean (5.6%) during long-range atmospheric transport. Stable carbon isotopic composition of oxalic acid increased from the coast (-17.5‰) to open ocean (-12.4‰), suggesting that photochemical aging of organic aerosols occurred during the atmospheric transport over the ocean. Stable carbon isotope ratios of bulk aerosol carbon also increased from the coast near Boston to the open ocean near Bermuda.

  13. Novel approach to recover cobalt and lithium from spent lithium-ion battery using oxalic acid.

    PubMed

    Zeng, Xianlai; Li, Jinhui; Shen, Bingyu

    2015-09-15

    With the booming of consumer electronics (CE) and electric vehicle (EV), a large number of spent lithium-ion battery (LIBs) have been generated worldwide. Resource depletion and environmental concern driven from the sustainable industry of CE and EV have motivated spent LIBs should be recovered urgently. However, the conventional process combined with leaching, precipitating, and filtering was quite complicated to recover cobalt and lithium from spent LIBs. In this work, we developed a novel recovery process, only combined with oxalic acid leaching and filtering. When the optimal parameters for leaching process is controlled at 150 min retention time, 95 °C heating temperature, 15 g L(-1) solid-liquid ratio, and 400 rpm rotation rate, the recovery rate of lithium and cobalt from spent LIBs can reach about 98% and 97%, respectively. Additionally, we also tentatively discovered the leaching mechanism of lithium cobalt oxide (LiCoO2) using oxalic acid, and the leaching order of the sampling LiCoO2 of spent LIBs. All the obtained results can contribute to a short-cut and high-efficiency process of spent LIBs recycling toward a sound closed-loop cycle.

  14. Background on health effects of acid aerosols.

    PubMed

    Lippmann, M

    1989-02-01

    This introduction to the 1987 NIEHS-EPA Symposium on the Health Effects of Acid Aerosols reviews the state of our knowledge on this topic as of the close of the 1984 NIEHS Conference on the Health Effects of Acid Precipitation (Environmental Health Perspectives, Volume 63) and the results of some key studies completed since that time. These studies, together with the results of the studies presented in the papers that follow, provide a substantial increment in our knowledge of the health effects of acid aerosols.

  15. Background on health effects of acid aerosols.

    PubMed Central

    Lippmann, M

    1989-01-01

    This introduction to the 1987 NIEHS-EPA Symposium on the Health Effects of Acid Aerosols reviews the state of our knowledge on this topic as of the close of the 1984 NIEHS Conference on the Health Effects of Acid Precipitation (Environmental Health Perspectives, Volume 63) and the results of some key studies completed since that time. These studies, together with the results of the studies presented in the papers that follow, provide a substantial increment in our knowledge of the health effects of acid aerosols. PMID:2707208

  16. Structural tuning of photoluminescence in nanoporous anodic alumina by hard anodization in oxalic and malonic acids

    NASA Astrophysics Data System (ADS)

    Santos, Abel; Alba, Maria; Rahman, Mahbubur M.; Formentín, Pilar; Ferré-Borrull, Josep; Pallarès, Josep; Marsal, Lluis F.

    2012-04-01

    We report on an exhaustive and systematic study about the photoluminescent properties of nanoporous anodic alumina membranes fabricated by the one-step anodization process under hard conditions in oxalic and malonic acids. This optical property is analysed as a function of several parameters (i.e. hard anodization voltage, pore diameter, membrane thickness, annealing temperature and acid electrolyte). This analysis makes it possible to tune the photoluminescent behaviour at will simply by modifying the structural characteristics of these membranes. This structural tuning ability is of special interest in such fields as optoelectronics, in which an accurate design of the basic nanostructures (e.g. microcavities, resonators, filters, supports, etc.) yields the control over their optical properties and, thus, upon the performance of the nanodevices derived from them (biosensors, interferometers, selective filters, etc.)

  17. Laboratory photochemical processing of aqueous aerosols: formation and degradation of dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls

    NASA Astrophysics Data System (ADS)

    Pavuluri, C. M.; Kawamura, K.; Mihalopoulos, N.; Swaminathan, T.

    2015-07-01

    To better understand the photochemical processing of dicarboxylic acids and related polar compounds, we conducted batch UV irradiation experiments on two types of aerosol samples collected from India, which represent anthropogenic (AA) and biogenic (BA) aerosols, for time periods of 0.5 to 120 h. The irradiated samples were analyzed for molecular compositions of diacids, oxoacids and α-dicarbonyls. The results show that photochemical degradation of oxalic (C2), malonic (C3) and other C8-C12 diacids overwhelmed their production in aqueous aerosols, whereas succinic acid (C4) and C5-C7 diacids showed a significant increase (ca. 10 times) during the course of irradiation experiments. The photochemical formation of oxoacids and α-dicarbonyls overwhelmed their degradation during the early stages of experiment except for ω-oxooctanoic acid (ωC8), which showed a similar pattern to that of C4. We also found a gradual decrease in the relative abundance of C2 to total diacids and an increase in the relative abundance of C4 during prolonged experiment. Based on the changes in concentrations and mass ratios of selected species with the irradiation time, we hypothesize that iron-catalyzed photolysis of C2 and C3 diacids controls their concentrations in Fe-rich atmospheric waters, whereas photochemical formation of C4 diacid (via ωC8) is enhanced with photochemical processing of aqueous aerosols in the atmosphere. This study demonstrates that the ambient aerosols contain abundant precursors that produce diacids, oxoacids and α-dicarbonyls, although some species such as oxalic acid decompose extensively during an early stage of photochemical processing.

  18. Laboratory photochemical processing of aqueous aerosols: formation and degradation of dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls

    NASA Astrophysics Data System (ADS)

    Pavuluri, C. M.; Kawamura, K.; Mihalopoulos, N.; Swaminathan, T.

    2015-01-01

    To better understand the photochemical processing of dicarboxylic acids and related polar compounds, we conducted batch UV irradiation experiments on two types of aerosol samples collected from India, which represent anthropogenic (AA) and biogenic aerosols (BA), for time periods of 0.5 to 120 h. The irradiated samples were analyzed for molecular compositions of diacids, oxoacids and α-dicarbonyls. The results show that photochemical degradation of oxalic (C2) and malonic (C3) and other C8-C12 diacids overwhelmed their production in aqueous aerosols whereas succinic acid (C4) and C5-C7 diacids showed a significant increase (ca. 10 times) during the course of irradiation experiments. The photochemical formation of oxoacids and α-dicarbonyls overwhelmed their degradation during the early stages of experiment, except for ω-oxooctanoic acid (ωC8) that showed a similar pattern to that of C4. We also found a gradual decrease in the relative abundance of C2 to total diacids and an increase in the relative abundance of C4 during prolonged experiment. Based on the changes in concentrations and mass ratios of selected species with the irradiation time, we hypothesize that iron-catalyzed photolysis of C2 and C3 diacids dominates their concentrations in Fe-rich atmospheric waters, whereas photochemical formation of C4 diacid (via ωC8) is enhanced with photochemical processing of aqueous aerosols in the atmosphere. This study demonstrates that the ambient aerosols contain abundant precursors that produce diacids, oxoacids and α-dicarbonyls, although some species such as oxalic acid decompose extensively during an early stage of photochemical processing.

  19. A novel method for determination of low molecular weight dicarboxylic acids in background atmospheric aerosol using ion chromatography.

    PubMed

    Tsai, Ying I; Hsieh, Li-Ying; Weng, Tzu-Hsiang; Ma, Yu-Chien; Kuo, Su-Ching

    2008-09-19

    This paper describes a novel gradient elution ion chromatographic method using a Dionex AS11 system for the determination of low molecular weight dicarboxylic acids (low-M(w) DCAs) in background atmospheric aerosol. Interference with the oxalic acid peak from sulfate in background PM(2.5) aerosol, 15.8 times the oxalic acid concentration, was remedied by removing sulfate using a barium cartridge, whilst interference with the malonic acid peak from carbonate was reduced by using a carbonate removal device. An alternative remedy to sulfate interference was use of an AS14 system using isocratic eluent, and this produced good resolution of oxalic acid from a high sulfate peak. In both the AS11 and the AS14 system, linear correlation coefficients were at all times >0.9990 with excellent linear range, the recoveries ranged from 92.8 to 106%, with relative standard deviation of 3.67-6.30%, whilst method detection limits (MDLs) ranged from 0.36microgL(-1) for malic acid to 3.87microgL(-1) for maleic acid. These data indicate that the analytical methods developed herein produce excellent separation efficiency and good determination of low-M(w) DCAs with satisfactory accuracy, recoveries, and MDLs. Samples left at room temperature (20 degrees C) for 300min in a simulation of the 'waiting time' involved in the proposed IC analysis decayed to between 86% (oxalic acid) and 39% (succinic and malonic acids) of their original concentration, whilst at 4 degrees C concentrations remained at 96-101% of original, indicating that maintaining samples at a low temperature prior to injection into the IC analyzer is vital for obtaining accurate results when analyzing low-M(w) DCAs. Oxalic acid was found to be the most prevalent low-M(w) DCA in background aerosol, comprising 57% of the total low-M(w) DCAs and 0.959% of the PM(2.5) aerosol mass, followed by succinic acid and malonic acid.

  20. Poly(acrylic acid) to induce competitive crystallization of a theophylline/oxalic acid cocrystal and a theophylline polymorph

    NASA Astrophysics Data System (ADS)

    Jang, Jisun; Kim, Il Won

    2016-01-01

    Polymeric additives to induce competitive crystallization of pharmaceutical compounds were explored. A cocrystal of theophylline and oxalic acid was used as a model system, and poly(acrylic acid), poly(caprolactone), and poly(ethylene glycol) were the additives. The cocrystal formation was selectively hindered with addition of poly(acrylic acid). First the size of the cocrystals were reduced, and eventually the cocrystallization was inhibited to generate neat theophylline crystals. The theophylline crystals were of a distinctively different crystal structure from known polymorphs, based on powder X-ray diffraction. They were also obtained in nanoscale size, when millimeter-scale crystals formed without poly(acrylic acid). Polymeric additives that could form specific interactions with crystallizing compounds seem to be useful tools for the phase and size control of pharmaceutical crystals.

  1. A Neat Trick Using Oxalic Acid Dihydrate and Potassium Permanganate and Other Experiments with Small Organic Amine or Oxygenated Compounds

    ERIC Educational Resources Information Center

    Kelland, Malcolm A.

    2011-01-01

    Solid potassium permanganate (KMnO[subscript 4]) is shown to react in a variety of ways with small organic amines or oxygenated compounds depending on whether they are liquids or solids and whether water is present. In particular, its reaction with solid oxalic acid dihydrate can be initiated by the moisture in one's breath, making an intriguing…

  2. Fatty Acids as Surfactants on Aerosol Particles

    NASA Astrophysics Data System (ADS)

    Tervahattu, H.; Juhanoja, J.; Niemi, J.

    2003-12-01

    Fatty acids (n-alcanoic acids) are common compounds in numerous anthropogenic and natural emissions. According to Rogge et al. (1993), catalyst-equipped automobiles emitted more than 600 μg km-1 of fatty acids which was over 50% of all identified organics in fine aerosol emissions. Coal burning produces fatty acids ranging from about 1700 mg kg-1 for bituminous coal to over 10000 mg kg-1 for lignite (Oros and Simoneit, 2000). Similarly, biomass burning is an important source for aerosol fatty acids. They are the major identified compound group in deciduous tree smoke, their total emission factor being measured as 1589 mg kg-1 which was 56% of all identified organic compounds (Oros and Simoneit, 2001a). Large amounts of fatty acid are also emitted from burning of conifer trees and grass (Oros and Simoneit, 2001a; Simoneit, 2002). Fatty acids have been reported to be major constituents of marine aerosols in many investigations (Barger and Garrett, 1976; Gagosian et. al, 1981; Sicre et al., 1990; Stephanou, 1992). It has been suggested that as the marine aerosol particles form, they acquire a coating of organic surfactants (Blanchard, 1964; Gill et al., 1983; Middlebrook et al., 1998; Ellison et al., 1999). Amphiphilic molecules, including lipids, can be assembled as monomolecular layers at air/water interfaces as well as transported to a solid support. Recently, we could show by time-of-flight secondary ion mass spectrometry that fatty acids are important ingredients of the outermost surface layer of the sea-salt aerosol particles (Tervahattu et al., 2002). In their TOF-SIMS studies on the surface composition of atmospheric aerosols, Peterson and Tyler (2002) found fatty acids on the surface of Montana forest fire particles. In this work we have studied by TOF-SIMS the surface chemical composition of aerosol particles emitted from field fires in the Baltic and other East European countries and transported to Finland as well as aerosol particles transported from

  3. Acidic sulfate aerosols: characterization and exposure.

    PubMed

    Lioy, P J; Waldman, J M

    1989-02-01

    Exposures to acidic aerosol in the atmosphere are calculated from data reported in the scientific literature. The majority of date was not derived from studies necessarily designed to examine human exposures. Most of the studies were designed to investigate the characteristics of the atmosphere. However, the measurements were useful in defining two potential exposure situations: regional stagnation and transport conditions and local plume impacts. Levels of acidic aerosol in excess of 20 to 40 micrograms/m3 (as H2SO4) have been observed for time durations ranging from 1 to 12 hr. These were associated with high, but not necessarily the highest, atmospheric SO4(2)- levels. Exposures of 100 to 900 micrograms/m3/hr were calculated for the acid events that were monitored. In contrast, earlier London studies indicated that apparent acidity in excess of 100 micrograms/m3 (as H2SO4) was present in the atmosphere, and exposures less than 2000 micrograms/m3/hr were possible. Our present knowledge about the frequency, magnitude, and duration of acidic sulfate aerosol events and episodes is insufficient. Efforts must be made to gather more data, but these should be done in such a way that evaluation of human exposure is the focus of the research. In addition, further data are required on the mechanisms of formation of H2SO4 and on what factors can be used to predict acidic sulfate episodes.

  4. Acidic sulfate aerosols: characterization and exposure.

    PubMed Central

    Lioy, P J; Waldman, J M

    1989-01-01

    Exposures to acidic aerosol in the atmosphere are calculated from data reported in the scientific literature. The majority of date was not derived from studies necessarily designed to examine human exposures. Most of the studies were designed to investigate the characteristics of the atmosphere. However, the measurements were useful in defining two potential exposure situations: regional stagnation and transport conditions and local plume impacts. Levels of acidic aerosol in excess of 20 to 40 micrograms/m3 (as H2SO4) have been observed for time durations ranging from 1 to 12 hr. These were associated with high, but not necessarily the highest, atmospheric SO4(2)- levels. Exposures of 100 to 900 micrograms/m3/hr were calculated for the acid events that were monitored. In contrast, earlier London studies indicated that apparent acidity in excess of 100 micrograms/m3 (as H2SO4) was present in the atmosphere, and exposures less than 2000 micrograms/m3/hr were possible. Our present knowledge about the frequency, magnitude, and duration of acidic sulfate aerosol events and episodes is insufficient. Efforts must be made to gather more data, but these should be done in such a way that evaluation of human exposure is the focus of the research. In addition, further data are required on the mechanisms of formation of H2SO4 and on what factors can be used to predict acidic sulfate episodes. PMID:2651103

  5. Stable carbon isotopic compositions of total carbon, dicarboxylic acids and glyoxylic acid in the tropical Indian aerosols: Implications for sources and photochemical processing of organic aerosols

    NASA Astrophysics Data System (ADS)

    Pavuluri, Chandra Mouli; Kawamura, Kimitaka; Swaminathan, T.; Tachibana, Eri

    2011-09-01

    The tropical Indian aerosols (PM10) collected on day- and nighttime bases in winter and summer, 2007 from Chennai (13.04°N; 80.17°E) were studied for stable carbon isotopic compositions (δ13C) of total carbon (TC), individual dicarboxylic acids (C2-C9) and glyoxylic acid (ωC2). δ13C values of TC ranged from -23.9‰ to -25.9‰ (-25.0 ± 0.6‰; n = 49). Oxalic (C2) (-17.1 ± 2.5‰), malonic (C3) (-20.8 ± 1.8‰), succinic (C4) (-22.5 ± 1.5‰) and adipic (C6) (-20.6 ± 4.1‰) acids and ωC2 acid (-22.4 ± 5.5‰) were found to be more enriched with 13C compared to TC. In contrast, suberic (C8) (-29.4 ± 1.8‰), phthalic (Ph) (-30.1 ± 3.5‰) and azelaic (C9) (-28.4 ± 5.8‰) acids showed smaller δ13C values than TC. Based on comparisons of δ13C values of TC in Chennai aerosols to those (-24.7 ± 2.2‰) found in unburned cow-dung samples collected from Chennai and isotopic signatures of the particles emitted from point sources, we found that biofuel/biomass burning are the major sources of carbonaceous aerosols in South and Southeast Asia. The decrease in δ13C values of C9 diacid by about 5‰ from winter to summer suggests that tropical plant emissions also significantly contribute to organic aerosol in this region. Significant increase in δ13C values from C4 to C2 diacids in Chennai aerosols could be attributed for their photochemical processing in the tropical atmosphere during long-range transport from source regions.

  6. Observations of sharp oxalate reductions in stratocumulus clouds at variable altitudes: organic acid and metal measurements during the 2011 E-PEACE campaign.

    PubMed

    Sorooshian, Armin; Wang, Zhen; Coggon, Matthew M; Jonsson, Haflidi H; Ervens, Barbara

    2013-07-16

    This work examines organic acid and metal concentrations in northeastern Pacific Ocean stratocumulus cloudwater samples collected by the CIRPAS Twin Otter between July and August 2011. Correlations between a suite of various monocarboxylic and dicarboxylic acid concentrations are consistent with documented aqueous-phase mechanistic relationships leading up to oxalate production. Monocarboxylic and dicarboxylic acids exhibited contrasting spatial profiles reflecting their different sources; the former were higher in concentration near the continent due to fresh organic emissions. Concentrations of sea salt crustal tracer species, oxalate, and malonate were positively correlated with low-level wind speed suggesting that an important route for oxalate and malonate entry in cloudwater is via some combination of association with coarse particles and gaseous precursors emitted from the ocean surface. Three case flights show that oxalate (and no other organic acid) concentrations drop by nearly an order of magnitude relative to samples in the same vicinity. A consistent feature in these cases was an inverse relationship between oxalate and several metals (Fe, Mn, K, Na, Mg, Ca), especially Fe. By means of box model studies we show that the loss of oxalate due to the photolysis of iron oxalato complexes is likely a significant oxalate sink in the study region due to the ubiquity of oxalate precursors, clouds, and metal emissions from ships, the ocean, and continental sources.

  7. Screening of indigenous oxalate degrading lactic acid bacteria from human faeces and South Indian fermented foods: assessment of probiotic potential.

    PubMed

    Gomathi, Sivasamy; Sasikumar, Ponnusamy; Anbazhagan, Kolandaswamy; Sasikumar, Sundaresan; Kavitha, Murugan; Selvi, M S; Selvam, Govindan Sadasivam

    2014-01-01

    Lactic acid bacteria (LAB) have the potential to degrade intestinal oxalate and this is increasingly being studied as a promising probiotic solution to manage kidney stone disease. In this study, oxalate degrading LAB were isolated from human faeces and south Indian fermented foods, subsequently assessed for potential probiotic property in vitro and in vivo. Based on preliminary characteristics, 251 out of 673 bacterial isolates were identified as LAB. A total of 17 strains were found to degrade oxalate significantly between 40.38% and 62.90% and were subjected to acid and bile tolerance test. Among them, nine strains exhibited considerable tolerance up to pH 3.0 and at 0.3% bile. These were identified as Lactobacillus fermentum and Lactobacillus salivarius using 16S rDNA sequencing. Three strains, Lactobacillus fermentum TY5, Lactobacillus fermentum AB1, and Lactobacillus salivarius AB11, exhibited good adhesion to HT-29 cells and strong antimicrobial activity. They also conferred resistance to kanamycin, rifampicin, and ampicillin, but were sensitive to chloramphenicol and erythromycin. The faecal recovery rate of these strains was observed as 15.16% (TY5), 6.71% (AB1), and 9.3% (AB11) which indicates the colonization ability. In conclusion, three efficient oxalate degrading LAB were identified and their safety assessments suggest that they may serve as good probiotic candidates for preventing hyperoxaluria.

  8. Screening of Indigenous Oxalate Degrading Lactic Acid Bacteria from Human Faeces and South Indian Fermented Foods: Assessment of Probiotic Potential

    PubMed Central

    Kavitha, Murugan; Selvi, M. S.; Selvam, Govindan Sadasivam

    2014-01-01

    Lactic acid bacteria (LAB) have the potential to degrade intestinal oxalate and this is increasingly being studied as a promising probiotic solution to manage kidney stone disease. In this study, oxalate degrading LAB were isolated from human faeces and south Indian fermented foods, subsequently assessed for potential probiotic property in vitro and in vivo. Based on preliminary characteristics, 251 out of 673 bacterial isolates were identified as LAB. A total of 17 strains were found to degrade oxalate significantly between 40.38% and 62.90% and were subjected to acid and bile tolerance test. Among them, nine strains exhibited considerable tolerance up to pH 3.0 and at 0.3% bile. These were identified as Lactobacillus fermentum and Lactobacillus salivarius using 16S rDNA sequencing. Three strains, Lactobacillus fermentum TY5, Lactobacillus fermentum AB1, and Lactobacillus salivarius AB11, exhibited good adhesion to HT-29 cells and strong antimicrobial activity. They also conferred resistance to kanamycin, rifampicin, and ampicillin, but were sensitive to chloramphenicol and erythromycin. The faecal recovery rate of these strains was observed as 15.16% (TY5), 6.71% (AB1), and 9.3% (AB11) which indicates the colonization ability. In conclusion, three efficient oxalate degrading LAB were identified and their safety assessments suggest that they may serve as good probiotic candidates for preventing hyperoxaluria. PMID:24723820

  9. Suppression of Growth Rate of Colony-Associated Fungi by High Fructose Corn Syrup Feeding Supplement, Formic Acid, and Oxalic Acid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Select colony-associated fungi (bee isolates). Absidia sp., Ascosphaera apis, Aspergillus flavus, Fusarium sp., Penicillium glabrum, Mucor sp., showed a 40% reduction in radial growth rate with formic acid, a 28% reduction with oxalic acid, and a 15% reduction with fructose and high fructose corn sy...

  10. Corrosion Testing of Carbon Steel in Oxalic Acid that Contains Dissolved Iron

    SciTech Connect

    Wiersma, Bruce J.; Mickalonis, John I.; Subramanian, Karthik H.

    2012-10-11

    Radioactive liquid waste has been stored in underground carbon steel tanks for nearly 60 years at the Savannah River Site. The site is currently in the process of removing the waste from these tanks in order to place it into vitrified, stable state for longer term storage. The last stage in the removal sequence is a chemical cleaning step that breaks up and dissolves metal oxide solids that cannot be easily pumped out of the tank. Oxalic acid (OA) will be used to chemically clean the tanks after waste retrieval is completed. The waste tanks at SRS were constructed from carbon steel materials and thus are vulnerable to corrosion in acidic media. In addition to structural impacts, the impact of corrosion on the hydrogen generated during the process must be assessed. Electrochemical and coupon immersion tests were used to investigate the corrosion mechanism at anticipated process conditions. The testing showed that the corrosion rates were dependent upon the reduction of the iron species that had dissolved in solution. Initial corrosion rates were elevated due to the reduction of the ferric species to ferrous species. At later times, as the ferric species depleted, the corrosion rate decreased. On the other hand, the hydrogen evolution reaction became more dominant.

  11. Porous aluminum room temperature anodizing process in a fluorinated-oxalic acid solution

    NASA Astrophysics Data System (ADS)

    Dhahri, S.; Fazio, E.; Barreca, F.; Neri, F.; Ezzaouia, H.

    2016-08-01

    Anodizing of aluminum is used for producing porous insulating films suitable for different applications in electronics and microelectronics. Porous-type aluminum films are most simply realized by galvanostatic anodizing in aqueous acidic solutions. The improvement in application of anodizing technique is associated with a substantial reduction of the anodizing voltage at appropriate current densities as well as to the possibility to carry out the synthesis process at room temperature in order to obtain a self-planarizing dielectric material incorporated in array of super-narrow metal lines. In this work, the anodizing of aluminum to obtain porous oxide was carried out, at room temperature, on three different substrates (glass, stainless steel and aluminum), using an oxalic acid-based electrolyte with the addition of a relatively low amount of 0.4 % of HF. Different surface morphologies, from nearly spherical to larger porous nanostructures with smooth edges, were observed by means of scanning electron microscopy. These evidences are explained by considering the formation, transport and adsorption of the fluorine species which react with the Al3+ ions. The behavior is also influenced by the nature of the original substrate.

  12. The effect of citric and oxalic acid doping on the superconducting properties of MgB2

    NASA Astrophysics Data System (ADS)

    Ojha, N.; Malik, V. K.; Singla, Rashmi; Bernhard, C.; Varma, G. D.

    2009-12-01

    In this paper we report the effect of carbon doping on the structural and superconducting properties of MgB2 using citric and oxalic acids as carbon sources. The bulk polycrystalline samples have been synthesized via a standard solid state reaction route with composition MgB2+x wt% of citric and oxalic acids (x = 0, 5 and 10). The x-ray diffraction results reveal the formation of dominantly MgB2 with only a small amount of impurity phase MgO and substitution of C at the B site of MgB2 for both dopants. Improvements in the upper critical field (HC2), irreversibility field (Hirr) and high field (>2.5 T) critical current density (JC) have been observed on C doping in the samples. The correlations between superconducting properties and structural characteristics of the samples are described and discussed in this paper.

  13. Effect of Macerase, Oxalic Acid, and EGTA on Deep Supercooling and Pit Membrane Structure of Xylem Parenchyma of Peach.

    PubMed

    Wisniewski, M; Davis, G; Arora, R

    1991-08-01

    The object of this study was to determine if calcium cross-linking of pectin in the pit membrane of xylem parenchyma restricts water movement which results in deep supercooling. Current year shoots of ;Loring' peach (Prunus persica) were infiltrated with oxalic acid or EGTA solutions for 24 or 48 hours and then either prepared for ultrastructural analysis or subjected to differential thermal analysis. The effect of 0.25 to 1.0% pectinase (weight/volume) on deep supercooling was also investigated. The use of 5 to 50 millimolar oxalic acid and pectinase resulted in a significant reduction (flattening) of the low temperature exotherm and a distinct swelling and partial degradation of the pit membrane. EGTA (10 millimolar) for 24 or 48 hours shifted the low temperature exotherm to warmer temperatures and effected the outermost layer of the pit membrane. A hypothesis is presented on pectin-mediated regulation of deep supercooling of xylem parenchyma.

  14. A growth mechanism of porous film formed on Al in 0.6 M oxalic acid electrolyte.

    PubMed

    Han, Seong Ho; Kim, Hyoung Chan

    2012-04-01

    Understanding of mechanism of porous film formation is of fundamental importance for anodizing in general because, the onset of pore initiation terminates the barrier film growth process over the macroscopic metal surface. Several mechanisms have been proposed to explain pore formation. They include direct injection of aluminum ions into electrolyte and a field-assisted dissolution mechanism. High-resolution scanning electron microscopy of anodized surfaces and direct TEM of ion beam thinned films and ultrarmicrotomed film sections have been employed to gain further insight into the mechanism of initial porous film growth in 0.6 M oxalic acid. From detailed examination of the behavior of the xenon-tagged layer in the film during pore initiation and development in oxalic acid, the film structure of the barrier layer is found to be unstable during pore initiation and the instability of the film structure is possibly related to the field-assisted structure modification process.

  15. One-year observations of size distribution characteristics of major aerosol constituents at a coastal receptor site in Hong Kong - Part 1: Inorganic ions and oxalate

    NASA Astrophysics Data System (ADS)

    Bian, Q.; Huang, X. H. H.; Yu, J. Z.

    2014-09-01

    Size distribution data of major aerosol constituents are essential in source apportioning of visibility degradation, testing and verification of air quality models incorporating aerosols. We report here 1-year observations of mass size distributions of major inorganic ions (sulfate, nitrate, chloride, ammonium, sodium, potassium, magnesium and calcium) and oxalate at a coastal suburban receptor site in Hong Kong, China. A total of 43 sets of size-segregated samples in the size range of 0.056-18 μm were collected from March 2011 to February 2012. The size distributions of sulfate, ammonium, potassium and oxalate were characterized by a dominant droplet mode with a mass mean aerodynamic diameter (MMAD) in the range of ~ 0.7-0.9 μm. Oxalate had a slightly larger MMAD than sulfate on days with temperatures above 22 °C as a result of the process of volatilization and repartitioning. Nitrate was mostly dominated by the coarse mode but enhanced presence in fine mode was detected on winter days with lower temperature and lower concentrations of sea salt and soil particles. This data set reveals an inversely proportional relationship between the fraction of nitrate in the fine mode and product of the sum of sodium and calcium in equivalent concentrations and the dissociation constant of ammonium nitrate (i.e., (1/([Na+] + 2[Ca2+]) × (1/Ke')) when Pn_fine is significant (> 10%). The seasonal variation observed for sea salt aerosol abundance, with lower values in summer and winter, is possibly linked with the lower marine salinities in these two seasons. Positive matrix factorization was applied to estimate the relative contributions of local formation and transport to the observed ambient sulfate level through the use of the combined data sets of size-segregated sulfate and select gaseous air pollutants. On average, the regional/super-regional transport of air pollutants was the dominant source at this receptor site, especially on high-sulfate days while local formation

  16. One-year observations of size distribution characteristics of major aerosol constituents at a coastal receptor site in Hong Kong - Part 1: Inorganic ions and oxalate

    NASA Astrophysics Data System (ADS)

    Bian, Q.; Huang, X. H. H.; Yu, J. Z.

    2014-01-01

    Size distribution data of major aerosol constituents are essential in source apportioning of visibility degradation, testing and verification of air quality models incorporating aerosols. We report here one-year observations of mass size distributions of major inorganic ions (sulfate, nitrate, chloride, ammonium, sodium, potassium, magnesium and calcium) and oxalate at a coastal suburban receptor site in Hong Kong, China. A total of 43 sets of size segregated samples in the size range of 0.056-18 μm were collected from March 2011 to February 2012. The size distributions of sulfate, ammonium, potassium and oxalate were characterized by a dominant droplet mode with a mass mean aerodynamic diameter (MMAD) in the range of ~0.7-0.9 μm. Oxalate had a slightly larger MMAD than sulfate on days with temperatures above 22 °C as a result of the process of volatilization and repartitioning. Nitrate was mostly dominated by the coarse mode but enhanced presence in fine mode was detected on winter days with lower temperature and lower concentrations of sea salt and soil particles. This data set reveals an inversely proportional relationship between the fraction of nitrate in the fine mode and product of the sum of sodium and calcium in equivalent concentrations and the dissociation constant of ammonium nitrate (i.e., (1/[Na+] + 2[Ca2+]) × (1/Ke')). The seasonal variation observed for sea salt aerosol abundance, with lower values in summer and winter, is possibly linked with the lower marine salinities in these two seasons. Positive matrix factorization was applied to estimate the relative contributions of local formation and transport to the observed ambient sulfate level through the use of the combined datasets of size-segregated sulfate and select gaseous air pollutants. On average, the regional/super-regional transport of air pollutants was the dominant source at this receptor site, especially on high sulfate days, while local formation processes contributed approximately

  17. Fermentation parameter optimization of microbial oxalic acid production from cashew apple juice.

    PubMed

    Betiku, Eriola; Emeko, Harrison A; Solomon, Bamidele O

    2016-02-01

    The potential of cashew apple juice (CAJ) as a carbon source for oxalic acid (OA) production via fermentation process was investigated in this study. The effects and interactions of CAJ concentration, time, pH, NaNO3 concentration and methanol concentration on OA production were determined in a central composite design (CCD) and the process was modelled and optimized using response surface methodology (RSM). The results showed that OA fermentation can be described significantly (p < 0.05) by a quadratic model giving regression coefficient (R (2)) of 0.9964. NaNO3 concentration was the most significant positive variable while methanol was not a significant variable. A maximum OA concentration of 122.68 g/l could be obtained using the optimum levels of CAJ of 150.0 g/l, pH of 5.4, time of 7.31 days, NaNO3 of 2 g/l and methanol of 1% volume. The production of OA was found to increase from 106.75 to 122.68 g/l using the statistically design optimization. This study revealed that CAJ could serve as an inexpensive and abundant feedstock for fermentative OA production, the resulting model could be used in the design of a typical pilot plant for a scale up production.

  18. Mechanism of lead immobilization by oxalic acid-activated phosphate rocks.

    PubMed

    Jiang, Guanjie; Liu, Yonghong; Huang, Li; Fu, Qingling; Deng, Youjun; Hu, Hongqing

    2012-01-01

    Lead (Pb) chemical fixation is an important environmental aspect for human health. Phosphate rocks (PRs) were utilized as an adsorbent to remove Pb from aqueous solution. Raw PRs and oxalic acid-activated PRs (APRs) were used to investigate the effect of chemical modification on the Pb-binding capacity in the pH range 2.0-5.0. The Pb adsorption rate of all treatments above pH 3.0 reached 90%. The Pb binding on PRs and APRs was pH-independent, except at pH 2.0 in activated treatments. The X-ray diffraction analysis confirmed that the raw PRs formed cerussite after reacting with the Pb solution, whereas the APRs formed pyromorphite. The Fourier Transform Infrared spectroscopy analysis indicated that carbonate (CO3(2-)) in raw PRs and phosphate (PO4(3)) groups in APRs played an important role in the Pb-binding process. After adsorption, anomalous block-shaped particles were observed by scanning electron microscopy with energy dispersive spectroscopy. The X-ray photoelectron spectroscopy data further indicated that both chemical and physical reactions occurred during the adsorption process according to the binding energy. Because of lower solubility of pyromorphite compared to cerussite, the APRs are more effective in immobilizing Pb than that of PRs.

  19. Comparing oxalic acid and sucrocide treatments for Varroa destructor (Acari: Varroidae) control under desert conditions.

    PubMed

    Sammataro, D; Finley, J; Underwood, R

    2008-08-01

    The effectiveness of oxalic acid (OA) and Sucrocide (S) (AVA Chemical Ventures, L.L.C., Portsmouth, NH) in reducing populations of the varroa mite Varroa destructor Anderson & Trueman (Acari: Varroidae) in honey bee, Apis mellifera L. (Hymenoptera: Apidae) colonies was measured under the desert conditions of Arizona, USA. OA and S were applied three times 7 d apart. A 3.2% solution of OA was applied in sugar syrup via a large volume syringe, trickling 5 ml per space between frames in the colony. S was applied at a concentration of 0.625% (mixed with water), according to the label directions, using a compressed air Chapin sprayer at 20 psi to apply 59 ml per frame space. Varroa mites, collected on a sticky board before, during, and after the treatments, were counted to assess the effectiveness of the treatments. This study showed that a desert climate zone did not confer any positive or negative results on the acaricidal properties of OA. Even with brood present in colonies, significant varroa mite mortality occurred in the OA colonies. In contrast, we found that Sucrocide was not effective as a mite control technique. Despite its ability to increase mite mortality in the short-term, varroa mite populations measured posttreatment were not affected any more by Sucrocide than by no treatment at all.

  20. Esophageal mucosa exfoliation induced by oxalic acid poisoning: A case report

    PubMed Central

    WANG, JIERU; KAN, BAOTIAN; JIAN, XIANGDONG; WU, XIAOPENG; YU, GUANCAI; SUN, JING

    2016-01-01

    This study reports the case of a 44-year-old woman with oral oxalic acid poisoning. As the illness progressed, the patient exhibited severe metabolic acidosis, large-area esophageal mucosa injury and acute kidney injury, which required dialysis. A guide wire slipped out of position during the process of hemodialysis and moved back and forth in the veins, but was removed successfully by interventional endovascular treatment. However, the patient's esophageal mucosa exfoliated, which lead to severe benign esophageal stenosis and dysphagia. Balloon distention was conducted twice in the upper digestive tract using X-ray location in combination with a dumb-bell bladder and interventional wire. The patient exhibited convulsions, shock, embolism and loss of consciousness while undergoing the second balloon distention procedure. Following symptomatic treatment, the patient eventually remained in a stable condition, the digestive tract expansion procedure was not resumed and a jejunostomy was performed in order to facilitate enteral nutrition, which was administered via the jejunum and had little stimulatory effect on the pancreas. Following various treatments, the patient's condition improved markedly, with renal function returning to normal. PMID:26889241

  1. Fermentation parameter optimization of microbial oxalic acid production from cashew apple juice.

    PubMed

    Betiku, Eriola; Emeko, Harrison A; Solomon, Bamidele O

    2016-02-01

    The potential of cashew apple juice (CAJ) as a carbon source for oxalic acid (OA) production via fermentation process was investigated in this study. The effects and interactions of CAJ concentration, time, pH, NaNO3 concentration and methanol concentration on OA production were determined in a central composite design (CCD) and the process was modelled and optimized using response surface methodology (RSM). The results showed that OA fermentation can be described significantly (p < 0.05) by a quadratic model giving regression coefficient (R (2)) of 0.9964. NaNO3 concentration was the most significant positive variable while methanol was not a significant variable. A maximum OA concentration of 122.68 g/l could be obtained using the optimum levels of CAJ of 150.0 g/l, pH of 5.4, time of 7.31 days, NaNO3 of 2 g/l and methanol of 1% volume. The production of OA was found to increase from 106.75 to 122.68 g/l using the statistically design optimization. This study revealed that CAJ could serve as an inexpensive and abundant feedstock for fermentative OA production, the resulting model could be used in the design of a typical pilot plant for a scale up production. PMID:27441258

  2. Mechanisms of enhanced total organic carbon elimination from oxalic acid solutions by electro-peroxone process.

    PubMed

    Wang, Huijiao; Yuan, Shi; Zhan, Juhong; Wang, Yujue; Yu, Gang; Deng, Shubo; Huang, Jun; Wang, Bin

    2015-09-01

    Electro-peroxone (E-peroxone) is a novel electrocatalytic ozonation process that combines ozonation and electrolysis process to enhance pollutant degradation during water and wastewater treatment. This enhancement has been mainly attributed to several mechanisms that increase O3 transformation to ·OH in the E-peroxone system, e.g., electro-generation of H2O2 from O2 at a carbon-based cathode and its subsequent peroxone reaction with O3 to ·OH, electro-reduction of O3 to ·OH at the cathode, and O3 decomposition to ·OH at high local pH near the cathode. To get more insight how these mechanisms contribute respectively to the enhancement, this study investigated total organic carbon (TOC) elimination from oxalic acid (OA) solutions by the E-peroxone process. Results show that the E-peroxone process significantly increased TOC elimination rate by 10.2-12.5 times compared with the linear addition of the individual rates of corresponding ozonation and electrolysis process. Kinetic analyses reveal that the electrochemically-driven peroxone reaction is the most important mechanism for the enhanced TOC elimination rate, while the other mechanisms contribute minor to the enhancement by a factor of 1.6-2.5. The results indicate that proper selection of electrodes that can effectively produce H2O2 at the cathode is critical to maximize TOC elimination in the E-peroxone process.

  3. Mechanisms of enhanced total organic carbon elimination from oxalic acid solutions by electro-peroxone process.

    PubMed

    Wang, Huijiao; Yuan, Shi; Zhan, Juhong; Wang, Yujue; Yu, Gang; Deng, Shubo; Huang, Jun; Wang, Bin

    2015-09-01

    Electro-peroxone (E-peroxone) is a novel electrocatalytic ozonation process that combines ozonation and electrolysis process to enhance pollutant degradation during water and wastewater treatment. This enhancement has been mainly attributed to several mechanisms that increase O3 transformation to ·OH in the E-peroxone system, e.g., electro-generation of H2O2 from O2 at a carbon-based cathode and its subsequent peroxone reaction with O3 to ·OH, electro-reduction of O3 to ·OH at the cathode, and O3 decomposition to ·OH at high local pH near the cathode. To get more insight how these mechanisms contribute respectively to the enhancement, this study investigated total organic carbon (TOC) elimination from oxalic acid (OA) solutions by the E-peroxone process. Results show that the E-peroxone process significantly increased TOC elimination rate by 10.2-12.5 times compared with the linear addition of the individual rates of corresponding ozonation and electrolysis process. Kinetic analyses reveal that the electrochemically-driven peroxone reaction is the most important mechanism for the enhanced TOC elimination rate, while the other mechanisms contribute minor to the enhancement by a factor of 1.6-2.5. The results indicate that proper selection of electrodes that can effectively produce H2O2 at the cathode is critical to maximize TOC elimination in the E-peroxone process. PMID:25989593

  4. Asthmatic responses to airborne acid aerosols

    SciTech Connect

    Ostro, B.D.; Lipsett, M.J.; Wiener, M.B.; Selner, J.C. )

    1991-06-01

    Controlled exposure studies suggest that asthmatics may be more sensitive to the respiratory effects of acidic aerosols than individuals without asthma. This study investigates whether acidic aerosols and other air pollutants are associated with respiratory symptoms in free-living asthmatics. Daily concentrations of hydrogen ion (H+), nitric acid, fine particulates, sulfates and nitrates were obtained during an intensive air monitoring effort in Denver, Colorado, in the winter of 1987-88. A panel of 207 asthmatics recorded respiratory symptoms, frequency of medication use, and related information in daily diaries. We used a multiple regression time-series model to analyze which air pollutants, if any, were associated with health outcomes reported by study participants. Airborne H+ was found to be significantly associated with several indicators of asthma status, including moderate or severe cough and shortness of breath. Cough was also associated with fine particulates, and shortness of breath with sulfates. Incorporating the participants' time spent outside and exercise intensity into the daily measure of exposure strengthened the association between these pollutants and asthmatic symptoms. Nitric acid and nitrates were not significantly associated with any respiratory symptom analyzed. In this population of asthmatics, several outdoor air pollutants, particularly airborne acidity, were associated with daily respiratory symptoms.

  5. Comparison of hot hydroxylamine hydrochloride and oxalic acid leaching of stream sediment and coated rock samples as anomaly enhancement techniques

    USGS Publications Warehouse

    Filipek, L.H.; Chao, T.T.; Theobald, P.K.

    1982-01-01

    A hot hydroxylamine hydrochloride (H-Hxl) extraction in 25% acetic acid is compared with the commonly used oxalic acid extraction as a method of anomaly enhancement for Cu and Zn in samples from two very different metal deposits and climatic environments. Results obtained on minus-80-mesh stream sediments from an area near the Magruder massive sulfide deposit in Lincoln County, Georgia, where the climate is humid subtropical, indicate that H-Hxl enhances the anomaly for Cu by a factor of 2 and for Zn by a factor of 1.5, compared to the oxalic method. Analyses of Fe oxide-coated rock samples from outcrops overlying the North Silver Bell porphyry copper deposit near Tucson, Arizona, where the climate is semi-arid to arid, indicate that both techniques effectively outline the zones of hydrothermal alteration. The H-Hxl extraction can also perform well in high-carbonate or high-clay environments, where other workers have suggested that oxalic acid is not very effective. Therefore, the H-Hxl method is recommended for general exploration use. ?? 1982.

  6. Evaluation of Hanford high level waste vitrification chemistry for an NCAW simulant -- FY 1994: Potential exothermic reactions in the presence of formic acid, glycolic acid, and oxalic acid

    SciTech Connect

    Sills, J.A.

    1995-07-01

    A potential for an uncontrollable exothermic reaction between nitrate and organic salts during preparation of a high level waste melter feed has been identified. In order to examine this potential more closely, the thermal behavior of simulated neutralized current acid waste (NCAW) treated with various organic reductants was studied. Differential scanning calorimetry (DSC) measurements were collected on simulated waste samples and their supernates treated with organics. Organic reductants used were formic acid, glycolic acid, and oxalic acid. For comparison, samples of untreated simulant and untreated simulant with added noble metals were tested. When heated, untreated simulant samples both with and without noble metals showed no exothermic behavior. All of the treated waste simulant samples showed exothermic behavior. Onset temperatures of exothermic reactions were 120 C to 210 C. Many onset temperatures, particularly those for formic acid treated samples, are well below 181 C, the estimated maximum steam coil temperature (considered to be a worst case maximum temperature for chemical process tank contents). The enthalpies of the reactions were {minus}180 {times} 10{sup {minus}3} J/Kg supernate ({minus}181 J/g) for the oxalic acid treated simulant supernate to {minus}1,150 {times} 10{sup {minus}3} J/Kg supernate ({minus}1,153 J/g) for the formic acid treated simulant supernate.

  7. Hygroscopic behavior of multicomponent organic aerosols and their internal mixtures with ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Jing, Bo; Tong, Shengrui; Liu, Qifan; Li, Kun; Wang, Weigang; Zhang, Yunhong; Ge, Maofa

    2016-03-01

    Water-soluble organic compounds (WSOCs) are important components of organics in the atmospheric fine particulate matter. Although WSOCs play an important role in the hygroscopicity of aerosols, knowledge on the water uptake behavior of internally mixed WSOC aerosols remains limited. Here, the hygroscopic properties of single components such as levoglucosan, oxalic acid, malonic acid, succinic acid, phthalic acid, and multicomponent WSOC aerosols mainly involving oxalic acid are investigated with the hygroscopicity tandem differential mobility analyzer (HTDMA). The coexisting hygroscopic species including levoglucosan, malonic acid, and phthalic acid have a strong influence on the hygroscopic growth and phase behavior of oxalic acid, even suppressing its crystallization completely during the drying process. The phase behaviors of oxalic acid/levoglucosan mixed particles are confirmed by infrared spectra. The discrepancies between measured growth factors and predictions from Extended Aerosol Inorganics Model (E-AIM) with the Universal Quasi-Chemical Functional Group Activity Coefficient (UNIFAC) method and Zdanovskii-Stokes-Robinson (ZSR) approach increase at medium and high relative humidity (RH) assuming oxalic acid in a crystalline solid state. For the internal mixture of oxalic acid with levoglucosan or succinic acid, there is enhanced water uptake at high RH compared to the model predictions based on reasonable oxalic acid phase assumption. Organic mixture has more complex effects on the hygroscopicity of ammonium sulfate than single species. Although hygroscopic species such as levoglucosan account for a small fraction in the multicomponent aerosols, they may still strongly influence the hygroscopic behavior of ammonium sulfate by changing the phase state of oxalic acid which plays the role of "intermediate" species. Considering the abundance of oxalic acid in the atmospheric aerosols, its mixtures with hygroscopic species may significantly promote water uptake

  8. Literature review for oxalate oxidation processes and plutonium oxalate solubility

    SciTech Connect

    Nash, C. A.

    2015-10-01

    A literature review of oxalate oxidation processes finds that manganese(II)-catalyzed nitric acid oxidation of oxalate in precipitate filtrate is a viable and well-documented process. The process has been operated on the large scale at Savannah River in the past, including oxidation of 20 tons of oxalic acid in F-Canyon. Research data under a variety of conditions show the process to be robust. This process is recommended for oxalate destruction in H-Canyon in the upcoming program to produce feed for the MOX facility. Prevention of plutonium oxalate precipitation in filtrate can be achieved by concentrated nitric acid/ferric nitrate sequestration of oxalate. Organic complexants do not appear practical to sequester plutonium. Testing is proposed to confirm the literature and calculation findings of this review at projected operating conditions for the upcoming campaign.

  9. Transported acid aerosols measured in southern Ontario

    NASA Astrophysics Data System (ADS)

    Keeler, Gerald J.; Spengler, John D.; Koutrakis, Petros; Allen, George A.; Raizenne, Mark; Stern, Bonnie

    During the period 29 June 1986-9 August 1986, a field health study assessing the acute health effects of air pollutants on children was conducted at a summer girls' camp on the northern shore of Lake Erie in SW Ontario. Continuous air pollution measurements of SO 2, O 3, NO x, particulate sulfates, light scattering, and meteorological measurements including temperature, dew point, and wind speed and direction were made. Twelve-hour integrated samples of size fractioned particles were also obtained using dichotomous samplers and Harvard impactors equipped with an ammonia denuder for subsequent hydrogen ion determination. Particulate samples were analyzed for trace elements by X-ray fluorescence and Neutron Activation, and for organic and elemental carbon by a thermal/optical technique. The measured aerosol was periodically very acidic with observed 12-h averaged H + concentrations in the range < 10-560 nmoles m -3. The aerosol H + appeared to represent the net strong acidity after H 2SO 4 reaction with NH 3(g). Average daytime concentrations were higher than night-time for aerosol H +, sulfate, fine mass and ozone. Prolonged episodes of atmospheric acidity, sulfate, and ozone were associated with air masses arriving at the measurement site from the west and from the southwest over Lake Erie. Sulfate concentrations measured at the lakeshore camp were more than twice those measured at inland sites during extreme pollution episodes. The concentration gradient observed with onshore flow was potentially due to enhanced deposition near the lakeshore caused by discontinuities in the meteorological fields in this region.

  10. ACTUAL-WASTE TESTS OF ENHANCED CHEMICAL CLEANING FOR RETRIEVAL OF SRS HLW SLUDGE TANK HEELS AND DECOMPOSITION OF OXALIC ACID

    SciTech Connect

    Martino, C.; King, W.; Ketusky, E.

    2012-01-12

    Savannah River National Laboratory conducted a series of tests on the Enhanced Chemical Cleaning (ECC) process using actual Savannah River Site waste material from Tanks 5F and 12H. Testing involved sludge dissolution with 2 wt% oxalic acid, the decomposition of the oxalates by ozonolysis (with and without the aid of ultraviolet light), the evaporation of water from the product, and tracking the concentrations of key components throughout the process. During ECC actual waste testing, the process was successful in decomposing oxalate to below the target levels without causing substantial physical or chemical changes in the product sludge.

  11. Mimicking the biomolecular control of calcium oxalate monohydrate crystal growth: effect of contiguous glutamic acids.

    PubMed

    Grohe, Bernd; Hug, Susanna; Langdon, Aaron; Jalkanen, Jari; Rogers, Kem A; Goldberg, Harvey A; Karttunen, Mikko; Hunter, Graeme K

    2012-08-21

    Scanning confocal interference microscopy (SCIM) and molecular dynamics (MD) simulations were used to investigate the adsorption of the synthetic polypeptide poly(l-glutamic acid) (poly-glu) to calcium oxalate monohydrate (COM) crystals and its effect on COM formation. At low concentrations (1 μg/mL), poly-glu inhibits growth most effectively in ⟨001⟩ directions, indicating strong interactions of the polypeptide with {121} crystal faces. Growth in <010> directions was inhibited only marginally by 1 μg/mL poly-glu, while growth in <100> directions did not appear to be affected. This suggests that, at low concentrations, poly-glu inhibits lattice-ion addition to the faces of COM in the order {121} > {010} ≥ {100}. At high concentrations (6 μg/mL), poly-glu resulted in the formation of dumbbell-shaped crystals featuring concave troughs on the {100} faces. The effects on crystal growth indicate that, at high concentrations, poly-glu interacts with the faces of COM in the order {100} > {121} > {010}. This mirrors MD simulations, which predicted that poly-glu will adsorb to a {100} terrace plane (most calcium-rich) in preference to a {121} (oblique) riser plane but will adsorb to {121} riser plane in preference to an {010} terrace plane (least calcium-rich). The effects of different poly-glu concentration on COM growth (1-6 μg/mL) may be due to variations between the faces in terms of growth mechanism and/or (nano)roughness, which can affect surface energy. In addition, 1 μg/mL might not be adequate to reach the critical concentration for poly-glu to significantly pin step movement on {100} and {010} faces. Understanding the mechanisms involved in these processes is essential for the development of agents to reduce recurrence of kidney stone disease.

  12. Oxalic acid and diacylglycerol 36:3 are cross-species markers of sleep debt.

    PubMed

    Weljie, Aalim M; Meerlo, Peter; Goel, Namni; Sengupta, Arjun; Kayser, Matthew S; Abel, Ted; Birnbaum, Morris J; Dinges, David F; Sehgal, Amita

    2015-02-24

    Sleep is an essential biological process that is thought to have a critical role in metabolic regulation. In humans, reduced sleep duration has been associated with risk for metabolic disorders, including weight gain, diabetes, obesity, and cardiovascular disease. However, our understanding of the molecular mechanisms underlying effects of sleep loss is only in its nascent stages. In this study we used rat and human models to simulate modern-day conditions of restricted sleep and addressed cross-species consequences via comprehensive metabolite profiling. Serum from sleep-restricted rats was analyzed using polar and nonpolar methods in two independent datasets (n = 10 per study, 3,380 measured features, 407 identified). A total of 38 features were changed across independent experiments, with the majority classified as lipids (18 from 28 identified). In a parallel human study, 92 metabolites were identified as potentially significant, with the majority also classified as lipids (32 of 37 identified). Intriguingly, two metabolites, oxalic acid and diacylglycerol 36:3, were robustly and quantitatively reduced in both species following sleep restriction, and recovered to near baseline levels after sleep restriction (P < 0.05, false-discovery rate < 0.2). Elevated phospholipids were also noted after sleep restriction in both species, as well as metabolites associated with an oxidizing environment. In addition, polar metabolites reflective of neurotransmitters, vitamin B3, and gut metabolism were elevated in sleep-restricted humans. These results are consistent with induction of peroxisome proliferator-activated receptors and disruptions of the circadian clock. The findings provide a potential link between known pathologies of reduced sleep duration and metabolic dysfunction, and potential biomarkers for sleep loss.

  13. Hygroscopic Behavior of Multicomponent Aerosols Involving NaCl and Dicarboxylic Acids.

    PubMed

    Peng, Chao; Jing, Bo; Guo, Yu-Cong; Zhang, Yun-Hong; Ge, Mao-Fa

    2016-02-25

    Atmospheric aerosols are usually complex mixtures of inorganic and organic compounds. The hygroscopicity of mixed particles is closely related to their chemical composition and interactions between components, which is still poorly understood. In this study, the hygroscopic properties of submicron particles composed of NaCl and dicarboxylic acids including oxalic acid (OA), malonic acid (MA), and succinic acid (SA) with various mass ratios are investigated with a hygroscopicity tandem differential mobility analyzer (HTDMA) system. Both the Zdanovskii-Stokes-Robinson (ZSR) method and extended aerosol inorganics model (E-AIM) are applied to predict the water uptake behaviors of sodium chloride/dicarboxylic acid mixtures. For NaCl/OA mixed particles, the measured growth factors were significantly lower than predictions from the model methods, indicating a change in particle composition caused by chloride depletion. The hygroscopic growth of NaCl/MA particles was well described by E-AIM, and that of NaCl/SA particles was dependent upon mixing ratio. Compared with model predictions, it was determined that water uptake of the NaCl/OA mixture could be enhanced and could be closer to the predictions by addition of levoglucosan or malonic acid, which retained water even at low relative humidity (RH), leading to inhibition of HCl evaporation during dehydration. These results demonstrate that the coexisting hygroscopic species have a strong influence on the phase state of particles, thus affecting chemical interactions between inorganic and organic compounds as well as the overall hygroscopicity of mixed particles. PMID:26820230

  14. Acidic sulfate aerosols: characterization and exposure

    SciTech Connect

    Lioy, P.J.; Waldman, J.M.

    1989-02-01

    Exposures to acidic aerosol in the atmosphere are calculated from data reported in the scientific literature. The majority of date was not derived from studies necessarily designed to examine human exposures. Most of the studies were designed to investigate the characteristics of the atmosphere. However, the measurements were useful in defining two potential exposure situations: regional stagnation and transport conditions and local plume impacts. Levels of acidicaerosol in excess of 20 to 40 micrograms/m/sup 3/ (as H/sub 2/SO/sub 4/) have been observed for time durations ranging from 1 to 12 hr. These were associated with high, but not necessarily the highest, atmospheric SO/sub 4/(2)- levels. Exposures of 100 to 900 micrograms/m/sup 3//hr were calculated for the acid events that were monitored. In contrast, earlier London studies indicated that apparent acidity in excess of 100 micrograms/m/sup 3/ (as H/sub 2/SO/sub 4/) was present in the atmosphere, and exposures less than 2000 micrograms/m/sup 3//hr were possible. Our present knowledge about the frequency, magnitude, and duration of acidic sulfate aerosol events and episodes is insufficient. Efforts must be made to gather more data, but these should be done in such a way that evaluation of human exposure is the focus of the research. In addition, further data are required on the mechanisms of formation of H/sub 2/SO/sub 4/ and on what factors can be used to predict acidic sulfate episodes. 96 references.

  15. Air pollution and asthma: clinical studies with sulfuric acid aerosols

    SciTech Connect

    Utell, M.J.; Frampton, M.W.; Morrow, P.E. )

    1991-11-01

    Until recently, acid deposition has been widely considered a serious ecological problem but not a threat to human health. The controlled clinical study is an important approach in linking acidic aerosol inhalation with respiratory effects. Asthmatic patients represent a subpopulation most responsive to sulfuric acid aerosols. In a series of studies with asthmatic volunteers, several factors have been identified that may modulate the intensity of the bronchoconstrictor response to inhaled acidic aerosols. We found (1) enhancement of the bronchoconstrictor response during exercise, (2) the more acidic aerosols provoke the greatest changes in lung function, and (3) mitigation of airway responses during sulfuric acid aerosol inhalation caused by high respiratory ammonia concentrations. Additional factors influencing responsiveness await identification.

  16. Enhanced efficiency of cadmium removal by Boehmeria nivea (L.) Gaud. in the presence of exogenous citric and oxalic acids.

    PubMed

    Li, Huaying; Liu, Yunguo; Zeng, Guangming; Zhou, Lu; Wang, Xin; Wang, Yaqin; Wang, Chunlin; Hu, Xinjiang; Xu, Weihua

    2014-12-01

    Boehmeria nivea (L.) Gaud. is a potential candidate for the remediation of Cd contaminated sites. The present investigation aims to explore Cd tolerance threshold and to quickly identify the role of exogenous organic acids in Cd uptake and abiotic metal stress damage. Elevated Cd levels (0-10mg/L) resulted in an obvious rise in Cd accumulation, ranging from 268.0 to 374.4 in root and 25.2 to 41.2mg/kg dry weight in shoot, respectively. Citric acid at 1.5 mmol/L significantly facilitated Cd uptake by 26.7% in root and by 1-fold in shoot, respectively. Cd translocation efficiency from root to shoot was improved by a maximum of 66.4% under 3 mmol/L of oxalic acid. Citric acid exhibited more prominent mitigating effect than oxalic acid due to its stronger ligand affinity for chelating with metal and avoiding the toxicity injury of free Cd ions more efficiently. The present work provides a potential strategy for efficient Cd remediation with B. nivea.

  17. EFFECT OF ACIDITY ON SECONDARY ORGANIC AEROSOL FORMATION FROM ISOPRENE

    EPA Science Inventory

    The effect of particle-phase acidity on secondary organic aerosol (SOA) formation from isoprene is investigated in a laboratory chamber study, in which the acidity of the inorganic seed aerosol was controlled systematically. The observed enhancement in SOA mass concentration is c...

  18. Vapor pressures and lattice energies of oxalic acid, mesotartaric acid, phloroglucinol, myoinositol, and their hydrates

    NASA Astrophysics Data System (ADS)

    de Wit, H. G. M.; Bouwstra, J. A.; Blok, J. G.; de Kruif, C. G.

    1983-02-01

    In the present investigation, we report the enthalpy of dehydration and the enthalpy of sublimation of a number of organic hydrates and their anhydrous counterparts. These values are used to test the transferability of a set of atom-atom potential parameters, originally derived for carboxylic acids. The calculations showed that the parameter set was transferable to a fairly good degree.

  19. Postharvest treatments with salicylic acid, acetylsalicylic acid or oxalic acid delayed ripening and enhanced bioactive compounds and antioxidant capacity in sweet cherry.

    PubMed

    Valero, Daniel; Díaz-Mula, Huertas M; Zapata, Pedro Javier; Castillo, Salvador; Guillén, Fabián; Martínez-Romero, Domingo; Serrano, María

    2011-05-25

    Sweet cherry cultivars ('Cristalina' and 'Prime Giant') harvested at commercial ripening stage were treated with salicylic acid (SA), acetylsalicylic acid (ASA) or oxalic acid (OA) at 1 mM and then stored for 20 days under cold temperature. Results showed that all treatments delayed the postharvest ripening process, manifested by lower acidity, color changes and firmness losses, and maintained quality attributes for longer periods than controls. In addition, total phenolics, anthocyanins and antioxidant activity increased in untreated fruit during the first 10 days of storage and then decreased, while in fruits of all treatments, these parameters increased continuously during storage without significant differences among treatments. Thus, postharvest treatments with natural compounds, such as SA, ASA or OA, could be innovative tools to extend the storability of sweet cherry with higher content of bioactive compounds and antioxidant activity as compared with control fruits. PMID:21506518

  20. Postharvest treatments with salicylic acid, acetylsalicylic acid or oxalic acid delayed ripening and enhanced bioactive compounds and antioxidant capacity in sweet cherry.

    PubMed

    Valero, Daniel; Díaz-Mula, Huertas M; Zapata, Pedro Javier; Castillo, Salvador; Guillén, Fabián; Martínez-Romero, Domingo; Serrano, María

    2011-05-25

    Sweet cherry cultivars ('Cristalina' and 'Prime Giant') harvested at commercial ripening stage were treated with salicylic acid (SA), acetylsalicylic acid (ASA) or oxalic acid (OA) at 1 mM and then stored for 20 days under cold temperature. Results showed that all treatments delayed the postharvest ripening process, manifested by lower acidity, color changes and firmness losses, and maintained quality attributes for longer periods than controls. In addition, total phenolics, anthocyanins and antioxidant activity increased in untreated fruit during the first 10 days of storage and then decreased, while in fruits of all treatments, these parameters increased continuously during storage without significant differences among treatments. Thus, postharvest treatments with natural compounds, such as SA, ASA or OA, could be innovative tools to extend the storability of sweet cherry with higher content of bioactive compounds and antioxidant activity as compared with control fruits.

  1. Opacity of monodisperse sulfuric acid aerosols

    NASA Astrophysics Data System (ADS)

    Pilat, Michael J.; Wilder, James M.

    The plume opacity and droplet diameters of a monodisperse sulfuric acid aerosol were calculated as a function of the initial H 2SO 4 concentration, initial H 2O concentration and final gas temperature after cooling from an original stack gas temperature of 300°C. Calculation assumptions include heterogeneous heteromolecular condensation of H 2SO 4 and H 2O onto monodisperse nuclei of 0.05 μm dia., three aerosol particle nuclei concentrations of 10 6, 10 7 and 10 8 cm -3 (at 300°C and 760 mm Hg); and a stack or plume diameter of 6 m. The calculated results show that for the conditions considered and with the stack temperatures in excess of 125°C, initial H 2SO 4 stack gas concentrations of 10ppm or less will result in calculated opacities of less than 20 % for a plume diameter of 6 m. The results show that the calculated opacity is significantly affected by the initial H 2SO 4 and initial H 2O concentrations and the final gas temperature. The increases in the calculated opacities upon cooling of the stack gases are similar in general to the increases in the measured opacities between instack and outstack reported by Nader and Conner (1978) for an oil-fired boiler.

  2. Hygroscopic behavior of multicomponent organic aerosols and their internal mixtures with ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Jing, B.; Tong, S. R.; Liu, Q. F.; Li, K.; Wang, W. G.; Zhang, Y. H.; Ge, M. F.

    2015-08-01

    Water soluble organic compounds (WSOCs) are important components of organics in the atmospheric fine particulate matter. Although WSOCs play an important role in the hygroscopicity of aerosols, water uptake behavior of internally mixed WSOC aerosols remains limited characterization. Here, the hygroscopic properties of single component such as levoglucosan, oxalic acid, malonic acid, succinic acid and phthalic acid and multicomponent WSOC aerosols mainly involving oxalic acid are investigated with the hygroscopicity tandem differential mobility analyzer (HTDMA). The coexisting hygroscopic species including levoglucosan, malonic acid and phthalic acid have strong influence on the hygroscopic growth and phase behavior of oxalic acid, even suppress its crystallization completely. The interactions between oxalic acid and levoglucosan are confirmed by infrared spectra. The discrepancies between measured growth factors and predictions from Extended Aerosol Inorganics Model (E-AIM) with UNIFAC method and Zdanovskii-Stokes-Robinson (ZSR) approach increase at medium and high relative humidity (RH) assuming oxalic acid in a solid state. For the internal mixture of oxalic acid with levoglucosan or succinic acid, there is enhanced water uptake at high RH due to positive chemical interactions between solutes. Organic mixture has more complex effect on the hygroscopicity of ammonium sulfate than single species. Although hygroscopic species such as levoglucosan accounts for a small fraction in the multicomponent aerosols, they may still strongly influence the hygroscopic behavior of ammonium sulfate by changing phase state of oxalic acid which plays the role of "intermediate" species. Considering the abundance of oxalic acid in the atmospheric aerosols, its mixtures with hygroscopic species may significantly promote water uptake under high RH conditions and thus affect the cloud condensation nuclei (CCN) activity, optical properties and chemical reactivity of atmospheric particles.

  3. LITERATURE REVIEW FOR OXALATE OXIDATION PROCESSES AND PLUTONIUM OXALATE SOLUBILITY

    SciTech Connect

    Nash, C.

    2012-02-03

    A literature review of oxalate oxidation processes finds that manganese(II)-catalyzed nitric acid oxidation of oxalate in precipitate filtrate is a viable and well-documented process. The process has been operated on the large scale at Savannah River in the past, including oxidation of 20 tons of oxalic acid in F-Canyon. Research data under a variety of conditions show the process to be robust. This process is recommended for oxalate destruction in H-Canyon in the upcoming program to produce feed for the MOX facility. Prevention of plutonium oxalate precipitation in filtrate can be achieved by concentrated nitric acid/ferric nitrate sequestration of oxalate. Organic complexants do not appear practical to sequester plutonium. Testing is proposed to confirm the literature and calculation findings of this review at projected operating conditions for the upcoming campaign. H Canyon plans to commence conversion of plutonium metal to low-fired plutonium oxide in 2012 for eventual use in the Mixed Oxide Fuel (MOX) Facility. The flowsheet includes sequential operations of metal dissolution, ion exchange, elution, oxalate precipitation, filtration, and calcination. All processes beyond dissolution will occur in HB-Line. The filtration step produces an aqueous filtrate that may have as much as 4 M nitric acid and 0.15 M oxalate. The oxalate needs to be removed from the stream to prevent possible downstream precipitation of residual plutonium when the solution is processed in H Canyon. In addition, sending the oxalate to the waste tank farm is undesirable. This report addresses the processing options for destroying the oxalate in existing H Canyon equipment.

  4. Pre-harvest application of oxalic acid increases quality and resistance to Penicillium expansum in kiwifruit during postharvest storage.

    PubMed

    Zhu, Yuyan; Yu, Jie; Brecht, Jeffrey K; Jiang, Tianjia; Zheng, Xiaolin

    2016-01-01

    Kiwifruit (Actinidia deliciosa cv. Bruno) fruits were sprayed with 5mM oxalic acid (OA) at 130, 137, and 144 days after full blossom, and then harvested at commercial maturity [soluble solid content (SSC) around 10.0%] and stored at room temperature (20 ± 1 °C). Pre-harvest application of OA led to fruit with higher ascorbic acid content at harvest, slowed the decreases in fruit firmness and ascorbic acid content and increase in SSC during storage, and also decreased the natural disease incidence, lesion diameter, and patulin accumulation in fruit inoculated with Penicillium expansum, indicating that the OA treatment increased quality and induced disease resistance in kiwifruit. It was suggested that the increase in activities of defense-related enzymes and in levels of substances related to disease resistance might collectively contribute to resistance in kiwifruit against fungi such as P. expansum in storage. PMID:26213007

  5. Pre-harvest application of oxalic acid increases quality and resistance to Penicillium expansum in kiwifruit during postharvest storage.

    PubMed

    Zhu, Yuyan; Yu, Jie; Brecht, Jeffrey K; Jiang, Tianjia; Zheng, Xiaolin

    2016-01-01

    Kiwifruit (Actinidia deliciosa cv. Bruno) fruits were sprayed with 5mM oxalic acid (OA) at 130, 137, and 144 days after full blossom, and then harvested at commercial maturity [soluble solid content (SSC) around 10.0%] and stored at room temperature (20 ± 1 °C). Pre-harvest application of OA led to fruit with higher ascorbic acid content at harvest, slowed the decreases in fruit firmness and ascorbic acid content and increase in SSC during storage, and also decreased the natural disease incidence, lesion diameter, and patulin accumulation in fruit inoculated with Penicillium expansum, indicating that the OA treatment increased quality and induced disease resistance in kiwifruit. It was suggested that the increase in activities of defense-related enzymes and in levels of substances related to disease resistance might collectively contribute to resistance in kiwifruit against fungi such as P. expansum in storage.

  6. Biocontrol agents-mediated suppression of oxalic acid induced cell death during Sclerotinia sclerotiorum-pea interaction.

    PubMed

    Jain, Akansha; Singh, Akanksha; Singh, Surendra; Sarma, Birinchi Kumar; Singh, Harikesh Bahadur

    2015-05-01

    Oxalic acid (OA) is an important pathogenic factor during early Sclerotinia sclerotiorum-host interaction and might work by reducing hydrogen peroxide production (H2 O2 ). In the present investigation, oxalic acid-induced cell death in pea was studied. Pea plants treated with biocontrol agents (BCAs) viz., Pseudomonas aeruginosa PJHU15, Bacillus subtilis BHHU100, and Trichoderma harzianum TNHU27 either singly and/or in consortium acted on S. sclerotiorum indirectly by enabling plants to inhibit the OA-mediated suppression of oxidative burst via induction of H2 O2 . Our results showed that BCA treated plants upon treatment with culture filtrate of the pathogen, conferred the resistance via. significantly decreasing relative cell death of pea against S. sclerotiorum compared to control plants without BCA treatment but treated with the culture filtrate of the pathogen. The results obtained from the present study indicate that the microbes especially in consortia play significant role in protection against S. sclerotiorum by modulating oxidative burst and partially enhancing tolerance by increasing the H2 O2 generation, which is otherwise suppressed by OA produced by the pathogen.

  7. Development and validation of a simple determination of urine metabolites (oxalate, citrate, uric acid and creatinine) by capillary zone electrophoresis.

    PubMed

    Muñoz, Jose A; López-Mesas, Montserrat; Valiente, Manuel

    2010-04-15

    Oxalate, citrate, uric acid and creatinine are important urine markers for the evaluation and treatment of urolithiasic patients. They have been traditionally analysed by enzymatic and chromatographic techniques which present practical drawbacks, mainly in the sample pre-treatment step. The purpose of this study was to evaluate those markers in urine samples, by an easy multi-analyte assay using capillary zone electrophoresis. The four urine metabolites were determined, at 25 degrees C, by using a 50 cm x 75 microm capillary in 50 mmol l(-1) phosphate buffer (pH 6.5), at constant voltage of -30 kV and UV detection at 195 nm (for oxalate and citrate) or 30 kV and 234 nm (for creatinine and uric acid). The sample pre-treatment was minimum, 5- and 20-fold dilution of the urine sample and acidification to pH 3-4. Validation parameters (linear range, sensitivity, accuracy, precision and detection limits) were statistically comparable to those obtained with the official methods normally used in the clinical practice. The effect of freezing as a conservation method of urine samples is also discussed in terms of recoveries of the analytes. The analytical method developed is highly useful as a diagnostic tool for detecting metabolic renal disorders due to its simplicity, time consuming, easy automation, cost efficiency and analytical effectiveness, accomplishing with the clinical requirements.

  8. Degradation of oxalic acid by the mycoparasite Coniothyrium minitans plays an important role in interacting with Sclerotinia sclerotiorum.

    PubMed

    Zeng, Li-Mei; Zhang, Jing; Han, Yong-Chao; Yang, Long; Wu, Ming-de; Jiang, Dao-Hong; Chen, Weidong; Li, Guo-Qing

    2014-08-01

    Coniothyrium minitans (Cm) is a mycoparasite of the phytopathogenic fungus Sclerotinia sclerotiorum (Ss). Ss produces a virulence factor oxalic acid (OA) which is toxic to plants and also to Cm, and Cm detoxifies OA by degradation. In this study, two oxalate decarboxylase genes, Cmoxdc1 and Cmoxdc2, were cloned from Cm strain Chy-1. OA and low pH induced expression of Cmoxdc1, but not Cmoxdc2. Cmoxdc1 was partially responsible for OA degradation, whereas Cmoxdc2 had no effect on OA degradation. Disruption of Cmoxdc1 in Cm reduced its ability to infect Ss in dual cultures where OA accumulated. Compared with Chy-1, the Cmoxdc1-disrupted mutants had reduced expression levels of two mycoparasitism-related genes chitinase (Cmch1) and β-1,3-glucanase (Cmg1), and had no detectable activity of extracellular proteases in the presence of OA. On the other hand, the cultural filtrates of the Cmoxdc1-disrupted mutants in OA-amended media showed enhanced antifungal activity, possibly because of increased production of antifungal substances under acidic pH condition resulted from reduced Cmoxdc1-mediated OA degradation. This study provides direct genetic evidence of OA degradation regulating mycoparasitism and antibiosis of Cm against Ss, and sheds light on the sophisticated strategies of Cm in interacting with metabolically active mycelia and dormant sclerotia of Ss. PMID:24467446

  9. Mode of Action: Oxalate Crystal-Induced Renal Tubule Degeneration and Glycolic Acid-Induced Dysmorphogenesis—Renal and Developmental Effects of Ethylene Glycol

    SciTech Connect

    Corley, Rick A.; Meek, M E.; Carney, E W.

    2005-10-01

    Ethylene glycol can cause both renal and developmental toxicity, with metabolism playing a key role in the mode of action (MOA) for each form of toxicity. Renal toxicity is ascribed to the terminal metabolite oxalic acid, which precipitates in the kidney in the form of calcium oxalate crystals and is believed to cause physical damage to the renal tubules. The human relevance of the renal toxicity of ethylene glycol is indicated by the similarity between animals and humans of metabolic pathways, the observation of renal oxalate crystals in toxicity studies in experimental animals and human poisonings, and cases of human kidney and bladder stones related to dietary oxalates and oxalate precursors. High-dose gavage exposures to ethylene glycol also cause axial skeletal defects in rodents (but not rabbits), with the intermediary metabolite, glycolic acid, identified as the causative agent. However, the mechanism by which glycolic acid perturbs development has not been investigated sufficiently to develop a plausible hypothesis of mode of action, nor have any cases of ethylene glycol-induced developmental effects been reported in humans. Given this, and the variations in sensitivity between animal species in response, the relevance to humans of ethylene glycol-induced developmental toxicity in animals is unknown at this time.

  10. Free amino acids in Antarctic aerosol: potential markers for the evolution and fate of marine aerosol

    NASA Astrophysics Data System (ADS)

    Barbaro, E.; Zangrando, R.; Vecchiato, M.; Piazza, R.; Cairns, W. R. L.; Capodaglio, G.; Barbante, C.; Gambaro, A.

    2015-05-01

    To investigate the impact of marine aerosols on global climate change it is important to study their chemical composition and size distribution. Amino acids are a component of the organic nitrogen in aerosols and particles containing amino acids have been found to be efficient ice nuclei. The main aim of this study was to investigate the L- and D-free amino acid composition as possible tracers of primary biological production in Antarctic aerosols from three different areas: two continental bases, Mario Zucchelli Station (MZS) on the coast of the Ross Sea, Concordia Station at Dome C on the Antarctic Plateau, and the Southern Ocean near the Antarctic continent. Studying the size distribution of amino acids in aerosols allowed us to characterize this component of the water-soluble organic carbon (WSOC) in marine aerosols near their source and after long-range transport. The presence of only free L-amino acids in our samples is indicative of the prevalence of phytoplanktonic material. Sampling at these three points allowed us to study the reactivity of these compounds during long-range transport. The mean total amino acid concentration detected at MZS was 11 pmol m-3, a higher percentage of amino acids were found in the fine fraction. The aerosol samples collected at Dome C had the lowest amino acid values (0.7 and 0.8 pmol m-3), and the coarse particles were found to have higher concentrations of amino acids compared to the coastal site. The amino acid composition in the aerosol collected at Dome C had also changed compared to the coastal site, suggesting that physical and chemical transformations had occurred during long range transport. During the sampling cruise on the R/V Italica on the Southern Ocean, high concentrations of amino acids were found in the total suspended particles, this we attribute to the presence of intact biological material (as microorganisms or plant material) in the sample.

  11. In vivo measurements of changes in pH triggered by oxalic acid in leaf tissue of transgenic oilseed rape.

    PubMed

    Zou, Qiu-Ju; Liu, Sheng-Yi; Dong, Xu-Yan; Bi, Yan-Hua; Cao, Yuan-Cheng; Xu, Qiao; Zhao, Yuan-Di; Chen, Hong

    2007-01-01

    Oxalic acid (OA), a non-host-specific toxin secreted by Sclerotinia sclerotiorum during pathogenesis, has been demonstrated to be a major phytotoxic and pathogenic factor. Oxalate oxidase (OXO) is an enzyme associated with the detoxification of OA, and hence the introduction of an OXO gene into oilseed rape (Brassica napus L.) to break down OA may be an alternative way of increasing the resistance of the plant to Sclerotinia sclerotiorum. In order to investigate the activation of OXO in transgenic oilseed rape, a convenient and accessible method was used to monitor changes in pH in response to stress induced by OA. The pH sensor, a platinum microcylinder electrode modified using polyaniline film, exhibited a linear response within the pH range from 3 to 7, with a Nernst response slope of 70 mV/pH at room temperature. The linear correlation coefficient was 0.9979. Changes induced by OA in the pH values of leaf tissue of different oilseed rape species from Brassica napus L. were monitored in real time in vivo using this electrode. The results clearly showed that the transgenic oilseed rape was more resistant to OA than non-transgenic oilseed rape.

  12. Oxaloacetate acetylhydrolase gene mutants of Sclerotinia sclerotiorum do not accumulate oxalic acid, but do produce limited lesions on host plants.

    PubMed

    Liang, Xiaofei; Liberti, Daniele; Li, Moyi; Kim, Young-Tae; Hutchens, Andrew; Wilson, Ron; Rollins, Jeffrey A

    2015-08-01

    The oxaloacetate acetylhydrolase (OAH, EC 3.7.1.1)-encoding gene Ss-oah1 was cloned and functionally characterized from Sclerotinia sclerotiorum. Ss-oah1 transcript accumulation mirrored oxalic acid (OA) accumulation with neutral pH induction dependent on the pH-responsive transcriptional regulator Ss-Pac1. Unlike previously characterized ultraviolet (UV)-induced oxalate-deficient mutants ('A' mutants) which retain the capacity to accumulate OA, gene deletion Δss-oah1 mutants did not accumulate OA in culture or during plant infection. This defect in OA accumulation was fully restored on reintroduction of the wild-type (WT) Ss-oah1 gene. The Δss-oah1 mutants were also deficient in compound appressorium and sclerotium development and exhibited a severe radial growth defect on medium buffered at neutral pH. On a variety of plant hosts, the Δss-oah1 mutants established very restricted lesions in which the infectious hyphae gradually lost viability. Cytological comparisons of WT and Δss-oah1 infections revealed low and no OA accumulation, respectively, in subcuticular hyphae. Both WT and mutant hyphae exhibited a transient association with viable host epidermal cells at the infection front. In summary, our experimental data establish a critical requirement for OAH activity in S. sclerotiorum OA biogenesis and pathogenesis, but also suggest that factors independent of OA contribute to the establishment of primary lesions. PMID:25285668

  13. A comparative density functional theory study of electronic structure and optical properties of γ-aminobutyric acid and its cocrystals with oxalic and benzoic acid

    NASA Astrophysics Data System (ADS)

    da Silva Filho, J. G.; Freire, V. N.; Caetano, E. W. S.; Ladeira, L. O.; Fulco, U. L.; Albuquerque, E. L.

    2013-11-01

    In this letter, we study the electronic structure and optical properties of the active medicinal component γ-aminobutyric acid (GABA) and its cocrystals with oxalic (OXA) and benzoic (BZA) acid by means of the density functional theory formalism. It is shown that the cocrystallization strongly weakens the zwitterionic character of the GABA molecule leading to striking differences among the electronic band structures and optical absorption spectra of the GABA crystal and GABA:OXA, GABA:BZA cocrystals, originating from distinct sets of hydrogen bonds. Calculated band widths and Δ-sol band gap estimates indicate that both GABA and GABA:OXA, GABA:BZA cocrystals are indirect gap insulators.

  14. Oxalate minerals on Mars?

    NASA Astrophysics Data System (ADS)

    Applin, D. M.; Izawa, M. R. M.; Cloutis, E. A.; Goltz, D.; Johnson, J. R.

    2015-06-01

    Small amounts of unidentified organic compounds have only recently been inferred on Mars despite strong reasons to expect significant concentrations and decades of searching. Based on X-ray diffraction and reflectance spectroscopic analyses we show that solid oxalic acid and its most common mineral salts are stable under the pressure and ultraviolet irradiation environment of the surface of Mars, and could represent a heretofore largely overlooked reservoir of organic carbon in the martian near-surface. In addition to the delivery to Mars by carbonaceous chondrites, oxalate minerals are among the predicted breakdown products of meteoritic organic matter delivered to the martian surface, as well as any endogenic organic carbon reaching the martian surface from the interior. A reinterpretation of pyrolysis experiments from the Viking, Phoenix, and Mars Science Laboratory missions shows that all are consistent with the presence of significant concentrations of oxalate minerals. Oxalate minerals could be important in numerous martian geochemical processes, including acting as a possible nitrogen sink (as ammonium oxalate), and contributing to the formation of “organic” carbonates, methane, and hydroxyl radicals.

  15. Actual-Waste Tests of Enhanced Chemical Cleaning for Retrieval of SRS HLW Sludge Tank Heels and Decomposition of Oxalic Acid - 12256

    SciTech Connect

    Martino, Christopher J.; King, William D.; Ketusky, Edward T.

    2012-07-01

    Savannah River National Laboratory conducted a series of tests on the Enhanced Chemical Cleaning (ECC) process using actual Savannah River Site waste material from Tanks 5F and 12H. Testing involved sludge dissolution with 2 wt% oxalic acid, the decomposition of the oxalates by ozonolysis (with and without the aid of ultraviolet light), the evaporation of water from the product, and tracking the concentrations of key components throughout the process. During ECC actual waste testing, the process was successful in decomposing oxalate to below the target levels without causing substantial physical or chemical changes in the product sludge. During ECC actual waste testing, the introduction of ozone was successful in decomposing oxalate to below the target levels. This testing did not identify physical or chemical changes in the ECC product sludge that would impact downstream processing. The results from these tests confirm observations made by AREVA NP during larger scale testing with waste simulants. This testing, however, had a decreased utilization of ozone, requiring approximately 5 moles of ozone per mole of oxalate decomposed. Decomposition of oxalates in sludge dissolved in 2 wt% OA to levels near 100 ppm oxalate using ECC process conditions required 8 to 12.5 hours without the aid of UV light and 4.5 to 8 hours with the aid of UV light. The pH and ORP were tracked during decomposition testing. Sludge components were tracked during OA decomposition, showing that most components have the highest soluble levels in the initial dissolved sludge and early decomposition samples and exhibit lower soluble levels as OA decomposition progresses. The Deposition Tank storage conditions that included pH adjustment to approximately 1 M free hydroxide tended to bring the soluble concentrations in the ECC product to nearly the same level for each test regardless of storage time, storage temperature, and contact with other tank sludge material. (authors)

  16. Atmospheric oxidation of isoprene and 1,3-Butadiene: influence of aerosol acidity and Relative humidity on secondary organic aerosol

    EPA Science Inventory

    The effects of acidic seed aerosols on the formation of secondary organic aerosol (SOA)have been examined in a number of previous studies, several of which have observed strong linear correlations between the aerosol acidity (measured as nmol H+ per m3 air s...

  17. Oxalic-acid leaching of rock, soil, and stream-sediment samples as an anomaly-accentuated technique

    USGS Publications Warehouse

    Alminas, Henry V.; Mosier, Elwin L.

    1976-01-01

    In many instances total-rock and sieved-soil and stream-sediment samples lack the sensitivity and contrast required for reconnaissance exploration and necessary in the search for blind ore deposits. Heavy-mineral concentrates incorporate the required sensitivity and contrast but are overly expensive for two reasons: time-consuming sample preparation is required to obtain them, and they cannot be easily derived from all bulk-sample types. Trace-metal-content comparisons of the oxalic-acid-leachable portions with heavy-mineral concentrates show that the leachates are equal to the heavy-mineral concentrates in sensitivity and contrast. Simplicity of preparation and the resultant cost savings are additional advantages of this proposed method.

  18. A new approach to the decontamination of asbestos-polluted waters by treatment with oxalic acid under power ultrasound.

    PubMed

    Turci, Francesco; Tomatis, Maura; Mantegna, Stefano; Cravotto, Giancarlo; Fubini, Bice

    2008-04-01

    A suspension of chrysotile asbestos fibres in aqueous 0.5M oxalic acid was subjected to power ultrasound with the aim to disrupt and detoxify the mineral by the leaching action of oxalic acid on its structural cations acting simultaneously with a vigorous acoustic cavitation. Sonication was performed in a "cavitating tube", a vertical hollow vibrating cylinder made of titanium, operating at 19.2 kHz and 150 W. Treatment lasted from 2.5 to 21 h. Scanning electron microscopy (SEM) showed that the joint action of the chelating agent and ultrasound (though not of either when applied independently) mostly converted asbestos fibres into micrometric aggregates and nano-sized debris, whose morphology totally differed from asbestos fibres. When treated suspensions were filtered through CA membranes (pore size 0.20 microm), more than half of the asbestos went through the filter because it had either been brought in solution or dispersed in the form of extremely small particles. Most of the structural metal ions were brought into solution (ICP-AES). After the treatment the BET surface area of the recovered solid was tenfold greater than the original. The crystalline fraction of residual solids, though resembling the original sample in XRD, was shown by micro-Raman spectra to be made of antigorite, a polymorph form of serpentine. Furthermore, as the length of these antigorite fibrils lay outside the fibre range rated as a health hazard under worldwide regulations, our procedure can be employed for the decontamination of chrysotile-polluted waters and sediments.

  19. The Effect of Methyl, Hydroxyl, and Ketone Functional Groups on the Heterogeneous Oxidation of Succinic Acid Aerosol by OH Radicals

    NASA Astrophysics Data System (ADS)

    Chan, M.; Zhang, H.; Wilson, K. R.

    2013-12-01

    The heterogeneous oxidation of atmospheric organic aerosols can influence their effects on climate, human health, and visibility. During oxidation, functionalization occurs when an oxygenated functional group is added to a molecule, leaving the carbon skeleton intact. Fragmentation involves carbon-carbon bond cleavage and produces two products with smaller carbon numbers than the parent compound. To gain better insights into how the molecular structure of more oxygenated organic compounds affects heterogeneous reactivity, succinic acid aerosols are photo-oxidized in an aerosol flow tube reactor, and the reaction products are analyzed using Direct Analysis in Real Time Mass Spectrometry for online chemical analysis. The effect of various functional groups (CH3, OH, C=O) along the carbon backbone on the heterogeneous reaction mechanisms are also investigated using model compounds. For this series of compounds, the formation of more oxygenated products through functionalization can be explained by well-known condensation-phase reactions such as Russell and Bennett and Summers. The number of fragmentation products is found to increase with the presence of OH and CH3 groups. This can be attributed to the increased number of tertiary carbons, enhancing the fragmentation after multiple oxidation steps. Smaller dicaids (oxalic acid and malonic acid) can be formed through the fragmentation processes in the heterogeneous oxidation of succinic acid. The effect of molecular structure on reaction kinetics, volatilization, and the relative importance of functionalization and fragmentation pathways will be discussed.

  20. Automated homogeneous oxalate precipitation of Pu(III)

    SciTech Connect

    Yarbro, S.L.; Schreiber, S.B.; Dunn, S.L.; Mills, C.W.

    1990-01-01

    Homogeneous oxalate precipitation using diethyl oxalate was compared to precipitating Pu(III) oxalate with solid oxalic acid. The diethyl oxalate technique at 75{degree}C is better because it gives 50% less plutonium in the filtrate with a reasonable filtering time. Also, the procedure for the homogeneous precipitation is easier to automate because the liquid diethyl oxalate is simpler to introduce into the precipitator than solid oxalic acid. It also provides flexibility because the hydrolysis rate and therefore the precipitation rate can be controlled by varying the temperature. 5 refs., 3 figs., 3 tabs.

  1. Organic and inorganic aerosol compositions in Ulaanbaatar, Mongolia, during the cold winter of 2007 to 2008: Dicarboxylic acids, ketocarboxylic acids, and α-dicarbonyls

    NASA Astrophysics Data System (ADS)

    Jung, Jinsang; Tsatsral, Batmunkh; Kim, Young J.; Kawamura, Kimitaka

    2010-11-01

    To investigate the distributions and sources of water-soluble organic acids in the Mongolian atmosphere, aerosol samples (PM2.5, n = 34) were collected at an urban site (47.92°N, 106.90°E, ˜1300 m above sea level) in Ulaanbaatar, the capital of Mongolia, during the cold winter. The samples were analyzed for water-soluble dicarboxylic acids (C2-C12) and related compounds (ketocarboxylic acids and α-dicarbonyls), as well as organic carbon (OC), elemental carbon, water-soluble OC, and inorganic ions. Distributions of dicarboxylic acids and related compounds were characterized by a predominance of terephthalic acid (tPh; 130 ± 51 ng m-3, 19% of total detected organic acids) followed by oxalic (107 ± 28 ng m-3, 15%), succinic (63 ± 20 ng m-3, 9%), glyoxylic (55 ± 18 ng m-3, 8%), and phthalic (54 ± 27 ng m-3, 8%) acids. Predominance of terephthalic acid, which has not been reported previously in atmospheric aerosols, was mainly due to uncontrolled burning of plastic bottles and bags in home stoves for heating and waste incineration during the cold winter. This study demonstrated that most of the air pollutants were directly emitted from local sources such as heat and power plants, home stoves, and automobiles. Development of an inversion layer (<700 m above ground level) over the basin of Ulaanbaatar accelerated the accumulation of pollutants, causing severe haze episodes during the winter season.

  2. Furnace-generated acid aerosols: speciation and pulmonary effects.

    PubMed

    Amdur, M O; Chen, L C

    1989-02-01

    Guinea pigs were exposed to ultrafine aerosols (less than 0.1 micron) of zinc oxide with a surface layer of sulfuric acid. These acid-coated aerosols are typical of primary emissions from smelters and coal combustors. Repeated daily 3-hr exposures for 5 days produce decrements in lung volumes and pulmonary diffusing capacity and elevations of lung weight/body weight ratio, protein, and number of neutrophils in pulmonary lavage fluid at concentrations of 20 micrograms/m3. A single 1-hr exposure to 20 micrograms/m3 causes increased bronchial reactivity. Higher concentrations of conventionally generated sulfuric acid mist are required to produce responses of similar magnitude.

  3. Characterization and reconstruction of historical London, England, acidic aerosol concentrations

    SciTech Connect

    Ito, K.; Thurston, G.D.

    1989-02-01

    Several past studies of the historical London air pollution record have reported an association between daily mortality and British Smoke levels. However, this pollution index does not give direct information on particulate mass or its chemical composition. A more specific particulate matter index, aerosol acidity, was measured at a site in central London, and daily data are available for the period 1963-1972. British smoke and SO/sub 2/ were also measured at the same site. Also, meteorological parameters were routinely measured at a nearby British Meteorological Office. Thus, daily fluctuation of the acidic aerosols was characterized in terms of other environmental parameters. Each of the other parameters analyzed seems necessary, but not sufficient to explain a high level of acidic aerosol. Overall, about half of the variance of log-transformed daily fluctuations of acidic aerosols can be explained by a combination of parameters including SO/sub 2/ and British smoke concentrations, temperature, ventilation by wind, and humidity. The rest of the variance cannot be explained by the parameters included in this analysis. Potential factors responsible for this unique variance would be variations in the availability of basic gases to cause neutralization and variation in the availability of catalytic metal salts. Because the acidic aerosol has a unique component of variation, it may be possible to distinguish health effects due to this specific pollutant from other available pollution indices or environmental factors.

  4. Characterization and reconstruction of historical London, England, acidic aerosol concentrations.

    PubMed

    Ito, K; Thurston, G D

    1989-02-01

    Several past studies of the historical London air pollution record have reported an association between daily mortality and British Smoke levels. However, this pollution index does not give direct information on particulate mass or its chemical composition. A more specific particulate matter index, aerosol acidity, was measured at a site in central London, and daily data are available for the period 1963-1972. British Smoke and SO2 were also measured at the same site. Also, meteorological parameters were routinely measured at a nearby British Meteorological Office. Thus, daily fluctuation of the acidic aerosols was characterized in terms of other environmental parameters. Each of the other parameters analyzed seems necessary, but not sufficient to explain a high level of acidic aerosol. Overall, about half of the variance of log-transformed daily fluctuations of acidic aerosols can be explained by a combination of parameters including SO2 and British Smoke concentrations, temperature, ventilation by wind, and humidity. The rest of the variance cannot be explained by the parameters included in this analysis. Potential factors responsible for this unique variance would be variations in the availability of basic gases to cause neutralization and variation in the availability of catalytic metal salts. Because the acidic aerosol has a unique component of variation, it may be possible to distinguish health effects due to this specific pollutant from other available pollution indices or environmental factors.

  5. Preharvest application of oxalic acid increased fruit size, bioactive compounds, and antioxidant capacity in sweet cherry cultivars (Prunus avium L.).

    PubMed

    Martínez-Esplá, Alejandra; Zapata, Pedro Javier; Valero, Daniel; García-Viguera, Cristina; Castillo, Salvador; Serrano, María

    2014-04-16

    Trees of 'Sweet Heart' and 'Sweet Late' sweet cherry cultivars (Prunus avium L.) were treated with oxalic acid (OA) at 0.5, 1.0, and 2.0 mM at 98, 112, and 126 days after full blossom. Results showed that all treatments increased fruit size at harvest, manifested by higher fruit volume and weight in cherries from treated trees than from controls, the higher effect being found with 2.0 mM OA (18 and 30% higher weight for 'Sweet Heart' and 'Sweet Late', respectively). Other quality parameters, such as color and firmness, were also increased by OA treatments, although no significant differences were found in total soluble solids or total acidity, showing that OA treatments did not affect the on-tree ripening process of sweet cherry. However, the increases in total anthocyanins, total phenolics, and antioxidant activity associated with the ripening process were higher in treated than in control cherries, leading to fruit with high bioactive compounds and antioxidant potential at commercial harvest (≅45% more anthocyanins and ≅20% more total phenolics). In addition, individual anthocyanins, flavonols, and chlorogenic acid derivatives were also increased by OA treatment. Thus, OA preharvest treatments could be an efficient and natural way to increase the quality and functional properties of sweet cherries. PMID:24684635

  6. Chrysotile asbestos detoxification with a combined treatment of oxalic acid and silicates producing amorphous silica and biomaterial.

    PubMed

    Valouma, Aikaterini; Verganelaki, Anastasia; Maravelaki-Kalaitzaki, Pagona; Gidarakos, Evangelos

    2016-03-15

    This study was primarily imposed by the ever increasing need for detoxification of asbestos and asbestos containing materials (ACM), with potential application onsite. The present work investigates potential detoxification of pure chrysotile (Chr) asbestos via a combined treatment of oxalic acid dihydrate (Oxac) (Η2C2Ο4·2Η2Ο) with silicates, such as tetraethoxysilane (TEOS) (SiH20C8O4) and pure water glass (WG) (potassium silicate) (K2SiO3). These reagents used in the experimental procedure, do not cause adverse effects on the environment and are cost effective. The results of FTIR, XRD, optical and scanning microscopy coupled with EDS analyses indicated that all of the applied treatments destructed the Chr structure and yielded silica of amorphous phase and the biomaterial glushinskite from the Oxac reacted with brucite [Mg(OH)2] layer. Each of the proposed formulations can be applied for the detoxification of asbestos, according to priorities related to the specific products of the recovery treatment. Therefore, Oxac acid leaching followed by the TEOS addition is preferred in cases of glushinskite recovery; TEOS treatment of asbestos with subsequent Oxac addition produced amorphous silica production; finally Oxac acid leaching followed by WG encapsulated the asbestos fibers and can be used in cases of onsite asbestos and ACM detoxification.

  7. Aluminium resistance requires resistance to acid stress: a case study with spinach that exudes oxalate rapidly when exposed to Al stress.

    PubMed

    Yang, Jian Li; Zheng, Shao Jian; He, Yun Feng; Matsumoto, Hideaki

    2005-04-01

    Spinach is a vegetable with a high oxalate concentration in its tissues. Oxalate efflux from spinach (Spinacia oleracea L. cv. Quanneng) roots was rapidly stimulated (within 30 min) by aluminium (Al) treatment. The efflux was constant within 6 h, but increased with increasing Al concentration. The efflux was confined to the root tip (0-5 mm), which showed a 5-fold greater efflux than the root zone distal to the tip (5-10 mm). Oxalate efflux could not be triggered by treatment with the trivalent cation lanthanum or by phosphorus deficiency, indicating that the efflux was specific to the Al treatment. All this evidence suggested that spinach possesses Al-resistance mechanisms. However, spinach was found to be as sensitive to Al toxicity as the Al-sensitive wheat line ES8, which had no Al-dependent organic acids efflux. The Al accumulated in the apical 5 mm of the roots of spinach which was also similar to that in the Al-sensitive wheat after 24 h treatment with 50 microM AlCl(3), indicating a non-exclusion mechanism. In addition, root elongation in spinach was significantly inhibited at pH 4.5, compared with that at pH 6.5. Based on this evidence, it is concluded that the sensitivity to acid stress in spinach could mask the potential role for oxalate to protect the plant roots from Al toxicity.

  8. Diurnal variations of total carbon, dicarboxylic acids, ketoacids and α-dicarbonyls in aerosols in the northern vicinity of Beijing

    NASA Astrophysics Data System (ADS)

    He, N.; Kawamura, K.; Okuzawa, K.; Kanaya, Y.; Wang, Z. F.

    2013-06-01

    Aerosol samples (TSP, n=58) were collected on day- and night-time basis at Mangshan in the north of Beijing, China in autumn 2007 to better understand the status of air quality and the influence of urban pollutants in the northern vicinity of Beijing. The samples were analyzed for aerosol mass, total carbon (TC), low molecular weight α, ω-dicarboxylic acids (C2-C12), ketoacids (ωC2-ωC9, pyruvic acid), α-dicarbonyls (glyoxal and methylglyoxal), as well as aromatic (phthalic, iso- and tere-phthalic) diacids. Aerosol mass and TC concentrations are higher in daytime than in nighttime. TC/aerosol mass ratios in this study are lower than those reported in megacities in East Asia, but higher than those reported in marine aerosols. Molecular distributions of diacids demonstrated that oxalic (C2) acid was the most abundant species, comprising 38-77% of total diacids, followed by succinic (C4) and malonic (C3) acids. For most compounds, the concentrations were higher in daytime than nighttime, indicating that diacids are produced in daytime by photochemical oxidation of organic precursors emitted from anthropogenic sources in Beijing during the transport to Mangshan area by the northward wind. However, we found that C2 concentrations are higher in nighttime than in daytime. A positive correlation of C2 to glyoxylic acid (ωC2) was obtained at night when relative humidity increased up to 100%, suggesting that aqueous phase production of C2 occurs in nighttime via the oxidation of ωC2. Depletion of C2 by photolysis of Fe-oxalato complexes might be another reason for the lower concentrations of C2 in daytime samples. High phthalic acid/C4 ratios in the aerosol samples suggest that automobile combustion and coal burning products are important sources, which are subjected to photochemical oxidation during the atmospheric transport of urban aerosols from Beijing. In contrast, higher concentrations of methylglyoxal in nighttime than daytime may suggest that isoprene emitted

  9. Estimation of the oxalate content of foods and daily oxalate intake

    NASA Technical Reports Server (NTRS)

    Holmes, R. P.; Kennedy, M.

    2000-01-01

    BACKGROUND: The amount of oxalate ingested may be an important risk factor in the development of idiopathic calcium oxalate nephrolithiasis. Reliable food tables listing the oxalate content of foods are currently not available. The aim of this research was to develop an accurate and reliable method to measure the food content of oxalate. METHODS: Capillary electrophoresis (CE) and ion chromatography (IC) were compared as direct techniques for the estimation of the oxalate content of foods. Foods were thoroughly homogenized in acid, heat extracted, and clarified by centrifugation and filtration before dilution in water for analysis. Five individuals consuming self-selected diets maintained food records for three days to determine their mean daily oxalate intakes. RESULTS: Both techniques were capable of adequately measuring the oxalate in foods with a significant oxalate content. With foods of very low oxalate content (<1.8 mg/100 g), IC was more reliable than CE. The mean daily intake of oxalate by the five individuals tested was 152 +/- 83 mg, ranging from 44 to 352 mg/day. CONCLUSIONS: CE appears to be the method of choice over IC for estimating the oxalate content of foods with a medium (>10 mg/100 g) to high oxalate content due to a faster analysis time and lower running costs, whereas IC may be better suited for the analysis of foods with a low oxalate content. Accurate estimates of the oxalate content of foods should permit the role of dietary oxalate in urinary oxalate excretion and stone formation to be clarified. Other factors, apart from the amount of oxalate ingested, appear to exert a major influence over the amount of oxalate excreted in the urine.

  10. Effects of aerosol formulation to amino acids and fatty acids contents in Haruan extract.

    PubMed

    Febriyenti; Bai-Baie, Saringat Bin; Laila, Lia

    2012-01-01

    Haruan (Channa striatus) extract was formulated to aerosol for wound and burn treatment. Haruan extract is containing amino acids and fatty acids that important for wound healing process. The purpose of this study is to observe the effect of formulation and other excipients in the formula to amino acids and fatty acids content in Haruan extract before and after formulated into aerosol. Precolumn derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC) method is used for amino acids analysis. Fatty acids in Haruan extract were esterified using transesterification method to form FAMEs before analyzed using GC. Boron trifluoride-methanol reagent is used for transesterification. Tyrosine and methionine concentrations were different after formulated. The concentrations were decrease. There are six fatty acids have amount that significantly different after formulated into concentrate and aerosol. Contents of these fatty acids were increase. Generally, fatty acids which had content increased after formulated were the long-chain fatty acids. This might be happen because of chain extension process. Saponification and decarboxylation would give the chain extended product. Therefore contents of long-chain fatty acids were increase. Generally, the aerosol formulation did not affect the amino acids concentrations in Haruan extract while some long-chain fatty acids concentrations were increase after formulated into concentrate and aerosol.

  11. Effect of organic and conventional cropping systems on ascorbic acid, vitamin C, flavonoids, nitrate, and oxalate in 27 varieties of spinach (Spinacia oleracea L.).

    PubMed

    Koh, Eunmi; Charoenprasert, Suthawan; Mitchell, Alyson E

    2012-03-28

    This study was undertaken to compare the levels of ascorbic acid, vitamin C, flavonoids, nitrate, and oxalate in 27 spinach varieties grown in certified organic and conventional cropping systems. Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-(ESI)MS/MS) of methanolic extracts of spinach demonstrated 17 flavonoids, including glucuronides and acylated di- and triglycosides of methylated and methylenedioxyderivatives of 6-oxygenated flavonoids. The mean levels of ascorbic acid and flavonoids were significantly (p < 0.001) higher in the organically grown [40.48 ± 6.16 and 2.83 ± 0.03 mg/kg of fresh weight (FW)] spinach compared to the conventionally grown spinach (25.75 ± 6.12 and 2.27 ± 0.02 mg/kg of FW). Conversely, the mean levels of nitrate were significantly (p < 0.001) higher in the conventionally grown spinach compared to the organically grown spinach. No significant effects were observed in the oxalate content of spinach from either production system. The levels of nitrate correlated negatively with those of ascorbic acid, vitamin C, and total flavonoids and showed a positive correlation with the oxalate content. These results suggest that organic cropping systems result in spinach with lower levels of nitrates and higher levels of flavonoids and ascorbic acid.

  12. Organics Substantially Reduce HO2 Uptake onto Aerosols Containing Transition Metal ions.

    PubMed

    Lakey, Pascale S J; George, Ingrid J; Baeza-Romero, Maria T; Whalley, Lisa K; Heard, Dwayne E

    2016-03-10

    A HO2 mass accommodation coefficient of α = 0.23 ± 0.07 was measured onto submicron copper(II)-doped ammonium sulfate aerosols at a relative humidity of 60 ± 3%, at 293 ± 2 K and at an initial HO2 concentration of ∼ 1 × 10(9) molecules cm(-3) by using an aerosol flow tube coupled to a sensitive fluorescence assay by gas expansion (FAGE) HO2 detection system. The effect upon the HO2 uptake coefficient γ of adding different organic species (malonic acid, citric acid, 1,2-diaminoethane, tartronic acid, ethylenediaminetetraacetic acid (EDTA), and oxalic acid) into the copper(II)-doped aerosols was investigated. The HO2 uptake coefficient decreased steadily from the mass accommodation value to γ = 0.008 ± 0.009 when EDTA was added in a one-to-one molar ratio with the copper(II) ions, and to γ = 0.003 ± 0.004 when oxalic acid was added into the aerosol in a ten-to-one molar ratio with the copper(II). EDTA binds strongly to copper(II) ions, potentially making them unavailable for catalytic destruction of HO2, and could also be acting as a surfactant or changing the viscosity of the aerosol. The addition of oxalic acid to the aerosol potentially forms low-volatility copper-oxalate complexes that reduce the uptake of HO2 either by changing the viscosity of the aerosol or by causing precipitation out of the aerosol forming a coating. It is likely that there is a high enough oxalate to copper(II) ion ratio in many types of atmospheric aerosols to decrease the HO2 uptake coefficient. No observable change in the HO2 uptake coefficient was measured when the other organic species (malonic acid, citric acid, 1,2-diaminoethane, and tartronic acid) were added in a ten-to-one molar ratio with the copper(II) ions.

  13. Water-soluble dicarboxylic acids and ω-oxocarboxylic acids in size-segregated aerosols over northern Japan during spring: sources and formation processes

    NASA Astrophysics Data System (ADS)

    Deshmukh, Dhananjay Kumar; Kawamura, Kimitaka; Kobayashi, Minoru; Gowda, Divyavani

    2016-04-01

    Seven sets (AF01-AF07) of size-segregated aerosol (12-sizes) samples were collected using a Micro-Orifice Uniform Deposit Impactor (MOUDI) in Sapporo, Japan during the spring of 2001 to understand the sources and atmospheric processes of water-soluble organic aerosols in the outflow region of Asian dusts. The samples were analyzed for dicarboxylic acids (C2-C12) and ω-oxocarboxylic acids as well as inorganic ions. The molecular distribution of diacids showed the predominance of oxalic acid (C2) followed by malonic and succinic acids whereas ω-oxoacids showed the predominance of glyoxylic acid (ωC2) in size-segregated aerosols. SO42- and NH4+ are enriched in submicron mode whereas NO3- and Ca2+ are in supermicron mode. Most of diacids and ω-oxoacids are enriched in supermicron mode in the samples (AF01-AF03) influenced by the long-range transport of mineral dusts whereas enhanced presence in submicron mode was observed in other sample sets. The strong correlations of C2 with Ca2+ (r = 0.95-0.99) and NO3- (r = 0.96-0.98) in supermicron mode in the samples AF01-AF03 suggest the adsorption or production of C2 diacid via heterogeneous reaction on the surface of mineral dust during long-range atmospheric transport. The preferential enrichment of diacids and ω-oxoacids in mineral dust has important implications for the solubility and cloud nucleation properties of the dominant fraction of water-soluble organic aerosols. This study demonstrates that biofuel and biomass burning and mineral dust originated in East Asia are two major factors to control the size distribution of diacids and related compounds over northern Japan.

  14. Exposure of acid aerosol for schoolchildren in metropolitan Taipei

    NASA Astrophysics Data System (ADS)

    Mao, I.-Fang; Lin, Chih-Hung; Lin, Chun-Ji; Chen, Yi-Ju; Sung, Fung-Chang; Chen, Mei-Lien

    Metropolitan Taipei, which is located in the subtropical area, is characterized by high population and automobile densities. For convenience, most primary schools are located near major roads. This study explores the exposure of acid aerosols for schoolchildren in areas in Taipei with different traffic densities. Acid aerosols were collected by using a honeycomb denuder filter pack sampling system (HDS). Experimental results indicated that the air pollutants were significantly correlated with traffic densities. The ambient air NO 2, SO 2, HNO 3, NO 3-, SO 42-, and aerosol acidity concentrations were 31.3 ppb, 4.7 ppb, 1.3 ppb, 1.9 μg m -3, 18.5 μg m -3, and 49.5 nmol m -3 in high traffic density areas, and 6.1 ppb, 1.8 ppb, 0.9 ppb, 0.7 μg m -3, 8.8 μg m -3 and 14.7 nmol m -3 in low traffic density areas. The exposure levels of acid aerosols for schoolchildren would be higher than the measurements because the sampling height was 5 m above the ground. The SO 2 levels were low (0.13-8.03 ppb) in the metropolitan Taipei. However, the SO 42- concentrations were relatively high, and might be attributed to natural emissions of sulfur-rich geothermal sources. The seasonal variations of acid aerosol concentrations were also observed. The high levels of acidic particles in spring time may be attributed to the Asian dust storm and low height of the mixture layer. We conclude that automobile contributed not only the primary pollutants but also the secondary acid aerosols through the photochemical reaction. Schoolchildren were exposed to twice the acid aerosol concentrations in high traffic density areas compared to those in low traffic density areas. The incidence of allergic rhinitis of schoolchildren in the high traffic density areas was the highest in spring time. Accompanied by high temperature variation and high levels of air pollution in spring, the health risk of schoolchildren had been observed.

  15. An improved thermodynamic model for the complexation of trivalent actinides and lanthanide with oxalic acid valid to high ionic strength.

    DOE PAGES

    Xiong, Yongliang; Thakur, Punam; Borkowski, Marian

    2015-07-30

    The dissociation constants of oxalic acid (Ox), and the stability constants of Am3+, Cm3+ and Eu3+ with Ox2– have been determined at 25 °C, over a range of concentration varying from 0.1 to 6.60 m NaClO4 using potentiometric titration and extraction techniques, respectively. The experimental data support the formation of complexes, M(Ox)n3 – 2n, where (M = Am3+, Cm3+ and Eu3+ and n = 1 and 2). The dissociation constant and the stability constant values measured as a function of NaClO4 concentration were used to estimate the Pitzer parameters for the respective interactions of Am3+, Cm3+ and Eu3+ with Ox.more » Furthermore, the stability constants data of Am3+ –Ox measured in NaClO4 and in NaCl solutions from the literature were simultaneously fitted in order to refine the existing actinide–oxalate complexation model that can be used universally in the safety assessment of radioactive waste disposal. The thermodynamic stability constant: log β0101 = 6.30 ± 0.06 and log β0102 = 10.84 ± 0.06 for Am3+ was obtained by simultaneously fitting data in NaCl and NaClO4 media. Additionally, log β0101 = 6.72 ± 0.08 and log β0102 = 11.05 ± 0.09 for the Cm3+ and log β0101 = 6.67 ± 0.08 and log β0102 = 11.15 ± 0.09 for the Eu3+ were calculated by extrapolation of data to zero ionic strength in NaClO4 medium only. For all stability constants, the Pitzer model gives an excellent representation of the data using interaction parameters β(0), β(1), and CΦ determined in this work. The thermodynamic model developed in this work will be useful in accurately modeling the potential solubility of trivalent actinides and early lanthanides to ionic strength of 6.60 m in low temperature environments in the presence of Ox. Furthermore, the work is also applicable to the accurate modeling transport of rare earth elements in various environments under the surface conditions.« less

  16. Short term tolvaptan increases water intake and effectively decreases urinary calcium oxalate, calcium phosphate, and uric acid supersaturations

    PubMed Central

    Cheungpasitporn, Wisit; Erickson, Stephen B.; Rule, Andrew D.; Enders, Felicity; Lieske, John C.

    2016-01-01

    Purpose Many patients cannot effectively increase water intake and urine volume to prevent urinary stones. Tolvaptan, a V2 receptor antagonist, blocks water reabsorption in the collecting duct and should reduce urinary supersaturation (SS) of stone forming solutes, but this has never been proven. Materials and Methods We conducted a double blind, randomized, placebo-controlled, crossover study in 21 adult calcium urinary stone formers stratified as majority calcium oxalate(CaOx, n=10) or calcium phosphate(CaP, n=11). Patients received tolvaptan 45 mg/day or placebo for 1 week, followed by a washout week and crossover to tolvaptan or placebo for week 3. A 24h urines was collected at the end of weeks 1 and 3. Results Tolvaptan vs. placebo decreased urinary osmolality (204±96 vs 529±213 mOsm/kg, P<0.001) and increased urinary volume (4.8±2.9 vs 1.8±0.9 L, P<0.001). The majority of urinary solute excretion rates including sodium and calcium did not significantly change, although oxalate secretion slightly increased (23±8 to 15±8 mg/24h, P = 0.009). Urinary CaOx SS (−0.01±1.14 vs 0.95±0.87 DG, P<0.001), CaP SS (−1.66±1.17 vs −0.13±1.02 DG, P<0.001) and Uric Acid SS (−2.05±4.05 vs −5.24±3.12 DG, P=0.04) all dramatically decreased. Effects did not differ between CaOx and CaP groups (P>0.05 for all interactions). Conclusions Tolvaptan increases urine volume and decreases urinary SS in calcium stone formers. Further study is needed to determine if long term use of V2 receptor antagonists results in fewer stone events. PMID:26598423

  17. Water-soluble organic carbon, dicarboxylic acids, ketoacids, and α-dicarbonyls in the tropical Indian aerosols

    NASA Astrophysics Data System (ADS)

    Pavuluri, Chandra Mouli; Kawamura, Kimitaka; Swaminathan, T.

    2010-06-01

    Tropical aerosol (PM10) samples (n = 49) collected from southeast coast of India were studied for water-soluble dicarboxylic acids (C2-C12), ketocarboxylic acids (C2-C9), and α-dicarbonyls (glyoxal and methylglyoxal), together with analyses of total carbon (TC) and water-soluble organic carbon (WSOC). Their distributions were characterized by a predominance of oxalic acid followed by terephthalic (t-Ph), malonic, and succinic acids. Total concentrations of diacids (227-1030 ng m-3), ketoacids (16-105 ng m-3), and dicarbonyls (4-23 ng m-3) are comparative to those from other Asian megacities such as Tokyo and Hong Kong. t-Ph acid was found as the second most abundant diacid in the Chennai aerosols. This feature has not been reported previously in atmospheric aerosols. t-Ph acid is most likely derived from the field burning of plastics. Water-soluble diacids were found to contribute 0.4%-3% of TC and 4%-11% of WSOC. Based on molecular distributions and backward air mass trajectories, we found that diacids and related compounds in coastal South Indian aerosols are influenced by South Asian and Indian Ocean monsoons. Organic aerosols are also suggested to be significantly transported long distances from North India and the Middle East in early winter and from Southeast Asia in late winter, but some originate from photochemical reactions over the Bay of Bengal. In contrast, the Arabian Sea, Indian Ocean, and South Indian continent are suggested as major source regions in summer. We also found daytime maxima of most diacids, except for C9 and t-Ph acids, which showed nighttime maxima in summer. Emissions from marine and terrestrial plants, combined with land/sea breezes and in situ photochemical oxidation, are suggested especially in summer as an important factor that controls the composition of water-soluble organic aerosols over the southeast coast of India. Regional emissions from anthropogenic sources are also important in megacity Chennai, but their influence is

  18. Photolytic destruction of oxalate in aqueous mixed waste

    SciTech Connect

    Wang, F.T.; Lum, B.Y.

    1995-03-01

    In aqueous plutonium processing, residual oxalic acid can be destroyed (oxalate kill) by UV light with hydrogen peroxide (H{sub 2}O{sub 2}) in 1 M HCl solutions. By controlling the amount of H{sub 2}O{sub 2}, the oxalate kill process will not affect the chloride concentration. In nitric acid solutions, UV light alone can destroy the oxalic acid. However, with H{sub 2}O{sub 2}, the rate of destruction is faster. After the destruction of oxalic acid, the acidic solutions may be reusable without further purification process.

  19. FTIR studies of low temperature sulfuric acid aerosols

    NASA Technical Reports Server (NTRS)

    Anthony, S. E.; Tisdale, R. T.; Disselkamp, R. S.; Tolbert, M. A.; Wilson, J. C.

    1995-01-01

    Sub-micrometer sized sulfuric acid H2SO4 particles were generated using a constant output atomizer source. The particles were then exposed to water vapor before being injected into a low temperature cell. Multipass transmission Fourier Transformation Infrared (FTIR) spectroscopy was used to determine the phase and composition of the aerosols as a function of time for periods of up to five hours. Binary H2SO4H2O aerosols with compositions from 35 to 95 wt % H2SO4 remained liquid for over 3 hours at room temperatures ranging from 189-240 K. These results suggest that it is very difficut to freeze SSAs via homogeneous nucleation. Attempts to form aerosols more dilute than 35 wt % H2SO4 resulted in ice formation.

  20. Dicarboxylic acids, ω-oxocarboxylic acids, α-dicarbonyls, WSOC, OC, EC, and inorganic ions in wintertime size-segregated aerosols from central India: Sources and formation processes.

    PubMed

    Deshmukh, Dhananjay K; Kawamura, Kimitaka; Deb, Manas K

    2016-10-01

    The size distributions of aerosols can provide evidences for their sources and formation processes in the atmosphere. Size-segregated aerosols (9-sizes) were collected in urban site (Raipur: 21.2°N and 82.3°E) in central India during winter of 2012-2013. The samples were analyzed for dicarboxylic acids (C2-C12), ω-oxocarboxylic acids (ωC2-ωC9), pyruvic acid and α-dicarbonyls (C2-C3) as well as elemental carbon (EC), organic carbon (OC), water-soluble OC (WSOC) and inorganic ions. Diacids showed a predominance of oxalic acid (C2) followed by succinic and azelaic acid whereas ω-oxoacids exhibited a predominance of glyoxylic acid and glyoxal was more abundant than methylglyoxal in all the sizes. Diacids, ω-oxoacids and α-dicarbonyls showed bimodal size distribution with peaks in fine and coarse modes. High correlations of fine mode diacids and related compounds with potassium and levoglucosan suggest that they were presumably due to a substantial contribution of primary emission from biomass burning and secondary production from biomass burning derived precursors. High correlations of C2 with higher carbon number diacids (C3-C9) suggest that they have similar sources and C2 may be produced via the decay of its higher homologous diacids in fine mode. Considerable portions of diacids and related compounds in coarse mode suggest that they were associated with mineral dust particles by their adsorption and photooxidation of anthropogenic and biogenic precursors via heterogeneous reaction on dust surface. This study demonstrates that biomass burning and dust particles are two major factors to control the size distribution of diacids and related compounds in the urban aerosols from central India. PMID:27414241

  1. Molecular distributions and stable carbon isotopic compositions of dicarboxylic acids and related compounds in aerosols from Sapporo, Japan: Implications for photochemical aging during long-range atmospheric transport

    NASA Astrophysics Data System (ADS)

    Aggarwal, Shankar G.; Kawamura, Kimitaka

    2008-07-01

    Molecular and stable carbon isotopic (δ13C value) compositions of dicarboxylic acids, ketoacids, and dicarbonyls in aerosol samples (i.e., total suspended particles) collected in Sapporo, northern Japan during spring and summer were determined to better understand the photochemical aging of organic aerosols during long-range transport from East Asia and Siberia. Their molecular distributions were characterized by the predominance of oxalic acid (C2) followed by malonic (C3) or occasionally succinic (C4) acids. Concentrations of total diacids ranged from 106-787 ng m-3 with ketoacids (13-81 ng m-3) and dicarbonyls (2.6-28 ng m-3) being less abundant. Water-soluble organic carbon (WSOC) comprised 23-69% of aerosol organic carbon (OC). OC to elemental carbon (EC) ratios were high (3.6-19, mean: 8.7). The ratios of C3/C4 and WSOC/OC did not show significant diurnal changes, suggesting that the Sapporo aerosols were not seriously affected by local photochemical processes and instead they were already aged. δ13C values of the dominant diacids (C2 - C4) ranged from -14.0 to -25.3‰. Largest δ13C values (-14.0 to -22.4‰, mean: -18.8‰) were obtained for C2, whereas smallest values (-25.1 to -31.4‰, mean: -28.1‰) were for azelaic acid (C9). In general, δ13C values of C2 - C4 diacids became less negative with aerosol aging (i.e., WSOC/OC), presumably due to isotopic fractionation during photochemical degradation of diacids. By comparing the δ13C values of diacids in the Sapporo aerosols with different air mass source regions, we suggest that although initial δ13C values of diacids depend on their precursor sources, the enrichment in 13C can be ascribed to aerosol photochemical aging.

  2. Molecular composition of dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls and fatty acids in atmospheric aerosols from Tanzania, East Africa during wet and dry seasons

    NASA Astrophysics Data System (ADS)

    Mkoma, S. L.; Kawamura, K.

    2013-02-01

    Atmospheric aerosol samples of PM2.5 and PM10 were collected during the wet and dry seasons in 2011 from a rural site in Tanzania and analysed for water-soluble dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls, and fatty acids using a gas chromatography/flame ionization detector (GC/FID) and GC/mass spectrometry. Here we report the molecular composition and sources of diacids and related compounds for wet and dry seasons. Oxalic acid (C2) was found as the most abundant diacid species followed by succinic and/or malonic acids whereas glyoxylic acid and glyoxal were the dominant ketoacid and α-dicarbonyl, respectively in both seasons in PM2.5 and PM10. Mean concentration of C2 in PM2.5 (121 ± 47 ng m-3) was lower in wet season than dry season (258 ± 69 ng m-3). Similarly, PM10 samples showed lower concentration of C2 (169 ± 42 ng m-3) in wet season than dry season (292 ± 165 ng m-3). Relative abundances of C2 in total diacids were 65% and 67% in PM2.5 and 65% and 64% in PM10 in the wet and dry seasons, respectively. Total concentrations of diacids (289-362 ng m-3), ketoacids (37.8-53.7 ng m-3), and α-dicarbonyls (5.7-7.8 ng m-3) in Tanzania are higher than those reported at a rural background site in Nylsvley (South Africa) but comparable or lower than those reported from sites in Asia and Europe. Diacids and ketoacids were found to be present mainly in PM2.5 in both seasons (total α-dicarbonyls in the dry season), suggesting a production of organic acids from pyrogenic sources and photochemical oxidations. Averaged contributions of total diacids to aerosol total carbon were 1.4% in PM2.5 and 2.1% in PM10 during wet season and 3.3% in PM2.5 and 3.9% in PM10 during dry season whereas those to water-soluble organic carbon were 2.2% and 4.7% in PM2.5 during wet season and 3.1% and 5.8% in PM10 during dry season. The higher ratios in dry season suggest an enhanced photochemical oxidation of organic precursors probably via heterogeneous reactions on

  3. Complex dynamic behavior in the bromate-oxalic acid-acetone-Mn(II) oscillating reaction in a continuous stirred tank reactor (CSTR)

    NASA Astrophysics Data System (ADS)

    Silva, Lucyane C.; Faria, Roberto B.

    2007-05-01

    The oscillating reaction bromate-oxalic acid-acetone-Mn(II)-sulfuric acid was observed for the first time in a CSTR at 20 °C. Depending on the bromate concentrations and flow rate, the system showed large amplitude oscillations, two kinds of mixed mode oscillations, quasiperiodicity and bursts of large amplitude oscillations, all mapped in a phase diagram. More complex behavior was favored at low bromate concentrations. The system without acetone was discovered to oscillate too, but the more complex patterns were not seen, indicating that acetone is implied in their formation.

  4. Supercooling versus crystallization of nitric acid/water aerosols

    SciTech Connect

    Disselkamp, R.S.; Anthony, S.E.; Tolbert, M.A.

    1995-12-31

    Polar Stratospheric Clouds (PSCs) have been implicated in Antarctic and Arctic ozone loss. These clouds are comprised of small particles (diameter {approximately}1 {mu}m) and play two essential roles in perturbing the chemistry of ozone during winter. First, PSCs promote heterogeneous reactions which activate chlorine. Second, PSCs permanently remove nitrogen oxides from the stratosphere due to particle sedimentation. Both PSC reactivity and denitrification depend on the particle phase and composition. In my talk, I will discuss laboratory modeling of PSCs. FTIR spectroscopy was used to investigate the phase and composition of nitric acid/water aerosols at temperatures from 190 to 229 K. Static aerosol samples were generated and probed spectroscopically for time periods of up to 100 minutes. For aerosols containing a molar ratio of 1:1 and 3:1 H{sub 2}O:HNO{sub 3}, extensive supercooling was observed with no crystallization in 100 minutes. However, aerosols containing a molar ratio of 2:1 H{sub 2}O:HNO{sub 3} crystallized readily to nitric acid dehydrate (NAD). The rate of NAD crystallization was found to increase with increasing temperature and will be discussed.

  5. Laboratory studies of nitric acid hydrate and sulfuric acid aerosols: Implications for polar stratospheric cloud formation

    SciTech Connect

    Miller, R.E.

    1995-12-31

    The optical properties of atmospheric aerosols are important in a number of modeling and remote sensing applications. We have devised a new approach for determining the frequency dependent real and imaginary refractive indices directly from the observation of the infrared spectra of the aerosols. We have applied this method to the study of water ice aerosols and comparisons with previous measurements confirm that the method is sound and accurate. The temperature dependence of the refractive index of ice has also been measured over the range 130 K to 210 K, which includes the region of interest for the study of Polar Stratospheric Clouds (PSC`s). The method has also been applied to the study of nitric acid dehydrate (NAD) and nitric acid trihydrate (NAT). Sulfuric acid/nitric acid/water ternary systems are also being studied with the aim of determining the nature of the phases formed and the associated freezing points as a function of the concentrations of the acids.

  6. Combined administration of oxalic acid, succimer and its analogue for the reversal of gallium arsenide-induced oxidative stress in rats.

    PubMed

    Flora, Swaran J S; Kannan, Gurusamy M; Pant, Bhagwat P; Jaiswal, Devendra K

    2002-06-01

    Gallium arsenide (GaAs), a group III-VA intermetallic semiconductor, possesses superior electronic and optical properties and has a wide application in the electronics industry. Exposure to GaAs in the semiconductor industry is a potential occupational hazard because cleaning and slicing GaAs ingots to yield the desired wafer could generate GaAs particles. The ability of GaAs to induce oxidative stress has not yet been reported. The present study reports the role of oxidative stress in GaAs-induced haematological and liver disorders and its possible reversal overturn by administration of meso-2,3-dimercaptosuccinic acid (DMSA) and one of its analogue, monoisoamyl DMSA (MiADMSA), either individually or in combination with oxalic acid. While DMSA and MiADMSA are potential arsenic chelators, oxalic acid is reported to be an effective gallium chelator. Male rats were exposed to 10 mg/kg GaAs orally, 5 days a week for 8 weeks. GaAs exposure was then stopped and rats were given a 0.5 mmol/kg dose of succimers (DMSA or MiADMSA), oxalic acid or a combination of the two, intraperitoneally once daily for 5 consecutive days. We found a significant fall in blood delta-aminolevulinic acid dehydratase (ALAD) activity and blood glutathione (GSH) level, and an increased urinary excretion of delta-aminolevulinic acid (ALA) and an increased malondialdehyde (MDA) level in erythrocytes of rats exposed to GaAs. Hepatic GSH levels decreased, whereas there was an increase in GSSG and MDA levels. The results suggest a role of oxidative stress in GaAs-induced haematological and hepatic damage. Administration of DMSA and MiADMSA produced effective recovery in most of the above variables. However, a greater effectiveness of the chelation treatment (i.e. removal of both gallium and arsenic from body organs) could be achieved by combined administration of succimer (DMSA) with oxalic acid since, after MiADMSA administration, a marked loss of essential metals (copper and zinc) is of concern.

  7. Zirconium-carbon hybrid sorbent for removal of fluoride from water: oxalic acid mediated Zr(IV) assembly and adsorption mechanism

    PubMed Central

    Halla, Velazquez-Jimenez Litza; Hurt Robert, H; Juan, Matos; Rene, Rangel-Mendez Jose

    2014-01-01

    When activated carbon (AC) is modified with zirconium(IV) by impregnation or precipitation, the fluoride adsorption capacity is typically improved. There is significant potential to improve these hybrid sorbent by controlling the impregnation conditions, which determine the assembly and dispersion of the Zr phases on carbon surfaces. Here, commercial activated carbon was modified with Zr(IV) together with oxalic acid (OA) used to maximize the zirconium dispersion and enhance fluoride adsorption. Adsorption experiments were carried out at pH 7 and 25 °C with a fluoride concentration of 40 mg L−1. The OA/Zr ratio was varied to determine the optimal conditions for subsequent fluoride adsorption. The data was analyzed using the Langmuir and Freundlich isotherm models. FTIR, XPS and the surface charge distribution were performed to elucidate the adsorption mechanism. Potentiometric titrations showed that the modified activated carbon (ZrOx-AC) possesses positive charge at pH lower than 7, and FTIR analysis demonstrated that zirconium ions interact mainly with carboxylic groups on the activated carbon surfaces. Moreover, XPS analysis demonstrated that Zr(IV) interacts with oxalate ions, and the fluoride adsorption mechanism is likely to involve –OH− exchange from zirconyl oxalate complexes. PMID:24359079

  8. Zirconium-carbon hybrid sorbent for removal of fluoride from water: oxalic acid mediated Zr(IV) assembly and adsorption mechanism.

    PubMed

    Velazquez-Jimenez, Litza Halla; Hurt, Robert H; Matos, Juan; Rangel-Mendez, Jose Rene

    2014-01-21

    When activated carbon (AC) is modified with zirconium(IV) by impregnation or precipitation, the fluoride adsorption capacity is typically improved. There is significant potential to improve these hybrid sorbents by controlling the impregnation conditions, which determine the assembly and dispersion of the Zr phases on carbon surfaces. Here, commercial activated carbon was modified with Zr(IV) together with oxalic acid (OA) used to maximize the zirconium dispersion and enhance fluoride adsorption. Adsorption experiments were carried out at pH 7 and 25 °C with a fluoride concentration of 40 mg L(-1). The OA/Zr ratio was varied to determine the optimal conditions for subsequent fluoride adsorption. The data was analyzed using the Langmuir and Freundlich isotherm models. FTIR, XPS, and the surface charge distribution were performed to elucidate the adsorption mechanism. Potentiometric titrations showed that the modified activated carbon (ZrOx-AC) possesses positive charge at pH lower than 7, and FTIR analysis demonstrated that zirconium ions interact mainly with carboxylic groups on the activated carbon surfaces. Moreover, XPS analysis demonstrated that Zr(IV) interacts with oxalate ions, and the fluoride adsorption mechanism is likely to involve -OH(-) exchange from zirconyl oxalate complexes.

  9. Venus -Mesospheric hazes of ice, dust, and acid aerosols

    NASA Astrophysics Data System (ADS)

    Turco, R. P.; Toon, O. B.; Whitten, R. C.; Keesee, R. G.

    1983-01-01

    Four distinct types of particles are suggested to be present in the upper atmosphere of Venus. The lowest and densest haze may consist of a submicron sulfuric acid aerosol which extends above the cloud tops, up to about 80 km, representing an extension of the upper cloud deck. Temperature structure measurements in the 70-120 km altitude range indicate the occasional appearance of two independent water ice layers, of which the lower may form between 80 and 100 km and is probably the detached haze layer noted in high contrast limb photography. A nucleation of this ice layer on sulfuric acid aerosols is hypothesized. Temperatures of the Venus mesopause, near 120 km altitude, are frequently cold enough to allow ice nucleation on meteoric dust or ambient ions, yielding a haze (analogous to noctilucent clouds on earth) which is expected to be tenuous to the point of optical invisibility.

  10. Speciation in experimental C-O-H fluids produced by the thermal dissociation of oxalic acid dihydrate

    USGS Publications Warehouse

    Morgan, G.B.; Chou, I.-Ming; Pasteris, J.D.

    1992-01-01

    Fluid speciations and their related reaction pathways were studied in C-O-H-system fluids produced by the thermal dissociation of oxalic acid dihydrate (OAD: H2C2O4 ?? 2H2O) sealed in silica glass capsules. Experiments were conducted in the temperature range 230-750??C, with bulk fluid densities in the range 0.01-0.53 g/cm3. Pressure was controlled by temperature and density in the isochoric systems. The quenched products of dissociation experiments were an aqueous liquid and one (supercritical fluid) or, rarely, two (vapor plus liquid) carbonic phase (s). In-situ Raman microanalyses were performed on the quenched carbonic phases at room temperature, at which fluid pressures ranged from about 50 to 340 bars. Bulk fluid speciations were reconstructed from the Raman analyses via mass balance constraints, and appear to monitor the true fluid speciations at run conditions. In experiments from the lowtemperature range (230-350??C), fluid speciations record the dissociation of OAD according to the reaction OAD = CO2 + CO + 3H2O. A process of the form CO + H2O = CO2 + H2 is driven to the right with increasing temperature. The hydrogen gas produced tends to escape from the sample systems via diffusion into/through the silica glass capsules, shifting bulk compositions toward equimolar binary H2O-CO2 mixtures. The speciations of fluids in experiments with minimal hydrogen loss show poor agreement with speciations calculated for equilibrium fluids by the corresponding-states model of Saxena and Fei (1988). Such disagreement suggests that the formations of CH4 and graphite are metastably inhibited in the current experiments, which correlates with their absence or trivial abundances in experimental products. Moreover, calculations in which the stabilities of methane and graphite are suppressed suggest that such metastable equilibrium is approached only in experiments at temperatures greater than about 600-650??C. These results have applications to fluid processes in geological

  11. An improved thermodynamic model for the complexation of trivalent actinides and lanthanide with oxalic acid valid to high ionic strength.

    SciTech Connect

    Xiong, Yongliang; Thakur, Punam; Borkowski, Marian

    2015-07-30

    The dissociation constants of oxalic acid (Ox), and the stability constants of Am3+, Cm3+ and Eu3+ with Ox2– have been determined at 25 °C, over a range of concentration varying from 0.1 to 6.60 m NaClO4 using potentiometric titration and extraction techniques, respectively. The experimental data support the formation of complexes, M(Ox)n3 – 2n, where (M = Am3+, Cm3+ and Eu3+ and n = 1 and 2). The dissociation constant and the stability constant values measured as a function of NaClO4 concentration were used to estimate the Pitzer parameters for the respective interactions of Am3+, Cm3+ and Eu3+ with Ox. Furthermore, the stability constants data of Am3+ –Ox measured in NaClO4 and in NaCl solutions from the literature were simultaneously fitted in order to refine the existing actinide–oxalate complexation model that can be used universally in the safety assessment of radioactive waste disposal. The thermodynamic stability constant: log β0101 = 6.30 ± 0.06 and log β0102 = 10.84 ± 0.06 for Am3+ was obtained by simultaneously fitting data in NaCl and NaClO4 media. Additionally, log β0101 = 6.72 ± 0.08 and log β0102 = 11.05 ± 0.09 for the Cm3+ and log β0101 = 6.67 ± 0.08 and log β0102 = 11.15 ± 0.09 for the Eu3+ were calculated by extrapolation of data to zero ionic strength in NaClO4 medium only. For all stability constants, the Pitzer model gives an excellent representation of the data using interaction parameters β(0), β(1), and CΦ determined in this work. The thermodynamic model developed in this work will be useful in accurately modeling the potential solubility of trivalent

  12. Removal of arsenic and cadmium with sequential soil washing techniques using Na2EDTA, oxalic and phosphoric acid: Optimization conditions, removal effectiveness and ecological risks.

    PubMed

    Wei, Meng; Chen, Jiajun; Wang, Xingwei

    2016-08-01

    Testing of sequential soil washing in triplicate using typical chelating agent (Na2EDTA), organic acid (oxalic acid) and inorganic weak acid (phosphoric acid) was conducted to remediate soil contaminated by heavy metals close to a mining area. The aim of the testing was to improve removal efficiency and reduce mobility of heavy metals. The sequential extraction procedure and further speciation analysis of heavy metals demonstrated that the primary components of arsenic and cadmium in the soil were residual As (O-As) and exchangeable fraction, which accounted for 60% and 70% of total arsenic and cadmium, respectively. It was determined that soil washing agents and their washing order were critical to removal efficiencies of metal fractions, metal bioavailability and potential mobility due to different levels of dissolution of residual fractions and inter-transformation of metal fractions. The optimal soil washing option for arsenic and cadmium was identified as phosphoric-oxalic acid-Na2EDTA sequence (POE) based on the high removal efficiency (41.9% for arsenic and 89.6% for cadmium) and the minimal harmful effects of the mobility and bioavailability of the remaining heavy metals.

  13. Removal of arsenic and cadmium with sequential soil washing techniques using Na2EDTA, oxalic and phosphoric acid: Optimization conditions, removal effectiveness and ecological risks.

    PubMed

    Wei, Meng; Chen, Jiajun; Wang, Xingwei

    2016-08-01

    Testing of sequential soil washing in triplicate using typical chelating agent (Na2EDTA), organic acid (oxalic acid) and inorganic weak acid (phosphoric acid) was conducted to remediate soil contaminated by heavy metals close to a mining area. The aim of the testing was to improve removal efficiency and reduce mobility of heavy metals. The sequential extraction procedure and further speciation analysis of heavy metals demonstrated that the primary components of arsenic and cadmium in the soil were residual As (O-As) and exchangeable fraction, which accounted for 60% and 70% of total arsenic and cadmium, respectively. It was determined that soil washing agents and their washing order were critical to removal efficiencies of metal fractions, metal bioavailability and potential mobility due to different levels of dissolution of residual fractions and inter-transformation of metal fractions. The optimal soil washing option for arsenic and cadmium was identified as phosphoric-oxalic acid-Na2EDTA sequence (POE) based on the high removal efficiency (41.9% for arsenic and 89.6% for cadmium) and the minimal harmful effects of the mobility and bioavailability of the remaining heavy metals. PMID:27179243

  14. Sulfuric acid aerosols in the atmospheres of the terrestrial planets

    NASA Astrophysics Data System (ADS)

    McGouldrick, Kevin; Toon, Owen B.; Grinspoon, David H.

    2011-08-01

    Clouds and hazes composed of sulfuric acid are observed to exist or postulated to have once existed on each of the terrestrial planets with atmospheres in our solar system. Venus today maintains a global cover of clouds composed of a sulfuric acid/water solution that extends in altitude from roughly 50 km to roughly 80 km. Terrestrial polar stratospheric clouds (PSCs) form on stratospheric sulfuric acid aerosols, and both PSCs and stratospheric aerosols play a critical role in the formation of the ozone hole. Stratospheric aerosols can modify the climate when they are enhanced following volcanic eruptions, and are a current focus for geoengineering studies. Rain is made more acidic by sulfuric acid originating from sulfur dioxide generated by industry on Earth. Analysis of the sulfur content of Martian rocks has led to the hypothesis that an early Martian atmosphere, rich in SO 2 and H 2O, could support a sulfur-infused hydrological cycle. Here we consider the plausibility of frozen sulfuric acid in the upper clouds of Venus, which could lead to lightning generation, with implications for observations by the European Space Agency's Venus Express and the Japan Aerospace Exploration Agency's Venus Climate Orbiter (also known as Akatsuki). We also present simulations of a sulfur-rich early Martian atmosphere. We find that about 40 cm/yr of precipitation having a pH of about 2.0 could fall in an early Martian atmosphere, assuming a surface temperature of 273 K, and SO 2 generation rates consistent with the formation of Tharsis. This modeled acid rain is a powerful sink for SO 2, quickly removing it and preventing it from having a significant greenhouse effect.

  15. COS in the stratosphere. [sulfuric acid aerosol precursor

    NASA Technical Reports Server (NTRS)

    Inn, E. C. Y.; Vedder, J. F.; Tyson, B. J.; Ohara, D.

    1979-01-01

    Carbonyl sulfide (COS) has been detected in the stratosphere, and mixing ratio measurements are reported for altitudes of 15.2 to 31.2 km. A large volume, cryogenic sampling system mounted on board a U-2 aircraft has been used for lower stratosphere measurements and a balloon platform for measurement at 31.2 km. These observations and measurements strongly support the concept that stratospheric COS is an important precursor in the formation of sulfuric acid aerosols.

  16. Mineralogical basis for the interpretation of multi-element (ICP-AES), oxalic acid, and aqua regia partial digestions of stream sediments for reconnaissance exploration geochemistry

    USGS Publications Warehouse

    Church, S.E.; Mosier, E.L.; Motooka, J.M.

    1987-01-01

    We have applied partial digestion procedures, primarily oxalic acid and aqua regia leaches, to several regional geochemical reconnaissance studies carried out using Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) analytical methods. We have chosen to use these two acids because the oxalic acid primarily attacks those compounds formed during secondary geochemical processes, whereas aqua regia will digest the primary sulfide phases as well as secondary phases. Application of the partial digestion technique has proven superior to total digestion because the concentration of metals in hydromorphic compounds and the sulfides is enhanced relative to the metals bound in the unattacked silicate phases. The aqua regia digestion attacks and leaches metals from the mafic chain silicates and the phyllosilicates (coordination number of VI or more), yielding a characteristic geochemical signature, but does not leach appreciable metal from many other silicates. In order to interpret the results from these leach studies, we have initiated an investigation of a large suite of hand-picked mineral separates. The study includes analyses of about two hundred minerals representing the common rock-forming minerals as well as end-member compositions of various silicates, oxides, sulfides, carbonates, sulfates, and some vanadates, molybdates, tungstates, and phosphates. The objective of this study is to evaluate the effect of leaching by acids of particular lattice sites in specific mineral structures. ?? 1987.

  17. Sources and atmospheric processes impacting oxalate at a suburban coastal site in Hong Kong: Insights inferred from 1 year hourly measurements

    NASA Astrophysics Data System (ADS)

    Zhou, Yang; Huang, Xiaohui Hilda; Bian, Qijing; Griffith, Stephen M.; Louie, Peter K. K.; Yu, Jian Zhen

    2015-09-01

    Oxalic acid is one of the most abundant dicarboxylic acids in the atmosphere, receiving a great deal of attention due to its potential influence on cloud condensation nucleus activities. In this work, we report 10 months of hourly oxalate measurements in particulate matter of less than 2.5 µm in aerodynamic diameter (PM2.5) by a Monitor for Aerosols and Gases in ambient Air at a suburban coastal site in Hong Kong from April 2012 to February 2013. A total of more than 6000 sets of oxalate and inorganic ion data were obtained. The mean (±SD) oxalate concentration was 0.34 (±0.18) µg m-3, accounting for 2.8% of the total ion mass and 1.5% of the PM2.5 mass. Seasonal variation showed higher concentrations in fall and winter (0.54 and 0.36 µg m-3, respectively) and lower concentrations in spring and summer (~0.26 µg m-3). Different from the inorganic ions, a shallow dip in the oxalate concentration consistently occurred in the morning after sunrise (around 9:00 A.M.) throughout all seasons. Our analysis suggests that this was likely due to photolysis of oxalate-Fe (III) complex under sunlight. In summer, a small daytime peak was discernable for oxalate and nitrate. This characteristic, together with a more evident diurnal variation of O3, indicates comparatively more active photochemical oxidation in summer than other seasons. High correlations were observed between oxalate and non-sea-salt SO42- (NSS) (R2 = 0.63) and Ox (O3 + NO2) (R2 = 0.48), indicating significant commonality in their secondary formation. Positive matrix factorization analysis of oxalate and other real-time gas and particle-phase component data estimates that secondary formation processes, including secondary gas or aqueous oxidation processes (49%), oxidation processes of biomass burning emissions (37%), accounted for the majority of PM2.5 oxalate. A backward trajectories cluster analysis found that higher oxalate/NSS ratios were associated with low pollution samples under the influence of

  18. Sulfuric acid aerosol exposure in humans assessed by bronchoalveolar lavage

    SciTech Connect

    Frampton, M.W.; Voter, K.Z.; Morrow, P.E.; Roberts, N.J. Jr.; Culp, D.J.; Cox, C.; Utell, M.J. )

    1992-09-01

    Epidemiologic and experimental evidence suggests that exposure to acidic aerosols may affect human health. Brief exposures to acidic aerosols alter mucociliary clearance and increase airway responsiveness, but effects on host defense mechanisms at the alveolar level have not been studied in humans. Twelve healthy, nonsmoking volunteers between 20 and 39 yr of age were exposed for 2 h to aerosols of approximately 1,000 micrograms/m3 sulfuric acid (H2SO4) or sodium chloride (NaCl (control)), with intermittent exercise, in a randomized, double-blind fashion. Each subject received both exposures, separated by at least 2 wk. Bronchoalveolar lavage (BAL) was performed 18 h after exposure in order to detect evidence of an inflammatory response, changes in alveolar cell subpopulations, or changes in alveolar macrophage (AM) function, which is important in host defense. When compared with NaCl, exposure to H2SO4 did not increase polymorphonuclear leukocytes in BAL fluid. The percentage of T lymphocytes decreased in association with H2SO4 exposure, but the difference was not statistically significant (14.9% after NaCl, 11.5% after H2SO4; p = 0.14). Antibody-mediated cytotoxicity of AM increased in association with H2SO4 exposure (percent lysis 19.1 after NaCl, 23.6 after H2SO4; p = 0.16). No significant change was seen in release of superoxide anion or inactivation of influenza virus in vitro. Brief exposures to H2SO4 aerosol at 1,000 micrograms/m3 do not cause an influx of inflammatory cells into the alveolar space, and no evidence was found for alteration in antimicrobial defense 18 h after exposure.

  19. Acid aerosol measurements at a suburban Connecticut site

    NASA Astrophysics Data System (ADS)

    Keeler, Gerald J.; Spengler, John D.; Castillo, Raymond A.

    Atmospheric acidity data were gathered during a year-long field project investigating the possible health effects of acid aerosol in a rural community in southwestern Connecticut. This site was chosen because the air quality is frequently influenced by pollutants transported from the New York-New Jersey corridor as well as from the Midwest U.S. An annular denuder filter-pack system utilized to obtain daily measurements of gaseous HNO 3, HONO, SO 2, and NH 3; plus fine particle SO 42-, NO 3-, and H +. Fine particle mass ( d ⩽ 2.1 μm) and PM10 (particles d ⩽ 10 μm) were also measured. Ozone concentrations and basic meteorological data were also obtained continuously. The atmosphere was acidic with average concentrations of HONO (16 nmol m -3), HNO 3 (42 nmol m -3), and H + (42 nmol m -3), observed from May to September 1988. Atmospheric ammonia concentrations were fairly low averaging 34 nmol m -3 during the same period, and suggesting the neutralizing capacity of the air was significant to neutralize all the acidic species present. Neutralization of acidic particles by reactions on the filter media after collection resulted in a loss of approximately 10% of the measured particle strong acidity for the summertime period investigated. Concentrations of ozone and acidic gases tended to peak with mixed layer flow from the south-southwest while particulate acidity was highest with flow predominantly from the west-soutwest. Hourly ozone concentrations greater than 100 ppb were observed on 31 different days during the monitoring, and concentrations greater than 150 ppb measured on 14 days. HNO 3 and aerosol strong acidity (H +) concentrations reached 174 and 199 nmol m -3, respectively during the summer months.

  20. A simple, efficient and environmentally benign synthetic protocol for the synthesis of spirooxindoles using choline chloride-oxalic acid eutectic mixture as catalyst/solvent system.

    PubMed

    Khandelwal, Sarita; Rajawat, Anshu; Tailor, Yogesh Kumar; Kumar, Mahendra

    2014-01-01

    An efficient and environmentally benign domino protocol has been presented for the synthesis of structurally diverse spirooxindoles spiroannulated with pyranopyridopyrimidines, indenopyridopyrimidines, and chromenopyridopyrimidines involving three-component reaction of aminouracils, isatins and cyclic carbonyl compounds in deep eutectic solvent (choline chloride-oxalic acid: 1:1) which acts as efficient catalyst and environmentally benign reaction medium. The present protocol offers several advantages such as operational simplicity with easy workup, shorter reaction times excellent yields with superior atom economy and environmentally benign reaction conditions with the use of cost-effective, recyclable, non-toxic and bio-degradable DES as catalyst/solvent.

  1. A simple, efficient and environmentally benign synthetic protocol for the synthesis of spirooxindoles using choline chloride-oxalic acid eutectic mixture as catalyst/solvent system.

    PubMed

    Khandelwal, Sarita; Rajawat, Anshu; Tailor, Yogesh Kumar; Kumar, Mahendra

    2014-01-01

    An efficient and environmentally benign domino protocol has been presented for the synthesis of structurally diverse spirooxindoles spiroannulated with pyranopyridopyrimidines, indenopyridopyrimidines, and chromenopyridopyrimidines involving three-component reaction of aminouracils, isatins and cyclic carbonyl compounds in deep eutectic solvent (choline chloride-oxalic acid: 1:1) which acts as efficient catalyst and environmentally benign reaction medium. The present protocol offers several advantages such as operational simplicity with easy workup, shorter reaction times excellent yields with superior atom economy and environmentally benign reaction conditions with the use of cost-effective, recyclable, non-toxic and bio-degradable DES as catalyst/solvent. PMID:25329839

  2. Ice nucleation in sulfuric acid/organic aerosols: implications for cirrus cloud formation

    NASA Astrophysics Data System (ADS)

    Beaver, M. R.; Elrod, M. J.; Garland, R. M.; Tolbert, M. A.

    2006-03-01

    Using an aerosol flow tube apparatus, we have studied the effects of aliphatic aldehydes (C3 to C10) and ketones (C3 and C9) on ice nucleation in sulfuric acid aerosols. Mixed aerosols were prepared by combining an organic vapor flow with a flow of sulfuric acid aerosols over a small mixing time (~60 s) at room temperature. No acid-catalyzed reactions were observed under these conditions, and physical uptake was responsible for the organic content of the sulfuric acid aerosols. In these experiments, aerosol organic content, determined by a Mie scattering analysis, was found to vary with the partial pressure of organic, the flow tube temperature, and the identity of the organic compound. The physical properties of the organic compounds (primarily the solubility and melting point) were found to play a dominant role in determining the mode of nucleation (homogenous or heterogeneous) and the specific freezing temperatures observed. Overall, very soluble, low-melting organics, such as acetone and propanal, caused a decrease in aerosol ice nucleation temperatures when compared with aqueous sulfuric acid aerosol. In contrast, sulfuric acid particles exposed to organic compounds of eight carbons and greater, of much lower solubility and higher melting temperatures, nucleate ice at temperatures above aqueous sulfuric acid aerosols. Organic compounds of intermediate carbon chain length, C4-C7, (of intermediate solubility and melting temperatures) nucleated ice at the same temperature as aqueous sulfuric acid aerosols. Interpretations and implications of these results for cirrus cloud formation are discussed.

  3. Ice nucleation in sulfuric acid/organic aerosols: implications for cirrus cloud formation

    NASA Astrophysics Data System (ADS)

    Beaver, M. R.; Elrod, M. J.; Garland, R. M.; Tolbert, M. A.

    2006-08-01

    Using an aerosol flow tube apparatus, we have studied the effects of aliphatic aldehydes (C3 to C10) and ketones (C3 and C9) on ice nucleation in sulfuric acid aerosols. Mixed aerosols were prepared by combining an organic vapor flow with a flow of sulfuric acid aerosols over a small mixing time (~60 s) at room temperature. No acid-catalyzed reactions were observed under these conditions, and physical uptake was responsible for the organic content of the sulfuric acid aerosols. In these experiments, aerosol organic content, determined by a Mie scattering analysis, was found to vary with the partial pressure of organic, the flow tube temperature, and the identity of the organic compound. The physical properties of the organic compounds (primarily the solubility and melting point) were found to play a dominant role in determining the inferred mode of nucleation (homogenous or heterogeneous) and the specific freezing temperatures observed. Overall, very soluble, low-melting organics, such as acetone and propanal, caused a decrease in aerosol ice nucleation temperatures when compared with aqueous sulfuric acid aerosol. In contrast, sulfuric acid particles exposed to organic compounds of eight carbons and greater, of much lower solubility and higher melting temperatures, nucleate ice at temperatures above aqueous sulfuric acid aerosols. Organic compounds of intermediate carbon chain length, C4-C7, (of intermediate solubility and melting temperatures) nucleated ice at the same temperature as aqueous sulfuric acid aerosols. Interpretations and implications of these results for cirrus cloud formation are discussed.

  4. Identification of keto- and hydroxy-dicarboxylic acids in remote marine aerosols from the western North Pacific: GC and GC/TOF-MS measurements

    NASA Astrophysics Data System (ADS)

    Vani, D.; Kawamura, K.; Tachibana, E.; Boreddy, S. K. R.

    2015-12-01

    Dicarboxylic acids (diacids) are dominant components of organic aerosols in the atmosphere. They contribute significantly to the total aerosol mass and have a serious impacts on global climate changes. However, studies on keto- and hydroxy-diacids in marine aerosols are limited. Compare to diacids, keto- and hydroxy-diacids are more hygroscopic due to the additional polar groups (OH and CO) and, hence, acts as cloud condensation nuclei (CCN). Molecular characterization of these compounds provides insight into organic aerosols sources and transformation pathways. We collected marine aerosols from remote Chichijima Island in the western North Pacific from December 2010 to November 2011 and studied for water-soluble keto- and hydroxy-diacids. Carboxyl groups were derivatized to dibutyl esters with 14% boron trifluoride/n-butanol, whereas hydroxyl groups were derivatized to trimethylsilyl ethers using N,O-Bis (trimethylsilyl) trifluoroacetamide (BSTFA). After two-step derivatization, samples were injected to GC, GC/MS and GC/TOF-MS. In the GC chromatogram, we detected several new peaks after BSTFA derivatization of dibutyl ester fraction. Based on mass spectral interpretation, we found these peaks as homologues series of hydroxy-diacids and keto-diacids. Some of these hydroxy-diacids have been individually reported in literature in the laboratory photo-oxidation experiments and forest environments samples. But, there are no evidences to prove their sources and formation mechanism in the atmosphere. Here, we report for the first time homologous series of hydroxy-diacids (hC3di-hC6di) and keto-diacid (oxaloacetic acid, enol and keto forms) in remote marine atmosphere. Molecular distributions of hydroxy-diacids generally showed the predominance of malic acid followed by tartronic acid. Both hydroxy- and keto-diacids show significant positive correlation with oxalic acid and SO42-, suggesting that they are generated in the atmosphere and play an important role in the

  5. Directed synthesis of crystalline plutonium (III) and (IV) oxalates: accessing redox-controlled separations in acidic solutions

    SciTech Connect

    Runde, Wolfgang; Brodnax, Lia F; Goff, George S; Bean, Amanda C; Scott, Brian L

    2009-01-01

    Both binary and ternary solid complexes of Pu(III) and Pu(IV) oxalates have been previously reported in the literature. However, uncertainties regarding the coordination chemistry and the extent of hydration of some compounds remain mainly because of the absence of any crystallographic characterization. Single crystals of hydrated oxalates of Pu(III), Pu{sub 2}(C{sub 2}O{sub 4}){sub 3}(H{sub 2}O){sub 6}{center_dot}3H{sub 2}O (I) and Pu(IV), KPu(C{sub 2}O{sub 4}){sub 2}(OH){center_dot}2.5H{sub 2}O (II), were synthesized under moderate hydrothermal conditions and characterized by single crystal X-ray diffraction studies. Compounds I and II are the first plutonium(III) or (IV) oxalate compounds to be structurally characterized via single crystal X-ray diffraction studies. Crystallographic data for I: monoclinic, space group P21/c, a = 11.246(3) A, b = 9.610(3) A, c = 10.315(3) A, Z = 4 and II: monoclinic, space group C2/c, a = 23.234(14) A, b = 7.502(4) A, c = 13.029(7) A, Z = 8.

  6. Dentin Hypersensitivity and Oxalates

    PubMed Central

    Cunha-Cruz, J.; Stout, J.R.; Heaton, L.J.; Wataha, J.C.

    2011-01-01

    Treatment of dentin hypersensitivity with oxalates is common, but oxalate efficacy remains unclear. Our objective was to systematically review clinical trials reporting an oxalate treatment compared with no treatment or placebo with a dentin hypersensitivity outcome. Risk-of-bias assessment and data extraction were performed independently by two reviewers. Standardized mean differences (SMD) were estimated by random-effects meta-analysis. Of 677 unique citations, 12 studies with high risk-of-bias were included. The summary SMD for 3% monohydrogen-monopotassium oxalate (n = 8 studies) was -0.71 [95% Confidence Interval: -1.48, 0.06]. Other treatments, including 30% dipotassium oxalate (n = 1), 30% dipotassium oxalate plus 3% monohydrogen monopotassium oxalate (n = 3), 6% monohydrogen monopotassium oxalate (n = 1), 6.8% ferric oxalate (n = 1), and oxalate-containing resin (n = 1), also were not statistically significantly different from placebo treatments. With the possible exception of 3% monohydrogen monopotassium oxalate, available evidence currently does not support the recommendation of dentin hypersensitivity treatment with oxalates. PMID:21191127

  7. α- And β Pahases of oxalic acid, H 2C 2O 4: Vibrational spectra, normal-coordinate calculations, and intermolecular forces

    NASA Astrophysics Data System (ADS)

    De Villepin, J.; Novak, A.; Bougeard, D.

    1982-12-01

    Infrared (4000-30 cm -1) and Raman (4000-0 cm -) spectra of single crystals of α-oxalic acid (Pcab, Z=4) have been investigated at 100 and 300 K. A complete assignment of all modes in terms of symmetry species and to internal, librational, translational, and hydrogen bond motions is given. In order to interpret the spectra and to determine the crystal field, several normal-coordinate calculations (free molecule, rigid body model, unit cell as a supermolecule) have been carried out. The calculations are in good agreement with the experimental results and show the importance of different intermolecular forces: OH … O hydrogen bonds and very short C … O interactions lead to both unusually strong correlation field splitting and high lattice frequencies while quadrupole-quadrupole and CO dipole-dipole interactions influence lattice and some internal vibrations, respectively. The intermolecular potentials obtained for α-oxalic acid are transferable to the β form having a different crystal structure (P2 1/c, Z = 2) and stronger hydrogen bonds.

  8. Uptake of Ambient Organic Gases to Acidic Sulfate Aerosols

    NASA Astrophysics Data System (ADS)

    Liggio, J.; Li, S.

    2009-05-01

    The formation of secondary organic aerosols (SOA) in the atmosphere has been an area of significant interest due to its climatic relevance, its effects on air quality and human health. Due largely to the underestimation of SOA by regional and global models, there has been an increasing number of studies focusing on alternate pathways leading to SOA. In this regard, recent work has shown that heterogeneous and liquid phase reactions, often leading to oligomeric material, may be a route to SOA via products of biogenic and anthropogenic origin. Although oligomer formation in chamber studies has been frequently observed, the applicability of these experiments to ambient conditions, and thus the overall importance of oligomerization reactions remain unclear. In the present study, ambient air is drawn into a Teflon smog chamber and exposed to acidic sulfate aerosols which have been formed in situ via the reaction of SO3 with water vapor. The aerosol composition is measured with a High Resolution Aerodyne Aerosol Mass Spectrometer (HR-ToF-AMS), and particle size distributions are monitored with a scanning mobility particle sizer (SMPS). The use of ambient air and relatively low inorganic particle loading potentially provides clearer insight into the importance of heterogeneous reactions. Results of experiments, with a range of sulfate loadings show that there are several competing processes occurring on different timescales. A significant uptake of ambient organic gases to the particles is observed immediately followed by a slow shift towards higher m/z over a period of several hours indicating that higher molecular weight products (possibly oligomers) are being formed through a reactive process. The results suggest that heterogeneous reactions can occur with ambient organic gases, even in the presence of ammonia, which may have significant implications to the ambient atmosphere where particles may be neutralized after their formation.

  9. Contributions of low molecular weight carboxylic acids to aerosols and wet deposition in a natural subtropical broad-leaved forest environment

    NASA Astrophysics Data System (ADS)

    Tsai, Ying I.; Kuo, Su-Ching

    2013-12-01

    The carboxylic acid component of autumn aerosol and wet deposition (fog water and rainwater) in a broad-leaved forest in central Taiwan was investigated. High levels of low molecular weight carboxylic acids (LMWCAs) were noted in all deposition types. Acetic acid, oxalic acid and formic acid were the most prevalent carboxylic acids, together accounting for 72.2% (fog water), 86.7% (rain water), 77.2% (PM2.5) and 88.3% (PM2.5-10) of total carboxylic acid. The forest fog water contained 2453.9 ± 1030.5 ng mL-1 of carboxylic acid, 2.71 times more than was contained in forest rainwater. In PM, most carboxylic acid existed in the fine PM2.5 aerosol (576.6 ± 254.1 ng m-3 or 6.28 times more than was contained in PM2.5-10. Most carboxylic acids in PM had higher concentrations during the day. Pyruvic acid concentration was higher during the night (2.97 times), however, owing to its rapid photodegradation during the day. Citric acid accounted for 9.1% of the total carboxylic acid in fog water compared with just 1.8% in rainwater, confirming its origin from emissions from leaves. Raman spectroscopy was used to observe the photochemical conversion of citric acid into intermediate products and this observation confirmed that the carboxylic acids identified in the forest dry and wet depositions originated directly from biological emissions in the forest environment.

  10. OXALATE MASS BALANCE DURING CHEMICAL CLEANING IN TANK 6F

    SciTech Connect

    Poirier, M.; Fink, S.

    2011-07-22

    The Savannah River Remediation (SRR) is preparing Tank 6F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRR personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 6F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate. Some conclusions from this work are: (1) Approximately 65% of the oxalate added as oxalic acid was removed with the decanted liquid. (2) Approximately 1% of the oxalate (added to the tank as oxalic acid) formed precipitates with compounds such as nickel, manganese, sodium, and iron (II), and was dissolved with nitric acid. (3) As much as 30% of the oxalate may have decomposed forming carbon dioxide. The balance does not fully account for all the oxalate added. The offset represents the combined uncertainty in the analyses and sampling.

  11. Light absorption by secondary organic aerosol from α-pinene: Effects of oxidants, seed aerosol acidity, and relative humidity

    SciTech Connect

    Song, Chen; Gyawali, Madhu; Zaveri, Rahul A.; Shilling, John E.; Arnott, W. Patrick

    2013-10-25

    It is well known that light absorption from dust and black carbon aerosols has a warming effect on climate while light scattering from sulfate, nitrate, and sea salt aerosols has a cooling effect. However, there are large uncertainties associated with light absorption and scattering by different types of organic aerosols, especially in the near-UV and UV spectral regions. In this paper, we present the results from a systematic laboratory study focused on measuring light absorption by secondary organic aerosols (SOAs) generated from dark α-pinene + O3 and α-pinene + NOx + O3 systems in the presence of neutral and acidic sulfate seed aerosols. Light absorption was monitored using photoacoustic spectrometers at four different wavelengths: 355, 405, 532, and 870 nm. Significant light absorption at 355 and 405 nm was observed for the SOA formed from α-pinene + O3 + NO3 system only in the presence of highly acidic sulfate seed aerosols under dry conditions. In contrast, no absorption was observed when the relative humidity was elevated to greater than 27% or in the presence of neutral sulfate seed aerosols. Organic nitrates in the SOA formed in the presence of neutral sulfate seed aerosols were found to be nonabsorbing, while the light-absorbing compounds are speculated to be aldol condensation oligomers with nitroxy organosulfate groups that are formed in highly acidic sulfate aerosols. Finally and overall, these results suggest that dark α-pinene + O3 and α-pinene + NOx + O3 systems do not form light-absorbing SOA under typical atmospheric conditions.

  12. Dicarboxylic acids, oxoacids, benzoic acid, α-dicarbonyls, WSOC, OC, and ions in spring aerosols from Okinawa Island in the western North Pacific Rim: size distributions and formation processes

    NASA Astrophysics Data System (ADS)

    Deshmukh, D. K.; Kawamura, K.; Lazaar, M.; Kunwar, B.; Boreddy, S. K. R.

    2015-09-01

    Size-segregated aerosols (9-stages from < 0.43 to > 11.3 μm in diameter) were collected at Cape Hedo, Okinawa in spring 2008 and analyzed for water-soluble diacids (C2-C12), ω-oxoacids (ωC2-ωC9), pyruvic acid, benzoic acid and α-dicarbonyls (C2-C3) as well as water-soluble organic carbon (WSOC), organic carbon (OC) and major ions. In all the size-segregated aerosols, oxalic acid (C2) was found as the most abundant species followed by malonic and succinic acids whereas glyoxylic acid (ωC2) was the dominant oxoacid and glyoxal (Gly) was more abundant than methylglyoxal. Diacids (C2-C5), ωC2 and Gly as well as WSOC and OC peaked at 0.65-1.1 μm in fine mode whereas azelaic (C9) and 9-oxononanoic (ωC9) acids peaked at 3.3-4.7 μm in coarse mode. Sulfate and ammonium are enriched in fine mode whereas sodium and chloride are in coarse mode. These results imply that water-soluble species in the marine aerosols could act as cloud condensation nuclei (CCN) to develop the cloud cover over the western North Pacific Rim. The organic species are likely produced by a combination of gas-phase photooxidation, and aerosol-phase or in-cloud processing during long-range transport. The coarse mode peaks of malonic and succinic acids were obtained in the samples with marine air masses, suggesting that they may be associated with the reaction on sea salt particles. Bimodal size distributions of longer-chain diacid (C9) and oxoacid (ωC9) with a major peak in the coarse mode suggest their production by photooxidation of biogenic unsaturated fatty acids via heterogeneous reactions on sea salt particles.

  13. Heterogeneous atmospheric reactions - Sulfuric acid aerosols as tropospheric sinks

    NASA Technical Reports Server (NTRS)

    Baldwin, A. C.; Golden, D. M.

    1979-01-01

    The reaction probabilities of various atmospheric species incident on a bulk sulfuric acid surface are measured in order to determine the role of sulfuric acid aerosols as pollutant sinks. Reaction products and unreacted starting materials leaving a Knudsen cell flow reactor after collision at 300 K with a H2SO4 surface or a soot surface were detected by mass spectrometry. Significant collision reaction probabilities are observed on a H2SO4 surface for H2O2, HNO3, HO2NO2, ClONO2, N2O5, H2O and NH3, and on soot for NH3. Estimates of the contribution of heterogeneous reactions to pollutant removal under atmospheric conditions indicate that while aerosol removal in the stratosphere is insignificant (loss rate constants approximately 10 to the -10th/sec), heterogeneous reactions may be the dominant loss process for several tropospheric species (loss rate constant approximately 10 to the -5th/sec, comparable to photolysis rate constants).

  14. Ambient aerosols remain highly acidic despite dramatic sulfate reductions

    NASA Astrophysics Data System (ADS)

    Nenes, Athanasios; Weber, Rodney; Guo, Hongyu; Russell, Armistead

    2016-04-01

    The pH of fine particles has many vital environmental impacts. By affecting aerosol concentrations, chemical composition and toxicity, particle pH is linked to regional air quality and climate, and adverse effects on human health. Sulfate is often the main acid component that drives pH of fine particles (i.e., PM2.5) and is neutralized to varying degrees by gas phase ammonia. Sulfate levels have decreased by approximately 70% over the Southeastern United States in the last fifteen years, but measured ammonia levels have been fairly steady implying the aerosol may becoming more neutral. Using a chemically comprehensive data set, combined with a thermodynamic analysis, we show that PM2.5 in the Southeastern U.S. is highly acidic (pH between 0 and 2), and that pH has remained relatively unchanged throughout the past decade and a half of decreasing sulfate. Even with further sulfate reductions, pH buffering by gas-particle partitioning of ammonia is expected to continue until sulfate drops to near background levels, indicating that fine particle pH will remain near current levels into the future. These results are non-intuitive and reshape expectations of how sulfur emission reductions impact air quality in the Southeastern U.S. and possibly other regions across the globe.

  15. Size distributions of dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls and fatty acids in atmospheric aerosols from Tanzania, East Africa during wet and dry seasons

    NASA Astrophysics Data System (ADS)

    Mkoma, S. L.; Kawamura, K.

    2012-09-01

    Atmospheric aerosol samples of PM2.5 and PM10 were collected during the wet and dry seasons in 2011 from a rural site in Tanzania and analysed for water-soluble dicarboxylic acids, ketocarboxylic acids, α-dicarbonyls and fatty acids using a gas chromatography (GC) and GC/mass spectrometry. Here we report the size distribution and sources of diacids and related compounds for wet and dry seasons. Oxalic acid (C2) was found as the most abundant diacid species followed by succinic and/or malonic acids whereas glyoxylic acid and glyoxal were the dominant ketoacids and α-dicarbonyls, respectively in both seasons in PM2.5 and PM10. Mean concentration of C2 in PM2.5 (121.5± 46.6 ng m-3) was lower in wet season than dry season (258.1± 69.5 ng m-3). Similarly, PM10 samples showed lower concentration of C2 (168.6 ± 42.4 ng m-3) in wet season than dry season (292.4± 164.8 ng m-3). Relative abundances of C2 in total diacids were 65.4% and 67.1% in PM2.5 and 64.6% and 63.9% in PM10 in the wet and dry seasons, respectively. Total concentrations of diacids (289-362 m-3), ketoacids (37.8-53.7ng m-3), and α-dicarbonyls (5.7-7.8 ng m-3) in Tanzania are higher to those reported at a rural background site in Nylsvley (South Africa) but comparable or lower to those reported from sites in Asia and Europe. Diacids and ketoacids were found to be present mainly in the fine fraction in both seasons (total α-dicarbonyls in the dry season), suggesting a production of organic aerosols from pyrogenic sources and photochemical oxidations. The averaged contributions of total diacid carbon to aerosol total carbon were 1.4% in PM2.5 and 2.1% in PM10 in wet season and 3.3% in PM2.5 and 3.9% in PM10 in dry season whereas those to water-soluble organic carbon were 2.2% and 4.7% inPM2.5 and 3.1% and 5.8% in PM10 during the wet and dry seasons, respectively. These ratios suggest an enhanced photochemical oxidation of organic precursors and heterogeneous reactions on aerosols under strong solar

  16. In vivo oxalate degradation by liposome encapsulated oxalate oxidase in rat model of hyperoxaluria

    PubMed Central

    Dahiya, Tulika; Pundir, C.S.

    2013-01-01

    Background & objectives: High level of urinary oxalate substantially increases the risk of hyperoxaluria, a significant risk factor for urolithiasis. The primary goal of this study was to reduce urinary oxalate excretion employing liposome encapsulated oxalate oxidase in animal model. Methods: A membrane bound oxalate oxidase was purified from Bougainvillea leaves. The enzyme in its native form was less effective at the physiological pH of the recipient animal. To increase its functional viability, the enzyme was immobilized on to ethylene maleic anhydride (EMA). Rats were injected with liposome encapsulated EMA- oxalate oxidase and the effect was observed on degradation of oxalic acid. Results: The enzyme was purified to apparent homogeneity with 60-fold purification and 31 per cent yield. The optimum pH of EMA-derivative enzyme was 6.0 and it showed 70 per cent of its optimal activity at pH 7.0. The EMA-bound enzyme encapsulated into liposome showed greater oxalate degradation in 15 per cent casein vitamin B6 deficient fed rats as compared with 30 per cent casein vitamin B6 deficient fed rats and control rats. Interpretation & conclusions: EMA-oxalate oxidase encapsulated liposome caused oxalate degradation in experimental hyperoxaluria indicating that the enzyme could be used as a therapeutic agent in hyperoxaluria leading to urinary stones. PMID:23481063

  17. Importance of relative humidity in the oxidative ageing of organic aerosols: case study of the ozonolysis of maleic acid aerosol

    NASA Astrophysics Data System (ADS)

    Gallimore, P. J.; Achakulwisut, P.; Pope, F. D.; Davies, J. F.; Spring, D. R.; Kalberer, M.

    2011-12-01

    Many important atmospheric aerosol processes depend on the chemical composition of the aerosol, e.g. water uptake and particle cloud interactions. Atmospheric ageing processes, such as oxidation reactions, significantly and continuously change the chemical composition of aerosol particles throughout their lifetime. These ageing processes are often poorly understood. In this study we utilize an aerosol flow tube set up and an ultra-high resolution mass spectrometer to explore the effect of relative humidity (RH) in the range of <5-90% on the ozonolysis of maleic acid aerosol which is employed as model organic aerosol system. Due to the slow reaction kinetics relatively high ozone concentrations of 160-200 ppm were used to achieve an appreciable degree of oxidation of maleic acid. The effect of oxidative ageing on the hygroscopicity of maleic acid particles is also investigated using an electrodynamic balance and thermodynamic modelling. RH has a profound effect on the oxidation of maleic acid particles. Very little oxidation is observed at RH < 50% and the only observed reaction products are glyoxylic acid and formic acid. In comparison, when RH > 50% there are about 15 oxidation products identified. This increased oxidation was observed even when the particles were exposed to high humidities long after a low RH ozonolysis reaction. This result might have negative implications for the use of water as an extraction solvent for the analysis of oxidized organic aerosols. These humidity-dependent differences in the composition of the ozonolyzed aerosol demonstrate that water is both a key reactant in the oxidation scheme and a determinant of particle phase and hence diffusivity. The measured chemical composition of the processed aerosol is used to model the hygroscopic growth, which compares favourably with water uptake results from the electrodynamic balance measurements. A reaction mechanism is presented which takes into account the RH dependent observations. This

  18. Health effects of acid aerosols formed by atmospheric mixtures

    SciTech Connect

    Kleinman, M.T.; Phalen, R.F.; Mautz, W.J.; Mannix, R.C.; McClure, T.R.; Crocker, T.T. )

    1989-02-01

    Under ambient conditions, sulfur and nitrogen oxides can react with photochemical products and airborne particles to form acidic vapors and aerosols. Inhalation toxicological studies were conducted, exposing laboratory animals, at rest and during exercise, to multicomponent atmospheric mixtures under conditions favorable to the formation of acidic reaction products. Effects of acid and ozone mixtures on early and late clearance of insoluble radioactive particles in the lungs of rats appeared to be dominated by the oxidant component (i.e., the mixture did cause effects that were significantly different from those of ozone alone). Histopathological evaluations showed that sulfuric acid particles alone did not cause inflammatory responses in centriacinar units of rat lung parenchyma (expressed in terms of percent lesion area) but did cause significant damage (cell killing followed by a wave of cell replication) in nasal respiratory epithelium, as measured by uptake of tritiated thymidine in the DNA of replicating cells. Mixtures of ozone and nitrogen dioxide, which form nitric acid, caused significant inflammatory responses in lung parenchyma (in excess of effects seen in rats exposed to ozone alone), but did not damage nasal epithelium. Mixtures containing acidic sulfate particles, ozone, and nitrogen dioxide damaged both lung parenchyma and nasal epithelia. In rats exposed at rest, the response of the lung appeared to be dominated by the oxidant gas-phase components, while responses in the nose were dominated by the acidic particles. In rats exposed at exercise, however, mixtures of ozone and sulfuric acid particles significantly (2.5-fold) elevated the degree of lung lesion formation over that seen in rats exposed to ozone alone under an identical exercise protocol.

  19. Health effects of acid aerosols formed by atmospheric mixtures.

    PubMed

    Kleinman, M T; Phalen, R F; Mautz, W J; Mannix, R C; McClure, T R; Crocker, T T

    1989-02-01

    Under ambient conditions, sulfur and nitrogen oxides can react with photochemical products and airborne particles to form acidic vapors and aerosols. Inhalation toxicological studies were conducted, exposing laboratory animals, at rest and during exercise, to multicomponent atmospheric mixtures under conditions favorable to the formation of acidic reaction products. Effects of acid and ozone mixtures on early and late clearance of insoluble radioactive particles in the lungs of rats appeared to be dominated by the oxidant component (i.e., the mixture did cause effects that were significantly different from those of ozone alone). Histopathological evaluations showed that sulfuric acid particles alone did not cause inflammatory responses in centriacinar units of rat lung parenchyma (expressed in terms of percent lesion area) but did cause significant damage (cell killing followed by a wave of cell replication) in nasal respiratory epithelium, as measured by uptake of tritiated thymidine in the DNA of replicating cells. Mixtures of ozone and nitrogen dioxide, which form nitric acid, caused significant inflammatory responses in lung parenchyma (in excess of effects seen in rats exposed to ozone alone), but did not damage nasal epithelium. Mixtures containing acidic sulfate particles, ozone, and nitrogen dioxide damaged both lung parenchyma and nasal epithelia. In rats exposed at rest, the response of the lung appeared to be dominated by the oxidant gas-phase components, while responses in the nose were dominated by the acidic particles. In rats exposed at exercise, however, mixtures of ozone and sulfuric acid particles significantly (2.5-fold) elevated the degree of lung lesion formation over that seen in rats exposed to ozone alone under an identical exercise protocol.

  20. Indoor exposures to fine aerosols and acid gases.

    PubMed

    Koutrakis, P; Brauer, M; Briggs, S L; Leaderer, B P

    1991-11-01

    Indoor exposures to aerosols and gases are associated with both indoor and outdoor air pollution sources. The identification of sources and the assessment of their relative contribution can be a complicated process due to a) the presence of numerous indoor sources, which can vary from building to building; b) the uncertainties associated with the estimation of the impact of outdoor sources on indoor air quality; c) the interactions between pollutants; and d) the importance of reactions between pollutants and indoor surfaces. It is well established that fine particles (diameter less than or equal to 2.5 microns) originating from outdoor sources such as automobiles, oil and coal combustion, incineration, and diverse industrial activities can penetrate into the indoor environment. Indoor/outdoor ratios, usually varying between 0.4 and 0.8, depend on parameters such as particle size and density, air exchange rate, and the surface-to-volume ratio of the indoor environment. Determining fine particle elemental composition makes it possible to identify the contribution of different outdoor sources. This paper focuses on the origin and the concentration of indoor aerosols and acid gases by highlighting the results from two indoor air quality studies. PMID:1821374

  1. Kinetics of Mo, Ni, V and Al leaching from a spent hydrodesulphurization catalyst in a solution containing oxalic acid and hydrogen peroxide.

    PubMed

    Szymczycha-Madeja, Anna

    2011-02-28

    The kinetics of molybdenum, nickel, vanadium and aluminium leaching from a spent hydrodesulphurization catalyst in a solution containing oxalic acid and hydrogen peroxide was investigated. The effects of temperature and particle size were examined. In addition, the reaction mechanism for the dissolution of the spent catalyst was discussed. The results of the kinetic analysis for various experimental conditions indicated that the reaction rate of leaching process is controlled by chemical reaction at the particle surface. The values of the activation energies of 31±2, 36±4, 30±4 and 57±3 kJ mol(-1) for Mo, Ni, V and Al, respectively, are characteristic for mechanism controlled by chemical reaction. PMID:21167639

  2. Formyl-coenzyme A (CoA):oxalate CoA-transferase from the acidophile Acetobacter aceti has a distinctive electrostatic surface and inherent acid stability

    PubMed Central

    Mullins, Elwood A; Starks, Courtney M; Francois, Julie A; Sael, Lee; Kihara, Daisuke; Kappock, T Joseph

    2012-01-01

    Bacterial formyl-CoA:oxalate CoA-transferase (FCOCT) and oxalyl-CoA decarboxylase work in tandem to perform a proton-consuming decarboxylation that has been suggested to have a role in generalized acid resistance. FCOCT is the product of uctB in the acidophilic acetic acid bacterium Acetobacter aceti. As expected for an acid-resistance factor, UctB remains folded at the low pH values encountered in the A. aceti cytoplasm. A comparison of crystal structures of FCOCTs and related proteins revealed few features in UctB that would distinguish it from nonacidophilic proteins and thereby account for its acid stability properties, other than a strikingly featureless electrostatic surface. The apparently neutral surface is a result of a “speckled” charge decoration, in which charged surface residues are surrounded by compensating charges but do not form salt bridges. A quantitative comparison among orthologs identified a pattern of residue substitution in UctB that may be a consequence of selection for protein stability by constant exposure to acetic acid. We suggest that this surface charge pattern, which is a distinctive feature of A. aceti proteins, creates a stabilizing electrostatic network without stiffening the protein or compromising protein–solvent interactions. PMID:22374910

  3. Formyl-coenzyme A (CoA):oxalate CoA-transferase from the acidophile Acetobacter aceti has a distinctive electrostatic surface and inherent acid stability.

    PubMed

    Mullins, Elwood A; Starks, Courtney M; Francois, Julie A; Sael, Lee; Kihara, Daisuke; Kappock, T Joseph

    2012-05-01

    Bacterial formyl-CoA:oxalate CoA-transferase (FCOCT) and oxalyl-CoA decarboxylase work in tandem to perform a proton-consuming decarboxylation that has been suggested to have a role in generalized acid resistance. FCOCT is the product of uctB in the acidophilic acetic acid bacterium Acetobacter aceti. As expected for an acid-resistance factor, UctB remains folded at the low pH values encountered in the A. aceti cytoplasm. A comparison of crystal structures of FCOCTs and related proteins revealed few features in UctB that would distinguish it from nonacidophilic proteins and thereby account for its acid stability properties, other than a strikingly featureless electrostatic surface. The apparently neutral surface is a result of a "speckled" charge decoration, in which charged surface residues are surrounded by compensating charges but do not form salt bridges. A quantitative comparison among orthologs identified a pattern of residue substitution in UctB that may be a consequence of selection for protein stability by constant exposure to acetic acid. We suggest that this surface charge pattern, which is a distinctive feature of A. aceti proteins, creates a stabilizing electrostatic network without stiffening the protein or compromising protein-solvent interactions.

  4. Oxalic acid mediated synthesis of WO{sub 3}.H{sub 2}O nanoplates and self-assembled nanoflowers under mild conditions

    SciTech Connect

    Li Linzhi; Zhao Jingzhe; Wang Yi; Li Yunling; Ma Dechong; Zhao Yan; Hou Shengnan; Hao Xinli

    2011-07-15

    Tungsten oxide hydrate (WO{sub 3}.H{sub 2}O) nanoplates and flower-like assemblies were successfully synthesized via a simple aqueous method. The effects of reaction parameters in solution on the preparation were studied. Nanoplates and nanoflowers can be selectively prepared by changing the amount of H{sub 2}C{sub 2}O{sub 4}. In-situ assembly of nanoplates to nanoflowers was also proposed for the formation of assembled nanostructures. In addition, the reaction time and temperature have important effects on the sizes of the as-obtained samples. Crystal structure, morphology, and composition of final nanostructures were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Optical properties of the synthesized samples and the growth mechanism were studied by UV-vis detection. Degradation experiments of Rhodamine B (RhB) were also performed on samples of nanoplates and nanoflowers under visible light illumination. Nanoflower sample exhibited preferable photocatalytic property to nanoplate sample. - Graphical abstract: The oxalic acid has a key role for the structure of WO{sub 3}.H{sub 2}O evolution from plates to flowers and the dehydration process of WO{sub 3}.2H{sub 2}O to WO{sub 3}.H{sub 2}O. Highlights: > Tungsten oxides hydrate was synthesized via a simple aqueous method. > The size of WO{sub 3}.H{sub 2}O was controlled by the reaction time and temperature. > The assembly of WO{sub 3}.H{sub 2}O nanoplates to nanoflowers was achieved with higher H{sub 2}C{sub 2}O{sub 4}/Na{sub 2}WO{sub 4} ratio. > Oxalic acid has a key role in the dehydration process of WO{sub 3}.2H{sub 2}O to WO{sub 3}.H{sub 2}O.

  5. Influence of crustal dust and sea spray supermicron particle concentrations and acidity on inorganic NO3− aerosol during the 2013 Southern Oxidant and Aerosol Study

    DOE PAGES

    Allen, H. M.; Draper, D. C.; Ayres, B. R.; Ault, A.; Bondy, A.; Takahama, S.; Modini, R. L.; Baumann, K.; Edgerton, E.; Knote, C.; et al

    2015-09-25

    Inorganic aerosol composition was measured in the southeastern United States, a region that exhibits high aerosol mass loading during the summer, as part of the 2013 Southern Oxidant and Aerosol Study (SOAS) campaign. Measurements using a Monitor for AeRosols and GAses (MARGA) revealed two periods of high aerosol nitrate (NO3−) concentrations during the campaign. These periods of high nitrate were correlated with increased concentrations of supermicron crustal and sea spray aerosol species, particularly Na+ and Ca2+, and with a shift towards aerosol with larger (1 to 2.5 μm) diameters. We suggest this nitrate aerosol forms by multiphase reactions of HNO3more » and particles, reactions that are facilitated by transport of crustal dust and sea spray aerosol from a source within the United States. The observed high aerosol acidity prevents the formation of NH4NO3, the inorganic nitrogen species often dominant in fine-mode aerosol at higher pH. In addition, calculation of the rate of the heterogeneous uptake of HNO3 on mineral aerosol supports the conclusion that aerosol NO3− is produced primarily by this process, and is likely limited by the availability of mineral cation-containing aerosol surface area. Modeling of NO3− and HNO3 by thermodynamic equilibrium models (ISORROPIA II and E-AIM) reveals the importance of including mineral cations in the southeastern United States to accurately balance ion species and predict gas–aerosol phase partitioning.« less

  6. Oxalates in some Indian green leafy vegetables.

    PubMed

    Radek, M; Savage, G P

    2008-05-01

    The soluble and total oxalate contents of 11 leafy vegetables grown in India were determined. Spinach, purple and green amaranth and colocasia contained high levels of total oxalates, which ranged from 5,138.0 +/- 37.6 mg/100 g dry matter up to 12,576.1 +/- 107.9 mg/100 g dry matter. Seven other leafy vegetables (curry, drumstick, shepu, fenugreek, coriander, radish and onion stalks) contained only insoluble oxalate, which ranged from 209.0 +/- 5.0 mg/100 g dry matter to 2,774.9 +/-18.4 mg/100 g dry matter. In vitro digestion of the samples showed that the gastric available oxalate was 10% lower than the values obtained from acid extraction and that intestinal available oxalate was 20% lower than the values obtained following hot water extraction. The percentage calcium bound in the insoluble oxalate fraction of the dried leafy vegetables ranged from 3.3% to 86.7% of the total calcium. Addition of four different sources of calcium (low fat milk, whole milk, calcium carbonate and calcium sulphate) resulted in a range of 32-100% reductions of intestinal available oxalate in the mixture. PMID:18335334

  7. Evidence for size and charge permselectivity of rat ascending colon. Effects of ricinoleate and bile salts on oxalic acid and neutral sugar transport.

    PubMed Central

    Kathpalia, S C; Favus, M J; Coe, F L

    1984-01-01

    We have measured unidirectional transmural fluxes of oxalate and neutral sugars across rat ascending colon in vitro, under short-circuit conditions, to characterize permeability barriers selective for size and charge. Ionic oxalate appears to be transported preferentially to sodium oxalate. Mucosal addition of taurocholate (1 mM), deoxycholate (1 mM), or ricinoleate (1 mM) increased bidirectional oxalate fluxes, and the ricinoleate effects were independent of medium calcium. Bidirectional fluxes of uncharged sugar molecules fell sharply at molecular weights above 76 (molecular radius above 3 A), and oxalate transport was retarded relative to that of uncharged molecules of similar size, suggesting that there is both size and charge permselectivity. Ricinoleate increased fluxes of all neutral molecules tested but changed neither the exclusion limits nor the cation selectivity of the epithelium. Bile salts and ricinoleate increase oxalate transport, probably by making more channels available, but do not alter size and charge selectivity. PMID:6432849

  8. Contribution of dietary oxalate to urinary oxalate excretion

    NASA Technical Reports Server (NTRS)

    Holmes, R. P.; Goodman, H. O.; Assimos, D. G.

    2001-01-01

    BACKGROUND: The amount of oxalate excreted in urine has a significant impact on calcium oxalate supersaturation and stone formation. Dietary oxalate is believed to make only a minor (10 to 20%) contribution to the amount of oxalate excreted in urine, but the validity of the experimental observations that support this conclusion can be questioned. An understanding of the actual contribution of dietary oxalate to urinary oxalate excretion is important, as it is potentially modifiable. METHODS: We varied the amount of dietary oxalate consumed by a group of adult individuals using formula diets and controlled, solid-food diets with a known oxalate content, determined by a recently developed analytical procedure. Controlled solid-food diets were consumed containing 10, 50, and 250 mg of oxalate/2500 kcal, as well as formula diets containing 0 and 180 mg oxalate/2500 kcal. Changes in the content of oxalate and other ions were assessed in 24-hour urine collections. RESULTS: Urinary oxalate excretion increased as dietary oxalate intake increased. With oxalate-containing diets, the mean contribution of dietary oxalate to urinary oxalate excretion ranged from 24.4 +/- 15.5% on the 10 mg/2500 kcal/day diet to 41.5 +/- 9.1% on the 250 mg/2500 kcal/day diet, much higher than previously estimated. When the calcium content of a diet containing 250 mg of oxalate was reduced from 1002 mg to 391 mg, urinary oxalate excretion increased by a mean of 28.2 +/- 4.8%, and the mean dietary contribution increased to 52.6 +/- 8.6%. CONCLUSIONS: These results suggest that dietary oxalate makes a much greater contribution to urinary oxalate excretion than previously recognized, that dietary calcium influences the bioavailability of ingested oxalate, and that the absorption of dietary oxalate may be an important factor in calcium oxalate stone formation.

  9. Hydrochloric acid aerosol formation by the interaction of hydrogen chloride with humid air

    NASA Technical Reports Server (NTRS)

    Rhein, R. A.

    1973-01-01

    The conditions in which hydrochloric acid aerosol is predicted by the interaction of hydrogen chloride gas with the water vapor in humid air are analyzed. The liquid gas phase equilibrium for the HCL-H2O system is expressed in terms of relative humidity and hydrogen chloride concentration as parts per million, units commonly used in pollution studies. Presented are the concentration (wt %) of HC1 in the aerosol and the concentration of aerosol (ppm) predicted.

  10. Gas-aerosol cycling of ammonia and nitric acid in The Netherlands

    NASA Astrophysics Data System (ADS)

    Roelofs, Geert-Jan; Derksen, Jeroen

    2010-05-01

    Atmospheric ammonia and nitric acid are present over NW Europe in large abundance. Observations made during the IMPACT measurement campaign (May 2008, Cabauw, The Netherlands) show a pronounced diurnal cycle of aerosol ammonium and nitrate on relatively dry days. Simultaneously, AERONET data show a distinct diurnal cycle in aerosol optical thickness (AOT). We used a global aerosol-climate model (ECHAM5-HAM) and a detailed aerosol-cloud column model to help analyse the observations from this period. The study shows that the diurnal cycle in AOT is partly associated with particle number concentration, with distinct peaks in the morning and evening. More important is relative humidity (RH). RH maximizes in the night and early morning, decreases during the morning and increases again in the evening. The particle wet radius, and therefore AOT, changes accordingly. In addition, the RH variability also influences chemistry associated with ammonia and nitric acid (formation of ammonium nitrate, dissolution in aerosol water), resulting in the observed diurnal cycle of aerosol ammonium and nitrate. The additional aerosol matter increases the hygroscopicity of the particles, and this leads to further swelling by water vapor condensation and a further increase of AOT. During the day, as RH decreases and the particles shrink, aerosol ammonium and nitrate are again partly expelled to the gas phase. This behaviour contributes significantly to the observed diurnal cycle in AOT, and it illustrates the complexity of using AOT as a proxy for aerosol concentrations in aerosol climate studies in the case of heavily polluted areas.

  11. A review of oxalate poisoning in domestic animals: tolerance and performance aspects.

    PubMed

    Rahman, M M; Abdullah, R B; Wan Khadijah, W E

    2013-08-01

    Published data on oxalate poisoning in domestic animals are reviewed, with a focus on tolerance and performance. Oxalic acid is one of a number of anti-nutrients found in forage. It can bind with dietary calcium (Ca) or magnesium (Mg) to form insoluble Ca or Mg oxalate, which then may lead to low serum Ca or Mg levels as well as to renal failure because of precipitation of these salts in the kidneys. Dietary oxalate plays an important role in the formation of Ca oxalate, and a high dietary intake of Ca may decrease oxalate absorption and its subsequent urinary excretion. Oxalate-rich plants can be supplemented with other plants as forage for domestic animals, which may help to reduce the overall intake of oxalate-rich plants. Non-ruminants appear to be more sensitive to oxalate than ruminants because in the latter, rumen bacteria help to degrade oxalate. If ruminants are slowly exposed to a diet high in oxalate, the population of oxalate-degrading bacteria in the rumen increases sufficiently to prevent oxalate poisoning. However, if large quantities of oxalate-rich plants are eaten, the rumen is overwhelmed and unable to metabolize the oxalate and oxalate-poisoning results. Based on published data, we consider that <2.0% soluble oxalate would be an appropriate level to avoid oxalate poisoning in ruminants, although blood Ca level may decrease. In the case of non-ruminants, <0.5% soluble oxalate may be acceptable. However, these proposed safe levels of soluble oxalate should be regarded as preliminary. Further studies, especially long-term studies, are needed to validate and improve the recommended safe levels in animals. This review will encourage further research on the relationships between dietary oxalate, other dietary factors and renal failure in domestic animals.

  12. Exposure assessment of oxidant gases and acidic aerosols

    SciTech Connect

    Lioy, P.J.

    1989-01-01

    Clearly the presence of high ozone and acidic species in North America is primarily dependent upon photochemical air pollution. Evidence shows, however, that high acid exposures may occur in specific types of areas of high sulfur fuel use during the winter. At the present time, our concerns about exposure to local populations and regional populations should be directed primarily toward the outdoor activity patterns of individuals in the summer, and how those activity patterns relate to the location, duration, and concentrations of ozone and acid aerosol in photochemical air pollution episodes. Lioy Dyba and Mage et al have examined the activity patterns of children in summer camps. Because they spend more time outside than the normal population, these children form an important group of exercising individuals subject to photochemical pollution exposures. The dose of ozone inhaled by the children in the two camps was within 50% and 25% of the dose inhaled by adults in controlled clinical situations that produced clinically significant decrements in pulmonary function and increased the symptoms after 6.6 hr exposure in a given day. The chamber studies have used only ozone, whereas in the environment this effect may be enhanced by the presence of a complex mixture. The work of Lioy et al in Mendham, New Jersey found that hydrogen ion seemed to play a role in the inability of the children to return immediately to their normal peak expiratory flow rate after exposure. The camp health study conducted in Dunsville, Ontario suggested that children participating in a summer camp where moderate levels of ozone (100 ppb) but high levels of acid (46 micrograms/m3) occurred during an episode had a similar response. Thus, for children or exercising adults who are outdoors for at least one hour or more during a given day, the presence and persistence of oxidants in the environment are of particular concern. 63 references.

  13. Biogeochemistry of oxalate in the antarctic cryptoendolithic lichen-dominated community.

    PubMed

    Johnston, C G; Vestal, J R

    1993-05-01

    Cryptoendolithic (hidden in rock) lichen-dominated microbial communities from the Ross Desert of Antarctica were shown to produce oxalate (oxalic acid). Oxalate increased mineral dissolution, which provides nutrients, creates characteristic weathering patterns, and may ultimately influence the biological residence time of the community. Oxalate was the only organic acid detectable by HPLC, and its presence was verified by GC/MS. Community photosynthetic metabolism was involved in oxalate production since rates of (14)C-oxalate production from (14)C02 were higher in light than in dark incubations. Flaking of the sandstone at the level of the lichen-dominated zone a few millimeters beneath the rock surface can be explained by dissolution of the sandstone cement, which was enhanced by Si, Fe, and Al oxalate complex formation. Added oxalate was observed to increase the solubility of Si, Fe, Al, P, and K. Oxalate's ability to form soluble trivalent metal-oxalate complexes correlated with the observed order of metal oxide depletion from the lichen-dominated zone (Mn > Fe > Al). Thermodynamic calculations predict that Fe oxalate complex formation mobilizes amorphous Fe oxides (ferrihydrite) in the lichen-dominated zone, and where oxalate is depleted, ferrihydrite should precipitate. Hematite, a more crystalline Fe oxide, should remain solid at in situ oxalate concentrations. Oxalate was not a carbon source for the indigenous heterotrophs, but the microbiota were involved in oxalate mineralization to CO2, since oxalate mineralization was reduced in poisoned incubations. Photooxidation of oxalate to C02 coupled with photoreduction of Fe(Ill) may be responsible for oxalate removal in situ, since rates of (14)C-oxalate mineralization in dark incubations were at least 50% lower than those in the light. Removal of oxalate from Si, Fe, and Al complexes should allow free dissolved Si, Fe, and Al to precipitate as amorphous silicates and metal oxides. This may explain increased

  14. Oxalate-degrading microorganisms or oxalate-degrading enzymes: which is the future therapy for enzymatic dissolution of calcium-oxalate uroliths in recurrent stone disease?

    PubMed

    Peck, Ammon B; Canales, Benjamin K; Nguyen, Cuong Q

    2016-02-01

    Renal urolithiasis is a pathological condition common to a multitude of genetic, physiological and nutritional disorders, ranging from general hyperoxaluria to obesity. The concept of quickly dissolving renal uroliths via chemolysis, especially calcium-oxalate kidney stones, has long been a clinical goal, but yet to be achieved. Over the past 25 years, there has been a serious effort to examine the prospects of using plant and microbial oxalate-degrading enzymes known to catabolize oxalic acid and oxalate salts. While evidence is emerging that bacterial probiotics can reduce recurrent calcium-oxalate kidney stone disease by lowering systemic hyperoxaluria, the possible use of free oxalate-degrading enzyme therapy remains a challenge with several hurdles to overcome before reaching clinical practice. PMID:26645869

  15. Use of Cavity Ring Down Spectroscopy to Characterize Organic Acids and Aerosols Emitted in Biomass Burning

    NASA Astrophysics Data System (ADS)

    Bililign, Solomon; Fiddler, Marc; Singh, Sujeeta

    2012-02-01

    One poorly understood, but significant class of volatile organic compounds (VOC) present in biomass burning is gas-phase organic acids and inorganic acids. These acids are extremely difficult to measure because of their adsorptive nature. Particulates and aerosols are also produced during biomass burning and impact the radiation budget of the Earth and, hence, impact global climate. Use cavity ring down spectroscopy (CRD) to measure absorption cross sections for OH overtone induced photochemistry in some organic acids (acetic acid and peracetic acid) will be presented and planed measurements of optical properties of aerosols composed of mixtures of different absorbing and non-absorbing species using CRD will be discussed.

  16. Pulmonary function and clearance after prolonged sulfuric acid aerosol exposure

    SciTech Connect

    Ives, P.J. ); Gerrity, T.R.; DeWitt, P.; Folinsbee, L.J. )

    1991-03-15

    The authors studied pulmonary function and clearance responses after a 4 H exposure to 75-100 {mu}g/m{sup 3} sulfuric acid aerosol (SAA). Healthy subjects, who exercised for 30 min/H at ventilation of about 25 L/min, were exposed once to clean air and once to SAA. Oral hygiene and acidic juice gargle were used to minimize oral ammonia. Lung function tests, including spirometry, plethysmography, and partial flow-volume (PEFV) curves were performed before and after exposure. Clearance of 99m-Technetium labeled iron oxide was assessed after each exposure. The first moment of fractional tracheobronchial retention (M1TBR), after correcting for 24 H retention and normalizing to time zero, was used as an index of clearance. There were no significant changes in lung volumes, airways resistance, or maximum expiratory flows after SAA exposure. Flow at 40% of total lung capacity on PEFV curves decreased 17% (NS) after SAA exposure. Tracheobronchial clearance was accelerated after a single exposure to SAA; M1TBR decreased from 73 {plus minus} 5 min (air) to 69 {plus minus} 5 min (SAA). These results suggest that acute prolonged exposure to low levels of SAA has minimal effects on lung mechanics in healthy subjects but does produce a modest acceleration of particle clearance.

  17. Acute oxalate nephropathy caused by ethylene glycol poisoning

    PubMed Central

    Seo, Jung Woong; Lee, Jong-Ho; Son, In Sung; Kim, Yong Jin; Kim, Do Young; Hwang, Yong; Chung, Hyun Ah; Choi, Hong Seok; Lim, So Dug

    2012-01-01

    Ethylene glycol (EG) is a sweet-tasting, odorless organic solvent found in many agents, such as anti-freeze. EG is composed of four organic acids: glycoaldehyde, glycolic acid, glyoxylic acid and oxalic acid in vivo. These metabolites are cellular toxins that can cause cardio-pulmonary failure, life-threatening metabolic acidosis, central nervous system depression, and kidney injury. Oxalic acid is the end product of EG, which can precipitate to crystals of calcium oxalate monohydrate in the tubular lumen and has been linked to acute kidney injury. We report a case of EG-induced oxalate nephropathy, with the diagnosis confirmed by kidney biopsy, which showed acute tubular injury of the kidneys with extensive intracellular and intraluminal calcium oxalate monohydrate crystal depositions. PMID:26889430

  18. An oxalyl-CoA dependent pathway of oxalate catabolism plays a role in regulating calcium oxalate crystal accumulation and defending against oxalate-secreting phytopathogens in Medicago truncatula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Considering the widespread occurrence of oxalate in nature and its broad impact on a host of organisms, it is surprising that so little is known about the turnover of this important acid. In plants, oxalate oxidase is the most well studied enzyme capable of degrading oxalate, but not all plants pos...

  19. Organosulfate formation during the uptake of pinonaldehyde on acidic sulfate aerosols

    NASA Astrophysics Data System (ADS)

    Liggio, John; Li, Shao-Meng

    2006-07-01

    Organosulfates are observed in studies of pinonaldehyde reactions with acidic sulfate aerosols using aerosol mass spectrometry, during which a significant fraction of the pinonaldehyde reaction products were found to consist of organosulfate compounds that account for 6-51% of the initial SO4= mass. Resultant aerosol mass spectra were consistent with proposed sulfate ester mechanisms, which likely form stable products. The existence of organosulfates was also confirmed in studies of the reaction system in bulk solution. The formation of organosulfates suggests that conventional inorganic SO4= chemical analysis may underestimate total SO4= mass in ambient aerosols.

  20. Evaluation of Oxalate Concentration in the U.S. Spinach Germplasm Collection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In addition to its high nutrient content, spinach (Spinacia oleracea L.) is also known to have greater amount of oxalic acid than most crops. Oxalic acid may form crystals with minerals to reduce the bioavailability and absorption of calcium and iron in diets, and calcium oxalate may deposit in the...

  1. Chemical characterization of secondary organic aerosol constituents from isoprene ozonolysis in the presence of acidic aerosol

    NASA Astrophysics Data System (ADS)

    Riva, Matthieu; Budisulistiorini, Sri Hapsari; Zhang, Zhenfa; Gold, Avram; Surratt, Jason D.

    2016-04-01

    Isoprene is the most abundant non-methane hydrocarbon emitted into Earth's atmosphere and is predominantly derived from terrestrial vegetation. Prior studies have focused largely on the hydroxyl (OH) radical-initiated oxidation of isoprene and have demonstrated that highly oxidized compounds, such as isoprene-derived epoxides, enhance the formation of secondary organic aerosol (SOA) through heterogeneous (multiphase) reactions on acidified sulfate aerosol. However, studies on the impact of acidified sulfate aerosol on SOA formation from isoprene ozonolysis are lacking and the current work systematically examines this reaction. SOA was generated in an indoor smog chamber from isoprene ozonolysis under dark conditions in the presence of non-acidified or acidified sulfate seed aerosol. The effect of OH radicals on SOA chemical composition was investigated using diethyl ether as an OH radical scavenger. Aerosols were collected and chemically characterized by ultra performance liquid chromatography/electrospray ionization high-resolution quadrupole time-of-flight mass spectrometry (UPLC/ESI-HR-QTOFMS) and gas chromatography/electron impact ionization-mass spectrometry (GC/EI-MS). Analysis revealed the formation of highly oxidized compounds, including organosulfates (OSs) and 2-methylterols, which were significantly enhanced in the presence of acidified sulfate seed aerosol. OSs identified in the chamber experiments were also observed and quantified in summertime fine aerosol collected from two rural locations in the southeastern United States during the 2013 Southern Oxidant and Aerosol Study (SOAS).

  2. Theoretical description of hydrogen bonding in oxalic acid dimer and trimer based on the combined extended-transition-state energy decomposition analysis and natural orbitals for chemical valence (ETS-NOCV)

    PubMed Central

    Mitoraj, Mariusz P.; Kurczab, Rafał; Boczar, Marek

    2010-01-01

    In the present study we have analyzed hydrogen bonding in dimer and trimer of oxalic acid, based on a recently proposed charge and energy decomposition scheme (ETS-NOCV). In the case of a dimer, two conformations, α and β, were considered. The deformation density contributions originating from NOCV’s revealed that the formation of hydrogen bonding is associated with the electronic charge deformation in both the σ—(Δρσ) and π-networks (Δρπ). It was demonstrated that σ-donation is realized by electron transfer from the lone pair of oxygen on one monomer into the empty \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\rho_{H - O}^* $$\\end{document} orbital of the second oxalic acid fragment. In addition, a covalent contribution is observed by the density transfer from hydrogen of H-O group in one oxalic acid monomer to the oxygen atom of the second fragment. The resonance assisted component (Δρπ), is based on the transfer of electron density from the π—orbital localized on the oxygen of OH on one oxalic acid monomer to the oxygen atom of the other fragment. ETS-NOCV allowed to conclude that the σ(O---HO) component is roughly eight times as important as π (RAHB) contribution in terms of energetic estimation. The electrostatic factor (ΔEelstat) is equally as important as orbital interaction term (ΔEorb). Finally, comparing β-dimer of oxalic acid with trimer we found practically no difference concerning each of the O---HO bonds, neither qualitative nor quantitative. Figure The contours of deformation density σ- and π-contributions describing the hydrogen bonding between the monomers in the oxalic acid dimer, together with the corresponding ETS-NOCV-based orbital-interaction energies (in kcal/mol). PMID:20505966

  3. Determination of uric acid in urine, saliva and calcium oxalate renal calculi by high-performance liquid chromatography/mass spectrometry.

    PubMed

    Perelló, Joan; Sanchis, Pilar; Grases, Félix

    2005-09-25

    A very simple and direct method for determination of uric acid, in various biological matrices, based on high-performance liquid chromatography and mass spectrometry is described. Chromatographic separations were performed with a stationary phase Zorbax Sax Column, an anion exchange resin, with 50% sodium citrate 1 mM at pH 6.5 and 50% acetonitrile as mobile phase delivered at a flow rate of 1 ml/min. The detector counted negative ions by monitoring m/z 167.1, which corresponds to the urate anion. The method does not use an internal standard but quality control samples were used. Intra-day precision ranged between 1.1 and 1.5%, whereas inter-day precision was between 1.3 and 2.8% (n=5) working with some selected standards. Recovery tests of added standard have been successfully performed in urine and saliva samples, thus showing an appropriate accuracy of the method. The limit of quantitation found was 70 microg/l. Different urine and saliva samples were analyzed using an alternative analytical methodology based on an enzymatic reaction and photometric detection at 520 nm, resulting both methods comparable at a 95% confidence level. The method has been also applied to the determination of trace amounts of uric acid in the core of some selected calcium oxalate renal calculi. PMID:16061429

  4. Arthritis associated with calcium oxalate crystals in an anephric patient treated with peritoneal dialysis

    SciTech Connect

    Rosenthal, A.; Ryan, L.M.; McCarty, D.J.

    1988-09-02

    The authors report a case of calcium oxalate arthropathy in a woman undergoing intermittent peritoneal dialysis who was not receiving pharmacologic doses of ascorbic acid. She developed acute arthritis, with calcium oxalate crystals in Heberden's and Bouchard's nodes, a phenomenon previously described in gout. Intermittent peritoneal dialysis may be less efficient than hemodialysis in clearing oxalate, and physicians should now consider calcium oxalate-associated arthritis in patients undergoing peritoneal dialysis who are not receiving large doses of ascorbic acid.

  5. High abundances of water-soluble dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls in the mountaintop aerosols over the North China Plain during wheat burning season

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Tachibana, E.; Okuzawa, K.; Aggarwal, S. G.; Kanaya, Y.; Wang, Z. F.

    2013-08-01

    Aerosol (TSP) samples were collected at the summit of Mount Tai (elevation: 1534 m a.s.l., 36.25° N, 117.10° E) located in the North China Plain using a high-volume air sampler and pre-combusted quartz filters. Sampling was conducted on day/night or 3 h basis in the period from 29 May to 28 June 2006 during the field burning of wheat straw residue and the post-burning season. The filter samples were analyzed for low-molecular-weight dicarboxylic acids, ketoacids and α-dicarbonyls using capillary gas chromatography (GC) and GC-MS employing water extraction and butyl ester derivatization. Molecular distributions of dicarboxylic acids (C2-C11, 220-6070 ng m-3) were characterized by a predominance of oxalic (C2) acid (105-3920 ng m-3) followed by succinic (C4) or malonic (C3) acid. Unsaturated aliphatic diacids, including maleic (M), isomaleic (iM) and fumaric (F) acids, were also detected together with aromatic diacids (phthalic, isophthalic and terephthalic acids). ω-oxocarboxylic acids (C2-C9, 24-610 ng m-3) were detected as the second most abundant compound class with the predominance of glyoxylic acid (11-360 ng m-3), followed by α-ketoacid (pyruvic acid, 3-140 ng m-3) and α-dicarbonyls (glyoxal, 1-230 ng m-3 and methylglyoxal, 2-120 ng m-3). We found that these levels (>6000 ng m-3 for diacids) are several times higher than those reported in Chinese megacities at ground levels. The concentrations of diacids increased from late May to early June, showing a maximum on 7 June, and then significantly decreased during the period 8-11 June, when the wind direction shifted from southerly to northerly. Similar temporal trends were found for ketocarboxylic acids and α-dicarbonyls as well as total carbon (TC) and water-soluble organic carbon (WSOC). The temporal variations of water-soluble organics were interpreted by the direct emission from the field burning of agricultural wastes (wheat straw) in the North China Plain and the subsequent photochemical oxidation of

  6. Heterogeneous conversion of calcite aerosol by nitric acid.

    PubMed

    Preszler Prince, A; Grassian, V H; Kleiber, P; Young, M A

    2007-02-01

    The reaction of nitric acid with calcite aerosol at varying relative humidities has been studied under suspended particle conditions in an atmospheric reaction chamber using infrared absorption spectroscopy. The reactant concentration in the chamber, as well as the appearance of gas phase products and surface adsorbed species, was spectroscopically monitored before and after mixing with CaCO(3) (calcite) particles. The interaction with HNO(3) was found to lead to gas phase CO(2) evolution and increased water uptake due to heterogeneous conversion of the carbonate to particulate nitrate. The reaction was enhanced as the relative humidity of the system was increased, especially at relative humidities above the reported deliquescence point of particulate Ca(NO(3))(2). The measured reaction extent demonstrates that the total calcite particulate mass is available for reaction with HNO(3) and the conversion process is not limited to the particle surface. The spectroscopy of the surface formed nitrate suggests a highly concentrated solution environment with a significant degree of ion pairing. The implications of the HNO(3) loss and the formation of the particulate nitrate product for atmospheric chemistry are discussed. PMID:17242744

  7. Sulfuric acid deposition from stratospheric geoengineering with sulfate aerosols

    NASA Astrophysics Data System (ADS)

    Kravitz, Ben; Robock, Alan; Oman, Luke; Stenchikov, Georgiy; Marquardt, Allison B.

    2009-07-01

    We used a general circulation model of Earth's climate to conduct geoengineering experiments involving stratospheric injection of sulfur dioxide and analyzed the resulting deposition of sulfate. When sulfur dioxide is injected into the tropical or Arctic stratosphere, the main additional surface deposition of sulfate occurs in midlatitude bands, because of strong cross-tropopause flux in the jet stream regions. We used critical load studies to determine the effects of this increase in sulfate deposition on terrestrial ecosystems by assuming the upper limit of hydration of all sulfate aerosols into sulfuric acid. For annual injection of 5 Tg of SO2 into the tropical stratosphere or 3 Tg of SO2 into the Arctic stratosphere, neither the maximum point value of sulfate deposition of approximately 1.5 mEq m-2 a-1 nor the largest additional deposition that would result from geoengineering of approximately 0.05 mEq m-2 a-1 is enough to negatively impact most ecosystems.

  8. Compound Specific Isotope Analysis of Fatty Acids in Southern African Aerosols

    NASA Astrophysics Data System (ADS)

    Billmark, K. A.; Macko, S. A.; Swap, R. J.

    2003-12-01

    This study, conducted as a part of the Southern African Regional Science Initiative (SAFARI 2000), applied compound specific isotope analysis to describe aerosols at source regions and rural locations. Stable carbon isotopic compositions of individual fatty acids were determined for aerosol samples collected at four sites throughout southern Africa. Mongu, Zambia and Skukuza, South Africa were chosen for their location within intense seasonal Miombo woodland savanna and bushveld savanna biomass burning source regions, respectively. Urban aerosols were collected at Johannesburg, South Africa and rural samples were collected at Sua Pan, Botswana. Fatty acid isotopic compositions varied temporally. Urban aerosols showed significant isotopic enrichment of selected short chain fatty acids (C < 20) compared to aerosols produced during biomass combustion. Sua Pan short chain fatty acid signatures were significantly different from the other non-urban sites, which suggests that sources other than biomass combustion products, such as organic eolian material, impact the Sua Pan aerosol profile. However, a high degree of correlation between Sua Pan and Skukuza long chain fatty acid δ 13C values confirm atmospheric linkages between the two areas and that isotopic signatures of combusted fatty acids are unaltered during atmospheric transport highlighting their potential for use as a conservative tracer.

  9. A one-pot gold seed-assisted synthesis of gold/platinum wire nanoassemblies and their enhanced electrocatalytic activity for the oxidation of oxalic acid

    NASA Astrophysics Data System (ADS)

    Bai, Juan; Fang, Chun-Long; Liu, Zong-Huai; Chen, Yu

    2016-01-01

    Three-dimensional (3D) noble metal nanoassemblies composed of one-dimensional (1D) nanowires have been attracting much interest due to the unique physical and chemical properties of 1D nanowires as well as the particular interconnected open-pore structure of 3D nanoassemblies. In this work, well-defined Au/Pt wire nanoassemblies were synthesized by using a facile NaBH4 reduction method in the presence of a branched form of polyethyleneimine (PEI). A study of the growth mechanism indicated the morphology of the final product to be highly related to the molecular structure of the polymeric amine. Also, the preferred Pt-on-Pt deposition contributed to the formation of the 1D Pt nanowires. The Au/Pt wire nanoassemblies were functionalized with PEI at the same time that these nanoassemblies were synthesized due to the strong N-Pt bond. The chemically functionalized Au/Pt wire nanoassemblies exhibited better electrocatalytic activity for the electro-oxidation of oxalic acid than did commercial Pt black.Three-dimensional (3D) noble metal nanoassemblies composed of one-dimensional (1D) nanowires have been attracting much interest due to the unique physical and chemical properties of 1D nanowires as well as the particular interconnected open-pore structure of 3D nanoassemblies. In this work, well-defined Au/Pt wire nanoassemblies were synthesized by using a facile NaBH4 reduction method in the presence of a branched form of polyethyleneimine (PEI). A study of the growth mechanism indicated the morphology of the final product to be highly related to the molecular structure of the polymeric amine. Also, the preferred Pt-on-Pt deposition contributed to the formation of the 1D Pt nanowires. The Au/Pt wire nanoassemblies were functionalized with PEI at the same time that these nanoassemblies were synthesized due to the strong N-Pt bond. The chemically functionalized Au/Pt wire nanoassemblies exhibited better electrocatalytic activity for the electro-oxidation of oxalic acid than

  10. Organics Substantially Reduce HO2 Uptake onto Aerosols Containing Transition Metal ions.

    PubMed

    Lakey, Pascale S J; George, Ingrid J; Baeza-Romero, Maria T; Whalley, Lisa K; Heard, Dwayne E

    2016-03-10

    A HO2 mass accommodation coefficient of α = 0.23 ± 0.07 was measured onto submicron copper(II)-doped ammonium sulfate aerosols at a relative humidity of 60 ± 3%, at 293 ± 2 K and at an initial HO2 concentration of ∼ 1 × 10(9) molecules cm(-3) by using an aerosol flow tube coupled to a sensitive fluorescence assay by gas expansion (FAGE) HO2 detection system. The effect upon the HO2 uptake coefficient γ of adding different organic species (malonic acid, citric acid, 1,2-diaminoethane, tartronic acid, ethylenediaminetetraacetic acid (EDTA), and oxalic acid) into the copper(II)-doped aerosols was investigated. The HO2 uptake coefficient decreased steadily from the mass accommodation value to γ = 0.008 ± 0.009 when EDTA was added in a one-to-one molar ratio with the copper(II) ions, and to γ = 0.003 ± 0.004 when oxalic acid was added into the aerosol in a ten-to-one molar ratio with the copper(II). EDTA binds strongly to copper(II) ions, potentially making them unavailable for catalytic destruction of HO2, and could also be acting as a surfactant or changing the viscosity of the aerosol. The addition of oxalic acid to the aerosol potentially forms low-volatility copper-oxalate complexes that reduce the uptake of HO2 either by changing the viscosity of the aerosol or by causing precipitation out of the aerosol forming a coating. It is likely that there is a high enough oxalate to copper(II) ion ratio in many types of atmospheric aerosols to decrease the HO2 uptake coefficient. No observable change in the HO2 uptake coefficient was measured when the other organic species (malonic acid, citric acid, 1,2-diaminoethane, and tartronic acid) were added in a ten-to-one molar ratio with the copper(II) ions. PMID:26484935

  11. Factors affecting the response of lung clearance systems to acid aerosols: role of exposure concentration, exposure time, and relative acidity.

    PubMed

    Schlesinger, R B

    1989-02-01

    The ability of the lungs to clear deposited material is essential for maintenance of lung homeostasis. Acid aerosols have been shown to alter the efficiency of this process. This paper assesses the role of acid aerosol exposure concentration (C), exposure time (T), and relative acidity in producing changes in clearance from both the tracheobronchial tree and respiratory region of the lungs of rabbits. The response was found to be due to total exposure, i.e., some combination form of C x T, and was also related to relative acidity.

  12. Stratospheric aerosol acidity, density, and refractive index deduced from SAGE 2 and NMC temperature data

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Poole, L. R.; Wang, P.-H.; Chiou, E. W.

    1994-01-01

    Water vapor concentrations obtained by the Stratospheric Aerosol and Gas Experiment 2 (SAGE 2) and collocated temperatures provided by the National Meteorological Center (NMC) from 1986 to 1990 are used to deduce seasonally and zonally averaged acidity, density, and refractive index of stratospheric aerosols. It is found that the weight percentage of sulfuric acid in the aerosols increases from about 60 just above the tropopause to about 86 at 35 km. The density increases from about 1.55 to 1.85 g/cu cm between the same altitude limits. Some seasonal variations of composition and density are evident at high latitudes. The refractive indices at 1.02, 0.694, and 0.532 micrometers increase, respectively, from about 1.425, 1.430, and 1.435 just above the tropopause to about 1.445, 1.455, and 1.458 at altitudes above 27 km, depending on the season and latitude. The aerosol properties presented can be used in models to study the effectiveness of heterogeneous chemistry, the mass loading of stratospheric aerosols, and the extinction and backscatter of aerosols at different wavelengths. Computed aerosol surface areas, rate coefficients for the heterogeneous reaction ClONO2 + H2O yields HOCl + HNO3 and aerosol mass concentrations before and after the Pinatubo eruption in June 1991 are shown as sample applications.

  13. High abundances of water-soluble dicarboxylic acids, ketocarboxylic acids and α-dicarbonyls in the mountain aerosols over the North China Plain during wheat burning season

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Tachibana, E.; Okuzawa, K.; Aggarwal, S. G.; Kanaya, Y.; Wang, Z. F.

    2013-02-01

    Aerosol (TSP) samples were collected at the summit of Mount Tai (elevation: 1534 m a.s.l., 36.25° N; 117.10° E) located in the North China Plain using a high-volume air sampler and pre-combusted quartz filters. Sampling was conducted on day/night or 3 h basis in the period from 29 May to 28 June 2006 during the field burning of wheat straw residue and the post-burning season. The filter samples were analyzed for low molecular weight dicarboxylic acids, ketoacids and α-dicarbonyls using capillary gas chromatography (GC) and GC-MS employing water extraction and butyl ester derivatization. Dicarboxylic acids (C2-C11, 220-6070 ng m-3) were characterized by a predominance of oxalic (C2) acid (105-3920 ng m-3) followed by succinic (C4) or malonic (C3) acid. Unsaturated aliphatic diacids, including maleic (M), isomaleic (iM) and fumaric (F) acid, were also detected together with aromatic diacids (phthalic, iso-phthalic and tere-phthalic acids). ω-Oxocarboxylic acids (C2-C9, 24-610 ng m-3) were detected as the second most abundant compound class with the predominance of glyoxylic acid (11-360 ng m-3), followed by α-ketoacid (pyruvic acid, 3-140 ng m-3) and α-dicarbonyls (glyoxal, 1-230 ng m-3 and methylglyoxal, 2-120 ng m-3). We found that these levels (> 6000 ng m-3 for diacids) are several times higher than those reported in Chinese megacities at ground levels. The concentrations of diacids increased from late May to early June showing a maximum on 7 June and then significantly decreased during 8-11 June when the wind direction shifted from northeasterly to northerly. Similar temporal trends were found for ketocarboxylic acids and α-dicarbonyls as well as total carbon (TC) and water-soluble organic carbon (WSOC). The temporal variations of water-soluble organics were interpreted by the direct emission from the field burning products of agricultural wastes (wheat straw) in the North China Plain and the subsequent photochemical oxidation of volatile and semi

  14. Progress, prospects, and research needs on the health effects of acid aerosols.

    PubMed

    Lippmann, M

    1989-02-01

    Research on human exposure to acidic aerosols and the health effects of such exposures has substantially strengthened the hypothesis that such aerosols are a causal factor for excesses in human mortality and morbidity that have been previously associated with crude exposure indices such as British Smoke, total suspended particulate matter, and sulfur dioxide. Research reported at this symposium also showed that combined exposures to acid aerosols and other ubiquitous air pollutants such as O3, NO2, HNO3, and SO2 produce greater effects in both humans and animals than exposures to each agent separately. The responses reported ranged from physiological functions to lung structure. Furthermore, some of the effects were cumulative with increasing duration of daily exposure and number of repetitive exposures. Critical areas for further research include better definition of the critical temporal parameters affecting exposure and response, effects of mixed pollutant exposures, and pathogenetic mechanisms for acid aerosol-induced chronic lung damage.

  15. Influence of crustal dust and sea spray supermicron particle concentrations and acidity on inorganic NO3- aerosol during the 2013 Southern Oxidant and Aerosol Study

    SciTech Connect

    Allen, Hannah M.; Draper, Danielle C.; Ayres, Benjamin R.; Ault, Andrew P.; Bondy, Amy L.; Takahama, S.; Modini, Robert; Baumann, K.; Edgerton, Eric S.; Knote, Christoph; Laskin, Alexander; Wang, Bingbing; Fry, Juliane L.

    2015-09-25

    The inorganic aerosol composition was measured in the southeastern United States, a region that exhibits high aerosol mass loading during the summer, as part of the 1 June to 15 July 2013 Southern Oxidant and Aerosol Study (SOAS) campaign. Measurements using a Monitor for AeRosols and GAses (MARGA), an ion chromatograph coupled with a wet rotating denuder and a steam-jet aerosol collector for monitoring of ambient inorganic gas and aerosol species, revealed two periods of high aerosol nitrate (NO3 ) concentrations during the campaign. These periods of high nitrate were correlated with increased concentrations of coarse mode mineral or sea spray aerosol species, particularly Na+ and Ca2+, and with a shift towards aerosol with larger (1 to 2.5 um) diameters. We suggest this nitrate aerosol forms by multiphase reactions of HNO3 and particles, reactions that are facilitated by transport of mineral dust and sea spray aerosol from a source within the United States. The observed high aerosol acidity prevents the formation of NH4NO3, the inorganic nitrogen species often dominant in fine-mode aerosol at higher pH. Calculation of the rate of the heterogeneous uptake of HNO3 on mineral aerosol supports the conclusion that aerosol NO3 is produced primarily by this process, and is likely limited by the availability of mineral dust surface area. Modeling of NO3 and HNO3 by thermodynamic equilibrium models (ISORROPIA II and E-AIM) reveals the importance of including mineral cations in the southeastern United States to accurately balance ion species and predict gas/aerosol phase partitioning.

  16. Reduction of Oxalate Levels in Tomato Fruit and Consequent Metabolic Remodeling Following Overexpression of a Fungal Oxalate Decarboxylase1[W

    PubMed Central

    Chakraborty, Niranjan; Ghosh, Rajgourab; Ghosh, Sudip; Narula, Kanika; Tayal, Rajul; Datta, Asis; Chakraborty, Subhra

    2013-01-01

    The plant metabolite oxalic acid is increasingly recognized as a food toxin with negative effects on human nutrition. Decarboxylative degradation of oxalic acid is catalyzed, in a substrate-specific reaction, by oxalate decarboxylase (OXDC), forming formic acid and carbon dioxide. Attempts to date to reduce oxalic acid levels and to understand the biological significance of OXDC in crop plants have met with little success. To investigate the role of OXDC and the metabolic consequences of oxalate down-regulation in a heterotrophic, oxalic acid-accumulating fruit, we generated transgenic tomato (Solanum lycopersicum) plants expressing an OXDC (FvOXDC) from the fungus Flammulina velutipes specifically in the fruit. These E8.2-OXDC fruit showed up to a 90% reduction in oxalate content, which correlated with concomitant increases in calcium, iron, and citrate. Expression of OXDC affected neither carbon dioxide assimilation rates nor resulted in any detectable morphological differences in the transgenic plants. Comparative proteomic analysis suggested that metabolic remodeling was associated with the decrease in oxalate content in transgenic fruit. Examination of the E8.2-OXDC fruit proteome revealed that OXDC-responsive proteins involved in metabolism and stress responses represented the most substantially up- and down-regulated categories, respectively, in the transgenic fruit, compared with those of wild-type plants. Collectively, our study provides insights into OXDC-regulated metabolic networks and may provide a widely applicable strategy for enhancing crop nutritional value. PMID:23482874

  17. ADVANCED OXIDATION: OXALATE DECOMPOSITION TESTING WITH OZONE

    SciTech Connect

    Ketusky, E.; Subramanian, K.

    2012-02-29

    At the Savannah River Site (SRS), oxalic acid is currently considered the preferred agent for chemically cleaning the large underground Liquid Radioactive Waste Tanks. It is applied only in the final stages of emptying a tank when generally less than 5,000 kg of waste solids remain, and slurrying based removal methods are no-longer effective. The use of oxalic acid is preferred because of its combined dissolution and chelating properties, as well as the fact that corrosion to the carbon steel tank walls can be controlled. Although oxalic acid is the preferred agent, there are significant potential downstream impacts. Impacts include: (1) Degraded evaporator operation; (2) Resultant oxalate precipitates taking away critically needed operating volume; and (3) Eventual creation of significant volumes of additional feed to salt processing. As an alternative to dealing with the downstream impacts, oxalate decomposition using variations of ozone based Advanced Oxidation Process (AOP) were investigated. In general AOPs use ozone or peroxide and a catalyst to create hydroxyl radicals. Hydroxyl radicals have among the highest oxidation potentials, and are commonly used to decompose organics. Although oxalate is considered among the most difficult organic to decompose, the ability of hydroxyl radicals to decompose oxalate is considered to be well demonstrated. In addition, as AOPs are considered to be 'green' their use enables any net chemical additions to the waste to be minimized. In order to test the ability to decompose the oxalate and determine the decomposition rates, a test rig was designed, where 10 vol% ozone would be educted into a spent oxalic acid decomposition loop, with the loop maintained at 70 C and recirculated at 40L/min. Each of the spent oxalic acid streams would be created from three oxalic acid strikes of an F-area simulant (i.e., Purex = high Fe/Al concentration) and H-area simulant (i.e., H area modified Purex = high Al/Fe concentration) after nearing

  18. A novel digestion method based on a choline chloride-oxalic acid deep eutectic solvent for determining Cu, Fe, and Zn in fish samples.

    PubMed

    Habibi, Emadaldin; Ghanemi, Kamal; Fallah-Mehrjardi, Mehdi; Dadolahi-Sohrab, Ali

    2013-01-31

    A novel and efficient digestion method based on choline chloride-oxalic acid (ChCl-Ox) deep eutectic solvent (DES) was developed for flame atomic absorption spectrometry (FAAS) determination of Cu, Zn, and Fe in biological fish samples. Key parameters that influence analyte recovery were investigated and optimized, using the fish protein certified reference material (CRM, DORM-3) throughout the procedure. In this method, 100 mg of the sample was dissolved in ChCl-Ox (1:2, molar ratio) at 100°C for 45 min. Then, 5.0 mL HNO(3) (1.0 M) was added. After centrifugation, the supernatant solution was filtered, diluted to a known volume, and analyzed by FAAS. Under optimized conditions, an excellent agreement between the obtained results and the certified values was observed, using Student's t-test (P=0.05); the extraction recovery of the all elements was greater than 95.3%. The proposed method was successfully applied to the determination of analytes in different tissues (muscle, liver, and gills) having a broad concentration range in a marine fish sample. The reproducibility of the method was validated by analyzing all samples by our method in a different laboratory, using inductively coupled plasma optical emission spectrometry (ICP-OES). For comparison, a conventional acid digestion (CAD) method was also used for the determination of analytes in all studied samples. The simplicity of the proposed experimental procedure, high extraction efficiency, short analysis time, lack of concentrated acids and oxidizing agents, and the use of safe and inexpensive components demonstrate the high potential of ChCl-Ox (1:2) for routine trace metal analysis in biological samples.

  19. A novel digestion method based on a choline chloride-oxalic acid deep eutectic solvent for determining Cu, Fe, and Zn in fish samples.

    PubMed

    Habibi, Emadaldin; Ghanemi, Kamal; Fallah-Mehrjardi, Mehdi; Dadolahi-Sohrab, Ali

    2013-01-31

    A novel and efficient digestion method based on choline chloride-oxalic acid (ChCl-Ox) deep eutectic solvent (DES) was developed for flame atomic absorption spectrometry (FAAS) determination of Cu, Zn, and Fe in biological fish samples. Key parameters that influence analyte recovery were investigated and optimized, using the fish protein certified reference material (CRM, DORM-3) throughout the procedure. In this method, 100 mg of the sample was dissolved in ChCl-Ox (1:2, molar ratio) at 100°C for 45 min. Then, 5.0 mL HNO(3) (1.0 M) was added. After centrifugation, the supernatant solution was filtered, diluted to a known volume, and analyzed by FAAS. Under optimized conditions, an excellent agreement between the obtained results and the certified values was observed, using Student's t-test (P=0.05); the extraction recovery of the all elements was greater than 95.3%. The proposed method was successfully applied to the determination of analytes in different tissues (muscle, liver, and gills) having a broad concentration range in a marine fish sample. The reproducibility of the method was validated by analyzing all samples by our method in a different laboratory, using inductively coupled plasma optical emission spectrometry (ICP-OES). For comparison, a conventional acid digestion (CAD) method was also used for the determination of analytes in all studied samples. The simplicity of the proposed experimental procedure, high extraction efficiency, short analysis time, lack of concentrated acids and oxidizing agents, and the use of safe and inexpensive components demonstrate the high potential of ChCl-Ox (1:2) for routine trace metal analysis in biological samples. PMID:23327946

  20. Surface aggregation of urinary proteins and aspartic acid-rich peptides on the faces of calcium oxalate monohydrate investigated by in situ force microscopy

    SciTech Connect

    Weaver, M L; Qiu, S R; Hoyer, J R; Casey, W H; Nancollas, G H; De Yoreo, J J

    2008-05-28

    The growth of calcium oxalate monohydrate in the presence of Tamm-Horsfall protein (THP), osteopontin (OPN), and the 27-residue synthetic peptides (DDDS){sub 6}DDD and (DDDG){sub 6}DDD [where D = aspartic acid and X = S (serine) or G (glycine)] was investigated via in situ atomic force microscopy (AFM). The results show that these three growth modulators create extensive deposits on the crystal faces. Depending on the modulator and crystal face, these deposits can occur as discrete aggregates, filamentary structures, or uniform coatings. These proteinaceous films can lead to either the inhibition or increase of the step speeds (with respect to the impurity-free system) depending on a range of factors that include peptide or protein concentration, supersaturation and ionic strength. While THP and the linear peptides act, respectively, to exclusively increase and inhibit growth on the (-101) face, both exhibit dual functionality on the (010) face, inhibiting growth at low supersaturation or high modulator concentration and accelerating growth at high supersaturation or low modulator concentration. Based on analyses of growth morphologies and dependencies of step speeds on supersaturation and protein or peptide concentration, we argue for a picture of growth modulation that accounts for the observations in terms of the strength of binding to the surfaces and steps and the interplay of electrostatic and solvent-induced forces at crystal surface.

  1. CO2-free power generation on an iron group nanoalloy catalyst via selective oxidation of ethylene glycol to oxalic acid in alkaline media.

    PubMed

    Matsumoto, Takeshi; Sadakiyo, Masaaki; Ooi, Mei Lee; Kitano, Sho; Yamamoto, Tomokazu; Matsumura, Syo; Kato, Kenichi; Takeguchi, Tatsuya; Yamauchi, Miho

    2014-07-08

    An Fe group ternary nanoalloy (NA) catalyst enabled selective electrocatalysis towards CO2-free power generation from highly deliverable ethylene glycol (EG). A solid-solution-type FeCoNi NA catalyst supported on carbon was prepared by a two-step reduction method. High-resolution electron microscopy techniques identified atomic-level mixing of constituent elements in the nanoalloy. We examined the distribution of oxidised species, including CO2, produced on the FeCoNi nanoalloy catalyst in the EG electrooxidation under alkaline conditions. The FeCoNi nanoalloy catalyst exhibited the highest selectivities toward the formation of C2 products and to oxalic acid, i.e., 99 and 60%, respectively, at 0.4 V vs. the reversible hydrogen electrode (RHE), without CO2 generation. We successfully generated power by a direct EG alkaline fuel cell employing the FeCoNi nanoalloy catalyst and a solid-oxide electrolyte with oxygen reduction ability, i.e., a completely precious-metal-free system.

  2. Analysis of nanopore arrangement and structural features of anodic alumina layers formed by two-step anodizing in oxalic acid using the dedicated executable software

    NASA Astrophysics Data System (ADS)

    Zaraska, Leszek; Stępniowski, Wojciech J.; Sulka, Grzegorz D.; Ciepiela, Eryk; Jaskuła, Marian

    2014-02-01

    Anodic porous alumina layers were fabricated by a two-step self-organized anodization in 0.3 M oxalic acid under various anodizing potentials ranging from 30 to 60 V at two different temperatures (10 and 17 ∘C). The effect of anodizing conditions on structural features and pore arrangement of AAO was investigated in detail by using the dedicated executable publication combined with ImageJ software. With increasing anodizing potential, a linear increase of the average pore diameter, interpore distance, wall thickness and barrier layer thickness, as well as a decrease of the pore density, were observed. In addition, the higher pore diameter and porosity values were obtained for samples anodized at the elevated temperature, independently of the anodizing potential. A degree of pore order was investigated on the basis of Delaunay triangulations (defect maps) and calculation of pair distribution or angle distribution functions (PDF or ADF), respectively. All methods confirmed that in order to obtain nanoporous alumina with the best, hexagonal pore arrangement, the potential of 40 V should be applied during anodization. It was confirmed that the dedicated executable publication can be used to a fast and complex analysis of nanopore arrangement and structural features of nanoporous oxide layers.

  3. Expanding the applications of the ilmenite mineral to the preparation of nanostructures: TiO2 nanorods and their photocatalytic properties in the degradation of oxalic acid.

    PubMed

    Tao, Tao; Chen, Ying; Zhou, Dan; Zhang, Hongzhou; Liu, Sanly; Amal, Rose; Sharma, Neeraj; Glushenkov, Alexey M

    2013-01-14

    The mineral ilmenite is one of the most abundant ores in the Earth's crust and it is the main source for the industrial production of bulk titanium oxide. At the same time, methods to convert ilmenite into nanostructures of TiO(2) (which are required for new advanced applications, such as solar cells, batteries, and photocatalysts) have not been explored to any significant extent. Herein, we describe a simple and effective method for the preparation of rutile TiO(2) nanorods from ball-milled ilmenite. These nanorods have small dimensions (width: 5-20 nm, length: 50-100 nm, thickness: 2-5 nm) and possess large specific surface areas (up to 97 m(2)  g(-1)). Dissolution/hydrolysis/precipitation is proposed as a growth mechanism. The nanorods were found to have attractive photocatalytic properties in the degradation of oxalic acid. Their photocatalytic activity is close to that of the benchmark Degussa P25 material and better than that of a commercial high-surface-area rutile powder. PMID:23180682

  4. Heterogeneous catalysis by solid superacids--14. Perfluorinated resinsulfonic acid (nafion-h) catalyzed Friedel-crafts alkylation of toluene and phenol with alkyl chloroformates and oxalates

    SciTech Connect

    Olah, G.A.; Meidar, D.; Malhotra, R.; Olah, J.A.; Narang, S.C.

    1980-01-01

    Product distributions obtained in the alkylation of toluene with methyl, ethyl, and isopropyl chloroformate and dimethyl oxalate and of phenol with methyl and ethyl chloroformate and dimethyl- and diethyloxalate.

  5. Ascorbic acid decomposition into oxalate ions: a simple synthetic route towards oxalato-bridged heterometallic 3d-4f clusters.

    PubMed

    Dinca, Alina S; Shova, Sergiu; Ion, Adrian E; Maxim, Catalin; Lloret, Francesc; Julve, Miguel; Andruh, Marius

    2015-04-28

    Two types of oxalato-bridged heterometallic 3d-4f dodeca- and hexanuclear compounds have been obtained by connecting six bi- and, respectively, trinuclear moieties through oxalato bridges arising from the slow decomposition of the L-ascorbic acid.

  6. Condensational growth and trace species scavenging in stratospheric sulfuric acid/water aerosol droplets

    NASA Technical Reports Server (NTRS)

    Tompson, Robert V., Jr.

    1991-01-01

    Stratospheric aerosols play a significant role in the environment. The composition of aerosols is believed to be a liquid solution of sulfuric acid and water with numerous trace species. Of these trace species, ozone in particular was recognized as being very important in its role of shielding the environment from harmful ultraviolet radiation. Also among the trace species are HCl and ClONO2, the so called chlorine reservoir species and various oxides of nitrogen. The quantity of stratospheric aerosol and its particle size distribution determines, to a large degree, the chemistry present in the stratosphere. Aerosols experience 3 types of growth: nucleation, condensation, and coagulation. The application of condensation investigations to the specific problem of stratospheric aerosols is discussed.

  7. Alterations in circadian rhythmicity in calcium oxalate renal stone formers.

    PubMed

    Touitou, Y; Touitou, C; Charransol, G; Reinberg, A; Thomas, J; Bogdan, A; Barthelemy, C; Desgrez, P

    1983-01-01

    The circadian (circannual for oxalic acid) variations of 13 urinary variables (volume, creatinine, calcium, oxalic acid, glycolic acid, 17-ketosteroids, 17-hydroxycorticosteroids, phosphates, urea, uric acid, chloride, sodium, and potassium) have been documented in 7 calcium oxalate renal stone formers and 7 healthy men (control group). Urine was collected every 4 h over a period of 24 h. All subjects had the same synchronization: diurnal activity from 07(00) to 23(00) +/- 1 h and nocturnal rest; meals were given at fixed clock hours (08(00), 12(30) and 20(00) +/- 1 h). A statistically-significant rhythm (p less than 0.05) was validated for all variables except urea and calcium in healthy men. In renal stone formers, 6 variables (calcium, oxalic acid, and glycolic acid in particular) had no detectable circadian rhythm. However, a periodicity of c. 8 h (ultradian rhythm) was demonstrated for calcium and oxalic acid with peaks being located around 02(00), 10(00), and 18(00). No circannual variations in oxalic acid output could be observed. The present study shows an alteration of the periodicity of calcium and oxalic metabolisms, i.e. the loss of a circadian (24-h) rhythm and the occurrence of an ultradian rhythm of 8 h. The risk of calcium-oxalate crystallisation appears thus greater at 02(00), 10(00), and 18(00). Furthermore, any study dealing with oxalic acid excretion should state the season of urine collection when comparing renal stone formers and healthy subjects, as significant differences in oxaluria may appear during the summer months and not during the rest of the year. PMID:6862698

  8. High aerosol acidity despite declining atmospheric sulfate concentrations over the past 15 years

    NASA Astrophysics Data System (ADS)

    Weber, Rodney J.; Guo, Hongyu; Russell, Armistead G.; Nenes, Athanasios

    2016-04-01

    Particle acidity affects aerosol concentrations, chemical composition and toxicity. Sulfate is often the main acid component of aerosols, and largely determines the acidity of fine particles under 2.5 μm in diameter, PM2.5. Over the past 15 years, atmospheric sulfate concentrations in the southeastern United States have decreased by 70%, whereas ammonia concentrations have been steady. Similar trends are occurring in many regions globally. Aerosol ammonium nitrate concentrations were assumed to increase to compensate for decreasing sulfate, which would result from increasing neutrality. Here we use observed gas and aerosol composition, humidity, and temperature data collected at a rural southeastern US site in June and July 2013 (ref. ), and a thermodynamic model that predicts pH and the gas-particle equilibrium concentrations of inorganic species from the observations to show that PM2.5 at the site is acidic. pH buffering by partitioning of ammonia between the gas and particle phases produced a relatively constant particle pH of 0-2 throughout the 15 years of decreasing atmospheric sulfate concentrations, and little change in particle ammonium nitrate concentrations. We conclude that the reductions in aerosol acidity widely anticipated from sulfur reductions, and expected acidity-related health and climate benefits, are unlikely to occur until atmospheric sulfate concentrations reach near pre-anthropogenic levels.

  9. THORIUM OXALATE-URANYL ACETATE COUPLED PROCEDURE FOR THE SEPARATION OF RADIOACTIVE MATERIALS

    DOEpatents

    Gofman, J.W.

    1959-08-11

    The recovery of fission products from neutronirradiated uranium is described. The neutron-irradiated uranium is dissolved in acid and thorium oxalate is precipitated in ihe solution formed, whereby the fission products are carried on the thorium oxalate. The separated thorium oxalate precipitate is then dissolved in an aqueous oxalate solution and the solution formed is acidified, limiting ihe excess acidity to a maximum of 2 N, whereby thorium oxalate precipitates and carries lanthanum-rareearth- and alkaline-earth-metal fission products while the zirconium-fission-product remains in solution. This precipitate, too, is dissolved in an aqaeous oxalate solution at elevated temperature, and lanthanum-rare-earth ions are added to the solution whereby lanthanum-rare-earth oxalate forms and the lanthanum-rare-earth-type and alkalineearth-metal-type fission products are carried on the oxalate. The precipitate is separated from the solution.

  10. Particle growth by acid-catalyzed heterogeneous reactions of organic carbonyls on preexisting aerosols.

    PubMed

    Jang, Myoseon; Carroll, Brian; Chandramouli, Bharadwaj; Kamens, Richard M

    2003-09-01

    Aerosol growth by the heterogeneous reactions of different aliphatic and alpha,beta-unsaturated carbonyls in the presence/absence of acidified seed aerosols was studied in a 2 m long flow reactor (2.5 cm i.d.) and a 0.5-m3 Teflon film bag under darkness. For the flow reactor experiments, 2,4-hexadienal, 5-methyl-3-hexen-2-one, 2-cyclohexenone, 3-methyl-2-cyclopentenone, 3-methyl-2-cyclohexenone, and octanal were studied. The carbonyls were selected based on their reactivity for acid-catalyzed reactions, their proton affinity, and their similarity to the ring-opening products from the atmospheric oxidation of aromatics. To facilitate acid-catalyzed heterogeneous hemiacetal/acetal formation, glycerol was injected along with inorganic seed aerosols into the flow reactor system. Carbonyl heterogeneous reactions were accelerated in the presence of acid catalysts (H2SO4), leading to higher aerosol yields than in their absence. Aldehydes were more reactive than ketones for acid-catalyzed reactions. The conjugated functionality also resulted in higher organic aerosol yieldsthan saturated aliphatic carbonyls because conjugation with the olefinic bond increases the basicity of the carbonyl leading to increased stability of the protonated carbonyl. Aerosol population was measured from a series of sampling ports along the length of the flow reactor using a scanning mobility particle sizer. Fourier transform infrared spectrometry of either an impacted liquid aerosol layer or direct reaction of carbonyls as a thin liquid layer on a zinc selenide FTIR disk was employed to demonstrate the direct transformation of chemical functional groups via the acid-catalyzed reactions. These results strongly indicate that atmospheric multifunctional organic carbonyls, which are created by atmospheric photooxidation reactions, can contribute significantly to secondary organic aerosol formation through acid-catalyzed heterogeneous reactions. Exploratory studies in 25- and 190-m3 outdoor chambers

  11. PREPARATION OF OXALATES OF METALS OF ATOMIC NUMBER GREATER THAN 88

    DOEpatents

    Duffield, R.B.

    1959-02-01

    A method is presented for the preparation of oxalates of metals of atomic number greater than 88. A solid peroxide of the heavy metal is contacted with an aqueous oxalic acid solution ai a temperature of about 50 C for a period of time sufficient to form the insoluble metal oxalate which is subsequentiy recovered as a pures crystalline compound.

  12. Ultra-structural mapping of sugarcane bagasse after oxalic acid fiber expansion (OAFEX) and ethanol production by Candida shehatae and Saccharomyces cerevisiae

    PubMed Central

    2013-01-01

    Background Diminishing supplies of fossil fuels and oil spills are rousing to explore the alternative sources of energy that can be produced from non-food/feed-based substrates. Due to its abundance, sugarcane bagasse (SB) could be a model substrate for the second-generation biofuel cellulosic ethanol. However, the efficient bioconversion of SB remains a challenge for the commercial production of cellulosic ethanol. We hypothesized that oxalic-acid-mediated thermochemical pretreatment (OAFEX) would overcome the native recalcitrance of SB by enhancing the cellulase amenability toward the embedded cellulosic microfibrils. Results OAFEX treatment revealed the solubilization of hemicellulose releasing sugars (12.56 g/l xylose and 1.85 g/l glucose), leaving cellulignin in an accessible form for enzymatic hydrolysis. The highest hydrolytic efficiency (66.51%) of cellulignin was achieved by enzymatic hydrolysis (Celluclast 1.5 L and Novozym 188). The ultrastructure characterization of SB using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, Fourier transform–near infrared spectroscopy (FT-NIR), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) revealed structural differences before and after OAFEX treatment with enzymatic hydrolysis. Furthermore, fermentation mediated by C. shehatae UFMG HM52.2 and S. cerevisiae 174 showed fuel ethanol production from detoxified acid (3.2 g/l, yield 0.353 g/g; 0.52 g/l, yield, 0.246 g/g) and enzymatic hydrolysates (4.83 g/l, yield, 0.28 g/g; 6.6 g/l, yield 0.46 g/g). Conclusions OAFEX treatment revealed marked hemicellulose degradation, improving the cellulases’ ability to access the cellulignin and release fermentable sugars from the pretreated substrate. The ultrastructure of SB after OAFEX and enzymatic hydrolysis of cellulignin established thorough insights at the molecular level. PMID:23324164

  13. Hydrochloric acid aerosol and gaseous hydrogen chloride partitioning in a cloud contaminated by solid rocket exhaust

    NASA Technical Reports Server (NTRS)

    Sebacher, D. I.; Bendura, R. J.; Wornom, D. E.

    1980-01-01

    Partitioning of hydrogen chloride between hydrochloric acid aerosol and gaseous HCl in the lower atmosphere was experimentally investigated in a solid rocket exhaust cloud diluted with humid ambient air. Airborne measurements were obtained of gaseous HCl, total HCl, relative humidity and temperature to evaluate the conditions under which aerosol formation occurs in the troposphere in the presence of hygroscopic HCl vapor. Equilibrium predictions of HCl aerosol formation accurately predict the measured HCl partitioning over a range of total HCl concentrations from 0.6 to 16 ppm.

  14. Kinetic study of esterification of sulfuric acid with alcohols in aerosol bulk phase

    NASA Astrophysics Data System (ADS)

    Li, J.; Jang, M.

    2013-09-01

    In this study, we hypothesize that the formation of organosulfates through the reactions between sulfuric acid and alcohols in the aerosol bulk phase is more efficient than that in solution chemistry. To prove this hypothesis, the kinetics of the organosulfate formation was investigated for both aliphatic alcohol with single OH group (e.g., 1-heptanol) and the multialcohols ranging from semivolatiles (e.g., hydrated-glyoxal and glycerol) to nonvolatiles (e.g., sucrose) using analytical techniques directly monitoring aerosol bulk phase. Both the forward (k1) and the backward (k-1) reaction rate constants of organosulfate formation via the particle phase esterification of 1-heptanol with sulfuric acid were estimated using a Fourier Transform Infrared (FTIR) spectrometer equipped with a flow chamber under varying humidities. Both k1 and k-1 are in orders of 10-3 L mol-1 min-1, which are three orders of magnitude higher than the reported values obtained in solution chemistry. The formation of organosulfate in the H2SO4 aerosol internally mixed with multialcohols was studied by measuring the proton concentration of the aerosol collected on the filter using a newly developed Colorimetry integrated with a Reflectance UV-Visible spectrometer (C-RUV). The formation of organosulfate significantly decreases aerosol acidity due to the transformation of H2SO4 into dialkylsulfates. The forward reaction rate constants for the dialkylsulfate formation in the multialcohol-H2SO4 aerosols were also three orders of magnitude greater than the reported values in solution chemistry. The water content (MH2O) in the multialcohol-H2SO4 particle was monitored using the FTIR spectrometer. A large reduction of MH2O accords with the high yield of organosulfate in aerosol. Based on this study, we conclude that organosulfate formation in atmospheric aerosol, where both alcohols and sulfuric acid are found together, is significant.

  15. Carboxylic acids in secondary aerosols from oxidation of cyclic monoterpenes by ozone

    SciTech Connect

    Glasius, M.; Lahaniati, M.; Calogirou, A.; Di Bella, D.; Jensen, N.R.; Hjorth, J.; Kotzias, D.; Larsen, B.R.

    2000-03-15

    A series of smog chamber experiments have been conducted in which five cyclic monoterpenes were oxidized by ozone. The evolved secondary aerosol was analyzed by GC-MS and HPLC-MS for nonvolatile polar oxidation products with emphasis on the identification of carboxylic acids. Three classes of compounds were determined at concentration levels corresponding to low percentage molar yields: i.e., dicarboxylic acids, oxocarboxylic acids, and hydroxyketocarboxylic acids. Carboxylic acids are highly polar and have lower vapor pressures than their corresponding aldehydes and may thus play an important role in secondary organic aerosol formation processes. The most abundant carboxylic acids were the following: cis-pinic acid AB1(cis-3-carboxy-2,2-dimethylcyclobutylethanoic acid) from {alpha} and {beta}-pinene; cis-pinonic acid A3 (cis-3-acetyl-2,2-dimethylcyclobutylethanoic acid) and cis-10-hydroxypinonic acid Ab6 (cis-2,2-dimethyl-3-hydroxyacetylcyclobutyl-ethanoic acid) from {alpha}-pinene and {beta}-pinene; cis-3-caric acid C1 (cis-2,2-dimethyl-1,3-cyclopropyldiethanoic acid), cis-3-caronic acid C3 (2,2-dimethyl-3-(2-oxopropyl)cyclopropanylethanoic acid), and cis-10-hydroxy-3-caronic acid C6 (cis-2,2-dimethyl-3(hydroxy-2-oxopropyl)cyclopropanylethanoic acid) from 3-carene; cis-sabinic acid S1 (cis-2-carboxy-1-isopropylcyclopropylethanoic acid) from sabinene; limonic acid L1 (3-isopropenylhexanedioic acid), limononic acid L3 (3-isopropenyl-6-oxo-heptanoic acid), 7-hydroxy-limononic acid L6 (3-isopropenyl-7-hydroxy-6-oxoheptanoic acid), and 7-hydroxylimononic acid Lg{prime} (7-hydroxy-3-isopropenyl-6-oxoheptanoic acid) from limonene.

  16. Catalytic performance of Fe3O4-CoO/Al2O3 catalyst in ozonation of 2-(2,4-dichlorophenoxy)propionic acid, nitrobenzene and oxalic acid in water.

    PubMed

    Tong, Shaoping; Shi, Rui; Zhang, Hua; Ma, Chunan

    2010-01-01

    Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe(NO3)3 x 9H2O and Co(NO3)2 x 6H2O as the precursors, and its catalytic performance was investigated in ozonation of 2-(2,4-dichlorophenoxy)propionic acid (2,4-DP), nitrobenzene and oxalic acid. The experimental results indicated that Fe3O4-CoO/Al2O3 catalyst enabled an interesting improvement of ozonation efficiency during the degradation of each organic pollutant, and the Fe3O4-CoO/Al2O3 catalytic ozonation system followed a radical-type mechanism. The kinetics of ozonation alone and Fe3O4-CoO/Al2O3 catalytic ozonation of three organic pollutants in aqueous solution were discussed under the mere consideration of direct ozone reaction and OH radical reaction to well investigate its performance. In the catalytic ozonation of 2,4-DP, the apparent reaction rate constants (k) were determined to be 1.456 x 10(-2) min(-1) for ozonation alone and 4.740 x 10(-2) min(-1) for O3/Fe3O4-CoO/Al203. And O3/Fe3O4-CoO/Al2O3 had a larger R(ct) (6.614 x 10(-9)) calculated by the relative method than O3 did (1.800 x 10(-9)), showing O3/Fe3O4-CoO/Al2O3 generated more hydroxyl radical. Similar results were also obtained in the catalytic ozonation of nitrobenzene and oxalic acid. The above results demonstrated that the catalytic performance of Fe3O4-CoO/Al2O3 in ozonation of studied organic substance was universal to a certain degree. PMID:21235195

  17. Comparison of dicarboxylic acids and related compounds in aerosol samples collected in Xi'an, China during haze and clean periods

    NASA Astrophysics Data System (ADS)

    Cheng, Chunlei; Wang, Gehui; Zhou, Bianhong; Meng, Jingjing; Li, Jianjun; Cao, Junji; Xiao, Shun

    2013-12-01

    PM10 aerosols from Xi'an, a mega city of China in winter and summer, 2009 were measured for secondary organic aerosols (SOA) (i.e., dicarboxylic acids (DCA), keto-carboxylic acids, and α-dicarbonyls), water-soluble organic (WSOC) and inorganic carbon (WSIC), elemental carbon (EC) and organic carbon (OC). Molecular compositions of SOA on haze and clean days in both seasons were compared to investigate their sources and formation mechanisms. DCA in the samples were 1843 ± 810 ng m-3 in winter and 1259 ± 781 ng m-3 in summer, respectively, which is similar and even higher than those measured in 2003. Oxalic acid (C2, 1162 ± 570 ng m-3 in winter and 1907 ± 707 ng m-3 in summer) is the predominant species of DCA, followed by t-phthalic (tPh) in winter and phthalic (Ph) in summer. Such a molecular composition is different from those in other Asian cities where succinic acid (C4) or malonic acid (C3) is the second highest species, which is mostly due to significant emissions from household combustion of coal and open burning of waste material in Xi'an. Mass ratios of C2/diacids, diacids/WSOC, WSOC/OC and individual diacid-C/WSOC are higher on the haze days than on the clean days in both seasons, suggesting an enhanced SOA production under the haze condition. We also found that the haze samples are acidic while the clean samples are almost neutral. Such a difference in particle acidity is consistent with the enhanced SOA production, because acid-catalysis is an important aqueous-phase formation pathway of SOA. Gly/mGly mass ratio showed higher values on haze days than on clean day in both seasons. We comprehensively investigated the ratio in literature and found a consistent pattern. Based on our observation results and those documented data we proposed for the first time that concentration ratio of Gly/mGly can be taken as an indicator of aerosol ageing.

  18. HCl in rocket exhaust clouds - Atmospheric dispersion, acid aerosol characteristics, and acid rain deposition

    NASA Technical Reports Server (NTRS)

    Pellett, G. L.; Sebacher, D. I.; Bendura, R. J.; Wornom, D. E.

    1983-01-01

    Both measurements and model calculations of the temporal dispersion of peak HCl (g + aq) concentration in Titan III exhaust clouds are found to be well characterized by one-term power-law decay expressions. The respective coefficients and decay exponents, however, are found to vary widely with meteorology. The HCl (g), HCl (g + aq), dewpoint, and temperature-pressure-altitude data for Titan III exhaust clouds are consistent with accurately calculated HCl/H2O vapor-liquid compositions for a model quasi-equilibrated flat surface aqueous aerosol. Some cloud evolution characteristics are also defined. Rapid and extensive condensation of aqueous acid clearly occurs during the first three min of cloud rise. Condensation is found to be intensified by the initial entrainment of relatively moist ambient air from lower levels, that is, from levels below eventual cloud stabilization. It is pointed out that if subsequent dilution air at stabilization altitude is significantly drier, a state of maximum condensation soon occurs, followed by an aerosol evaporation phase.

  19. Photochemical organonitrate formation in wet aerosols

    NASA Astrophysics Data System (ADS)

    Lim, Yong Bin; Kim, Hwajin; Kim, Jin Young; Turpin, Barbara J.

    2016-10-01

    Water is the most abundant component of atmospheric fine aerosol. However, despite rapid progress, multiphase chemistry involving wet aerosols is still poorly understood. In this work, we report results from smog chamber photooxidation of glyoxal- and OH-containing ammonium sulfate or sulfuric acid particles in the presence of NOx and O3 at high and low relative humidity. Particles were analyzed using ultra-performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). During the 3 h irradiation, OH oxidation products of glyoxal that are also produced in dilute aqueous solutions (e.g., oxalic acids and tartaric acids) were formed in both ammonium sulfate (AS) aerosols and sulfuric acid (SA) aerosols. However, the major products were organonitrogens (CHNO), organosulfates (CHOS), and organonitrogen sulfates (CHNOS). These were also the dominant products formed in the dark chamber, indicating non-radical formation. In the humid chamber (> 70 % relative humidity, RH), two main products for both AS and SA aerosols were organonitrates, which appeared at m / z- 147 and 226. They were formed in the aqueous phase via non-radical reactions of glyoxal and nitric acid, and their formation was enhanced by photochemistry because of the photochemical formation of nitric acid via reactions of peroxy radicals, NOx and OH during the irradiation.

  20. Effects of acid-washing filter treatment on quantification of aerosol organic compounds

    NASA Astrophysics Data System (ADS)

    Yang, Liming; Lim, Jaehyun; Yu, Liya E.

    The tests of standard mixtures and four sets of atmospheric particulate samples showed that an acid-wash (AW) pretreatment of fluorocarbon-coated glass fiber filters prior to aerosol sampling enhanced the quantifiable organic compounds for more than 29% (or 66 ng m -3); in particular, 47-273 ng m -3 (21-366%) more water-soluble organic compounds (WSOCs) were measured. When the acid-pretreated filters were employed, up to nine more organic species were measured in the individual daily samples. Because the acid pretreatment reduced the metal contaminants in the glass fiber filters, using the AW filters for aerosol sampling allows higher extraction recoveries of organic compounds. Since the fingerprinting compounds were more accurately determined when the aerosol samples were collected on the AW filters, better assessment of emission sources and toxicity of air pollutants can be obtained.

  1. Backscatter laser depolarization studies of simulated stratospheric aerosols - Crystallized sulfuric acid droplets

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun

    1989-01-01

    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystalization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

  2. Backscatter laser depolarization studies of simulated stratospheric aerosols: Crystallized sulfuric acid droplets

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun

    1988-01-01

    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystallization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

  3. Characterization of novel di- and tricarboxylic acids in fine tropical aerosols.

    PubMed

    Zdráhal, Z; Vermeylen, R; Claeys, M; Maenhaut, W; Guyon, P; Artaxo, P

    2001-04-01

    Three unknown di- and tricarboxylic acids were characterized in the fine size fraction of aerosols which were collected during the wet season in the Amazon basin (Rondonia, Brazil). For the structural characterization of the methyl esters of these unknown compounds, mass spectrometry with electron ionization (EI) and tandem mass spectral techniques combined with gas chromatographic (GC) separation were employed. Fragment and parent ion spectra were recorded during elution of the GC peaks by linked scanning of the B and E sectors in combination with high-energy collision-induced dissociation. The fragmentation patterns of significant ions in the first-order EI spectra were also obtained for nonanedioic acid, which was examined as a model compound. The compounds were tentatively identified as 4-acetyloxyheptanedioic acid and cis and trans isomers of 5-hexene-1,1,6-tricarboxylic acid. Since there were indications of biomass burning during the aerosol sampling the di- and tricarboxylic acids characterized in the present work could be markers for biomass burning. Furthermore, the characterization of di- and tricarboxylic acids in the fine size fraction of atmospheric aerosols may be important for assessing the effects of organic aerosols in cloud formation.

  4. Soluble species in the Arctic summer troposphere - acidic gases, aerosols, and precipitation

    SciTech Connect

    Talbot, R.W.; Vijgen, A.S.; Harriss, R.C. Old Dominion Univ., Norfolk, VA )

    1992-10-01

    The large-scale spatial distribution from 0.15-to 6 km altitude in the North American Arctic troposphere of several soluble acidic gases and major aerosol species during the summertime is reported. The distribution is found to be compositionally consistent on a large spatial scale. The summertime troposphere is an acidic environment, with HCOOH and CH3COOH the principal acidic gases while acidic sulfate aerosols dominate the particulate phase. There appears to be a surface source of NH3 over the pack ice which may originate from decay of dead marine organisms on the ice surface, evolution from surface ocean waters in open ice leads, or release from rotting sea ice. At low altitude over the pack ice this NH34 appears to partially neutralize aerosol acidity. Over sub-Arctic tundra in southeastern Alaska, inputs of marine biogenic sulfur from the Bering Sea appear to be an important source of boundary layer aerosol SO4(2-). The rainwater acidity over the tundra is typical of remote regions. 61 refs.

  5. Soluble species in the Arctic summer troposphere - Acidic gases, aerosols, and precipitation

    NASA Technical Reports Server (NTRS)

    Talbot, R. W.; Vijgen, A. S.; Harriss, R. C.

    1992-01-01

    The large-scale spatial distribution from 0.15-to 6 km altitude in the North American Arctic troposphere of several soluble acidic gases and major aerosol species during the summertime is reported. The distribution is found to be compositionally consistent on a large spatial scale. The summertime troposphere is an acidic environment, with HCOOH and CH3COOH the principal acidic gases while acidic sulfate aerosols dominate the particulate phase. There appears to be a surface source of NH3 over the pack ice which may originate from decay of dead marine organisms on the ice surface, evolution from surface ocean waters in open ice leads, or release from rotting sea ice. At low altitude over the pack ice this NH34 appears to partially neutralize aerosol acidity. Over sub-Arctic tundra in southeastern Alaska, inputs of marine biogenic sulfur from the Bering Sea appear to be an important source of boundary layer aerosol SO4(2-). The rainwater acidity over the tundra is typical of remote regions.

  6. On the prolonged lifetime of the El Chichon sulfuric acid aerosol cloud

    NASA Technical Reports Server (NTRS)

    Hofmann, D. J.; Rosen, J. M.

    1987-01-01

    The observed decay of the aerosol mixing ratio following the eruption of El Chichon appears to have been 20-30 percent slower than that following the eruption of Fuego in 1974, even though the sulfuric acid droplets were observed to grow to considerably larger sizes after El Chichon. This suggests the possible presence of a condensation nuclei and sulfuric acid vapor source and continued growth phenomena occurring well after the El Chichon eruption. It is proposed that the source of these nuclei and the associated vapor may be derived from annual evaporation and condensation of aerosol in the high polar regions during stratospheric warming events, with subsequent spreading to lower latitudes.

  7. Effects of ozone and sulfuric acid aerosol on gas trapping in the guinea pig lung

    SciTech Connect

    Silbaugh, S.A.; Mauderly, J.L.

    1986-01-01

    Four groups of 20 guinea pigs were sequentially exposed by inhalation to either air followed by sulfuric acid aerosol, ozone followed by sulfuric acid aerosol, ozone followed by air, or air followed by air to determine whether ozone preexposure sensitizes guinea pigs to the airway constrictive effects of sulfuric acid aerosol. All first exposures to ozone or air were 2 h in duration; all second exposures to sulfuric acid or air were for 1 h. All ozone and sulfuric acid exposures were 0.8 ppm and 12 mg/m3, respectively. Animals were observed for respiratory distress during exposure, and excised lungs were quantitated for trapped gas and wet/dry ratios. None of the guinea pigs developed dyspnea, and wet/dry ratios were not altered. Ozone significantly (p less than 0.05) increased trapped gas volumes, which were 44% (ozone-acid) to 68% (ozone-air) greater than in the air-air group. Trapped gas volume was 23% greater in the ozone-acid group than in the air-acid group, but the difference was not statistically significant (p less than 0.20). Thus, ozone increased gas trapping but did not significantly sensitize guinea pigs to the bronchoconstrictive action of sulfuric acid.

  8. An advanced LC-MS (Q-TOF) technique for the detection of amino acids in atmospheric aerosols

    EPA Science Inventory

    Methodology for detection of native (underivitized) amino acids in atmospheric aerosols has been developed. This article describes the use of LC-MS (Q-TOF) and microwave-assisted gas phase hydrolysis for detection of free and combined amino acids in aerosols collected in a Southe...

  9. Characterization of sources for southern African aerosols through fatty acid and trajectory analyses

    NASA Astrophysics Data System (ADS)

    Billmark, Kaycie A.; Swap, Robert J.; Macko, Stephen A.

    2003-07-01

    Biogeochemical cycles in southern Africa are affected by emissions from extensive biomass burning. Emitted trace gases and aerosols frequently accumulate and recirculate in the well-defined synoptic pattern that persists for long time periods over southern Africa. The role of organic aerosols during atmospheric transport and the influence of neighboring air masses on biogeochemical dynamics in this nutrient-limited region are insufficiently studied. The Southern African Regional Science Initiative (SAFARI 2000) was conducted in part to investigate the impacts of this large-scale transport and deposition of increasingly anthropogenic emissions on southern African biogeochemical cycling. This study explores the understanding of regional atmospheric transport through the identification of chemical biomarkers to describe aerosols collected during the SAFARI 2000 dry season research campaign. Total suspended particulate aerosol samples were collected diurnally for a period of two weeks in Mongu, Zambia. Mongu is bordered by the Zambezi River on the west and the Miombo woodland savanna in all other directions. It also lies on the northern extent of the Kalahari Desert. This region is characterized by high biomass burning emissions of river floodplain grasses and woodland savanna during the dry season. Fatty acids were extracted from the collected aerosols and analyzed using gas chromatography. The resultant fatty acid compositions were examined for temporal patterns and trends. Furthermore, these results were compared to both synoptic meteorological patterns over the region, as well as to modeled air parcel trajectories, to gain insight into changes in aerosol composition resulting from changes in atmospheric transports from regions of different vegetation. The results of these analyses confirm that abundances of fatty acids are dependent on local and synoptic meteorology and can thus be used as an additional geochemical tracer to better describe aerosol sources and

  10. Model for a surface film of fatty acids on rain water and aerosol particles

    NASA Astrophysics Data System (ADS)

    Seidl, Winfried

    Organic compounds with polar groups can form films on the water surface which lower the surface tension and may hinder the transport of water vapor and trace gases through the interface. A model is presented which describes in detail surface films formed by fatty acids. The model has been applied to measured concentrations of fatty acids on rain water and atmospheric aerosol particles. In most cases only a diluted film has been calculated which does not affect their physical and chemical properties. The exception was a clean region in the western USA, where the fatty acid concentrations are sufficiently high to form a dense film on atmospheric aerosol particles. An algorithm for the identification of the sources of fatty acids was developed. It showed leaf abrasion or biomass burning as a major source of fatty acids in the western USA.

  11. Backscatter laser depolarization studies of simulated stratospheric aerosols: crystallized sulfuric acid droplets.

    PubMed

    Sassen, K; Zhao, H; Yu, B K

    1989-08-01

    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 microm) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of delta approximately 0.02, but delta approximately 0.10-0.15 are generated from acid droplet crystallization effects associated with recycled aerosols and the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar delta approximately 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (delta approximately 0) or ice crystal (delta approximately 0.5) clouds.

  12. Efficient electron-induced removal of oxalate ions and formation of copper nanoparticles from copper(II) oxalate precursor layers

    PubMed Central

    Rückriem, Kai; Grotheer, Sarah; Vieker, Henning; Penner, Paul; Beyer, André; Gölzhäuser, Armin

    2016-01-01

    Summary Copper(II) oxalate grown on carboxy-terminated self-assembled monolayers (SAM) using a step-by-step approach was used as precursor for the electron-induced synthesis of surface-supported copper nanoparticles. The precursor material was deposited by dipping the surfaces alternately in ethanolic solutions of copper(II) acetate and oxalic acid with intermediate thorough rinsing steps. The deposition of copper(II) oxalate and the efficient electron-induced removal of the oxalate ions was monitored by reflection absorption infrared spectroscopy (RAIRS). Helium ion microscopy (HIM) reveals the formation of spherical nanoparticles with well-defined size and X-ray photoelectron spectroscopy (XPS) confirms their metallic nature. Continued irradiation after depletion of oxalate does not lead to further particle growth giving evidence that nanoparticle formation is primarily controlled by the available amount of precursor. PMID:27547602

  13. Efficient electron-induced removal of oxalate ions and formation of copper nanoparticles from copper(II) oxalate precursor layers.

    PubMed

    Rückriem, Kai; Grotheer, Sarah; Vieker, Henning; Penner, Paul; Beyer, André; Gölzhäuser, Armin; Swiderek, Petra

    2016-01-01

    Copper(II) oxalate grown on carboxy-terminated self-assembled monolayers (SAM) using a step-by-step approach was used as precursor for the electron-induced synthesis of surface-supported copper nanoparticles. The precursor material was deposited by dipping the surfaces alternately in ethanolic solutions of copper(II) acetate and oxalic acid with intermediate thorough rinsing steps. The deposition of copper(II) oxalate and the efficient electron-induced removal of the oxalate ions was monitored by reflection absorption infrared spectroscopy (RAIRS). Helium ion microscopy (HIM) reveals the formation of spherical nanoparticles with well-defined size and X-ray photoelectron spectroscopy (XPS) confirms their metallic nature. Continued irradiation after depletion of oxalate does not lead to further particle growth giving evidence that nanoparticle formation is primarily controlled by the available amount of precursor. PMID:27547602

  14. Ion balances of size-resolved tropospheric aerosol samples: implications for the acidity and atmospheric processing of aerosols

    NASA Astrophysics Data System (ADS)

    Kerminen, Veli-Matti; Hillamo, Risto; Teinilä, Kimmo; Pakkanen, Tuomo; Allegrini, Ivo; Sparapani, Roberto

    A large set of size-resolved aerosol samples was inspected with regard to their ion balance to shed light on how the aerosol acidity changes with particle size in the lower troposphere and what implications this might have for the atmospheric processing of aerosols. Quite different behaviour between the remote and more polluted environments could be observed. At the remote sites, practically the whole accumulation mode had cation-to-anion ratios clearly below unity, indicating that these particles were quite acidic. The supermicron size range was considerably less acidic and may in some cases have been close to neutral or even alkaline. An interesting feature common to the remote sites was a clear jump in the cation-to-anion ratio when going from the accumulation to the Aitken mode. The most likely reason for this was cloud processing which, via in-cloud sulphate production, makes the smallest accumulation-mode particles more acidic than the non-activated Aitken-mode particles. A direct consequence of the less acidic nature of the Aitken mode is that it can take up semi-volatile, water-soluble gases much easier than the accumulation mode. This feature may have significant implications for atmospheric cloud condensation nuclei production in remote environments. In rural and urban locations, the cation-to-anion ratio was close to unity over most of the accumulation mode, but increased significantly when going to either larger or smaller particle sizes. The high cation-to-anion ratios in the supermicron size range were ascribed to carbonate associated with mineral dust. The ubiquitous presence of carbonate in these particles indicates that they were neutral or alkaline, making them good sites for heterogeneous reactions involving acidic trace gases. The high cation-to-anion ratios in the Aitken mode suggest that these particles contained some water-soluble anions not detected by our chemical analysis. This is worth keeping in mind when investigating the hygroscopic

  15. Carboxylic acids in PM 2.5 over Pinus morrisonicola forest and related photoreaction mechanisms identified via Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Kuo, Su-Ching; Tsai, Ying I.; Tsai, Cheng-Hsien; Hsieh, Li-Ying

    2011-12-01

    The PM 2.5 aerosol from within an area of Pinus morrisonicola Hayata in Taiwan was collected and analyzed for its low molecular weight carboxylic acid (LMWCAs) content. Oxalic acid was the major LMWCA in the aerosol, followed by acetic, tartaric and maleic acids. This differs significantly from the LMWCA composition of PM 2.5 aerosol reported for a southern Taiwan suburban region (oxalic > succinic > malonic) [Atmospheric Environment 42, 6836-6850 (2008)]. P. morrisonicola Hayata emits oxalic, malic and formic acids and yet there was an abundance of maleic and tartaric acids in the PM 2.5 forest aerosol, indicating that tartaric acid is derived from the transformation of other P. morrisonicola Hayata emissions. Raman spectroscopy was applied and 28 species of LMWCAs and inorganic species were identified. The photochemical mechanisms of maleic and tartaric acids were studied and it was found that the abundant tartaric acid in forest aerosol is most probably the photochemical product from reactions of maleic acid. Furthermore, tartaric acid is photochemically transformed into formic acid and ultimately into CO 2.

  16. Aerosol acidity characterization of large metropolitan areas: Pilot and planning for Philadelphia

    SciTech Connect

    Waldman, J.M.; Koutrakis, P.; Burton, R.; Wilson, W.E.; Purdue, L.J.

    1993-01-01

    The report described the EPA's multi-year program to investigate the specific issues surrounding human exposures to aerosol activity. Philadelphia, a large metropolitan area in the heart of the northeastern seaboard afflicted with photochemical regional smog during the summertime, was chosen as the first city in the program. A pilot study of ambient concentrations was conducted in July 1991. An annular denuder system (ADS) sampler was operated for two weeks near downtown Philadelphia, with a second unit operated in central, suburban New Jersey, the same location of measurements in past years. The Philadelphia site was found to have higher concentrations of most major aerosol species, ammonia and acidic particles than in New Jersey, showing that aerosol neutralization within the urban center will not necessarily totally eliminate acidic particle exposures.

  17. A case study of urban particle acidity and its influence on secondary organic aerosol.

    PubMed

    Zhang, Qi; Jimenez, Jose L; Worsnop, Douglas R; Canagaratna, Manjula

    2007-05-01

    Size-resolved indicators of aerosol acidity, including H+ ion concentrations (H+Aer) and the ratio of stoichiometric neutralization are evaluated in submicrometer aerosols using highly time-resolved aerosol mass spectrometer (AMS) data from Pittsburgh. The pH and ionic strength within the aqueous particle phase are also estimated using the Aerosol Inorganics Model (AIM). Different mechanisms that contribute to the presence of acidic particles in Pittsburgh are discussed. The largest H+Aer loadings and lowest levels of stoichiometric neutralization were detected when PM1 loadings were high and dominated by SO4(2-). The average size distribution of H+Aer loading shows an accumulation mode at Dva approximately 600 nm and an enhanced smaller mode that centers at Dva approximately 200 nm and tails into smaller sizes. The acidity in the accumulation mode particles suggests that there is generally not enough gas-phase NH3 available on a regional scale to completely neutralize sulfate in Pittsburgh. The lack of stoichiometric neutralization in the 200 nm mode particles is likely caused by the relatively slow mixing of gas-phase NH3 into SO2-rich plumes containing younger particles. We examined the influence of particle acidity on secondary organic aerosol (SOA) formation by comparing the mass concentrations and size distributions of oxygenated organic aerosol (00A--surrogate for SOA in Pittsburgh) during periods when particles are, on average, acidic to those when particles are bulk neutralized. The average mass concentration of ODA during the acidic periods (3.1 +/- 1.7 microg m(-3)) is higher than that during the neutralized periods (2.5 +/- 1.3 microg m(-3)). Possible reasons for this enhancement include increased condensation of SOA species, acid-catalyzed SOA formation, and/or differences in air mass transport and history. However, even if the entire enhancement (approximately 0.6 microg m(-3)) can be attributed to acid catalysis, the upperbound increase of SOA mass

  18. Viscosity controls humidity dependence of N2O5 uptake to citric acid aerosol

    NASA Astrophysics Data System (ADS)

    Gržinić, G.; Bartels-Rausch, T.; Berkemeier, T.; Türler, A.; Ammann, M.

    2015-08-01

    The heterogeneous loss of dinitrogen pentoxide (N2O5) to aerosol particles has a significant impact on the night time nitrogen oxide cycle and therefore the oxidative capacity in the troposphere. Using a 13N short lived radioactive tracer method we studied the uptake kinetics of N2O5 on citric acid aerosol particles as a function of relative humidity (RH). The results show that citric acid exhibits lower reactivity than similar di- and polycarboxylic acids, with uptake coefficients between ~ 3 × 10-4-~ 3 × 10-3 depending on humidity (17-70 % RH). This humidity dependence can be explained by a changing viscosity and, hence, diffusivity in the organic matrix. Since the viscosity of highly concentrated citric acid solutions is not well established, we present four different parameterizations of N2O5 diffusivity based on the available literature data or estimates for viscosity and diffusivity. Above 50 % RH, uptake is consistent with the reacto-diffusive kinetic regime whereas below 50 % RH, the uptake coefficient is higher than expected from hydrolysis of N2O5 within the bulk of the particles, and the uptake kinetics may be limited by loss on the surface only. This study demonstrates the impact of viscosity in highly oxidized and highly functionalized secondary organic aerosol material on the heterogeneous chemistry of N2O5 and may explain some of the unexpectedly low loss rates to aerosol derived from field studies.

  19. GC/MS Characterization of Fatty Acids Extracted From Southern African Aerosols

    NASA Astrophysics Data System (ADS)

    Shields, L. G.; Billmark, K. A.; Swap, R. J.; Macko, S. A.

    2001-12-01

    Fatty acids of total suspended particulate aerosol samples, collected in Mongu, Zambia during the Southern African Regional Science Initiative (SAFARI 2000) field campaign, were analyzed to characterize emissions from an important source of aerosols in the southern African region. The sample site was chosen specifically so as to decrease the influence of industrial emissions and to focus primarily on the emissions from biomass burning, of which fatty acids are a significant component. Previous investigations in southern Africa have identified emissions from biomass burning as a significant contributor to the haze layer prevalent across the subcontinent. In order to better understand the origins of the materials within the haze layer, characteristic compounds of different source materials were identified in the aerosols. This characterization may clarify the contributions to total aerosol loads from other sources, including marine aerosols or mineral dust. By determining the distributions and concentrations of distinct organic components, this study enables future investigations to quantify the contribution of emissions from biomass burning at specific geographic locations.

  20. Dicarboxylic acids, oxoacids, benzoic acid, α-dicarbonyls, WSOC, OC, and ions in spring aerosols from Okinawa Island in the western North Pacific Rim: size distributions and formation processes

    NASA Astrophysics Data System (ADS)

    Deshmukh, Dhananjay K.; Kawamura, Kimitaka; Lazaar, Manuel; Kunwar, Bhagawati; Boreddy, Suresh K. R.

    2016-04-01

    Size-segregated aerosols (nine stages from < 0.43 to > 11.3 µm in diameter) were collected at Cape Hedo, Okinawa, in spring 2008 and analyzed for water-soluble diacids (C2-C12), ω-oxoacids (ωC2-ωC9), pyruvic acid, benzoic acid, and α-dicarbonyls (C2-C3) as well as water-soluble organic carbon (WSOC), organic carbon (OC), and major ions (Na+, NH4+, K+, Mg2+, Ca2+, Cl-, NO3-, SO42-, and MSA-). In all the size-segregated aerosols, oxalic acid (C2) was found to be the most abundant species, followed by malonic and succinic acids, whereas glyoxylic acid (ωC2) was the dominant oxoacid and glyoxal (Gly) was more abundant than methylglyoxal. Diacids (C2-C5), ωC2, and Gly as well as WSOC and OC peaked at fine mode (0.65-1.1 µm) whereas azelaic (C9) and 9-oxononanoic (ωC9) acids peaked at coarse mode (3.3-4.7 µm). Sulfate and ammonium were enriched in fine mode, whereas sodium and chloride were in coarse mode. Strong correlations of C2-C5 diacids, ωC2 and Gly with sulfate were observed in fine mode (r = 0.86-0.99), indicating a commonality in their secondary formation. Their significant correlations with liquid water content in fine mode (r = 0.82-0.95) further suggest an importance of the aqueous-phase production in Okinawa aerosols. They may also have been directly emitted from biomass burning in fine mode as supported by strong correlations with potassium (r = 0.85-0.96), which is a tracer of biomass burning. Bimodal size distributions of longer-chain diacid (C9) and oxoacid (ωC9) with a major peak in the coarse mode suggest that they were emitted from the sea surface microlayers and/or produced by heterogeneous oxidation of biogenic unsaturated fatty acids on sea salt particles.

  1. On the growth of nitric and sulfuric acid aerosol particles under stratospheric conditions

    NASA Technical Reports Server (NTRS)

    Hamill, Patrick; Turco, R. P.; Toon, O. B.

    1988-01-01

    A theory for the formation of frozen aerosol particles in the Antarctic stratosphere was developed and applied to the formation of polar stratospheric clouds. The theory suggests that the condensed ice particles are composed primarily of nitric acid and water, with small admixtures of sulfuric and hydrochloric acids in solid solution. The proposed particle formation mechanism is in agreement with the magnitude and seasonal behavior of the optical extinction observed in the winter polar stratosphere.

  2. Reflex-mediated desquamation of bronchiolar epithelium in guinea pigs exposed acutely to sulfuric acid aerosol.

    PubMed Central

    Brownstein, D. G.

    1980-01-01

    Terminal conducting airways are known to be vulnerable to direct injury by a variety of noxious aerosols. Sulfuric acid aerosol, a by-product of fossil fuel combustion, produces desquamation of terminal bronchiolar epithelium in guinea pigs that is believed to result from direct deep lung irritation, an effect separable from reflex airway constriction induced by sulfuric acid. To characterize desquamation of bronchiolar epithelium, 20 guinea pigs were exposed to 32.6 mg/cu m sulfuric acid aerosol with a mass median aerodynamic diameter of 1.0 micron for 4 hours. The guinea pigs were killed upon termination of the exposure, or 24 hours later, and airway alterations were evaluated by light and transmission electron microscopy. To test whether the development of bronchiolar epithelial desquamation is independent of reflex airway constriction, 24 guinea pigs were exposed to an identical aerosol for 4 hours after pretreating half with 5 mg/kg atropine sulfate intraperitoneally to inhibit airway constriction. Sulfuric acid produced diffuse pulmonary hyperinflation with areas of consolidation and atelectasis. Epithelial desquamation occurred in airways supplying regions of developing atelectasis and was most extensive in terminal bronchioles. Parasympathetic effector blockade with atropine eliminated epithelial desquamation. These results indicate that sulfuric acid-produced desquamation of terminal bronchiolar epithelium is not separable from reflex airway constriction and that terminal conducting airways are vulnerable not only to direct injury by noxious aerosols but also to indirect, reflex-mediated injury. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 PMID:7361847

  3. Hydroxydicarboxylic acids: markers for secondary organic aerosol from the photooxidation of alpha-pinene.

    PubMed

    Claeys, Magda; Szmigielski, Rafal; Kourtchev, Ivan; van der Veken, Pieter; Vermeylen, Reinhilde; Maenhaut, Willy; Jaoui, Mohammed; Kleindienst, Tadeusz E; Lewandowski, Michael; Offenberg, John H; Edney, Edward O

    2007-03-01

    Detailed organic analysis of fine (PM2.5) rural aerosol collected during summer at K-puszta, Hungary from a mixed deciduous/coniferous forest site shows the presence of polar oxygenated compounds that are also formed in laboratory irradiated alpha-pinene/NOx/air mixtures. In the present work, two major photooxidation products of alpha-pinene were characterized as the hydroxydicarboxylic acids, 3-hydroxyglutaric acid, and 2-hydroxy-4-isopropyladipic acid, based on chemical, chromatographic, and mass spectral data. Different types of volatile derivatives, including trimethylsilyl ester/ether, methyl ester trimethylsilyl ether, and ethyl ester trimethylsilyl ether derivatives were measured by gas chromatography/mass spectrometry (GC/MS), and their electron ionization (El) spectra were interpreted in detail. The proposed structures of the hydroxydicarboxylic acids were confirmed or supported with reference compounds. 2-Hydroxy-4-isopropyladipic acid formally corresponds to a further reaction product of pinic acid involving addition of a molecule of water and opening of the dimethylcyclobutane ring; this proposal is supported by a laboratory irradiation experiment with alpha-pinene/NOJ0 air. In addition, we report the presence of a structurally related minor alpha-pinene photooxidation product, which was tentatively identified as the C7 homolog of 3-hydroxyglutaric acid, 3-hydroxy-4,4-dimethylglutaric acid. The detection of 2-hydroxy-4-isopropyladipic acid in ambient aerosol provides an explanation for the relatively low atmospheric concentrations of pinic acid found during daytime in forest environments.

  4. Selective adsorption in two porous triazolate–oxalate-bridged antiferromagnetic metal-azolate frameworks obtained via in situ decarboxylation of 3-amino-1,2,4-triazole-5-carboxylic acid

    SciTech Connect

    Hou, Juan-Juan; Xu, Xia; Jiang, Ning; Wu, Ya-Qin; Zhang, Xian-Ming

    2015-03-15

    Solvothermal reactions of metal salts, 3-amino-1,2,4-triazole-5-carboxylic acid (H{sub 2}atzc) and ammonium oxalate in different temperature produced two metal azolate frameworks, namely, [Cu{sub 3}(atzc){sub 2}(atz)(ox)]·1.5H{sub 2}O (1) and [Co{sub 5}(atz){sub 4}(ox){sub 3}(HCOO){sub 2}]·DMF (2) (H{sub 2}atzc=3-amino-1,2,4-triazole-5-carboxylic acid, Hatz=3-amino-1,2,4-triazole, and ox=oxalate), in which the atzc precusor was in situ decarboxylated. Structural determination reveals that 1 contains [Cu{sub 3}(atzc){sub 2}(atz)]{sup 2−} layers of mixed μ{sub 4}-atzc and μ{sub 3}-atz ligands, which are pillared by ox{sup 2−} groups to form a 3D porous framework. Compound 2 contains 2D layers with basic spindle-shaped decanuclear units, which extended by ox{sup 2−} and formates to form 3D porous framework. Gas adsorption investigation revealed that two kinds of frameworks exhibited selective CO{sub 2} over N{sub 2} sorption. Moreover, activated 2 shows H{sub 2} storage capacity. Additionally, magnetic properties of both the compounds have been investigated. - Graphical abstract: Solvothermal reactions of metal salts, 3-amino-1,2,4-triazole-5-carboxylate and oxalate produced two metal azolate frameworks, which could store gas molecules, especially H{sub 2} due to small pores. in situ decarboxylation of precursor was observed. - Highlights: • Two MAFs were synthesized via in situ decarboxylation of H{sub 2}atzc. • Both activated frameworks exhibited selective CO{sub 2} over N{sub 2} sorption. • Activated 2 could adsorb H{sub 2}, which makes it promising candidates for gas storage.

  5. Intercommunity differences in acid aerosol (H+)/sulfate (SO4(2-) ratios.

    PubMed

    Ozkaynak, H; Xue, J; Zhou, H; Spengler, J D; Thurston, G D

    1996-01-01

    Exposures to acid aerosols have been associated with acute and chronic health effects. Beginning in 1988, extensive monitoring of acid aerosols (H+), sulfates (SO4(2-)), and ammonia (NH3) was conducted in 24 communities in the United States and Canada in order to characterize the seasonal and daily variations of these pollutants. More recently, in 1992 and 1993, summer monitoring of the same pollutants was conducted by Harvard researchers at multiple locations in Philadelphia, Pennsylvania to examine the factors causing spatial variation in the acidity levels in the greater metropolitan Philadelphia area. Earlier, a similar study also was conducted by Harvard in a more rural community, State College, Ohio, providing data on acidity, sulfate, and ammonia levels. In addition to these studies, New York University researchers have gathered substantial data on aerosol acidity, sulfates, and NH3 levels from sites in the New York City metropolitan region, Albany, Buffalo, and the Toronto metropolitan region between 1988 and 1992. This paper examines the relationships among H+, SO4(2-), ozone, and population density using summer measurements from sites in 24 cities across the United States and Canada, as well as Philadelphia, State College, the New York City region, Buffalo, and Albany. While past studies have consistently shown that H+ and SO4(2-) are correlated over time at sites in eastern North America, the results of our analysis show that spatial variations in the ratios of mean acid-to-sulfate levels also can be predicted satisfactorily with the use of either a linear or a quadratic model, once variations in population density are addressed (R2 = 0.6). These models may be useful in retrospective epidemiological investigations of acid aerosol exposures and health effects, using widely available sulfate measurements and data on local population size.

  6. The influence of magnesium chloride on blood and urine parameters in calcium oxalate stone patients.

    PubMed

    Brundig, P; Berg, W; Schneider, H J

    1981-01-01

    The influence of magnesium chloride on various blood and urine parameters in calcium oxalate stone patients is studied. High dose magnesium therapy was found to increase urinary magnesium concentrations, whereas the oxalic acid concentration is reduced. The experiments support the statements on the role of magnesium in endogenous oxalic acid depression and the inhibition of the intestinal resorption. For urolith prevention it will be necessary to apply high magnesium doses of easily absorbable and well-tolerated medicaments.

  7. Solubility of HOBr in Acidic Solution and Implications for Liberation of Halogens Via Aerosol Processing

    NASA Technical Reports Server (NTRS)

    Iraci, Laura T.; Michelsen, R. R.; Rammer, T. A.; Ashbourn, S. F. M.

    2004-01-01

    Halogen species are known to catalytically destroy ozone in several regions of the atmosphere. In addition to direct catalytic losses, bromine compounds can indirectly enhance ozone loss through coupling to other radical families. Hypobromous acid (HOBr) is a key species in the linkage of BrOx to ClOx and HOx. The aqueous- phase coupling reaction HOBr + HCI (right arrow) BrCl + H2O may provide a pathway for chlorine activation on sulfate aerosols at temperatures warmer than those required for polar stratospheric cloud formation. We have measured t h e solubility of HOBr in 45 - 70 wt% sulfuric acid solutions. Over the temperature range 201 - 252 K, HOBr is quite soluble in sulfuric acid, H* = 10(exp 4) - 10(exp 7) mol dm(exp -3) atm(exp -1). The expected inverse dependence of H* on temperature was observed, but only a weak dependence on acidity was found. The solubility of HOBr is comparable to that of HBr, indicating that equilibrium concentrations of HOBr could equal or exceed those of HBr in upper tropospheric and lower stratospheric aerosols. Despite the high solubility of HOBr, aerosol volumes are not large enough to sequester a significant fraction of inorganic bromine from the gas phase. Our measurements of HOBr uptake in aqueous sulfuric acid in the presence of other brominated gases show the evolution of gaseous products including Br2O and Br2.

  8. Biogeochemistry of oxalate in the antarctic cryptoendolithic lichen-dominated community.

    PubMed

    Johnston, C G; Vestal, J R

    1993-05-01

    Cryptoendolithic (hidden in rock) lichen-dominated microbial communities from the Ross Desert of Antarctica were shown to produce oxalate (oxalic acid). Oxalate increased mineral dissolution, which provides nutrients, creates characteristic weathering patterns, and may ultimately influence the biological residence time of the community. Oxalate was the only organic acid detectable by HPLC, and its presence was verified by GC/MS. Community photosynthetic metabolism was involved in oxalate production since rates of (14)C-oxalate production from (14)C02 were higher in light than in dark incubations. Flaking of the sandstone at the level of the lichen-dominated zone a few millimeters beneath the rock surface can be explained by dissolution of the sandstone cement, which was enhanced by Si, Fe, and Al oxalate complex formation. Added oxalate was observed to increase the solubility of Si, Fe, Al, P, and K. Oxalate's ability to form soluble trivalent metal-oxalate complexes correlated with the observed order of metal oxide depletion from the lichen-dominated zone (Mn > Fe > Al). Thermodynamic calculations predict that Fe oxalate complex formation mobilizes amorphous Fe oxides (ferrihydrite) in the lichen-dominated zone, and where oxalate is depleted, ferrihydrite should precipitate. Hematite, a more crystalline Fe oxide, should remain solid at in situ oxalate concentrations. Oxalate was not a carbon source for the indigenous heterotrophs, but the microbiota were involved in oxalate mineralization to CO2, since oxalate mineralization was reduced in poisoned incubations. Photooxidation of oxalate to C02 coupled with photoreduction of Fe(Ill) may be responsible for oxalate removal in situ, since rates of (14)C-oxalate mineralization in dark incubations were at least 50% lower than those in the light. Removal of oxalate from Si, Fe, and Al complexes should allow free dissolved Si, Fe, and Al to precipitate as amorphous silicates and metal oxides. This may explain increased

  9. Field method comparison for the characterization of acid aerosols and gases

    NASA Astrophysics Data System (ADS)

    Suh, Helen H.; Allen, George A.; Aurian-Blájeni, Benedict; Koutrakis, Petros; Burton, Robert M.

    This paper presents findings from two intercomparison studies of acid aerosol measurement systems, which were conducted in Uniontown and State College, PA, during the summers of 1990 and 1991, respectively. As part of these studies, acid aerosol and gas concentrations (NH 3, HNO 3, HNO 2, SO 2, H +, NH 4+, NO 3, SO 42-) were measured using five systems: the Harvard/EPA Annular Denuder Systems (HEADS), the Personal Annular Denuder System (PADS), the Continuous Sulfate/Thermal Speciation system (CSTS), the Micro-Orifice Impactor (MOI), and the Harvard Marple Impactor (HI). Concentrations were measured over 3, 12, and 24 h periods, with resultant acid aerosol and gas measurements compared for each system. Results from these studies show excellent agreement among the particulate measurement systems. The sulfate (SO 42-), aerosol strong acidity (H +), and ammonium (NH 4+) concentrations measured by all systems were highly correlated. In addition, 3 and 12 h particulate measurements were comparable for HEADS, MO1, and PADS samplers. Although significantly different, mean relative differences between HEADS measurements and those obtained using the HI and CSTS (SO 42- only) systems were small. For the gases nitric acid (HNO 3) and sulfur dioxide (SO 2), the performance of the HEADS sampler was found to be independent of sample duration, as the 3 and 12 h HEADS measurements were comparable. The PADS sampler, however, was found to measure concentrations of both HNO 3 and SO 2 poorly. PADS measurements, of HNO 3 in particular, were significantly lower than corresponding HEADS measurements. These lower values probably resulted from their deposition on the inlet surfaces of the PADS sampler. The performance of the measurement systems for ammonia (NH 3), nitrous acid (HONO), and nitrate (NO 3-) could not be determined, since their outdoor levels generally were near or below the limit of detection (LOD).

  10. Genetic evidence for differences in the pathways of druse and prismatic calcium oxalate crystal formation in Medicago truncatula

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Current evidence supports a single pathway of oxalate biosynthesis utilising ascorbic acid as the precursor. In this study, we begin to address the possibility that more than one pathway of oxalate biosynthesis and calcium oxalate formation occurs in Medicago truncatula Gaertn. (cv. Jemalong genotyp...

  11. Soluble species in the Arctic summer troposphere: Acidic gases, aerosols, and precipitation

    NASA Astrophysics Data System (ADS)

    Talbot, R. W.; Vijgen, A. S.; Harriss, R. C.

    1992-10-01

    We report here the distribution of selected acidic gases and aerosol species in the North American Arctic and sub-Arctic summer troposphere. The summertime troposphere is an acidic environment, with HCOOH and CH3COOH the principal acidic gases and acidic sulfate aerosols dominating the particulate phase. Our data show that the acidic gas and aerosol composition is uniform on a large spatial scale. There appears to be a surface source of NH4+ over the Arctic Ocean pack ice which may reflect release of NH3 from decay of dead marine organisms on the ice surface near ice leads, release from rotting sea ice, or an upward flux from surface ocean waters in open ice leads. This NH3 appears to partially neutralize aerosol acidity in the boundary layer. Over sub-Arctic tundra in southwestern Alaska inputs of marine biogenic sulfur from the nearby Bering Sea appear to be an important source of boundary layer aerosol SO42-. While there were only minor effects on aerosol chemistry over the tundra from sea salt, the rainwater chemistry showed influence from marine aerosols which were apparently incorporated into air masses during frontal passages moving inland from the Bering Sea. The rainwater acidity over the tundra (pH 4.69) is typical of remote regions. The principal acidity components are H2SO4 and carboxylic acids, especially HCOOH. The carboxylic acids appear to have a strong continental biogenic source, but hydrocarbons of marine origin and emissions from forest fires may also be important. The wet deposition fluxes of NO3--N and SO42--S over sub-Arctic tundra during July-August 1988 were 2.1 and 2.4 mmol m-2 yr-1. Wet deposition of NO3- was nearly 3 times higher than the average NOy deposition flux, which is believed to represent primarily dry deposition of HNO3 (Bakwin et al., this issue). Our measurements indicate that the mid-troposphere in the Arctic is generally contaminated with low levels of anthropogenic pollutants even in summer when direct atmospheric coupling

  12. Selective adsorption in two porous triazolate-oxalate-bridged antiferromagnetic metal-azolate frameworks obtained via in situ decarboxylation of 3-amino-1,2,4-triazole-5-carboxylic acid

    NASA Astrophysics Data System (ADS)

    Hou, Juan-Juan; Xu, Xia; Jiang, Ning; Wu, Ya-Qin; Zhang, Xian-Ming

    2015-03-01

    Solvothermal reactions of metal salts, 3-amino-1,2,4-triazole-5-carboxylic acid (H2atzc) and ammonium oxalate in different temperature produced two metal azolate frameworks, namely, [Cu3(atzc)2(atz)(ox)]·1.5H2O (1) and [Co5(atz)4(ox)3(HCOO)2]·DMF (2) (H2atzc=3-amino-1,2,4-triazole-5-carboxylic acid, Hatz=3-amino-1,2,4-triazole, and ox=oxalate), in which the atzc precusor was in situ decarboxylated. Structural determination reveals that 1 contains [Cu3(atzc)2(atz)]2- layers of mixed μ4-atzc and μ3-atz ligands, which are pillared by ox2- groups to form a 3D porous framework. Compound 2 contains 2D layers with basic spindle-shaped decanuclear units, which extended by ox2- and formates to form 3D porous framework. Gas adsorption investigation revealed that two kinds of frameworks exhibited selective CO2 over N2 sorption. Moreover, activated 2 shows H2 storage capacity. Additionally, magnetic properties of both the compounds have been investigated.

  13. The thermodynamic and kinetic impacts of organics on marine aerosols

    NASA Astrophysics Data System (ADS)

    Crahan, Kathleen

    Organics can change the manner in which aerosols scatter radiation directly as hydrated aerosols and indirectly as in-cloud activated aerosols, through changing the solution activity, the surface tension, and the accommodation coefficient of the hydrated aerosol. This work explores the kinetic and thermodynamic impacts of the organic component of marine aerosols through data collected over four field campaigns and through several models used to reproduce observations. The Rough Evaporation Duct (RED) project was conducted in the summer of 2001 off the coast of Oahu using the Twin Otter Aircraft and the Floating Instrument Platform research platform for data collection. The Cloud-Aerosol Research in the Marine Atmosphere (CARMA) campaigns were conducted over three summers (2002, 2004, 2005) off the coast of Monterey, California. During the CARMA campaigns, a thick, moist, stratocumulus deck was present during most days, and the Twin Otter Aircraft was the primary research platform used to collect data. However, the research goals and exact instrumentation onboard the Twin Otter varied from campaign to campaign, and each data set was analyzed individually. Data collected from CARMA I were used to explore the mechanism of oxalic acid production in cloud droplets. Oxalate was observed in the clouds in excess to below cloud concentrations by an average of 0.11 mug m-3, suggesting an in-cloud production. The tentative identification in cloud water of an intermediate species in the aqueous oxalate production mechanism lends further support to an in-cloud oxalate source. The data sets collected during the RED campaign and the CARMA II and CARMA III campaigns were used to investigate the impact of aerosol chemical speciation on aerosol hygroscopic behavior. Several models were used to correlate the observations in the subsaturated regime to theory including an explicit thermodynamic model, simple Kohler theory, and a parameterization of the solution activity. These models

  14. Sulfur-rich geothermal emissions elevate acid aerosol levels in metropolitan Taipei.

    PubMed

    Lin, Chih-Hung; Mao, I-Fang; Tsai, Pei-Hsien; Chuang, Hsin-Yi; Chen, Yi-Ju; Chen, Mei-Lien

    2010-08-01

    Several studies have demonstrated that millions of people globally are potentially exposed to volcanic gases. Hydrogen sulfide is a typical gas in volcanic and geothermal areas. The gas is toxic at high concentrations that predominantly affects the nervous, cardiovascular, and respiratory systems. The WHO air quality guideline for hydrogen sulfide is 150 microg m(-3) (105 ppb). The northwest part of Taipei is surrounded by sulfur-rich geothermal and hot springs. Active fumaroles and bubbling springs around the geothermal area emit acidic gases. In combination with automobile emissions, the pollution of acid aerosols is characteristic of the metropolis. This study considered sulfur-rich geothermal, suburban and downtown locations of this metropolis to evaluate geothermally emitted acid aerosol and H(2)S pollution. Acid aerosols were collected using a honeycomb denuder filter pack sampling system (HDS), and then analyzed by ion chromatography (IC). Results indicated that long-term geothermal emissions, automobile emissions and photochemical reactions have led to significant variations in air pollution among regions of metropolitan Taipei. The highest H(2)S concentration was 1705 ppb in the geothermal area with low traffic density and the mean concentration was 404.06 ppb, which was higher than WHO guideline and might cause eye irritation. The SO(2) concentrations were relatively low (mean concentration was 3.9 ppb) in this area. It may partially result from the chemical reduction reaction in the geothermal emission, which converted the SO(2) gas into SO(4)(2-) and H(2)S. Consequently, very high sulfate concentrations (mean concentration higher than 25.0 microg m(-3)) were also observed in the area. The geothermal areas also emitted relatively high levels of aerosol acidity, Cl(-), F(-), PO(4)(3-), and N-containing aerosols. As a result, concentrations of HNO(3), NO(2)(-), PO(4)(3-), and SO(4)(2-) in metropolitan Taipei are significantly higher than those in other

  15. Urinary oxalate and glycolate excretion and plasma oxalate concentration.

    PubMed Central

    Barratt, T M; Kasidas, G P; Murdoch, I; Rose, G A

    1991-01-01

    The diagnosis of primary hyperoxaluria in young children is hampered by the lack of a reliable reference range for urinary oxalate excretion, especially in infants. We present data on urinary oxalate and glycolate excretion in 137 normal children, on the plasma oxalate concentration in 33 normal children and 53 with chronic renal failure, and on amniotic fluid oxalate concentration in 63 uncomplicated pregnancies. The urinary oxalate:creatinine molar ratios were log normally distributed: mean (range) values were less than 1 year 0.061 (0.015-0.26), 1-5 years 0.036 (0.011-0.12), 5-12 years 0.030 (0.0059-0.15), and greater than 12 years 0.013 (0.0021-0.083). Geometric mean (range) plasma oxalate concentration in the normal children was 1.53 (0.78-3.02) mumols/l and was independent of age. The mean (SD) plasma oxalate: creatinine molar ratio in these normal children and 50 with chronic renal failure was 0.033 (0.013), and was independent of age and renal function. Mean (SD) amniotic fluid oxalate concentration was 19.0 (4.3) mumols/l. PMID:2031609

  16. The effect of low solubility organic acids on the hygroscopicity of sodium halide aerosols

    NASA Astrophysics Data System (ADS)

    Miñambres, L.; Méndez, E.; Sánchez, M. N.; Castaño, F.; Basterretxea, F. J.

    2014-10-01

    In order to accurately assess the influence of fatty acids on the hygroscopic and other physicochemical properties of sea salt aerosols, hexanoic, octanoic or lauric acid together with sodium halide salts (NaCl, NaBr and NaI) have been chosen to be investigated in this study. The hygroscopic properties of sodium halide sub-micrometre particles covered with organic acids have been examined by Fourier-transform infrared spectroscopy in an aerosol flow cell. Covered particles were generated by flowing atomized sodium halide particles (either dry or aqueous) through a heated oven containing the gaseous acid. The obtained results indicate that gaseous organic acids easily nucleate onto dry and aqueous sodium halide particles. On the other hand, scanning electron microscopy (SEM) images indicate that lauric acid coating on NaCl particles makes them to aggregate in small clusters. The hygroscopic behaviour of covered sodium halide particles in deliquescence mode shows different features with the exchange of the halide ion, whereas the organic surfactant has little effect in NaBr particles, NaCl and NaI covered particles experience appreciable shifts in their deliquescence relative humidities, with different trends observed for each of the acids studied. In efflorescence mode, the overall effect of the organic covering is to retard the loss of water in the particles. It has been observed that the presence of gaseous water in heterogeneously nucleated particles tends to displace the cover of hexanoic acid to energetically stabilize the system.

  17. The effect of low solublility organic acids on the hygroscopicity of sodium halide aerosols

    NASA Astrophysics Data System (ADS)

    Miñambres, L.; Méndez, E.; Sánchez, M. N.; Castaño, F.; Basterretxea, F. J.

    2014-02-01

    In order to accurately assess the influence of fatty acids on the hygroscopic and other physicochemical properties of sea salt aerosols, hexanoic, octanoic or lauric acid together with sodium halide salts (NaCl, NaBr and NaI) have been chosen to be performed in this study. The hygroscopic properties of sodium halide submicrometer particles covered with organic acids have been examined by Fourier-transform infrared spectroscopy in an aerosol flow cell. Covered particles were generated by flowing atomized sodium halide particles (either dry or aqueous) through a heated oven containing the gaseous acid. The obtained results indicate that gaseous organic acids easily nucleate onto dry and aqueous sodium halide particles. On the other hand, Scanning Electron Microscopy (SEM) images indicate that lauric acid coating on NaCl particles makes them to aggregate in small clusters. The hygroscopic behaviour of covered sodium halide particles in deliquescence mode shows different features with the exchange of the halide ion: whereas the organic covering has little effect in NaBr particles, NaCl and NaI covered particles change their deliquescence relative humidities, with different trends observed for each of the acids studied. In efflorescence mode, the overall effect of the organic covering is to retard the loss of water in the particles. It has been observed that the presence of gaseous water in heterogeneously nucleated particles tends to displace the cover of hexanoic acid to energetically stabilize the system.

  18. Uptake of 13N-labeled N2O5 to citric acid aerosol particles

    NASA Astrophysics Data System (ADS)

    Grzinic, Goran; Bartels-Rausch, Thorsten; Birrer, Mario; Türler, Andreas; Ammann, Markus

    2013-04-01

    Dinitrogen pentoxide is a significant reactive intermediate in the night time chemistry of nitrogen oxides. Depending on atmospheric conditions it can act either as a NO3 radical reservoir or as a major NOx sink by heterogeneous hydrolysis on aerosol surfaces. As such, it can influence tropospheric ozone production and therefore the oxidative capacity of the atmosphere. Furthermore it's suspected of being a non negligible source of tropospheric Cl, even over continental areas [1,2]. We used the short-lived radioactive tracer 13N delivered by PSI's PROTRAC facility [3] in conjunction with an aerosol flow tube reactor in order to study N2O5 uptake kinetics on aerosol particles. 13NO is mixed with non labeled NO and O3 in a gas reactor where N2O5 is synthesized under dry conditions to prevent hydrolysis on the reactor walls. The resulting N2O5 flow is fed into an aerosol flow tube reactor together with a humidified aerosol flow. By using movable inlets we can vary the length of the aerosol flow tube and thus the reaction time. The gas feed from the reactor is then directed into a narrow parallel plate diffusion denuder system that allows for selective separation of the gaseous species present in the gas phase. Aerosol particles are trapped on a particle filter placed at the end of the denuder system. The activity of 13N labeled species trapped on the denuder plates and in the particle filter can be monitored via scintillation counters. Aerosol uptake measurements were performed with citric acid aerosols in a humidity range of 27-61.5% RH. The results obtained from our measurements have shown that the uptake coefficient increases with humidity from 1.65±0.3x10-3 (~27% RH) to 1.25±0.3x10-2 (45% RH) and 2.00±0.3x10-2 (61.5% RH). Comparison to literature data shows that this is similar to values reported for some polycarboxylic acids (like malonic acid), while being higher than some others [4]. The increase is likely related to the increasing amount of water associated

  19. Viscosity controls humidity dependence of N2O5 uptake to citric acid aerosol

    NASA Astrophysics Data System (ADS)

    Gržinić, G.; Bartels-Rausch, T.; Berkemeier, T.; Türler, A.; Ammann, M.

    2015-12-01

    The heterogeneous loss of dinitrogen pentoxide (N2O5) to aerosol particles has a significant impact on the night-time nitrogen oxide cycle and therefore the oxidative capacity in the troposphere. Using a 13N short-lived radioactive tracer method, we studied the uptake kinetics of N2O5 on citric acid aerosol particles as a function of relative humidity (RH). The results show that citric acid exhibits lower reactivity than similar dicarboxylic and polycarboxylic acids, with uptake coefficients between ∼ 3 × 10-4-∼ 3 × 10-3 depending on humidity (17-70 % RH). At RH above 50 %, the magnitude and the humidity dependence can be best explained by the viscosity of citric acid as compared to aqueous solutions of simpler organic and inorganic solutes and the variation of viscosity with RH and, hence, diffusivity in the organic matrix. Since the diffusion rates of N2O5 in highly concentrated citric acid solutions are not well established, we present four different parameterizations of N2O5 diffusivity based on the available literature data or estimates for viscosity and diffusivity of H2O. Above 50 % RH, uptake is consistent with the reacto-diffusive kinetic regime whereas below 50 % RH, the uptake coefficient is higher than expected from hydrolysis of N2O5 within the bulk of the particles, and the uptake kinetics is most likely limited by loss on the surface only. This study demonstrates the impact of viscosity in highly oxidized and highly functionalized secondary organic aerosol material on the heterogeneous chemistry of N2O5 and may explain some of the unexpectedly low loss rates to aerosol derived from field studies.

  20. The Acid Catalyzed Nitration of Methanol: Formation of Methyl Nitrate via Aerosol Chemistry

    NASA Technical Reports Server (NTRS)

    Riffel, Brent G.; Michelsen, Rebecca R.; Iraci, Laura T.

    2004-01-01

    The liquid phase acid catalyzed reaction of methanol with nitric acid to yield methyl nitrate under atmospheric conditions has been investigated using gas phase infrared spectroscopy. This nitration reaction is expected to occur in acidic aerosol particles found in the upper troposphere/lower stratosphere as highly soluble methanol and nitric acid diffuse into these aerosols. Gaseous methyl nitrate is released upon formation, suggesting that some fraction of NO(x) may he liberated from nitric acid (methyl nitrate is later photolyzed to NO(x)) before it is removed from the atmosphere by wet deposition. Thus, this reaction may have important implications for the NO(x) budget. Reactions have been initiated in 45-62 wt% H2SO4 solutions at 10.0 C. Methyl nitrate production rates increased exponentially with acidity within the acidity regime studied. Preliminary calculations suggest that the nitronium ion (NO2(+) is the active nitrating agent under these conditions. The reaction order in methanol appears to depend on the water/methanol ratio and varies from first to zeroth order under conditions investigated. The nitration is first order in nitronium at all acidities investigated. A second order rate constant, kappa(sub 2), has been calculated to be 1 x 10(exp 8)/ M s when the reaction is first order in methanol. Calculations suggest the nitration is first order in methanol under tropospheric conditions. The infinitesimal percentage of nitric acid in the nitronium ion form in this acidity regime probably makes this reaction insignificant for the upper troposphere; however, this nitration may become significant in the mid stratosphere where colder temperatures increase nitric acid solubility and higher sulfuric acid content shifts nitric acid speciation toward the nitronium ion.

  1. Distribution of Components in Ion Exchange Materials Taken from the K East Basin and Leaching of Ion Exchange Materials by Nitric/Hydrofluoric Acid and Nitric/Oxalic Acid

    SciTech Connect

    Delegard, C.H.; Rinehart, D.E.; Hoopes, F.V.

    1999-04-02

    Laboratory tests were performed to examine the efficacy of mixed nitric/hydrofluoric acid followed by mixed nitric/oxalic acid leach treatments to decontaminate ion exchange materials that have been found in a number of samples retrieved from K East (KE)Basin sludge. The ion exchange materials contain organic ion exchange resins and zeolite inorganic ion exchange material. Based on process records, the ion exchange resins found in the K Basins is a mixed-bed, strong acid/strong base material marketed as Purolite NRW-037. The zeolite material is Zeolon-900, a granular material composed of the mineral mordenite. Radionuclides sorbed or associated with the ion exchange material can restrict its disposal to the Environmental Restoration Disposal Facility (ERDF). The need for testing to support development of a treatment process for K Basin sludge has been described in Section 4.2 of ''Testing Strategy to Support the Development of K Basins Sludge Treatment Process'' (Flament 1998). Elutriation and washing steps are designed to remove the organic resins from the K Basin sludge. To help understand the effects of the anticipated separation steps, tests were performed with well-rinsed ion exchange (IX) material from KE Basin floor sludge (sample H-08 BEAD G) and with well-rinsed IX having small quantities of added KE canister composite sludge (sample KECOMP). Tests also were performed to determine the relative quantities of organic and inorganic IX materials present in the H-08 K Basin sludge material. Based on chemical analyses of the separated fractions, the rinsed and dry IX material H-08 BEAD G was found to contain 36 weight percent inorganic material (primarily zeolite). The as-received (unrinsed) and dried H-08 material was estimated to contain 45 weight percent inorganic material.

  2. Contributions of modern and dead organic carbon to individual fatty acid homologues in spring aerosols collected from northern Japan

    NASA Astrophysics Data System (ADS)

    Kawamura, Kimitaka; Matsumoto, Kohei; Uchida, Masao; Shibata, Yasuyuki

    2010-11-01

    Radiocarbon (14C) and stable carbon isotope ratios (δ13C) have been used as proxies to evaluate the contributions of modern/fossil carbon and marine/terrestrial organic matter, respectively, in geochemical samples. However, there are few such studies in atmospheric aerosols. Here, we measured 14C contents and δ13C of individual n-fatty acids in an aerosol sample collected from northern Japan in spring 2001 during Asian dust season. Our results show that the distribution of fatty acids in the spring aerosols was characterized by a strong even/odd carbon number predominance with two maxima at C16 and C26. Their δ13C (range: -30.6 to -20.5‰) showed higher values (average: -24.5‰) for lower molecular weight (LMW) fatty acids (C16 - C19) and lower values (average: -29.7‰) for higher MW (HMW) fatty acids (C20 - C32). This difference suggests that LMW acids are mainly derived from lacustrine and/or marine algal sources whereas HMW acids are predominantly from terrestrial C3 higher plants. Δ14C values of fatty acids were found to range from -96.9 to +122.9‰ with lower values for HMW acids and higher values for LMW acids. LMW acids in the aerosols contain only modern carbon. In contrast, HMW acids ≥C24 were found to contain up to 9.7 wt% dead carbon, although their major portion (up to 92.3%) is composed of modern carbon. Backward trajectory analyses indicated that the source regions of the spring aerosols were dominated by central and north China (62%). This study suggests that the old fatty acids in the spring aerosols are most likely originated from the loess deposits in China via long-range atmospheric transport over the western North Pacific, although their contribution to the aerosols was relatively small.

  3. OXALATE DEPOSITION ON ASBESTOS BODIES

    EPA Science Inventory

    The clinical and histopathologic findings in three patients with a deposition of calcium oxalate crystals on ferruginous bodies after occupational exposure to asbestos are provided. In addition, we test the hypothesis that this oxalate can be generated through a nonenzymatic o...

  4. Acute lung function responses to ambient acid aerosol exposures in children

    SciTech Connect

    Raizenne, M.E.; Burnett, R.T.; Stern, B.; Franklin, C.A.; Spengler, J.D.

    1989-02-01

    We examined the relationship between lung function changes and ambient acid aerosol episodes in children attending a residential summer camp. Young females (112) performed daily spirometry, and 96 were assessed on one occasion for airway hyperresponsiveness using a methacholine bronchoprovocation test. Air quality measurements were performed on site and four distinct acid aerosol episodes were observed during the 41-day study. The maximum values observed during the 41-day study were: O/sub 3/ at 143 ppb; H/sub 2/SO/sub 4/ at 47.7 micrograms/m/sup 3/; and (H+) at 550 nmole/m/sup 3/. Maximum decrements of 3.5 and 7% for FEV1 and PEF, respectively, were observed to be associated with the air pollution episodes. There was some evidence of a differential lung function response to the episodes where children with a positive response to a methacholine challenge had larger decrements compared to their nonresponsive counterparts.

  5. Acute lung function responses to ambient acid aerosol exposures in children.

    PubMed

    Raizenne, M E; Burnett, R T; Stern, B; Franklin, C A; Spengler, J D

    1989-02-01

    We examined the relationship between lung function changes and ambient acid aerosol episodes in children attending a residential summer camp. Young females (112) performed daily spirometry, and 96 were assessed on one occasion for airway hyperresponsiveness using a methacholine bronchoprovocation test. Air quality measurements were performed on site and four distinct acid aerosol episodes were observed during the 41-day study. The maximum values observed during the 41-day study were: O3 at 143 ppb; H2SO4 at 47.7 micrograms/m3; and [H+] at 550 nmole/m3. Maximum decrements of 3.5 and 7% for FEV1 and PEF, respectively, were observed to be associated with the air pollution episodes. There was some evidence of a differential lung function response to the episodes where children with a positive response to a methacholine challenge had larger decrements compared to their nonresponsive counterparts.

  6. USE OF AN EQUILIBRIUM MODEL TO FORECAST DISSOLUTION EFFECTIVENESS, SAFETY IMPACTS, AND DOWNSTREAM PROCESSABILITY FROM OXALIC ACID AIDED SLUDGE REMOVAL IN SAVANNAH RIVER SITE HIGH LEVEL WASTE TANKS 1-15

    SciTech Connect

    KETUSKY, EDWARD

    2005-10-31

    This thesis details a graduate research effort written to fulfill the Magister of Technologiae in Chemical Engineering requirements at the University of South Africa. The research evaluates the ability of equilibrium based software to forecast dissolution, evaluate safety impacts, and determine downstream processability changes associated with using oxalic acid solutions to dissolve sludge heels in Savannah River Site High Level Waste (HLW) Tanks 1-15. First, a dissolution model is constructed and validated. Coupled with a model, a material balance determines the fate of hypothetical worst-case sludge in the treatment and neutralization tanks during each chemical adjustment. Although sludge is dissolved, after neutralization more is created within HLW. An energy balance determines overpressurization and overheating to be unlikely. Corrosion induced hydrogen may overwhelm the purge ventilation. Limiting the heel volume treated/acid added and processing the solids through vitrification is preferred and should not significantly increase the number of glass canisters.

  7. Spatial separation of individual substances in effloresced crystals of ternary ammonium sulphate/dicarboxylic acid/water aerosols.

    PubMed

    Treuel, Lennart; Sandmann, Alice; Zellner, Reinhard

    2011-04-18

    This work examines the crystals resulting from the efflorescence of internally mixed aqueous aerosols comprising ammonium sulphate and different dicarboxylic acids. Most studies on the deliquescence of aerosols use previously effloresced aerosols in their experiments. However, during efflorescence a highly supersaturated solution crystallises in a kinetically controlled way unlike the case of thermodynamically controlled crystallisation. Herein the distribution of individual substances within the effloresced crystals is investigated using Raman scanning experiments. The data presented show an intriguingly complex behaviour of these ternary and quarternary aerosols. A spatial separation of substances in the crystals resulting from the efflorescence of previously internally mixed ternary salt/dicarboxylic acid/water aerosol droplets is demonstrated and mechanistic aspects are discussed. PMID:21472958

  8. An analysis of the meteorological parameters affecting ambient concentrations of acid aerosols in Uniontown, Pennsylvania

    NASA Astrophysics Data System (ADS)

    Zelenka, Michael P.

    Ambient concentrations of aerosol strong acidity (H +) that were collected in Uniontown, Pennsylvania, during the summer of 1990 were evaluated to determine the relationships between meteorology and the magnitude of the H + concentrations. An extensive database containing 17 meteorological parameters was compiled for the Uniontown - Pittsburgh region. The database included both surface and upper air meteorological parameters. Concentrations of ambient acid sulfate aerosols collected in Uniontown, Pennsylvania, in the summer of 1990 were greatly affected by both local and regional meteorological conditions. Seven distinct meteorological synoptic types or regimes were identified for the summer months. A clear association was shown between episodic events of elevated ambient H + concentrations and one of the regimes, referred to here as synoptic type 5, which occurred when an anticyclone set up to the east of the mid-Atlantic states. Much of the variability (approximately 45%) in H + concentrations for the overall model was explained by the surface air temperature. Approximately 10% of the H' variability was explained by westerly winds as expressed by the U components of the morning 850 mb wind and the mean daily surface wind at Uniontown. Results showed that for days under the influence of synoptic type 5, which was associated with the highest levels of ambient H', the surface temperature explained approximately one-third of the variability in H' concentrations. The height of the mixing layer also affected the variability in H + concentrations, accounting for nearly a quarter of the variance. These results show that an analysis of the surface wind speed and direction alone will not adequately explain the variability in the concentrations of ambient acid aerosols. Analyses of the meteorological parameters affecting ambient concentrations of acid aerosols should include the mixing height, as well as the temperature, wind speed, and wind direction; both at the surface

  9. Yearly trend of dicarboxylic acids in organic aerosols from south of Sweden and source attribution

    NASA Astrophysics Data System (ADS)

    Hyder, Murtaza; Genberg, Johan; Sandahl, Margareta; Swietlicki, Erik; Jönsson, Jan Åke

    2012-09-01

    Seven aliphatic dicarboxylic acids (C3-C9) along with phthalic acid, pinic acid and pinonic acid were determined in 35 aerosol (PM10) samples collected over the year at Vavihill sampling station in south of Sweden. Mixture of dichloromethane and methanol (ratio 1:3) was preferred over water for extraction of samples and extraction was assisted by ultrasonic agitation. Analytes were derivatized using N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) containing 1% trimethylsilyl chloride and analyzed using gas chromatography/mass spectrometry. Among studied analytes, azelaic acid was found maximum with an average concentration of 6.0 ± 3.6 ng m-3 and minimum concentration was found for pimelic acid (1.06 ± 0.63 ng m-3). A correlation coefficients analysis was used for defining the possible sources of analytes. Higher dicarboxylic acids (C7-C9) showed a strong correlation with each other (correlation coefficients (r) range, 0.96-0.97). Pinic and pinonic acids showed an increase in concentration during summer. Lower carbon number dicarboxylic acids (C3-C6) and phthalic acid were found strongly correlated, but showed a poor correlation with higher carbon number dicarboxylic acids (C7-C9), suggesting a different source for them. Biomass burning, vehicle exhaust, photo-oxidation of volatile organic compounds (natural and anthropogenic emissions) were possible sources for dicarboxylic acids.

  10. Evidence for a cytoplasmic pathway of oxalate biosynthesis in Aspergillus niger

    SciTech Connect

    Kubicek, C.P.; Schreferl-Kunar, G.; Woehrer, W.; Roehr, M.

    1988-03-01

    Oxalate accumulation of up to 8 g/liter was induced in Aspergillus niger by shifting the pH from 6 to 8. This required the presence of P/sub i/ and a nitrogen source and was inhibited by the protein synthesis inhibitor cycloheximide. Exogenously added /sup 14/CO/sub 2/ was not incorporated into oxalate, but was incorporated into acetate and malate, thus indicating the biosynthesis of oxalate by hydrolytic cleavage of oxaloacetate. Inhibition of mitochondrial citrate metabolism by fluorocitrate did not significantly decrease the oxalate yield. The putative enzyme that was responsible for this oxaloacetate hydrolase (EC 3.7.1.1), which was induced de novo during the pH shift. Subcellular fractionation of oxalic acid-forming mycelia of A. niger showed that this enzyme is located in the cytoplasm of A. niger. The results are consistent with a cytoplasmic pathway of oxalate formation which does not involve the tricarboxylic acid cycle.

  11. Stratospheric Sulfuric Acid and Black Carbon Aerosol Measured During POLARIS and its Role in Ozone Chemistry

    NASA Technical Reports Server (NTRS)

    Strawa, Anthony W.; Pueschel, R. F.; Drdla, K.; Verma, S.; Gore, Warren J. (Technical Monitor)

    1998-01-01

    Stratospheric aerosol can affect the environment in three ways. Sulfuric acid aerosol have been shown to act as sites for the reduction of reactive nitrogen and chlorine and as condensation sites to form Polar Stratospheric Clouds, under very cold conditions, which facilitate ozone depletion. Recently, modeling studies have suggested a link between BCA (Black Carbon Aerosol) and ozone chemistry. These studies suggest that HNO3, NO2, and O3 may be reduced heterogeneously on BCA particles. The ozone reaction converts ozone to oxygen molecules, while HNO3 and NO2 react to form NOx. Finally, a buildup of BCA could reduce the single-scatter albedo of aerosol below a value of 0.98, a critical value that has been postulated to change the effect of stratospheric aerosol from cooling to warming. Correlations between measured BCA amounts and aircraft usage have been reported. Attempts to link BCA to ozone chemistry and other stratospheric processes have been hindered by questions concerning the amount of BCA that exists in the stratosphere, the magnitude of reaction probabilities, and the scarcity of BCA measurements. The Ames Wire Impactors (AWI) participated in POLARIS as part of the complement of experiments on the NASA ER-2. One of our main objectives was to determine the amount of aerosol surface area, particularly BCA, available for reaction with stratospheric constituents and assess if possible, the importance of these reactions. The AWI collects aerosol and BCA particles on thin Palladium wires that are exposed to the ambient air in a controlled manner. The samples are returned to the laboratory for subsequent analysis. The product of the AWI analysis is the size, surface area, and volume distributions, morphology and elemental composition of aerosol and BCA. This paper presents results from our experiments during POLARIS and puts these measurements in the context of POLARIS and other missions in which we have participated. It describes modifications to the AWI data

  12. An Oxalyl-CoA Dependent Pathway of Oxalate Catabolism Plays a Role in Regulating Calcium Oxalate Crystal Accumulation and Defending against Oxalate-Secreting Phytopathogens in Medicago truncatula

    PubMed Central

    Foster, Justin; Luo, Bin; Nakata, Paul A.

    2016-01-01

    Considering the widespread occurrence of oxalate in nature and its broad impact on a host of organisms, it is surprising that so little is known about the turnover of this important acid. In plants, oxalate oxidase is the most well studied enzyme capable of degrading oxalate, but not all plants possess this activity. Recently, an Acyl Activating Enzyme 3 (AAE3), encoding an oxalyl-CoA synthetase, was identified in Arabidopsis. AAE3 has been proposed to catalyze the first step in an alternative pathway of oxalate degradation. Whether this enzyme and proposed pathway is important to other plants is unknown. Here, we identify the Medicago truncatula AAE3 (MtAAE3) and show that it encodes an oxalyl-CoA synthetase activity exhibiting high activity against oxalate with a Km = 81 ± 9 μM and Vmax = 19 ± 0.9 μmoles min-1mg protein-1. GFP-MtAAE3 localization suggested that this enzyme functions within the cytosol of the cell. Mtaae3 knock-down line showed a reduction in its ability to degrade oxalate into CO2. This reduction in the capacity to degrade oxalate resulted in the accumulation of druse crystals of calcium oxalate in the Mtaae3 knock-down line and an increased susceptibility to oxalate-secreting phytopathogens such as Sclerotinia sclerotiorum. Taken together, these results suggest that AAE3 dependent turnover of oxalate is important to different plants and functions in the regulation of tissue calcium oxalate crystal accumulation and in defense against oxalate-secreting phytopathogens. PMID:26900946

  13. Pulmonary clearance of three aerosolized solutes in oleic acid-induced lung injury

    SciTech Connect

    Huchon, G.J.; Montgomery, A.B.; Lipavsky, A.; Hoeffel, J.M.; Murray, J.F.

    1988-03-01

    We studied the effects of oleic acid (OA) on pulmonary clearance of three aerosolized radioactive solutes: /sup 99m/Tc-diethylenetriamine pentaacetate (/sup 99m/Tc-DTPA), /sup 67/Ga-desferoxamine (/sup 67/Ga-DFOM), and /sup 111/In-transferrin (/sup 111/In-TF). Either 0.09 ml/kg OA or an equivalent volume of 0.9% NaCl (controls) was administered intravenously to 48 anesthetized, paralyzed dogs. Each animal received one aerosolized solute either 60 min after (protocol A) or 30 min before (protocol B) the infusion of OA or NaCl. In protocol A clearances of all three solutes were similar in OA and control animals. In contrast, in protocol B clearances of all three solutes increased significantly during OA infusion; during the next 60 min clearances of /sup 99m/Tc-DTPA and /sup 67/Ga-DFOM returned to control values but 111In-TF remained increased. We conclude that 1) in OA-induced permeability edema pulmonary clearance of aerosolized solutes is increased when the aerosol is delivered 30 min before but not 60 min after injury, and 2) increased clearance persists only for large molecules, presumably because smaller molecules cross injured epithelium quickly and completely. These phenomena are best explained by a nonhomogeneous distribution of OA-induced injury.

  14. Inactivation of Encephalomyocarditis Virus in Aerosols: Fate of Virus Protein and Ribonucleic Acid

    PubMed Central

    De Jong, J. C.; Harmsen, M.; Trouwborst, T.; Winkler, K. C.

    1974-01-01

    After aerosolization at relative humidities of 50% or lower, encephalomyocarditis virus is rapidly inactivated. In this process the protein coat of the virion is damaged. This appears as a loss of hemagglutination activity and loss of affinity for hemagglutination inhibiting antibodies. The ribonucleic acid of the virus retains its infectivity but it becomes susceptible to ribonuclease. It sediments in sucrose gradients when centrifuged at high speed with the same velocity as free infectious ribonucleic acid extracted with phenol from intact encephalomyocarditis virus. PMID:4358862

  15. Update on Oxalate Crystal Disease

    PubMed Central

    Lorenz, Elizabeth C.; Michet, Claude J.; Milliner, Dawn S.; Lieske, John C.

    2013-01-01

    Oxalate arthropathy is a rare cause of arthritis characterized by deposition of calcium oxalate crystals within synovial fluid. This condition typically occurs in patients with underlying primary or secondary hyperoxaluria. Primary hyperoxaluria constitutes a group of genetic disorders resulting in endogenous overproduction of oxalate, whereas secondary hyperoxaluria results from gastrointestinal disorders associated with fat malabsorption and increased absorption of dietary oxalate. In both conditions oxalate crystals can deposit in the kidney leading to renal failure. Since oxalate is primarily renally eliminated, it accumulates throughout the body in renal failure, a state termed oxalosis. Affected organs can include bones, joints, heart, eyes and skin. Since patients can present with renal failure and oxalosis before the underlying diagnosis of hyperoxaluria has been made, it is important to consider hyperoxaluria in patients who present with unexplained soft tissue crystal deposition. The best treatment of oxalosis is prevention. If patients present with advanced disease, treatment of oxalate arthritis consists of symptom management and control of the underlying disease process. PMID:23666469

  16. Interactions of Gas-Phase Nitric/Nitrous Acids and Primary Organic Aerosol in the Atmosphere of Houston, TX

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Griffin, R. J.; Dibb, J. E.; Anderson, C. H.; Whitlow, S. I.; Lefer, B. L.; Flynn, J.; Rappenglück, B.

    2007-12-01

    Concentrations of aerosol and gas-phase pollutants were measured on the roof of an 18-story building during the Texas Air Quality Study II Radical and Aerosol Measurement Project (TRAMP) from August 15 through September 28, 2006. Aerosol measurements included size-resolved, non-refractory mass concentrations of ammonium, nitrate, sulfate, chloride, and organic aerosol in submicron particles using an Aerodyne quadrupole aerosol mass spectrometer (Q-AMS). Particulate water-soluble organic carbon (PWSOC) was quantified using a mist chamber/total organic carbon analysis system. Concentration data for gas-phase pollutants included those for nitric acid (HNO3), nitrous acid (HONO), and hydrochloric acid (HCl) collected using a mist chamber/ion chromatographic technique, oxides of nitrogen (NOx) collected using a chemiluminescent method, and carbon monoxide (CO) collected using an infrared gas correlation wheel instrument. Coincident increases in nitrate and organic aerosol mass concentrations were observed on many occasions throughout the measurement campaign, most frequently during the morning rush hour. Based on the lack of organic aerosol processing (defined by the ratio of m/z = 44/57 in the Q-AMS spectra), strong correlation with NOx and CO, and a lack of significant increase in PWSOC concentration, the spikes in organic aerosol were likely associated with primary organic aerosol (POA). During these events, gas-phase HNO3 concentration decreases were observed simultaneously with increases in gas-phase HONO concentrations. These data likely indicate uptake of HNO3 and subsequent heterogeneous conversion to HONO involving POA. Preliminary calculations show that HNO3 partitioning could account for the majority of the observed HONO and aerosol nitrate concentrations during these events. Q-AMS chloride and HCl data also indicate uptake of chloride by particles during these events. This phenomenon was also observed during the night, but these nocturnal events were less

  17. Isoprene Epoxydiols as Precursors to Secondary Organic Aerosol Formation: Acid-Catalyzed Reactive Uptake Studies with Authentic Compounds

    PubMed Central

    Lin, Ying-Hsuan; Zhang, Zhenfa; Docherty, Kenneth S.; Zhang, Haofei; Budisulistiorini, Sri Hapsari; Rubitschun, Caitlin L.; Shaw, Stephanie L.; Knipping, Eladio M.; Edgerton, Eric S.; Kleindienst, Tadeusz E.; Gold, Avram; Surratt, Jason D.

    2011-01-01

    Isoprene epoxydiols (IEPOX), formed from the photooxidation of isoprene under low-NOx conditions, have recently been proposed as precursors of secondary organic aerosol (SOA) on the basis of mass spectrometric evidence. In the present study, IEPOX isomers were synthesized in high purity (> 99%) to investigate their potential to form SOA via reactive uptake in a series of controlled dark chamber studies followed by reaction product analyses. IEPOX-derived SOA was substantially observed only in the presence of acidic aerosols, with conservative lower-bound yields of 4.7–6.4% for β-IEPOX and 3.4–5.5% for δ-IEPOX, providing direct evidence for IEPOX isomers as precursors to isoprene SOA. These chamber studies demonstrate that IEPOX uptake explains the formation of known isoprene SOA tracers found in ambient aerosols, including 2-methyltetrols, C5-alkene triols, dimers, and IEPOX-derived organosulfates. Additionally, we show reactive uptake on the acidified sulfate aerosols supports a previously unreported acid-catalyzed intramolecular rearrangement of IEPOX to cis- and trans-3-methyltetrahydrofuran-3,4-diols (3-MeTHF-3,4-diols) in the particle phase. Analysis of these novel tracer compounds by aerosol mass spectrometry (AMS) suggests that they contribute to a unique factor resolved from positive matrix factorization (PMF) of AMS organic aerosol spectra collected from low-NOx, isoprene-dominated regions influenced by the presence of acidic aerosols. PMID:22103348

  18. Plant and Soil Emissions of Amines and Amino Acids: A Source of Secondary Aerosol Precursors

    NASA Astrophysics Data System (ADS)

    Jackson, M. L.; Doskey, P. V.; Pypker, T. G.

    2011-12-01

    Ammonia (NH3) is the most abundant alkaline gas in the atmosphere and forms secondary aerosol by neutralizing sulfuric and nitric acids that are released during combustion of fossil fuels. Ammonia is primarily emitted by cropping and livestock operations. However, C2 and C3 amines (pKb 3.3-3.4), which are stronger bases than NH3 (pKb 4.7) have been observed in nuclei mode aerosol that is the precursor to secondary aerosol. Mixtures of amines and amino acids have been identified in diverse environments in aerosol, fog water, cloud water, the soluble fraction of precipitation, and in dew. Glycine (pKb 4.2), serine (pKb 4.8) and alanine (pKb 3.7 and 4.1 for the D and L forms, respectively) are typically the most abundant species. The only reported values of gas-phase glycine, serine and alanine were in marine air and ranged from 6-14 pptv. The origin of atmospheric amines and amino acids has not been fully identified, although sources are likely similar to NH3. Nitrate assimilation in plants forms glycine, serine, and L-alanine, while D-alanine is present in bacterial cell walls. Glycine is converted to serine during C3 plant photorespiration, producing CO2 and NH3. Bacteria metabolize glycine and alanine to methylamine and ethylamine via decarboxylation. Likely sources of amino acids are plants and bacteria, thus concentrations near continental sources are likely greater than those measured in marine air. The overall goal of the research is to examine seasonal variations and relationships between the exchange of CO2, NH3, amines, and amino acids with a corn/soybean rotation in the Midwest Corn Belt. The study presents gaseous profiles of organic amine compounds from various species of vegetation using a mist chamber trapping technique and analysis of the derivatized species by high pressure liquid chromatography with fluorescence detection. Amino acid and amine profiles were obtained for red oak (Quercus rubra), sugar maple (Acer saccharinum), white pine (Pinus

  19. Secondary organic aerosol-forming reactions of glyoxal with amino acids.

    PubMed

    De Haan, David O; Corrigan, Ashley L; Smith, Kyle W; Stroik, Daniel R; Turley, Jacob J; Lee, Frances E; Tolbert, Margaret A; Jimenez, Jose L; Cordova, Kyle E; Ferrell, Grant R

    2009-04-15

    Glyoxal, the simplest and most abundant alpha-dicarbonyl compound in the atmosphere, is scavenged by clouds and aerosol, where it reacts with nucleophiles to form low-volatility products. Here we examine the reactions of glyoxal with five amino acids common in clouds. When glyoxal and glycine, serine, aspartic acid or ornithine are present at concentrations as low as 30/microM in evaporating aqueous droplets or bulk solutions, 1,3-disubstituted imidazoles are formed in irreversible second-order reactions detected by nuclear magnetic resonance (NMR), aerosol mass spectrometry (AMS) and electrospray ionization mass spectrometry (ESI-MS). In contrast, glyoxal reacts with arginine preferentially at side chain amino groups, forming nonaromatic five-membered rings. All reactions were accompanied by browning. The uptake of 45 ppb glyoxal by solid-phase glycine aerosol at 50% RH was also studied and found to cause particle growth and the production of imidazole measured by scanning mobility particle sizing and AMS, respectively, with a glyoxal uptake coefficient alpha = 0.0004. Comparison of reaction kinetics in bulk and in drying droplets shows that conversion of glyoxal dihydrate to monohydrate accelerates the reaction by over 3 orders of magnitude, allowing these reactions to occur at atmospheric conditions.

  20. Secondary organic aerosol-forming reactions of glyoxal with amino acids.

    PubMed

    De Haan, David O; Corrigan, Ashley L; Smith, Kyle W; Stroik, Daniel R; Turley, Jacob J; Lee, Frances E; Tolbert, Margaret A; Jimenez, Jose L; Cordova, Kyle E; Ferrell, Grant R

    2009-04-15

    Glyoxal, the simplest and most abundant alpha-dicarbonyl compound in the atmosphere, is scavenged by clouds and aerosol, where it reacts with nucleophiles to form low-volatility products. Here we examine the reactions of glyoxal with five amino acids common in clouds. When glyoxal and glycine, serine, aspartic acid or ornithine are present at concentrations as low as 30/microM in evaporating aqueous droplets or bulk solutions, 1,3-disubstituted imidazoles are formed in irreversible second-order reactions detected by nuclear magnetic resonance (NMR), aerosol mass spectrometry (AMS) and electrospray ionization mass spectrometry (ESI-MS). In contrast, glyoxal reacts with arginine preferentially at side chain amino groups, forming nonaromatic five-membered rings. All reactions were accompanied by browning. The uptake of 45 ppb glyoxal by solid-phase glycine aerosol at 50% RH was also studied and found to cause particle growth and the production of imidazole measured by scanning mobility particle sizing and AMS, respectively, with a glyoxal uptake coefficient alpha = 0.0004. Comparison of reaction kinetics in bulk and in drying droplets shows that conversion of glyoxal dihydrate to monohydrate accelerates the reaction by over 3 orders of magnitude, allowing these reactions to occur at atmospheric conditions. PMID:19475956

  1. Complex refractive indices in the infrared of nitric acid trihydrate aerosols

    SciTech Connect

    Richwine, L.J.; Clapp, M.L.; Miller, R.E.

    1995-10-01

    The refractive indices of nitric acid trihydrate (NAT) have been determined from the infrared spectra of laboratory generated aerosols. The aerosols are formed via homogeneous nucleation in a flow cell with separate regions for nucleation and observation, allowing for independent control of the temperature conditions in these regions. A spectrum of small, non-scattering particles is recorded to determine the frequency dependent imaginary refractive index, within a scaling factor. A subtractive Kramers-Kronig routine is then used to calculate the real index. The scaling factor for the imaginary indices is determined by fitting a spectrum associated with larger, scattering particles, which depends on both the real and imaginary portions of the refractive indices. The complex refractive indices of NAT are reported over the range 700 cm{sup -1} to 4000 cm{sup -1}. While in good qualitative agreement with previously reported results, there are significant quantitative differences which are discussed. 21 refs., 3 figs.

  2. Photochemistry of Glyoxal in Wet Aerosols: Smog Chamber Study

    NASA Astrophysics Data System (ADS)

    Lim, Y. B.; Kim, H.; Turpin, B. J.

    2015-12-01

    Aqueous chemistry is an important pathway for the formation of secondary organic aerosol (SOA). Reaction vessel studies provide evidence that in the aqueous phase photooxidation of water soluble organic compounds (e.g., glyoxal, methylglyoxal) form multifunctional organic products and oligomers. In this work, we extend this bulk-phase chemistry to the condensed-phase chemistry that occurs in/on aerosols by conducting smog chamber experiments — photooxidation of ammonium sulfate and sulfuric acid aerosols containing glyoxal and hydrogen peroxide in the presence of NOx under dry/humid conditions. Particles were analyzed using ultra performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). In the irradiated chamber, photooxidation products of glyoxal as seen in reaction vessel experiments (e.g., oxalic acids and tartaric acids) were also formed in both ammonium sulfate aerosols and sulfuric acid aerosols at humid and even dry conditions. However, the major products were organosulfurs (CHOS), organonitrogens (CHON), and nitrooxy-organosulfates (CHONS), which were also dominantly formed in the dark chamber. These products were formed via non-radical reactions, which depend on acidity and humidity. However, the real-time profiles in the dark chamber and the irradiated chamber were very different, suggesting photochemistry substantially affects non-radical formation in the condensed phase.

  3. Measurement of acidic aerosol species in eastern Europe: implications for air pollution epidemiology.

    PubMed Central

    Brauer, M; Dumyahn, T S; Spengler, J D; Gutschmidt, K; Heinrich, J; Wichmann, H E

    1995-01-01

    A large number of studies have indicated associations between particulate air pollution and adverse health outcomes. Wintertime air pollution in particular has been associated with increased mortality. Identification of causal constituents of inhalable particulate matter has been elusive, although one candidate has been the acidity of the aerosol. Here we report measurements of acidic aerosol species made for approximately 1.5 years in Erfurt, Germany, and Sokolov, Czech Republic. In both locations, the burning of high-sulfur coal is the primary source of ambient air pollution. Twenty-four-hour average measurements were made for PM10, [particulate matter with an aerodynamic diameter (da) < or = 10 microns], as well as fine particle (da < 2.5 microns) H+ and SO4(2-) for the entire study. Additionally, separate day and night measurements of fine particle H+, SO4(2-), NO3-, and NH4+ and the gases, SO2, HNO3, HONO, and NH3 were collected with an annular denuder/filter pack system over a 7-month (late winter-summer) period with additional measurements during pollution episodes the following winter. At both sites, 24-hr SO2 (mean concentrations of 52 micrograms/m3, with peak levels of > 585 micrograms/m3) and PM10 (mean concentration 60 micrograms m3) concentrations were quite high. However, aerosol SO4(2-) concentrations (mean concentration of approximately 10 micrograms/m3) were not as great as expected given the high SO2 concentrations, and acidity was very low (mean concentration of < 1 microgram/m3, with peak levels of only 7 micrograms/m3). Low acidity is likely to be the result of NH3 neutralization and slow conversion of SO2 to SO4(2-).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7656878

  4. Controlled exposures of volunteers to respirable carbon and sulfuric acid aerosols

    SciTech Connect

    Anderson, K.R.; Avol, E.L.; Edwards, S.A.; Shamoo, D.A.; Ruchuan Peng; Linn, W.S.; Hackney, J.D. )

    1992-06-01

    Respirable carbon or fly ash particles are suspected to increase the respiratory toxicity of coexisting acidic air pollutants, by concentrating acid on their surfaces and so delivering it efficiently to the lower respiratory tract. To investigate this issue, the authors exposed 15 healthy and 15 asthmatic volunteers in a controlled-environment chamber to four test atmospheres: (1) clean air; (2) 0.5-{mu}m H{sub 2}SO{sub 4} aerosol at {approx}100 {mu}g/m{sup 3}, generated from water solution; (3) 0.5-{mu}m carbon aerosol at {approx}250 {mu}g/m{sup 3}, generated from highly pure carbon black with specific surface area comparable to ambient pollution particles; and (4) carbon as in (3) plus {approx}100 {mu}g/m{sup 3} of ultrafine H{sub 2}SO{sub 4} aerosol generated from fuming sulfuric acid. Electron microscopy showed that nearly all acid in (4) became attached to carbon particle surfaces, and that most particles remained in the sub-{mu}m size range. Exposures were performed double-blind, 1 week apart. They lasted 1 hr each, with alternate 10-min periods of heavy exercise (ventilation {approx}50 L/min) and rest. Subjects gargled citrus juice before exposure to suppress airway ammonia. Lung function and symptoms were measured pre-exposure, after initial exercise, and at end-exposure. Bronchial reactivity to methacholine was measured after exposure. Statistical analyses tested for effects of H{sub 2}SO{sub 4} or carbon, separate or interactive, on health measures.

  5. Medical therapy, calcium oxalate urolithiasis

    NASA Technical Reports Server (NTRS)

    Ruml, L. A.; Pearle, M. S.; Pak, C. Y.

    1997-01-01

    The development of diagnostic protocols that identify specific risk factors for calcium oxalate nephrolithiasis has led to the formulation of directed medical regimens that are aimed at correcting the underlying metabolic disturbances. Initiation of these treatment programs has reduced markedly the rate of stone formation in the majority of patients who form stones. This article discusses the rationale that underlies the choice of medical therapy for the various pathophysiologic causes of calcium oxalate nephrolithiasis and the appropriate use of available medications.

  6. Trans-hemispheric contribution of C2-C10 α, ω-dicarboxylic acids, and related polar compounds to water-soluble organic carbon in the western Pacific aerosols in relation to photochemical oxidation reactions

    NASA Astrophysics Data System (ADS)

    SempéRé, Richard; Kawamura, Kimitaka

    2003-06-01

    Marine aerosol samples were collected during a western Pacific cruise covering the latitude range between 35°N and 40°S (140°E-180°E). They were analyzed for total carbon (TC), total nitrogen (TN), water-soluble organic carbon (WSOC) along with the molecular distributions of C2-C10 α, ω-dicarboxylic acids, and related polar compounds, mainly, ω-oxocarboxylic acids (C2-C9) and α-dicarbonyls (C2-C3). Oxalic acid (C2) was the most abundant followed by malonic (C3) and succinic (C4) acids. The total diacid concentration range was 7-605 ng m-3 (av. 85 ng m-3) and the diacid-carbon accounted for 2-15% (average 8%) of WSOC which comprised 29-55% (average 40%) of TC. Dry depositions of total diacids over the northern and southern Pacific Ocean were estimated to be 256-1907 μg m-2 yr-1 (average 735; n = 4) and 22-396 μg m-2 yr-1 (average 134; n = 14), respectively, whereas the air-to-sea flux of oxalic acid was 18-1351 μg m-2 yr-1 (average 466 μg m-2 yr-1) and 7.5-275 μg m-2 yr-1 (average 75 μg m-2 yr-1) in the Northern and Southern Hemispheres. We observed that the concentration ratios of diacid-C/WSOC, azelaic acid (C9)/ω-oxononanoic acid, maleic acid (iC4cis)/fumaric (iC4trans) acid and succinic acid (C4)/total diacids were correlated with air temperature. These findings showed that the intensity of photochemical oxidation reactions and thus the variation in sunlight intensity characterized here by air temperature, significantly control the molecular distribution of water-soluble organic compounds during the long-range transport of anthropogenic and/or biogenic higher molecular weight organic compounds.

  7. Heterogeneous OH Oxidation of Two Structure Isomers of Dimethylsuccinic Acid Aerosol: Reactivity and Oxidation Products

    NASA Astrophysics Data System (ADS)

    Chan, M. N.; Cheng, C. T.; Wilson, K. R.

    2014-12-01

    Organic aerosol contribute a significant mass fraction of ambient aerosol carbon and can continuously undergo oxidation by colliding with gas phase OH radicals. Although heterogeneous oxidation plays a significant role in the chemical transformation of organic aerosol, the effect of molecular structure on the reactivity and oxidation products remains unclear. We investigate the effect of branched methyl groups on the reactivity of two dimethylsuccinic acids (2,2-dimethylsuccinic acid (2,2-DMSA) and 2,3-dimethylsuccinic acid (2,3-DMSA)) toward gas phase OH radicals in an atmospheric pressure aerosol flow tube reactor. The oxidation products formed upon oxidation is characterized in real time by the Direct Analysis in Real Time (DART), an ambient soft ionization source. The 2,2-DMSA and 2,3-DMSA are structural isomers with the same oxidation state (OSC = -0.33) and carbon number (NC = 6), but different branching characteristics (2,2-DMSA has one secondary carbon and 2,3-DMSA has two tertiary carbons). The difference in molecular distribution of oxidation products observed in these two structural isomers would allow one to assess the sensitivity of kinetics and chemistry to the position of branched methyl group in the DMSA upon oxidation. We observe that the reactivity of 2,3-DMSA toward OH radicals is about 2 times faster than that of 2,2-DMSA. This difference in OH reactivity may attribute to the stability of the carbon-centered radical generated after hydrogen abstraction because an alkyl radical formed from the hydrogen abstraction on a tertiary carbon in 2,3-DMSA is more stable than on a secondary carbon in 2,2-DMSA. For both 2,2-DMSA and 2,3-DMSA, the molecular distribution and evolution of oxidation products is characterized by a predominance of functionalization products at the early oxidation stages. When the oxidation further proceeds, the fragmentation becomes more favorable and the oxidation mainly leads to the reduction of the carbon chain length through

  8. Mechanistic study of secondary organic aerosol components formed from nucleophilic addition reactions of methacrylic acid epoxide

    NASA Astrophysics Data System (ADS)

    Birdsall, A. W.; Miner, C. R.; Mael, L. E.; Elrod, M. J.

    2014-08-01

    Recently, methacrylic acid epoxide (MAE) has been proposed as a precursor to an important class of isoprene-derived compounds found in secondary organic aerosol (SOA): 2-methylglyceric acid (2-MG) and a set of oligomers, nitric acid esters and sulfuric acid esters related to 2-MG. However, the specific chemical mechanisms by which MAE could form these compounds have not been previously studied. In order to determine the relevance of these processes to atmospheric aerosol, MAE and 2-MG have been synthesized and a series of bulk solution-phase experiments aimed at studying the reactivity of MAE using nuclear magnetic resonance (NMR) spectroscopy have been performed. The present results indicate that the acid-catalyzed MAE reaction is more than 600 times slower than a similar reaction of an important isoprene-derived epoxide, but is still expected to be kinetically feasible in the atmosphere on more acidic SOA. The specific mechanism by which MAE leads to oligomers was identified, and the reactions of MAE with a number of atmospherically relevant nucleophiles were also investigated. Because the nucleophilic strengths of water, sulfate, alcohols (including 2-MG), and acids (including MAE and 2-MG) in their reactions with MAE were found to be of a similar magnitude, it is expected that a diverse variety of MAE + nucleophile product species may be formed on ambient SOA. Thus, the results indicate that epoxide chain reaction oligomerization will be limited by the presence of high concentrations of non-epoxide nucleophiles (such as water); this finding is consistent with previous environmental chamber investigations of the relative humidity-dependence of 2-MG-derived oligomerization processes and suggests that extensive oligomerization may not be likely on ambient SOA because of other competitive MAE reaction mechanisms.

  9. Mechanistic study of secondary organic aerosol components formed from nucleophilic addition reactions of methacrylic acid epoxide

    NASA Astrophysics Data System (ADS)

    Birdsall, A. W.; Miner, C. R.; Mael, L. E.; Elrod, M. J.

    2014-12-01

    Recently, methacrylic acid epoxide (MAE) has been proposed as a precursor to an important class of isoprene-derived compounds found in secondary organic aerosol (SOA): 2-methylglyceric acid (2-MG) and a set of oligomers, nitric acid esters, and sulfuric acid esters related to 2-MG. However, the specific chemical mechanisms by which MAE could form these compounds have not been previously studied with experimental methods. In order to determine the relevance of these processes to atmospheric aerosol, MAE and 2-MG have been synthesized and a series of bulk solution-phase experiments aimed at studying the reactivity of MAE using nuclear magnetic resonance (NMR) spectroscopy have been performed. The present results indicate that the acid-catalyzed MAE reaction is more than 600 times slower than a similar reaction of an important isoprene-derived epoxide, but is still expected to be kinetically feasible in the atmosphere on more acidic SOA. The specific mechanism by which MAE leads to oligomers was identified, and the reactions of MAE with a number of atmospherically relevant nucleophiles were also investigated. Because the nucleophilic strengths of water, sulfate, alcohols (including 2-MG), and acids (including MAE and 2-MG) in their reactions with MAE were found to be of similar magnitudes, it is expected that a diverse variety of MAE + nucleophile product species may be formed on ambient SOA. Thus, the results indicate that epoxide chain reaction oligomerization will be limited by the presence of high concentrations of non-epoxide nucleophiles (such as water); this finding is consistent with previous environmental chamber investigations of the relative humidity dependence of 2-MG-derived oligomerization processes and suggests that extensive oligomerization may not be likely on ambient SOA because of other competitive MAE reaction mechanisms.

  10. Method for characterization of low molecular weight organic acids in atmospheric aerosols using ion chromatography mass spectrometry.

    PubMed

    Brent, Lacey C; Reiner, Jessica L; Dickerson, Russell R; Sander, Lane C

    2014-08-01

    The structural composition of PM2.5 monitored in the atmosphere is usually divided by the analysis of organic carbon, black (also called elemental) carbon, and inorganic salts. The characterization of the chemical composition of aerosols represents a significant challenge to analysts, and studies are frequently limited to determination of aerosol bulk properties. To better understand the potential health effects and combined interactions of components in aerosols, a variety of measurement techniques for individual analytes in PM2.5 need to be implemented. The method developed here for the measurement of organic acids achieves class separation of aliphatic monoacids, aliphatic diacids, aromatic acids, and polyacids. The selective ion monitoring capability of a triple quadropole mass analyzer was frequently capable of overcoming instances of incomplete separations. Standard Reference Material (SRM) 1649b Urban Dust was characterized; 34 organic acids were qualitatively identified, and 6 organic acids were quantified.

  11. Contribution of calcium oxalate to soil-exchangeable calcium

    USGS Publications Warehouse

    Dauer, Jenny M.; Perakis, Steven S.

    2013-01-01

    Acid deposition and repeated biomass harvest have decreased soil calcium (Ca) availability in many temperate forests worldwide, yet existing methods for assessing available soil Ca do not fully characterize soil Ca forms. To account for discrepancies in ecosystem Ca budgets, it has been hypothesized that the highly insoluble biomineral Ca oxalate might represent an additional soil Ca pool that is not detected in standard measures of soil-exchangeable Ca. We asked whether several standard method extractants for soil-exchangeable Ca could also access Ca held in Ca oxalate crystals using spike recovery tests in both pure solutions and soil extractions. In solutions of the extractants ammonium chloride, ammonium acetate, and barium chloride, we observed 2% to 104% dissolution of Ca oxalate crystals, with dissolution increasing with both solution molarity and ionic potential of cation extractant. In spike recovery tests using a low-Ca soil, we estimate that 1 M ammonium acetate extraction dissolved sufficient Ca oxalate to contribute an additional 52% to standard measurements of soil-exchangeable Ca. However, in a high-Ca soil, the amount of Ca oxalate spike that would dissolve in 1 M ammonium acetate extraction was difficult to detect against the large pool of exchangeable Ca. We conclude that Ca oxalate can contribute substantially to standard estimates of soil-exchangeable Ca in acid forest soils with low soil-exchangeable Ca. Consequently, measures of exchangeable Ca are unlikely to fully resolve discrepancies in ecosystem Ca mass balance unless the contribution of Ca oxalate to exchangeable Ca is also assessed.

  12. An oxalyl-CoA synthetase is important for oxalate metabolism in Saccharomyces cerevisiae

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although oxalic acid is common in nature, our understanding of the mechanism(s) regulating its turnover remains incomplete. In this study we identify Saccharomyces cerevisiae acyl-activating enzyme 3 (ScAAE3) as an enzyme capable of catalyzing the conversion of oxalate to oxalyl-CoA. Based on our fi...

  13. Deep catalytic oxidative desulfurization (ODS) of dibenzothiophene (DBT) with oxalate-based deep eutectic solvents (DESs).

    PubMed

    Lü, Hongying; Li, Pengcheng; Deng, Changliang; Ren, Wanzhong; Wang, Shunan; Liu, Pan; Zhang, Han

    2015-07-01

    An oxalate-based DES with a tetrabutyl ammonium chloride and oxalate acid molar ratio of 1/2 (TBO1 : 2) exhibited high activity in oxidative desulfurization (ODS) of dibenzothiophene (DBT) under mild reaction conditions. It is potentially a promising and highly environmentally friendly approach for desulfurization of fuels. PMID:26051675

  14. Impacts of Sulfate Seed Acidity and Water Content on Isoprene Secondary Organic Aerosol Formation.

    PubMed

    Wong, Jenny P S; Lee, Alex K Y; Abbatt, Jonathan P D

    2015-11-17

    The effects of particle-phase water and the acidity of pre-existing sulfate seed particles on the formation of isoprene secondary organic aerosol (SOA) was investigated. SOA was generated from the photo-oxidation of isoprene in a flow tube reactor at 70% relative humidity (RH) and room temperature in the presence of three different sulfate seeds (effloresced and deliquesced ammonium sulfate and ammonium bisulfate) under low NOx conditions. High OH exposure conditions lead to little isoprene epoxydiol (IEPOX) SOA being generated. The primary result is that particle-phase water had the largest effect on the amount of SOA formed, with 60% more SOA formation occurring with deliquesced ammonium sulfate seeds as compared to that on effloresced ones. The additional organic material was highly oxidized. Although the amount of SOA formed did not exhibit a dependence on the range of seed particle acidity examined, perhaps because of the low amount of IEPOX SOA, the levels of high-molecular-weight material increased with acidity. While the uptake of organics was partially reversible under drying, the results nevertheless indicate that particle-phase water enhanced the amount of organic aerosol material formed and that the RH cycling of sulfate particles may mediate the extent of isoprene SOA formation in the atmosphere. PMID:26460477

  15. Aldol Condensation Products and Polyacetals in Organic Films Formed from Reactions of Propanal in Sulfuric Acid at Upper Troposphere/Lower Stratosphere (UT/LS) Aerosol Acidities

    NASA Astrophysics Data System (ADS)

    Bui, J. V. H.; Perez-Montano, S.; Li, E. S. W.; Nelson, T. E.; Ha, K. T.; Leong, L.; Iraci, L. T.; Van Wyngarden, A. L.

    2015-12-01

    Aerosols in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt. %) which is highly reflective towards UV and visible radiation. However, airborne measurements have shown that these particles may also contain a significant amount of organic material. Experiments combining organics (propanal, glyoxal and/or methylglyoxal) with sulfuric acid at concentrations typical of UT/LS aerosols produced highly colored surface films (and solutions) that have the potential to impact chemical, optical and/or cloud-forming properties of aerosols. In order to assess the potential for such films to impact aerosol chemistry or climate properties, experiments were performed to identify the chemical processes responsible for film formation. Surface films were analyzed via Attenuated Total Reflectance-FTIR and Nuclear Magnetic Resonance spectroscopies and are shown to consist primarily of aldol condensation products and cyclic and linear polyacetals, the latter of which are likely responsible for separation from the aqueous phase.

  16. Ammonium addition (and aerosol pH) has a dramatic impact on the volatility and yield of glyoxal secondary organic aerosol.

    PubMed

    Ortiz-Montalvo, Diana L; Häkkinen, Silja A K; Schwier, Allison N; Lim, Yong B; McNeill, V Faye; Turpin, Barbara J

    2014-01-01

    Glyoxal is an important precursor to secondary organic aerosol (SOA) formed through aqueous chemistry in clouds, fogs, and wet aerosols, yet the gas-particle partitioning of the resulting mixture is not well understood. This work characterizes the volatility behavior of the glyoxal precursor/product mix formed after aqueous hydroxyl radical oxidation and droplet evaporation under cloud-relevant conditions for 10 min, thus aiding the prediction of SOA via this pathway (SOACld). This work uses kinetic modeling for droplet composition, droplet evaporation experiments and temperature-programmed desorption aerosol-chemical ionization mass spectrometer analysis of gas-particle partitioning. An effective vapor pressure (p'L,eff) of ∼10(-7) atm and an enthalpy of vaporization (ΔHvap,eff) of ∼70 kJ/mol were estimated for this mixture. These estimates are similar to those of oxalic acid, which is a major product. Addition of ammonium until the pH reached 7 (with ammonium hydroxide) reduced the p'L,eff to <10(-9) atm and increased the ΔHvap,eff to >80 kJ/mol, at least in part via the formation of ammonium oxalate. pH 7 samples behaved like ammonium oxalate, which has a vapor pressure of ∼10(-11) atm. We conclude that ammonium addition has a large effect on the gas-particle partitioning of the mixture, substantially enhancing the yield of SOACld from glyoxal. PMID:24328102

  17. Ammonium addition (and aerosol pH) has a dramatic impact on the volatility and yield of glyoxal secondary organic aerosol.

    PubMed

    Ortiz-Montalvo, Diana L; Häkkinen, Silja A K; Schwier, Allison N; Lim, Yong B; McNeill, V Faye; Turpin, Barbara J

    2014-01-01

    Glyoxal is an important precursor to secondary organic aerosol (SOA) formed through aqueous chemistry in clouds, fogs, and wet aerosols, yet the gas-particle partitioning of the resulting mixture is not well understood. This work characterizes the volatility behavior of the glyoxal precursor/product mix formed after aqueous hydroxyl radical oxidation and droplet evaporation under cloud-relevant conditions for 10 min, thus aiding the prediction of SOA via this pathway (SOACld). This work uses kinetic modeling for droplet composition, droplet evaporation experiments and temperature-programmed desorption aerosol-chemical ionization mass spectrometer analysis of gas-particle partitioning. An effective vapor pressure (p'L,eff) of ∼10(-7) atm and an enthalpy of vaporization (ΔHvap,eff) of ∼70 kJ/mol were estimated for this mixture. These estimates are similar to those of oxalic acid, which is a major product. Addition of ammonium until the pH reached 7 (with ammonium hydroxide) reduced the p'L,eff to <10(-9) atm and increased the ΔHvap,eff to >80 kJ/mol, at least in part via the formation of ammonium oxalate. pH 7 samples behaved like ammonium oxalate, which has a vapor pressure of ∼10(-11) atm. We conclude that ammonium addition has a large effect on the gas-particle partitioning of the mixture, substantially enhancing the yield of SOACld from glyoxal.

  18. Reflectance spectroscopy of oxalate minerals and relevance to Solar System carbon inventories

    NASA Astrophysics Data System (ADS)

    Applin, Daniel M.; Izawa, Matthew R. M.; Cloutis, Edward A.

    2016-11-01

    The diversity of oxalate formation mechanisms suggests that significant concentrations of oxalic acid and oxalate minerals could be widely distributed in the Solar System. We have carried out a systematic study of the reflectance spectra of oxalate minerals and oxalic acid, covering the 0.2-16 μm wavelength region. Our analyses show that oxalates exhibit unique spectral features that enable discrimination between oxalate phases and from other commonly occurring compounds, including carbonates, in all regions of the spectrum except for the visible. Using these spectral data, we consider the possible contribution of oxalate minerals to previously observed reflectance spectra of many objects throughout the Solar System, including satellites, comets, and asteroids. We find that polycarboxylic acid dimers and their salts may explain the reflectance spectra of many carbonaceous asteroids in the 3 μm spectral region. We suggest surface concentration of these compounds may be a type of space weathering from the photochemical and oxidative decomposition of the organic macromolecular material found in carbonaceous chondrites. The stability and ubiquity of these minerals on Earth, in extraterrestrial materials, and in association with biological processes make them useful for many applications in Earth and planetary sciences.

  19. Enhanced histamine release from lung mast cells of guinea pigs exposed to sulfuric acid aerosols

    SciTech Connect

    Fujimaki, Hidekazu ); Katayama, Noboru; Wakamori, Kazuo )

    1992-06-01

    To clarify the relationship between air pollution and mast cell response, the effects of sulfuric acid aerosols on histamine release from lung mast cells of guinea pigs were investigated. Guinea pigs were exposed to 0.3, 1.0 and 3.2 mg/m{sup 3} sulfuric acid (H{sub 2}SO{sub 4}) aerosols or 4 ppm nitrogen dioxide (NO{sub 2}) for 2 and 4 weeks. After the exposure, lung mast cell suspensions were isolated by collagenase treatment and antigen- or A23187-induced histamine release was measured. Antigen-induced histamine release from mast cells was significantly enhanced by the exposure to 1.0 and 3.2 mg/m{sup 3} H{sub 2}SO{sub 4} for 2 weeks, but exposure to H{sub 2}SO{sub 4} for 4 weeks did not show the enhancement of antigen-induced histamine release. A23187-induced histamine release was significantly enhanced by the exposure to 1.0 mg/m{sup 3} H{sub 2}SO{sub 4} or 4 ppm NO{sub 2} for 2 weeks, but suppression of histamine release from lung mast cells stimulated with A23187 was observed by the exposure to 3.2 mg/m{sup 3} H{sub 2}So{sub 4} for 4 weeks. The exposure to 0.3 mg/m{sup 3} H{sub 2}So{sub 4} showed no changes in antigen- and A23187-induced histamine release. The combination of 1.0 mg/m{sup 3} H{sub 2}So{sub 4} with 4 ppm NO{sub 2} for 2 weeks resulted in no changes in antigen- and A23187-induced histamine release. These results suggested that functional properties of lung mast cells may be altered by a low concentration of H{sub 2}So{sub 4} aerosol exposure.

  20. Heterogeneous conversion of NO2 on secondary organic aerosol surfaces: A possible source of nitrous acid (HONO) in the atmosphere?

    NASA Astrophysics Data System (ADS)

    Bröske, R.; Kleffmann, J.; Wiesen, P.

    2003-05-01

    The heterogeneous conversion of NO2 on different secondary organic aerosols (SOA) was investigated with the focus on a possible formation of nitrous acid (HONO). In one set of experiments different organic aerosols were produced in the reactions of O3 with alpha-pinene, limonene or catechol and OH radicals with toluene or limonene, respectively. The aerosols were sampled on filters and exposed to humidified NO2 mixtures under atmospheric conditions. The estimated upper limits for the uptake coefficients of NO2 and the reactive uptake coefficients NO2 -> HONO are in the range of 10-6 and 10-7, respectively. The integrated HONO formation for 1 h reaction time was <1013 cm-2 geometrical surface and <1017 g-1 particle mass. In a second set of experiments the conversion of NO2 into HONO in the presence of organic particles was carried out in an aerosol flow tube under atmospheric conditions. In this case the aerosols were produced in the reaction of O3 with beta-pinene, limonene or catechol, respectively. The upper limits for the reactive uptake coefficients NO2 -> HONO were in the range of 7 x 10-7 - 9 x 10-6. The results from the present study show that heterogeneous formation of nitrous acid on secondary organic aerosols (SOA) is unimportant for the atmosphere.

  1. Heterogeneous conversion of NO2 on secondary organic aerosol surfaces: A possible source of nitrous acid (HONO) in the atmosphere?

    NASA Astrophysics Data System (ADS)

    Bröske, R.; Kleffmann, J.; Wiesen, P.

    2003-02-01

    The heterogeneous conversion of NO2 on different secondary organic aerosols (SOA) was investigated with the focus on a possible formation of nitrous acid (HONO). In one set of experiments different organic aerosols were produced in the reactions of O3 with α-pinene, limonene or catechol and OH radicals with toluene or limonene, respectively. The aerosols were sampled on filters and exposed to humidified NO2 mixtures under atmospheric conditions. The estimated upper limits for the uptake coefficients of NO2 and the reactive uptake coefficients NO2 →HONO are in the range of 10-6 and 10-7, respectively. The integrated HONO formation for 1 h reaction time was <1013 cm-2 geometrical surface and <1017 g-1 particle mass. In a second set of experiments the conversion of NO2 into HONO in the presence of organic particles was carried out in an aerosol flow tube under atmospheric conditions. In this case the aerosols were produced in the reaction of O3 with β-pinene, limonene or catechol, respectively. The upper limits for the reactive uptake coefficients NO2 → HONO were in the range of 7×10-7 -9×10-6. The results from the present study show that heterogeneous formation of nitrous acid on secondary organic aerosols (SOA) is unimportant for the atmosphere.

  2. Reactions Between Water Soluble Organic Acids and Nitrates in Atmospheric Aerosols: Recycling of Nitric Acid and Formation of Organic Salts

    SciTech Connect

    Wang, Bingbing; Laskin, Alexander

    2014-03-25

    Atmospheric particles often include a complex mixture of nitrate and secondary organic materials accumulated within the same individual particles. Nitrate as an important inorganic component can be chemically formed in the atmosphere. For instance, formation of sodium nitrate (NaNO3) and calcium nitrate Ca(NO3)2 when nitrogen oxide and nitric acid (HNO3) species react with sea salt and calcite, respectively. Organic acids contribute a significant fraction of photochemically formed secondary organics that can condense on the preexisting nitrate-containing particles. Here, we present a systematic microanalysis study on chemical composition of laboratory generated particles composed of water soluble organic acids and nitrates (i.e. NaNO3 and Ca(NO3)2) investigated using computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and Fourier transform infrared micro-spectroscopy (micro-FTIR). The results show that water-soluble organic acids can react with nitrates releasing gaseous HNO3 during dehydration process. These reactions are attributed to acid displacement of nitrate with weak organic acids driven by the evaporation of HNO3 into gas phase due to its relatively high volatility. The reactions result in significant nitrate depletion and formation of organic salts in mixed organic acids/nitrate particles that in turn may affect their physical and chemical properties relevant to atmospheric environment and climate. Airborne nitrate concentrations are estimated by thermodynamic calculations corresponding to various nitrate depletions in selected organic acids of atmospheric relevance. The results indicate a potential mechanism of HNO3 recycling, which may further affect concentrations of gas- and aerosol-phase species in the atmosphere and the heterogeneous reaction chemistry between them.

  3. Influence of crustal dust and sea spray supermicron particle concentrations and acidity on inorganic NO3 aerosol during the 2013 Southern Oxidant and Aerosol Study

    SciTech Connect

    Allen, H. M.; Draper, D. C.; Ayres, B. R.; Ault, A.; Bondy, A.; Takahama, S.; Modini, R. L.; Baumann, K.; Edgerton, E.; Knote, C.; Laskin, A.; Wang, B.; Fry, J. L.

    2015-09-25

    Inorganic aerosol composition was measured in the southeastern United States, a region that exhibits high aerosol mass loading during the summer, as part of the 2013 Southern Oxidant and Aerosol Study (SOAS) campaign. Measurements using a Monitor for AeRosols and GAses (MARGA) revealed two periods of high aerosol nitrate (NO3) concentrations during the campaign. These periods of high nitrate were correlated with increased concentrations of supermicron crustal and sea spray aerosol species, particularly Na+ and Ca2+, and with a shift towards aerosol with larger (1 to 2.5 μm) diameters. We suggest this nitrate aerosol forms by multiphase reactions of HNO3 and particles, reactions that are facilitated by transport of crustal dust and sea spray aerosol from a source within the United States. The observed high aerosol acidity prevents the formation of NH4NO3, the inorganic nitrogen species often dominant in fine-mode aerosol at higher pH. In addition, calculation of the rate of the heterogeneous uptake of HNO3 on mineral aerosol supports the conclusion that aerosol NO3 is produced primarily by this process, and is likely limited by the availability of mineral cation-containing aerosol surface area. Modeling of NO3 and HNO3 by thermodynamic equilibrium models (ISORROPIA II and E-AIM) reveals the importance of including mineral cations in the southeastern United States to accurately balance ion species and predict gas–aerosol phase partitioning.

  4. Modeling of growth and evaporation effects on the extinction of 1.0-micron solar radiation traversing stratospheric sulfuric acid aerosols

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Deepak, A.

    1981-01-01

    The effects of growth and evaporation of stratospheric sulfuric acid aerosols on the extinction of solar radiation traversing such an aerosol medium are reported for the case of 1.0-micron solar radiation. Modeling results show that aerosol extinction is not very sensitive to the change of ambient water vapor concentration, but is sensitive to ambient temperature changes, especially at low ambient temperatures and high ambient water vapor concentration. A clarification is given of the effects of initial aerosol size distribution and composition on the change of aerosol extinction due to growth and evaporation processes. It is shown that experiments designed to observe solar radiation extinction of aerosols may also be applied to the determination of observed changes in aerosol optical properties, environmental parameters, or the physical and optical characteristics of sulfate aerosols.

  5. Compound-specific carbon isotope analyses of individual long-chain alkanes and alkanoic acids in Harmattan aerosols

    NASA Astrophysics Data System (ADS)

    Simoneit, Bernd R. T.

    The higher molecular weight n-alkane, n-alkanol and n-alkanoic acid series from higher plant wax are ubiquitous components of aerosol particles in remote areas. The carbon isotopic compositions of individual n-alkanes and n-alkanoic acids have been determined in samples of Harmattan aerosol and composited vegetation wax from Nigeria. The data confirm the terrestrial origin of these compounds and support the distinction among the vegetation sources of C 4 plants (savannah) from C 3 and CAM plants (wet climate, mixed vegetation). The superimposed petroleum components from vehicular emissions in urban areas could not be differentiated from C 3 vegetation by compound-specific isotope analysis.

  6. Halogen-induced organic aerosol (XOA) formation and decarboxylation of carboxylic acids by reactive halogen species - a time-resolved aerosol flow-reactor study

    NASA Astrophysics Data System (ADS)

    Ofner, Johannes; Zetzsch, Cornelius

    2013-04-01

    Reactive halogen species (RHS) are released to the atmosphere from various sources like photo-activated sea-salt aerosol and salt lakes. Recent studies (Cai et al., 2006 and 2008, Ofner et al., 2012) indicate that RHS are able to interact with SOA precursors similarly to common atmospheric oxidizing gases like OH radicals and ozone. The reaction of RHS with SOA precursors like terpenes forms so-called halogen-induced organic aerosol (XOA). On the other hand, RHS are also able to change the composition of functional groups, e.g. to initiate the decarboxylation of carboxylic acids (Ofner et al., 2012). The present study uses a 50 cm aerosol flow-reactor, equipped with a solar simulator to investigate the time-resolved evolution and transformation of vibrational features in the mid-infrared region. The aerosol flow-reactor is coupled to a home-made multi-reflection cell (Ofner et al., 2010), integrated into a Bruker IFS 113v FTIR spectrometer. The reactor is operated with an inlet feed (organic compound) and a surrounding feed (reactive halogen species). The moveable inlet of the flow reactor allows us to vary reaction times between a few seconds and up to about 3 minutes. Saturated vapours of different SOA precursors and carboxylic acids were fed into the flow reactor using the moveable inlet. The surrounding feed inside the flow reactor was a mixture of zero air with molecular chlorine as the precursor for the formation of reactive halogen species. Using this setup, the formation of halogen-induced organic aerosol could be monitored with a high time resolution using FTIR spectroscopy. XOA formation is characterized by hydrogen-atom abstraction, carbon-chlorine bond formation and later, even formation of carboxylic acids. Several changes of the entire structure of the organic precursor, caused by the reaction of RHS, are visible. While XOA formation is a very fast process, the decarboxylation of carboxylic acids, induced by RHS is rather slow. However, XOA formation

  7. Plutonium oxalate precipitation for trace elemental determination in plutonium materials

    DOE PAGES

    Xu, Ning; Gallimore, David; Lujan, Elmer; Garduno, Katherine; Walker, Laurie; Taylor, Fiona; Thompson, Pam; Tandon, Lav

    2015-05-26

    In this study, an analytical chemistry method has been developed that removes the plutonium (Pu) matrix from the dissolved Pu metal or oxide solution prior to the determination of trace impurities that are present in the metal or oxide. In this study, a Pu oxalate approach was employed to separate Pu from trace impurities. After Pu(III) was precipitated with oxalic acid and separated by centrifugation, trace elemental constituents in the supernatant were analyzed by inductively coupled plasma-optical emission spectroscopy with minimized spectral interferences from the sample matrix.

  8. Low-molecular-weight hydroxyacids in marine atmospheric aerosol: evidence of a marine microbial origin

    NASA Astrophysics Data System (ADS)

    Miyazaki, Y.; Sawano, M.; Kawamura, K.

    2014-04-01

    Lactic acid (LA) and glycolic acid (GA), which are low-molecular-weight hydroxyacids, were identified in the particle and gas phases within the marine atmospheric boundary layer over the western subarctic North Pacific. Major portion of LA (81%) and GA (57%) were present in the particulate phase, which is consistent with the presence of a hydroxyl group in these molecules leading to the low volatility of the compounds. The average concentration of LA in more biologically influenced marine aerosols (average 33 ± 58 ng m-3) was substantially higher than that in less biologically influenced aerosols (average 11 ± 12 ng m-3). Over the oceacnic region of phytoplankton blooms, the concentration of aerosol LA was comparable to that of oxalic acid, which was the most abundant diacid during the study period. A positive correlation was found between the LA concentrations in more biologically influenced aerosols and chlorophyll a in seawater (r2 = 0.56), suggesting an important production of aerosol LA possibly associated with microbial (e.g., lactobacillus) activity in seawater and/or aerosols. Our finding provides a new insight into the poorly quantified microbial sources of marine organic aerosols (OA) because such low-molecular-weight hydroxyacids are key intermediates for OA formation.

  9. Low-molecular-weight hydroxyacids in marine atmospheric aerosol: evidence of a marine microbial origin

    NASA Astrophysics Data System (ADS)

    Miyazaki, Y.; Sawano, M.; Kawamura, K.

    2014-08-01

    Lactic acid (LA) and glycolic acid (GA), which are low-molecular-weight hydroxyacids, were identified in the particle and gas phases within the marine atmospheric boundary layer over the western subarctic North Pacific. A major portion of LA (81%) and GA (57%) was present in the particulate phase, which is consistent with the presence of a hydroxyl group in these molecules leading to the low volatility of the compounds. The average concentration (±SD) of LA in more biologically influenced marine aerosols (33 ± 58 ng m-3) was substantially higher than that in less biologically influenced aerosols (11 ± 12 ng m-3). Over the oceanic region of phytoplankton blooms, the concentration of aerosol LA was comparable to that of oxalic acid, which was the most abundant diacid during the study period. A positive correlation was found between the LA concentrations in more biologically influenced aerosols and chlorophyll a in seawater (r2 = 0.56), suggesting an important production of aerosol LA possibly associated with microbial (e.g., lactobacillus) activity in seawater and/or aerosols. Our finding provides a new insight into the poorly quantified microbial sources of marine organic aerosols (OAs) because such low-molecular-weight hydroxyacids are key intermediates for OA formation.

  10. Acidic species and chloride depletion in coarse aerosol particles in the US east coast.

    PubMed

    Zhao, Yunliang; Gao, Yuan

    2008-12-15

    To investigate the interactions of water-soluble acidic species associated with coarse mode aerosol particles (1.8-10 microm) and chlorine depletion, ten sets of size-segregated aerosol samples were collected by a 10-stage Micro-Orifice Uniform Deposit Impactor (MOUDI) in Newark, New Jersey on the U.S. east coast. The samples were grouped into two categories according to the air-mass back trajectories and mass ratios of sodium to magnesium and calcium: Group I was primarily impacted by marine air mass and Group II was dominated by the continental air mass. In Group I, the concentrations of coarse mode nitrate and chloride depletion showed a strong correlation (R2=0.88). Without considering other cations, nitrate was found to account for all of the chloride depletion in coarse particles for most samples. The association of coarse mode nitrate with sea-salt particles is favored when the mass ratio of sodium to calcium is approximately equal to or greater than unity. Excess sulfate accounts for a maximum of 33% of chloride depletion in the coarse particles. Regarding chloride depletion in the different particle sizes, excess nitrate and sulfate account for 89% of the chloride depletion in the particle size range of 1.8-3.2 microm in the sample from July 13-14; all of the determined dicarboxylic acids and mono-carboxylic acids cannot compensate for the rest of the chloride depletion. In Group II, high percentages of chloride depletion were not observed. With nitrate being dominant in chlorine depletion observed at this location, N-containing species from pollution emissions may have profound impact on atmospheric composition through altering chlorine chemistry in this region. PMID:18973925

  11. Oxalate Mass Balance During Chemical Cleaning in Tank 5F

    SciTech Connect

    Poirier, M.; Fink, S.

    2011-07-08

    The Savannah River Site (SRS) is preparing Tank 5F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning to determine whether the tank is ready for closure. SRS personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. Analysis of the anions showed the measured oxalate removed from Tank 5F to be approximately 50% of the amount added in the oxalic acid. To close the oxalate mass balance, the author collected solid samples, leached them with nitric acid, and measured the concentration of cations and anions in the leachate.

  12. 2-Hydroxyterpenylic acid: An oxygenated marker compound for a-pinene secondary organic aerosol in ambient fine aerosol

    EPA Science Inventory

    An oxygenated MW 188 compound is commonly observed in substantial abundance in atmospheric aerosol samples and was proposed in previous studies as an α-pinene-related marker compound that is associated with aging processes. Owing to difficulties in producing this compound in suff...

  13. Heterogeneous chemistry of glyoxal on acidic solutions. An oligomerization pathway for secondary organic aerosol formation.

    PubMed

    Gomez, Mario E; Lin, Yun; Guo, Song; Zhang, Renyi

    2015-05-14

    The heterogeneous chemistry of glyoxal on sulfuric acid surfaces has been investigated at various acid concentrations and temperatures, utilizing a low-pressure fast flow laminar reactor coupled to an ion drift-chemical ionization mass spectrometer (ID-CIMS). The uptake coefficient (γ) of glyoxal ranges from (1.2 ± 0.06) × 10(-2) to (2.5 ± 0.01) × 10(-3) for 60-93 wt % H2SO4 at 253-273 K. The effective Henry's Law constant (H*) ranges from (98.9 ± 4.9) × 10(5) to (1.6 ± 0.1) × 10(5) M atm(-1) for 60-93 wt % at 263-273 K. Both the uptake coefficient and Henry's Law constant increase with decreasing acid concentration and temperature. Our results reveal a reaction mechanism of hydration followed by oligomerization for glyoxal on acidic media, indicating an efficient aqueous reaction of glyoxal on hygroscopic particles leading to secondary organic aerosol formation.

  14. Aerosol Disinfection Capacity of Slightly Acidic Hypochlorous Acid Water Towards Newcastle Disease Virus in the Air: An In Vivo Experiment.

    PubMed

    Hakim, Hakimullah; Thammakarn, Chanathip; Suguro, Atsushi; Ishida, Yuki; Nakajima, Katsuhiro; Kitazawa, Minori; Takehara, Kazuaki

    2015-12-01

    Existence of bioaerosol contaminants in farms and outbreaks of some infectious organisms with the ability of transmission by air increase the need for enhancement of biosecurity, especially for the application of aerosol disinfectants. Here we selected slightly acidic hypochlorous acid water (SAHW) as a candidate and evaluated its virucidal efficacy toward a virus in the air. Three-day-old conventional chicks were challenged with 25 doses of Newcastle disease live vaccine (B1 strain) by spray with nebulizer (particle size <3 μm in diameter), while at the same time reverse osmosis water as the control and SAHW containing 50 or 100 parts per million (ppm) free available chlorine in pH 6 were sprayed on the treated chicks with other nebulizers. Exposed chicks were kept in separated cages in an isolator and observed for clinical signs. Oropharyngeal swab samples were collected from 2 to 5 days postexposure from each chick, and then the samples were titrated with primary chicken kidney cells to detect the virus. Cytopathic effects were observed, and a hemagglutination test was performed to confirm the result at 5 days postinoculation. Clinical signs (sneezing) were recorded, and the virus was isolated from the control and 50 ppm treatment groups, while no clinical signs were observed in and no virus was isolated from the 100 ppm treatment group. The virulent Newcastle disease virus (NDV) strain Sato, too, was immediately inactivated by SAHW containing 50 ppm chlorine in the aqueous phase. These data suggest that SAHW containing 100 ppm chlorine can be used for aerosol disinfection of NDV in farms. PMID:26629621

  15. Aerosol Disinfection Capacity of Slightly Acidic Hypochlorous Acid Water Towards Newcastle Disease Virus in the Air: An In Vivo Experiment.

    PubMed

    Hakim, Hakimullah; Thammakarn, Chanathip; Suguro, Atsushi; Ishida, Yuki; Nakajima, Katsuhiro; Kitazawa, Minori; Takehara, Kazuaki

    2015-12-01

    Existence of bioaerosol contaminants in farms and outbreaks of some infectious organisms with the ability of transmission by air increase the need for enhancement of biosecurity, especially for the application of aerosol disinfectants. Here we selected slightly acidic hypochlorous acid water (SAHW) as a candidate and evaluated its virucidal efficacy toward a virus in the air. Three-day-old conventional chicks were challenged with 25 doses of Newcastle disease live vaccine (B1 strain) by spray with nebulizer (particle size <3 μm in diameter), while at the same time reverse osmosis water as the control and SAHW containing 50 or 100 parts per million (ppm) free available chlorine in pH 6 were sprayed on the treated chicks with other nebulizers. Exposed chicks were kept in separated cages in an isolator and observed for clinical signs. Oropharyngeal swab samples were collected from 2 to 5 days postexposure from each chick, and then the samples were titrated with primary chicken kidney cells to detect the virus. Cytopathic effects were observed, and a hemagglutination test was performed to confirm the result at 5 days postinoculation. Clinical signs (sneezing) were recorded, and the virus was isolated from the control and 50 ppm treatment groups, while no clinical signs were observed in and no virus was isolated from the 100 ppm treatment group. The virulent Newcastle disease virus (NDV) strain Sato, too, was immediately inactivated by SAHW containing 50 ppm chlorine in the aqueous phase. These data suggest that SAHW containing 100 ppm chlorine can be used for aerosol disinfection of NDV in farms.

  16. Effect of Organic Coatings, Humidity and Aerosol Acidity on Multiphase Chemistry of Isoprene Epoxydiols.

    PubMed

    Riva, Matthieu; Bell, David M; Hansen, Anne-Maria Kaldal; Drozd, Greg T; Zhang, Zhenfa; Gold, Avram; Imre, Dan; Surratt, Jason D; Glasius, Marianne; Zelenyuk, Alla

    2016-06-01

    Multiphase chemistry of isomeric isoprene epoxydiols (IEPOX) has been shown to be the dominant source of isoprene-derived secondary organic aerosol (SOA). Recent studies have reported particles composed of ammonium bisulfate (ABS) mixed with model organics exhibit slower rates of IEPOX uptake. In the present study, we investigate the effect of atmospherically relevant organic coatings of α-pinene (AP) SOA on the reactive uptake of trans-β-IEPOX onto ABS particles under different conditions and coating thicknesses. Single particle mass spectrometry was used to characterize in real-time particle size, shape, density, and quantitative composition before and after reaction with IEPOX. We find that IEPOX uptake by pure sulfate particles is a volume-controlled process, which results in particles with uniform concentration of IEPOX-derived SOA across a wide range of sizes. Aerosol acidity was shown to enhance IEPOX-derived SOA formation, consistent with recent studies. The presence of water has a weaker impact on IEPOX-derived SOA yield, but significantly enhanced formation of 2-methyltetrols, consistent with offline filter analysis. In contrast, IEPOX uptake by ABS particles coated with AP-derived SOA is lower compared to that of pure ABS particles, strongly dependent on particle composition, and therefore on particle size. PMID:27176464

  17. Effect of Organic Coatings, Humidity and Aerosol Acidity on Multiphase Chemistry of Isoprene Epoxydiols.

    PubMed

    Riva, Matthieu; Bell, David M; Hansen, Anne-Maria Kaldal; Drozd, Greg T; Zhang, Zhenfa; Gold, Avram; Imre, Dan; Surratt, Jason D; Glasius, Marianne; Zelenyuk, Alla

    2016-06-01

    Multiphase chemistry of isomeric isoprene epoxydiols (IEPOX) has been shown to be the dominant source of isoprene-derived secondary organic aerosol (SOA). Recent studies have reported particles composed of ammonium bisulfate (ABS) mixed with model organics exhibit slower rates of IEPOX uptake. In the present study, we investigate the effect of atmospherically relevant organic coatings of α-pinene (AP) SOA on the reactive uptake of trans-β-IEPOX onto ABS particles under different conditions and coating thicknesses. Single particle mass spectrometry was used to characterize in real-time particle size, shape, density, and quantitative composition before and after reaction with IEPOX. We find that IEPOX uptake by pure sulfate particles is a volume-controlled process, which results in particles with uniform concentration of IEPOX-derived SOA across a wide range of sizes. Aerosol acidity was shown to enhance IEPOX-derived SOA formation, consistent with recent studies. The presence of water has a weaker impact on IEPOX-derived SOA yield, but significantly enhanced formation of 2-methyltetrols, consistent with offline filter analysis. In contrast, IEPOX uptake by ABS particles coated with AP-derived SOA is lower compared to that of pure ABS particles, strongly dependent on particle composition, and therefore on particle size.

  18. Importance of Unimolecular HO2 Elimination in the Heterogeneous OH Reaction of Highly Oxygenated Tartaric Acid Aerosol.

    PubMed

    Cheng, Chiu Tung; Chan, Man Nin; Wilson, Kevin R

    2016-07-28

    Oxygenated organic molecules are abundant in atmospheric aerosols and are transformed by oxidation reactions near the aerosol surface by gas-phase oxidants such as hydroxyl (OH) radicals. To gain better insights into how the structure of an organic molecule, particularly in the presence of hydroxyl groups, controls the heterogeneous reaction mechanisms of oxygenated organic compounds, this study investigates the OH-radical initiated oxidation of aqueous tartaric acid (C4H6O6) droplets using an aerosol flow tube reactor. The molecular composition of the aerosols before and after reaction is characterized by a soft atmospheric pressure ionization source (Direct Analysis in Real Time) coupled with a high-resolution mass spectrometer. The aerosol mass spectra reveal that four major reaction products are formed: a single C4 functionalization product (C4H4O6) and three C3 fragmentation products (C3H4O4, C3H2O4, and C3H2O5). The C4 functionalization product does not appear to originate from peroxy radical self-reactions but instead forms via an α-hydroxylperoxy radical produced by a hydrogen atom abstraction by OH at the tertiary carbon site. The proximity of a hydroxyl group to peroxy group enhances the unimolecular HO2 elimination from the α-hydroxylperoxy intermediate. This alcohol-to-ketone conversion yields 2-hydroxy-3-oxosuccinic acid (C4H4O6), the major reaction product. While in general, C-C bond scission reactions are expected to dominate the chemistry of organic compounds with high average carbon oxidation states (OSC), our results show that molecular structure can play a larger role in the heterogeneous transformation of tartaric acid (OSC = 1.5). These results are also compared with two structurally related dicarboxylic acids (succinic acid and 2,3-dimethylsuccinic acid) to elucidate how the identity and location of functional groups (methyl and hydroxyl groups) alter heterogeneous reaction mechanisms. PMID:27397411

  19. Protection of Metal Artifacts with the Formation of Metal-Oxalates Complexes by Beauveria bassiana.

    PubMed

    Joseph, Edith; Cario, Sylvie; Simon, Anaële; Wörle, Marie; Mazzeo, Rocco; Junier, Pilar; Job, Daniel

    2011-01-01

    Several fungi present high tolerance to toxic metals and some are able to transform metals into metal-oxalate complexes. In this study, the ability of Beauveria bassiana to produce copper oxalates was evaluated. Growth performance was tested on various copper-containing media. B. bassiana proved highly resistant to copper, tolerating concentrations of up to 20 g L(-1), and precipitating copper oxalates on all media tested. Chromatographic analyses showed that this species produced oxalic acid as sole metal chelator. The production of metal-oxalates can be used in the restoration and conservation of archeological and modern metal artifacts. The production of copper oxalates was confirmed directly using metallic pieces (both archeological and modern). The conversion of corrosion products into copper oxalates was demonstrated as well. In order to assess whether the capability of B. bassiana to produce metal-oxalates could be applied to other metals, iron and silver were tested as well. Iron appears to be directly sequestered in the wall of the fungal hyphae forming oxalates. However, the formation of a homogeneous layer on the object is not yet optimal. On silver, a co-precipitation of copper and silver oxalates occurred. As this greenish patina would not be acceptable on silver objects, silver reduction was explored as a tarnishing remediation. First experiments showed the transformation of silver nitrate into nanoparticles of elemental silver by an unknown extracellular mechanism. The production of copper oxalates is immediately applicable for the conservation of copper-based artifacts. For iron and silver this is not yet the case. However, the vast ability of B. bassiana to transform toxic metals using different immobilization mechanisms seems to offer considerable possibilities for industrial applications, such as the bioremediation of contaminated soils or the green synthesis of chemicals. PMID:22291684

  20. The 2005 catastrophic acid crater lake drainage, lahar, and acidic aerosol formation at Mount Chiginagak volcano, Alaska, USA: Field observations and preliminary water and vegetation chemistry results

    USGS Publications Warehouse

    Schaefer, J.R.; Scott, W.E.; Evans, William C.; Jorgenson, J.; McGimsey, R.G.; Wang, B.

    2008-01-01

    A mass of snow and ice 400-m-wide and 105-m-thick began melting in the summit crater of Mount Chiginagak volcano sometime between November 2004 and early May 2005, presumably owing to increased heat flux from the hydrothermal system, or possibly from magma intrusion and degassing. In early May 2005, an estimated 3.8??106 m3 of sulfurous, clay-rich debris and acidic water, with an accompanying acidic aerosol component, exited the crater through a tunnel at the base of a glacier that breaches the south crater rim. Over 27 km downstream, the acidic waters of the flood inundated an important salmon spawning drainage, acidifying Mother Goose Lake from surface to depth (approximately 0.5 km3 in volume at a pH of 2.9 to 3.1), killing all aquatic life, and preventing the annual salmon run. Over 2 months later, crater lake water sampled 8 km downstream of the outlet after considerable dilution from glacial meltwater was a weak sulfuric acid solution (pH = 3.2, SO4 = 504 mg/L, Cl = 53.6 mg/L, and F = 7.92 mg/L). The acid flood waters caused severe vegetation damage, including plant death and leaf kill along the flood path. The crater lake drainage was accompanied by an ambioructic flow of acidic aerosols that followed the flood path, contributing to defoliation and necrotic leaf damage to vegetation in a 29 km2 area along and above affected streams, in areas to heights of over 150 m above stream level. Moss species killed in the event contained high levels of sulfur, indicating extremely elevated atmospheric sulfurcontent. The most abundant airborne phytotoxic constituent was likely sulfuric acid aerosols that were generated during the catastrophic partial crater lake drainage event. Two mechanisms of acidic aerosol formation are proposed: (1) generation of aerosol mist through turbulent flow of acidic water and (2) catastrophic gas exsolution. This previously undocumented phenomenon of simultaneous vegetationdamaging acidic aerosols accompanying drainage of an acidic crater

  1. The 2005 catastrophic acid crater lake drainage, lahar, and acidic aerosol formation at Mount Chiginagak volcano, Alaska, USA: Field observations and preliminary water and vegetation chemistry results

    NASA Astrophysics Data System (ADS)

    Schaefer, Janet R.; Scott, William E.; Evans, William C.; Jorgenson, Janet; McGimsey, Robert G.; Wang, Bronwen

    2008-07-01

    A mass of snow and ice 400-m-wide and 105-m-thick began melting in the summit crater of Mount Chiginagak volcano sometime between November 2004 and early May 2005, presumably owing to increased heat flux from the hydrothermal system, or possibly from magma intrusion and degassing. In early May 2005, an estimated 3.8 × 106 m3 of sulfurous, clay-rich debris and acidic water, with an accompanying acidic aerosol component, exited the crater through a tunnel at the base of a glacier that breaches the south crater rim. Over 27 km downstream, the acidic waters of the flood inundated an important salmon spawning drainage, acidifying Mother Goose Lake from surface to depth (approximately 0.5 km3 in volume at a pH of 2.9 to 3.1), killing all aquatic life, and preventing the annual salmon run. Over 2 months later, crater lake water sampled 8 km downstream of the outlet after considerable dilution from glacial meltwater was a weak sulfuric acid solution (pH = 3.2, SO4 = 504 mg/L, Cl = 53.6 mg/L, and F = 7.92 mg/L). The acid flood waters caused severe vegetation damage, including plant death and leaf kill along the flood path. The crater lake drainage was accompanied by an ambioructic flow of acidic aerosols that followed the flood path, contributing to defoliation and necrotic leaf damage to vegetation in a 29 km2 area along and above affected streams, in areas to heights of over 150 m above stream level. Moss species killed in the event contained high levels of sulfur, indicating extremely elevated atmospheric sulfur content. The most abundant airborne phytotoxic constituent was likely sulfuric acid aerosols that were generated during the catastrophic partial crater lake drainage event. Two mechanisms of acidic aerosol formation are proposed: (1) generation of aerosol mist through turbulent flow of acidic water and (2) catastrophic gas exsolution. This previously undocumented phenomenon of simultaneous vegetation-damaging acidic aerosols accompanying drainage of an acidic

  2. Renal histopathology and crystal deposits in patients with small bowel resection and calcium oxalate stone disease.

    PubMed

    Evan, Andrew P; Lingeman, James E; Worcester, Elaine M; Bledsoe, Sharon B; Sommer, Andre J; Williams, James C; Krambeck, Amy E; Philips, Carrie L; Coe, Fredric L

    2010-08-01

    We present here the anatomy and histopathology of kidneys from 11 patients with renal stones following small bowel resection, including 10 with Crohn's disease and 1 resection in infancy for unknown cause. They presented predominantly with calcium oxalate stones. Risks of formation included hyperoxaluria (urine oxalate excretion greater than 45 mg per day) in half of the cases, and acidic urine of reduced volume. As was found with ileostomy and obesity bypass, inner medullary collecting ducts (IMCDs) contained crystal deposits associated with cell injury, interstitial inflammation, and papillary deformity. Cortical changes included modest glomerular sclerosis, tubular atrophy, and interstitial fibrosis. Randall's plaque (interstitial papillary apatite) was abundant, with calcium oxalate stone overgrowth similar to that seen in ileostomy, idiopathic calcium oxalate stone formers, and primary hyperparathyroidism. Abundant plaque was compatible with the low urine volume and pH. The IMCD deposits all contained apatite, with calcium oxalate present in three cases, similar to findings in patients with obesity bypass but not an ileostomy. The mechanisms for calcium oxalate stone formation in IMCDs include elevated urine and presumably tubule fluid calcium oxalate supersaturation, but a low calcium to oxalate ratio. However, the mechanisms for the presence of IMCD apatite remain unknown.

  3. DRIFTS studies on the photodegradation of tannic acid as a model for HULIS in atmospheric aerosols.

    PubMed

    Cowen, Scott; Al-Abadleh, Hind A

    2009-09-28

    Humic like substances (HULIS) are important components of atmospheric aerosols, yet little is known about their photochemical transformation and the role of adsorbed water in this photochemistry. We report herein in situ and surface-sensitive spectroscopic studies on (1) the photodegradation of solid tannic acid, (2) structure of adsorbed water before and after photodegradation, and (3) the change in the hydrophilicity of tannic acid as a result of this photochemistry. Tannic acid (TA) was chosen as a synthetic proxy for HULIS because it has a defined molecular structure. Photochemical studies were conducted using diffuse reflectance infrared spectroscopy (DRIFTS) as a function of time (3 h), relative humidity (5-30%) and total irradiance (7, 20, 290 W m(-2) at 555 nm). Water adsorption isotherm measurements were recorded before and after photodegradation, which provided information on the structure of interfacial water and the thermodynamics of adsorption. The structure of water adsorbed on TA resembles that of water at the interface with polar organic solvents. Difference spectral data collected during irradiation shows loss features in the 1700-1000 cm(-1) range and growth in carbonyl features that are blue shifted relative to the starting material, suggesting oxidative photodegradation of TA and formation of aryl aldehydes. Under our experimental conditions, we observed no enhancement in water uptake after photodegradation relative to that on unirradiated samples. The implications of our results to the understanding of heterogeneous photochemistry of HULIS and the role of adsorbed water in these reactions are discussed.

  4. Possible nitric acid coating formation over Pinatubo aerosols inferred with a microphysical code: A case study during EASOE

    SciTech Connect

    Rizi, V. Univ. degli Studi, L'Aquila ); Redaelli, G.; Verdecchia, M.; Visconti, G. ); Stefanutti, L. ); Wolf, J.P. )

    1994-06-22

    The authors present a case study of observations made with ground based lidar from Sodankyla, Finland, of stratospheric particles. Their interest was in using lidar to distinguish ice particles from polar stratospheric clouds, but the large density of volcanic aerosols present from the Mt. Pinatubo eruption, made this task more difficult during the 1991-92 winter. The authors observed a major difference in the reflected signals coming from one region over a two day period in January 1992, and argue here the origin of this may have been due to condensation of nitric acid on the surface of volcanic aerosols present in this stratospheric layer. They support this argument with microphysical calculations.

  5. Studies of acid aerosols in six cities and in a new multi-city investigation: design issues.

    PubMed

    Speizer, F E

    1989-02-01

    Techniques for measuring acid aerosols in the ambient environment have been developed only recently. As part of the on-going Harvard Study on the Health Effects of Sulfur Dioxide and Respirable Particulates, we have developed monitoring equipment for acidic particles that can be used in multiple field settings. Preliminary data suggest that these strong acid aerosol measurements may correlate with respiratory symptoms more closely than similar measurements of particulate matter less than 15 microns in size. These results have led to the beginning of a U.S.-Canadian cooperative study to assess the chronic effects of acid aerosols on the health of North American children. Communities are being selected on the basis of anticipated levels of H2SO4 in ambient air along with predicted levels of ozone and nitrates. Each community will undergo a 1-year period of every other day, 24-hr monitoring with newly developed monitoring equipment that will allow for quantification of H+ ion concentrations, as well as for specific measures of ozone and acid fractions. At the end of the 1-year period, while measurements are still being made, approximately 600 children aged 7 to 11 in each of up to 24 communities will be assessed with standardized questionnaires completed by parents, and pulmonary function will be measured in the children while in school. By estimating chronic exposure from the year-long measurement of acid aerosols and consideration of specific criteria for selecting communities to study, we hope to minimize potential confounding to allow us to assess the chronic impact of strong acid in the atmosphere on the respiratory health of these children.

  6. Separation and recovery of plutonium from oxalate supernatant using CMPO

    SciTech Connect

    Mathur, J.N.; Murali, M.S.; Rizvi, G.H.; Iyer, R.H.; Michael, K.M.; Kapoor, S.C.; Dhumwad, R.K.; Badheka, L.P.; Banerji, A. )

    1994-08-01

    A simple and efficient procedure has been developed to quantitatively recover Pu from oxalate supernatant using a mixture of octyl (phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and TBP in dodecane. Pu(IV) in the range of 6.9 to 34.6 mg/l was quantitatively extracted into 0.2M CMPO + 1.2 M TBP in dodecane from an aqueous solution containing 3.0 M HNO[sub 3] and 0.1 M H[sub 2]C[sub 2]O[sub 4]. At such low concentrations of Pu, the distribution ratio (D) did not change but the increase in oxalic acid concentration drastically reduced these values. The variation in HNO[sub 3] concentration at a fixed concentration of 0.2 M CMPO + U 1.2 M TBP has shown a dramatic increase in the D values, being 0.3 at 1.0 M and >10[sup 4] at 7.5 M. The extraction was almost quantitative even at the aqueous-to-organic ratio of 10:1. Plutonium could be quantitatively recovered by (i) stripping with 0.5 M acetic acid and (ii) coprecipitating it directly from the organic phase with 0.3 M oxalic acid + 0.3 M calcium nitrate + sodium nitrite. [approximately] 92% of the Pu was found in the precipitate and [approximately] 7% in the supernant. Using this procedure, Pu in a concentrated form ([approximately] 50 times) could be recovered from the oxalate supernatant solutions without recourse to the destruction of oxalate ion. 19 refs., 5 figs., 5 tabs.

  7. Kinetics of Acid-Catalyzed Dehydration of Cyclic Hemiacetals in Organic Aerosol Particles in Equilibrium with Nitric Acid Vapor.

    PubMed

    Ranney, April P; Ziemann, Paul J

    2016-04-28

    Previous studies have shown that 1,4-hydroxycarbonyls, which are often major products of the atmospheric oxidation of hydrocarbons, can undergo acid-catalyzed cyclization and dehydration in aerosol particles to form highly reactive unsaturated dihydrofurans. In this study the kinetics of dehydration of cyclic hemiacetals, the rate-limiting step in this process, was investigated in a series of environmental chamber experiments in which secondary organic aerosol (SOA) containing cyclic hemiacetals was formed from the reaction of n-pentadecane with OH radicals in dry air in the presence of HNO3. A particle beam mass spectrometer was used to monitor the formation and dehydration of cyclic hemiacetals in real time, and SOA and HNO3 were quantified in filter samples by gravimetric analysis and ion chromatography. Measured dehydration rate constants increased linearly with increasing concentration of HNO3 in the gas phase and in SOA, corresponding to catalytic rate constants of 0.27 h(-1) ppmv(-1) and 7.0 h(-1) M(-1), respectively. The measured Henry's law constant for partitioning of HNO3 into SOA was 3.7 × 10(4) M atm(-1), ∼25% of the value for dissolution into water, and the acid dissociation constant was estimated to be <8 × 10(-4), at least a factor of 10(4) less than that for HNO3 in water. The results indicate that HNO3 was only weakly dissociated in the SOA and that dehydration of cyclic hemiacetals was catalyzed by molecular HNO3 rather than by H(+). The Henry's law constant and kinetics relationships measured here can be used to improve mechanisms and models of SOA formation from the oxidation of hydrocarbons in dry air in the presence of NOx, which are conditions commonly used in laboratory studies. The fate of cyclic hemiacetals in the atmosphere, where the effects of higher relative humidity, organic/aqueous phase separation, and acid catalysis by molecular H2SO4 and/or H(+) are likely to be important, is discussed. PMID:27043733

  8. Kinetics of Acid-Catalyzed Dehydration of Cyclic Hemiacetals in Organic Aerosol Particles in Equilibrium with Nitric Acid Vapor.

    PubMed

    Ranney, April P; Ziemann, Paul J

    2016-04-28

    Previous studies have shown that 1,4-hydroxycarbonyls, which are often major products of the atmospheric oxidation of hydrocarbons, can undergo acid-catalyzed cyclization and dehydration in aerosol particles to form highly reactive unsaturated dihydrofurans. In this study the kinetics of dehydration of cyclic hemiacetals, the rate-limiting step in this process, was investigated in a series of environmental chamber experiments in which secondary organic aerosol (SOA) containing cyclic hemiacetals was formed from the reaction of n-pentadecane with OH radicals in dry air in the presence of HNO3. A particle beam mass spectrometer was used to monitor the formation and dehydration of cyclic hemiacetals in real time, and SOA and HNO3 were quantified in filter samples by gravimetric analysis and ion chromatography. Measured dehydration rate constants increased linearly with increasing concentration of HNO3 in the gas phase and in SOA, corresponding to catalytic rate constants of 0.27 h(-1) ppmv(-1) and 7.0 h(-1) M(-1), respectively. The measured Henry's law constant for partitioning of HNO3 into SOA was 3.7 × 10(4) M atm(-1), ∼25% of the value for dissolution into water, and the acid dissociation constant was estimated to be <8 × 10(-4), at least a factor of 10(4) less than that for HNO3 in water. The results indicate that HNO3 was only weakly dissociated in the SOA and that dehydration of cyclic hemiacetals was catalyzed by molecular HNO3 rather than by H(+). The Henry's law constant and kinetics relationships measured here can be used to improve mechanisms and models of SOA formation from the oxidation of hydrocarbons in dry air in the presence of NOx, which are conditions commonly used in laboratory studies. The fate of cyclic hemiacetals in the atmosphere, where the effects of higher relative humidity, organic/aqueous phase separation, and acid catalysis by molecular H2SO4 and/or H(+) are likely to be important, is discussed.

  9. Heterogeneous Reactivity of Nitric Acid with Nascent Sea Spray Aerosol: Large Differences Observed between and within Individual Particles.

    PubMed

    Ault, Andrew P; Guasco, Timothy L; Baltrusaitis, Jonas; Ryder, Olivia S; Trueblood, Jonathan V; Collins, Douglas B; Ruppel, Matthew J; Cuadra-Rodriguez, Luis A; Prather, Kimberly A; Grassian, Vicki H

    2014-08-01

    Current climate and atmospheric chemistry models assume that all sea spray particles react as if they are pure NaCl. However, recent studies of sea spray aerosol particles have shown that distinct particle types exist (including sea salt, organic carbon, and biological particles) as well as mixtures of these and, within each particle type, there is a range of single-particle chemical compositions. Because of these differences, individual particles should display a range of reactivities with trace atmospheric gases. Herein, to address this, we study the composition of individual sea spray aerosol particles after heterogeneous reaction with nitric acid. As expected, a replacement reaction of chloride with nitrate is observed; however, there is a large range of reactivities spanning from no reaction to complete reaction between and within individual sea spray aerosol particles. These data clearly support the need for laboratory studies of individual, environmentally relevant particles to improve our fundamental understanding as to the properties that determine reactivity.

  10. Synthesis of calcium oxalate crystals in culture medium irradiated with non-equilibrium atmospheric-pressure plasma

    NASA Astrophysics Data System (ADS)

    Kurake, Naoyuki; Tanaka, Hiromasa; Ishikawa, Kenji; Nakamura, Kae; Kajiyama, Hiroaki; Kikkawa, Fumitaka; Mizuno, Masaaki; Yamanishi, Yoko; Hori, Masaru

    2016-09-01

    Octahedral particulates several tens of microns in size were synthesized in a culture medium irradiated through contact with a plume of non-equilibrium atmospheric-pressure plasma (NEAPP). The particulates were identified in the crystalline phase as calcium oxalate dihydrate (COD). The original medium contained constituents such as NaCl, d-glucose, CaCl2, and NaHCO3 but not oxalate or oxalic acid. The oxalate was clearly synthesized and crystallized in the medium as thermodynamically unstable COD crystals after the NEAPP irradiation.

  11. REINVESTIGATING THE PROCESS IMPACTS FROM OXALIC ACIDHIGH LEVEL WASTE TANK CLEANING

    SciTech Connect

    Ketusky, E

    2008-01-22

    The impacts and acceptability of using oxalic acid to clean the Savannah River Site, High Level Waste Tanks 1-8, were re-investigated using a two-phased approach. For the first phase, using a representative Tank 1-8 sludge, the chemical equilibrium based software, OLI ESP{copyright} and Savannah River Site laboratory test results were used to develop a chemically speciated material balance and a general oxalate mass balance. Using 8 wt% oxalic acid with a 100% molar excess, for every 1 kg of sludge solid that was dissolved, about 3.4 kg of resultant solids would form for eventual vitrification, while about 0.6 kg of soluble oxalate would precipitate in the evaporator system, and form a salt heel. Using available analyses, a list of potential safety and process impacts were developed, screened, and evaluated for acceptability. The results showed that the use of oxalic acid had two distinct types of impacts, those which were safety based and required potential upgrades or additional studies. Assuming such were performed and adequate, no further actions were required. The second type of impacts were also acceptable, but were long-term, and as such, would need to be managed. These impacts were directly caused by the solubility characteristics of oxalate in a concentrated sodium solution and, occurred after pH restoration. Since oxalate destruction methods are commonly available, their use should be considered. Using an oxalate destruction method could enable the benefits of oxalic to applied, while eliminating the long-term impacts that must be managed, and hence should be considered.

  12. Effects of ozone and acid aerosol exposures on surfactant-associated protein A in the lung

    SciTech Connect

    Su, W.Y.

    1993-01-01

    This study examined the effect of ozone and/or acid aerosol exposure on the level of surfactant associated protein A (SP-A), its gene expression and functionality in the lung. Guinea pigs were exposed to (1) a single exposure to 0.2 to 0.8 ppm ozone for 6 hr and sacrificed at 0 to 120 hr postexposure, (2) 0.8 ppm ozone, 6 hr/day for 3 to 5 days and sacrificed immediately postexposure, or (3) 0.8 ppm ozone, 600 [mu]g/m[sup 3] sulfuric acid, or ozone plus acid for 6 hr and sacrificed at 72 hr postexposure. The concentration of SP-A was determined by ELISA in lavage fluid, lavage cell pellets, and lung tissue compartments. SP-A gene expression was examined in lung tissue by Northern and slot blot analysis. Effect of ozone exposure on functionality of surfactant was tested by its ability to modulate phagocytic cell respiratory burst in a luminol-amplified chemiluminescence (CL) assay of phagocytic cells simulated by PMA or opsonized-zymosan. There were isolated, but significant, changes in SP-A concentrations in the lavage cell and the lavage fluid compartments at 24 and 48 hr after single exposure to 0.8 ppm ozone, respectively. Exposure to ozone and ozone plus acid also slightly increased total SP-A level in the lung. No change in SP-A gene expression was detected under the exposure conditions examined. However, surfactant from ozone exposed animals significantly enhanced CL response of phagocytic cells stimulated by either PMA or opsonized-zymosan. Blocking of the enhancement of CL by a rabbit anti-human SP-A antibody strongly suggested that SP-A may contribute in the altered respiratory burst of phagocytic cells induced by surfactant from ozone exposed animals.

  13. Ozonolysis of oleic acid adsorbed to polar and nonpolar aerosol particles.

    PubMed

    Rosen, Elias P; Garland, Eva R; Baer, Tomas

    2008-10-16

    Single-particle kinetic studies of the reaction between oleic acid and O 3 have been conducted on two different types of core particles: polystyrene latex (PSL) and silica. Oleic acid was found to adsorb to both particle types in multilayer islands that resulted in an adsorbed layer of a total volume estimated to be less than one monolayer. The rate of the surface reaction between surface-adsorbed oleic acid and O 3 has been shown for the first time to be influenced by the composition of the aerosol substrate in a mixed organic/inorganic particle. A Langmuir-Hinshelwood mechanism was applied to the observed dependence of the pseudo-first-order rate constant with [O 3], and the resulting fit parameters for the ozone partition coefficient ( K O 3 ) and maximum first order rate constant ( k 1,max ) suggest that the reaction proceeded faster on the less polar PSL core at lower [O 3] due to the increased residence time of O 3 on the PSL surface, but the reaction was ultimately more efficient on the silica surface at high [O 3]. Values for the uptake coefficient, gamma oleic , for reaction of oleic acid on PSL spheres decrease from 2.5 x 10 (-5) to 1 x 10 (-5) with increasing [O 3] from 4 to 25 ppm and overlap at high [O 3] with the estimated values for gamma oleic on silica, which decrease from 1.6 x 10 (-5) to 1.3 x 10 (-5). The relationship between gamma oleic and the more common expression for gamma O 3 is discussed.

  14. Volatility and oxidative aging of aqueous maleic acid aerosol droplets and the dependence on relative humidity.

    PubMed

    Dennis-Smither, Benjamin J; Marshall, Frances H; Miles, Rachael E H; Preston, Thomas C; Reid, Jonathan P

    2014-07-31

    The microphysical structure and heterogeneous oxidation by ozone of single aerosol particles containing maleic acid (MA) has been studied using aerosol optical tweezers and cavity enhanced Raman spectroscopy. The evaporation rate of MA from aqueous droplets has been measured over a range of relative humidities and the pure component vapor pressure determined to be (1.7 ± 0.2) × 10(-3) Pa. Variation in the refractive index (RI) of an aqueous MA droplet with relative humidity (RH) allowed the subcooled liquid RI of MA to be estimated as 1.481 ± 0.001. Measurements of the hygroscopic growth are shown to be consistent with equilibrium model predictions from previous studies. Simultaneous measurements of the droplet composition, size, and refractive index have been made during ozonolysis at RHs in the range 50-80%, providing insight into the volatility of organic products, changes in the droplet hygroscopicity, and optical properties. Exposure of the aqueous droplets to ozone leads to the formation of products with a wide range of volatilities spanning from involatile to volatile. Reactive uptake coefficients show a weak dependence on ozone concentration, but no dependence on RH or salt concentration. The time evolving RI depends significantly on the RH at which the oxidation proceeds and can even show opposing trends; while the RI increases with ozone exposure at low relative humidity, the RI decreases when the oxidation proceeds at high relative humidity. The variations in RI are broadly consistent with a framework for predicting RIs for organic components published by Cappa et al. ( J. Geophys. Res. 2011 , 116 , D15204 ). Once oxidized, particles are shown to form amorphous phases on drying rather than crystallization, with slow evaporation kinetics of residual water. PMID:25003240

  15. Effects of acid aerosol exposure on the surface properties of airway mucus

    SciTech Connect

    Lee, M.M.; Schuerch, S.; Roth, S.H.

    1995-12-31

    It was hypothesized that the mucous layer lining the tracheas of rats and guinea pigs contains surfactant material capable of lowering the air/mucus surface tension, {gamma}, and that exposure to an irritant aerosol would raise the {gamma}. The {gamma} of the surface film was measured directly by a spreading droplet technique and indirectly by displacement of polymethyl methacrylate particles into the aqueous layer. The morphology of the mucous film was examined by electron microscopy after nonaqueous fixation. {gamma} was 33.3 {plus_minus} 0.70 (SE) mN/m and 32.3 {plus_minus} 0.68 (SE) mN/m for the normal rat and guinea pig trachea, respectively. Exposure for 4 h to aerosols of sulfuric acid (94.1 {plus_minus} 18.68 (SD) and 43.3 {plus_minus} 4.57 (SD) mg/m{sup 3}) caused a several-fold increase in thickness of the mucous layer with exudation of protein-like material. The osmiophilic surfactant film at the air/mucus interface became irregularly thickened and multilayered. Despite these morphological changes {gamma} remained low, 33.2 {plus_minus} 0.43 (SE) mN/m and 32.6 {plus_minus} 0.60 (SE) mN/m for rats and guinea pigs, respectively, and displacement of particles into the subphase was not compromised. The results indicate that rodent tracheas are able to maintain a low surface tension in the presence of injury. 24 refs., 9 figs.

  16. Bimodal distribution of sulfuric acid aerosols in the upper haze of Venus

    NASA Astrophysics Data System (ADS)

    Gao, Peter; Zhang, Xi; Crisp, David; Bardeen, Charles G.; Yung, Yuk L.

    2014-03-01

    Observations by the SPICAV/SOIR instruments aboard Venus Express have revealed that the upper haze (UH) of Venus, between 70 and 90 km, is variable on the order of days and that it is populated by two particle modes. We use a one-dimensional microphysics and vertical transport model based on the Community Aerosol and Radiation Model for Atmospheres to evaluate whether interaction of upwelled cloud particles and sulfuric acid particles nucleated in situ on meteoric dust are able to generate the two observed modes, and whether their observed variability are due in part to the action of vertical transient winds at the cloud tops. Nucleation of photochemically produced sulfuric acid onto polysulfur condensation nuclei generates mode 1 cloud droplets, which then diffuse upwards into the UH. Droplets generated in the UH from nucleation of sulfuric acid onto meteoric dust coagulate with the upwelled cloud particles and therefore cannot reproduce the observed bimodal size distribution. By comparison, the mass transport enabled by transient winds at the cloud tops, possibly caused by sustained subsolar cloud top convection, are able to generate a bimodal size distribution in a time scale consistent with Venus Express observations. Below the altitude where the cloud particles are generated, sedimentation and vigorous convection causes the formation of large mode 2 and mode 3 particles in the middle and lower clouds. Evaporation of the particles below the clouds causes a local sulfuric acid vapor maximum that results in upwelling of sulfuric acid back into the clouds. In the case where the polysulfur condensation nuclei are small and their production rate is high, coagulation of small droplets onto larger droplets in the middle cloud may set up an oscillation in the size modes of the particles such that precipitation of sulfuric acid “rain” may be possible immediately below the clouds once every few Earth months. Reduction of the polysulfur condensation nuclei production

  17. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities

    PubMed Central

    Van Wyngarden, A. L.; Pérez-Montaño, S.; Bui, J. V. H.; Li, E. S. W.; Nelson, T. E.; Ha, K. T.; Leong, L.; Iraci, L. T.

    2016-01-01

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40–80 wt %) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H2SO4) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, attenuated total reflectance–Fourier transform infrared (ATR-FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene that was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher-order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence of products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal and

  18. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities

    NASA Astrophysics Data System (ADS)

    Van Wyngarden, A. L.; Pérez-Montaño, S.; Bui, J. V. H.; Li, E. S. W.; Nelson, T. E.; Ha, K. T.; Leong, L.; Iraci, L. T.

    2014-11-01

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt %) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H2SO4) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, Attenuated Total Reflectance-Fourier Transform Infrared and 1H Nuclear Magnetic Resonance spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene, which was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence for products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal and methylglyoxal

  19. Complex chemical composition of colored surface films formed from reactions of propanal in sulfuric acid at upper troposphere/lower stratosphere aerosol acidities

    NASA Astrophysics Data System (ADS)

    Van Wyngarden, A. L.; Pérez-Montaño, S.; Bui, J. V. H.; Li, E. S. W.; Nelson, T. E.; Ha, K. T.; Leong, L.; Iraci, L. T.

    2015-04-01

    Particles in the upper troposphere and lower stratosphere (UT/LS) consist mostly of concentrated sulfuric acid (40-80 wt%) in water. However, airborne measurements have shown that these particles also contain a significant fraction of organic compounds of unknown chemical composition. Acid-catalyzed reactions of carbonyl species are believed to be responsible for significant transfer of gas phase organic species into tropospheric aerosols and are potentially more important at the high acidities characteristic of UT/LS particles. In this study, experiments combining sulfuric acid (H2SO4) with propanal and with mixtures of propanal with glyoxal and/or methylglyoxal at acidities typical of UT/LS aerosols produced highly colored surface films (and solutions) that may have implications for aerosol properties. In order to identify the chemical processes responsible for the formation of the surface films, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and 1H nuclear magnetic resonance (NMR) spectroscopies were used to analyze the chemical composition of the films. Films formed from propanal were a complex mixture of aldol condensation products, acetals and propanal itself. The major aldol condensation products were the dimer (2-methyl-2-pentenal) and 1,3,5-trimethylbenzene that was formed by cyclization of the linear aldol condensation trimer. Additionally, the strong visible absorption of the films indicates that higher-order aldol condensation products must also be present as minor species. The major acetal species were 2,4,6-triethyl-1,3,5-trioxane and longer-chain linear polyacetals which are likely to separate from the aqueous phase. Films formed on mixtures of propanal with glyoxal and/or methylglyoxal also showed evidence of products of cross-reactions. Since cross-reactions would be more likely than self-reactions under atmospheric conditions, similar reactions of aldehydes like propanal with common aerosol organic species like glyoxal and

  20. Acute oxalate nephropathy due to ‘Averrhoa bilimbi’ fruit juice ingestion

    PubMed Central

    Bakul, G.; Unni, V. N.; Seethaleksmy, N. V.; Mathew, A.; Rajesh, R.; Kurien, G.; Rajesh, J.; Jayaraj, P. M.; Kishore, D. S.; Jose, P. P.

    2013-01-01

    Irumban puli (Averrhoa bilimbi) is commonly used as a traditional remedy in the state of Kerala. Freshly made concentrated juice has a very high oxalic acid content and consumption carries a high risk of developing acute renal failure (ARF) by deposition of calcium oxalate crystals in renal tubules. Acute oxalate nephropathy (AON) due to secondary oxalosis after consumption of Irumban puli juice is uncommon. AON due to A. bilimbi has not been reported before. We present a series of ten patients from five hospitals in the State of Kerala who developed ARF after intake of I. puli fruit juice. Seven patients needed hemodialysis whereas the other three improved with conservative management. PMID:23960349

  1. Aerosol pH buffering in the southeastern US: Fine particles remain highly acidic despite large reductions in sulfate

    NASA Astrophysics Data System (ADS)

    Weber, R. J.; Guo, H.; Russell, A. G.; Nenes, A.

    2015-12-01

    pH is a critical aerosol property that impacts many atmospheric processes, including biogenic secondary organic aerosol formation, gas-particle phase partitioning, and mineral dust or redox metal mobilization. Particle pH has also been linked to adverse health effects. Using a comprehensive data set from the Southern Oxidant and Aerosol Study (SOAS) as the basis for thermodynamic modeling, we have shown that particles are currently highly acidic in the southeastern US, with pH between 0 and 2. Sulfate and ammonium are the main acid-base components that determine particle pH in this region, however they have different sources and their concentrations are changing. Over 15 years of network data show that sulfur dioxide emission reductions have resulted in a roughly 70 percent decrease in sulfate, whereas ammonia emissions, mainly link to agricultural activities, have been largely steady, as have gas phase ammonia concentrations. This has led to the view that particles are becoming more neutralized. However, sensitivity analysis, based on thermodynamic modeling, to changing sulfate concentrations indicates that particles have remained highly acidic over the past decade, despite the large reductions in sulfate. Furthermore, anticipated continued reductions of sulfate and relatively constant ammonia emissions into the future will not significantly change particle pH until sulfate drops to clean continental background levels. The result reshapes our expectation of future particle pH and implies that atmospheric processes and adverse health effects linked to particle acidity will remain unchanged for some time into the future.

  2. Phase, morphology, and hygroscopicity of mixed oleic acid/sodium chloride/water aerosol particles before and after ozonolysis.

    PubMed

    Dennis-Smither, Benjamin J; Hanford, Kate L; Kwamena, Nana-Owusua A; Miles, Rachael E H; Reid, Jonathan P

    2012-06-21

    Aerosol optical tweezers are used to probe the phase, morphology, and hygroscopicity of single aerosol particles consisting of an inorganic component, sodium chloride, and a water insoluble organic component, oleic acid. Coagulation of oleic acid aerosol with an optically trapped aqueous sodium chloride droplet leads to formation of a phase-separated particle with two partially engulfed liquid phases. The dependence of the phase and morphology of the trapped particle with variation in relative humidity (RH) is investigated by cavity enhanced Raman spectroscopy over the RH range <5% to >95%. The efflorescence and deliquescence behavior of the inorganic component is shown to be unaffected by the presence of the organic phase. Whereas efflorescence occurs promptly (<1 s), the deliquescence process requires both dissolution of the inorganic component and the adoption of an equilibrium morphology for the resulting two phase particle, occurring on a time-scale of <20 s. Comparative measurements of the hygroscopicity of mixed aqueous sodium chloride/oleic acid droplets with undoped aqueous sodium chloride droplets show that the oleic acid does not impact on the equilibration partitioning of water between the inorganic component and the gas phase or the time response of evaporation/condensation. The oxidative aging of the particles through reaction with ozone is shown to increase the hygroscopicity of the organic component.

  3. Crystal growth methods dedicated to low solubility actinide oxalates

    NASA Astrophysics Data System (ADS)

    Tamain, C.; Arab-Chapelet, B.; Rivenet, M.; Grandjean, S.; Abraham, F.

    2016-04-01

    Two novel crystal growth syntheses dedicated to low solubility actinide-oxalate systems and adapted to glove box handling are described. These methods based on the use of precursors of either actinide metal or oxalic acid have been optimized on lanthanide systems (analogue of actinides(III)) and then assessed on real actinide systems. They allow the synthesis of several actinide oxalate single crystals, Am2(C2O4)3(H2O)3·xH2O, Th(C2O4)2·6H2O, M2+x[PuIV2-xPuIIIx(C2O4)5]·nH2O and M1-x[PuIII1-xPuIVx(C2O4)2·H2O]·nH2O. It is the first time that these well-known compounds are formed by crystal growth methods, thus enabling direct structural studies on transuranic element systems and acquisition of basic data beyond deductions from isomorphic (or not) lanthanide compounds. Characterizations by X-ray diffraction, UV-visible solid spectroscopy, demonstrate the potentialities of these two crystal growth methods to obtain oxalate compounds.

  4. The hygroscopic properties of dicarboxylic and multifunctional acids: measurements and UNIFAC predictions.

    PubMed

    Peng, C; Chan, M N; Chan, C K

    2001-11-15

    The role of water-soluble organic compounds on the hygroscopic properties of atmospheric aerosols has recently been the subject of many studies. In particular, low molecular weight dicarboxylic acids and some multifunctional organic acids have been found or are expected to exist in atmospheric aerosols in urban, semiurban, rural, and remote sites. Unlike for their inorganic counterparts, the hygroscopic properties of organic acids have not been well characterized. In this study, the hygroscopic properties of selected water-soluble dicarboxylic acids (oxalic acid, malonic acid, succinic acid, and glutaric acid) and multifunctional acids (citric acid, DL-malic acid, and L-(+)-tartaric acid) were studied using single droplets levitated in an electrodynamic balance at 25 degrees C. The water activities of bulk samples of dilute solutions were also measured. Solute evaporation was observed in the dicarboxylic acids but not in the multifunctional acids. Oxalic acid, succinic acid, and glutaric acid droplets crystallize upon evaporation of water, but, except for glutaric acid droplets, do not deliquesce even at 90% relative humidity (RH). Mass transfer limitation of the deliquescence process was observed in glutaric acid. Neither crystallization nor deliquescence was observed in malonic acid, citric acid, DL-malic acid, or L-(+)-tartaric acid. Malonic acid and these three hydroxy-carboxylic acids absorb water even at RH much lower than their respective deliquescence RH. The growth factor (Gf), defined as the ratio of the particle diameter at RH = 10% to that at RH = 90%, of oxalic acid and succinic acid was close to unity, indicating no hygroscopicity in this range. The remaining acids (malonic acid, glutaric acid, citric acid, malic acid, and tartaric acid) showed roughly similar hygroscopicity of a Gf of 1.30-1.53, which is similar to that of "more hygroscopic" aerosols in field measurements reported in the literature. A generalized equation for these four acids, Gf

  5. Evaporation kinetics of aqueous acetic acid droplets: effects of soluble organic aerosol components on the mechanism of water evaporation.

    PubMed

    Duffey, Kaitlin C; Shih, Orion; Wong, Nolan L; Drisdell, Walter S; Saykally, Richard J; Cohen, Ronald C

    2013-07-28

    The presence of organic surfactants in atmospheric aerosol may lead to a depression of cloud droplet growth and evaporation rates affecting the radiative properties and lifetime of clouds. Both the magnitude and mechanism of this effect, however, remain poorly constrained. We have used Raman thermometry measurements of freely evaporating micro-droplets to determine evaporation coefficients for several concentrations of acetic acid, which is ubiquitous in atmospheric aerosol and has been shown to adsorb strongly to the air-water interface. We find no suppression of the evaporation kinetics over the concentration range studied (1-5 M). The evaporation coefficient determined for 2 M acetic acid is 0.53 ± 0.12, indistinguishable from that of pure water (0.62 ± 0.09).

  6. Gas-particle partitioning of organic acids during the Southern Oxidant and Aerosol Study (SOAS): measurements and modeling

    NASA Astrophysics Data System (ADS)

    Thompson, S.; Yatavelli, R.; Stark, H.; Kimmel, J.; Krechmer, J.; Day, D. A.; Isaacman, G. A.; Goldstein, A. H.; Khan, M. A. H.; Holzinger, R.; Lopez-Hilfiker, F.; Mohr, C.; Thornton, J. A.; Jayne, J. T.; Worsnop, D. R.; Jimenez, J. L.

    2014-12-01

    Gas-Particle partitioning measurements of organic acids were carried out during the Southern Oxidant and Aerosol Study (SOAS, June-July 2013) at the Centerville, AL Supersite in the Southeast US, a region with significant isoprene and terpene emissions. Organic acid measurements were made with a Chemical Ionization High Resolution Time-of-Flight Mass Spectrometer (HRToF-CIMS) with a Filter Inlet for Gases and AEROsols (FIGAERO) and acetate (CH3COO-) as the reagent ion. We investigate both individual species and bulk organic acids and partitioning to organic and water phases in the aerosol. Measured partitioning is compared to data from three other instruments that can also quantify gas-particle partitioning with high time resolution: another HRToF-CIMS using iodide (I-) as the reagent ion to ionize acids and other highly oxidized compounds, a Semivolatile Thermal Desorption Aerosol GC/MS (SV-TAG), and a Thermal Desorption Proton Transfer Time-of-Flight Mass Spectrometer (TD-PTRMS The partitioning measurements for three of the instruments are generally consistent, with results in the same range for most species and following similar temporal trends and diurnal cycles. The TD-PTRMS measures on average ½ the partitioning to the particle phase of the acetate CIMS. Both the measurements and the model of partitioning to the organic phase respond quickly to temperature, and the model agrees with the measured partitioning within the error of the measurement for multiple compounds, although many compounds do not match the modeled partitioning, especially at lower m/z. This discrepancy may be due to thermal decomposition of larger molecules into smaller ones when heated.

  7. Artificial primary marine aerosol production: a laboratory study with varying water temperature, salinity, and succinic acid concentration

    NASA Astrophysics Data System (ADS)

    Zábori, J.; Matisāns, M.; Krejci, R.; Nilsson, E. D.; Ström, J.

    2012-11-01

    Primary marine aerosols are an important component of the climate system, especially in the remote marine environment. With diminishing sea-ice cover, better understanding of the role of sea spray aerosol on climate in the polar regions is required. As for Arctic Ocean water, laboratory experiments with NaCl water confirm that a few degrees change in the water temperature (Tw) gives a large change in the number of primary particles. Small particles with a dry diameter between 0.01 μm and 0.25 μm dominate the aerosol number density, but their relative dominance decreases with increasing water temperature from 0 °C where they represent 85-90% of the total aerosol number to 10 °C, where they represent 60-70% of the total aerosol number. This effect is most likely related to a change in physical properties and not to modification of sea water chemistry. A change of salinity between 15 g kg-1 and 35 g kg-1 did not influence the shape of a particle number size distribution. Although the magnitude of the size distribution for a water temperature change between 0 °C and 16 °C changed, the shape did not. An experiment where succinic acid was added to a NaCl water solution showed, that the number concentration of particles with 0.010 μm < Dp < 4.5 μm decreased on average by 10% when the succinic acid concentration in NaCl water at a water temperature of 0 °C was increased from 0 μmol L-1 to 94 μmol L-1. A shift to larger sizes in the particle number size distribution is observed from pure NaCl water to Arctic Ocean water. This is likely a consequence of organics and different inorganic salts present in Arctic Ocean water in addition to the NaCl.

  8. Raman spectra of oxalates in lichen encrustations on Renaissance frescoes

    NASA Astrophysics Data System (ADS)

    Edwards, H. G. M.; Farwell, D. W.; Seaward, M. R. D.

    The vibrational Raman spectra of lichen encrustations on biodeteriorated Renaissance frescoes have been recorded using a laser Raman microprobe. The major chemical species identified in the encrustations is calcium oxalate. Other vibrational features in the Raman spectra have been assigned to fragments of the substratum incorporated from the biodeterioration process and to organic by-products of lichen metabolism such as erythrin, lecanoric acid and meso-erythritol.

  9. Turning sunlight into stone: the oxalate-carbonate pathway in a tropical tree ecosystem

    NASA Astrophysics Data System (ADS)

    Cailleau, G.; Braissant, O.; Verrecchia, E. P.

    2011-02-01

    An African oxalogenic tree, the iroko tree (Milicia excelsa), has the property to enhance carbonate precipitation in tropical oxisols, where such accumulations are not expected due to the theoretical acidic conditions of these soils. This uncommon process is linked to the oxalate-carbonate pathway, which increases soil pH through oxalate oxidation. In order to investigate the oxalate-carbonate pathway in the iroko system, fluxes of matter have been identified, described, and evaluated from field to microscopic scales. In the first centimeters of the soil profile, decaying of the organic matter allows the release of whewellite crystals, mainly due to the action of termites and saprophytic fungi. Regarding the carbonate flux, another direct consequence of wood feeding is a concomitant flux of carbonate formed in wood tissues, which is not consumed by termites. Nevertheless, calcite biomineralization of the tree is not a consequence of in situ oxalate consumption, but rather related to the oxalate oxidation inside the upper part of the soil. The consequence of this oxidation is the presence of carbonate ions in the soil solution pumped through the roots, leading to preferential mineralization of the roots and the trunk base. An ideal scenario for the iroko biomineralization and soil carbonate accumulation starts with oxalatization: as the iroko tree grows, the organic matter flux to the soil constitutes the litter. Therefore, an oxalate pool is formed on the forest ground. Then, wood rotting gents (mainly termites, fungi, and bacteria) release significant amounts of oxalate crystals from decaying plant tissues. In addition some of these gents are themselves producers of oxalate (fungi). Both processes contribute to a soil pool of "available" oxalate crystals. Oxalate consumption by oxalotrophic bacteria can start. Carbonate and calcium ions present in the soil solution represent the end products of the oxalate-carbonate pathway. The solution is pumped through the

  10. Turning sunlight into stone: the oxalate-carbonate pathway in a tropical tree ecosystem

    NASA Astrophysics Data System (ADS)

    Cailleau, G.; Braissant, O.; Verrecchia, E. P.

    2011-07-01

    An African oxalogenic tree, the iroko tree (Milicia excelsa), has the property to enhance carbonate precipitation in tropical oxisols, where such accumulations are not expected due to the acidic conditions in these types of soils. This uncommon process is linked to the oxalate-carbonate pathway, which increases soil pH through oxalate oxidation. In order to investigate the oxalate-carbonate pathway in the iroko system, fluxes of matter have been identified, described, and evaluated from field to microscopic scales. In the first centimeters of the soil profile, decaying of the organic matter allows the release of whewellite crystals, mainly due to the action of termites and saprophytic fungi. In addition, a concomitant flux of carbonate formed in wood tissues contributes to the carbonate flux and is identified as a direct consequence of wood feeding by termites. Nevertheless, calcite biomineralization of the tree is not a consequence of in situ oxalate consumption, but rather related to the oxalate oxidation inside the upper part of the soil. The consequence of this oxidation is the presence of carbonate ions in the soil solution pumped through the roots, leading to preferential mineralization of the roots and the trunk base. An ideal scenario for the iroko biomineralization and soil carbonate accumulation starts with oxalatization: as the iroko tree grows, the organic matter flux to the soil constitutes the litter, and an oxalate pool is formed on the forest ground. Then, wood rotting agents (mainly termites, saprophytic fungi, and bacteria) release significant amounts of oxalate crystals from decaying plant tissues. In addition, some of these agents are themselves producers of oxalate (e.g. fungi). Both processes contribute to a soil pool of "available" oxalate crystals. Oxalate consumption by oxalotrophic bacteria can then start. Carbonate and calcium ions present in the soil solution represent the end products of the oxalate-carbonate pathway. The solution is

  11. Gas/particle partitioning behavior of perfluorocarboxylic acids with terrestrial aerosols.

    PubMed

    Arp, Hans Peter H; Goss, Kai-Uwe

    2009-11-15

    Experimentally determined gas/particle partitioning constants, K(ip), using inverse gas chromatography (IGC) are presented for perfluorocarboxylic acids (PFCAs), covering a diverse set of terrestrial aerosols over an ambient range of relative humidity (RH) and temperature. The results are compared to estimated K(ip) values using a recently developed model that has been validated for diverse neutral and ionizable organic compounds. The modeling results consistently underestimate the experimental results. This is likely due to additional partition mechanisms unique for surfactants not being accounted for in the model, namely aggregate formation and water surface adsorption. These processes likely also biased the IGC K(ip) measurements compared to ambient PFCA concentrations. Nevertheless, both the experimental and modeling results indicate that partitioning to terrestrial particles in ambient atmospheres is negligible, though sorption to condensed water can be substantial. This favors rain sequestration as a more important atmospheric removal mechanism than dry particle sequestration. PFCAs found on particle filters during ambient sampling are thus accountable to vapor-phase PFCAs or aqueous-phase PFCAs sorbing directly to the filters, or the trapping of perfluorocarboxylate-salt particles. Further work on understanding the partitioning and speciation of PFCAs in atmospheric water droplets is needed to further quantify and understand their atmospheric behavior. To aid in this, a general RH dependent K(ip) model for surfactants is presented.

  12. Aerosol products, mechanisms, and kinetics of heterogeneous reactions of ozone with oleic acid in pure and mixed particles.

    PubMed

    Ziemann, Paul J

    2005-01-01

    Reactions of O3 with pure and mixed oleic acid particles and bulk solutions were investigated using a thermal desorption particle beam mass spectrometer. The results provide information on the effect of particle matrix on reaction products, mechanisms, and kinetics. The major aerosol products are alpha-acyloxyalkyl hydroperoxides, secondary ozonides, alpha-alkoxyalkyl hydroperoxides, and oxocarboxylic acids formed primarily through reactions of Criegee intermediates with products or with particle matrix compounds. For example, it is estimated that for the reaction of pure oleic acid particles with O3 the aerosol products consist of approximately 68% organic peroxides, 28% 9-oxononanoic acid, and 4% azelaic acid. Although the reaction rate of pure oleic acid particles corresponds to an atmospheric lifetime of minutes, reactions in liquid/solid particle matrices can be orders of magnitude slower. The peroxide products are relatively stable when exposed to matrices typical of atmospheric particles, indicating that the lifetimes of these compounds in the atmosphere may be long enough to allow for long-range transport.

  13. Marine submicron aerosol gradients, sources and sinks

    NASA Astrophysics Data System (ADS)

    Ceburnis, Darius; Rinaldi, Matteo; Ovadnevaite, Jurgita; Martucci, Giovanni; Giulianelli, Lara; O'Dowd, Colin D.

    2016-10-01

    Aerosol principal sources and sinks over eastern North Atlantic waters were studied through the deployment of an aerosol chemistry gradient sampling system. The chemical gradients of primary and secondary aerosol components - specifically, sea salt (SS), water-insoluble organic matter (WIOM), water-soluble organic matter (WSOM), nitrate, ammonium, oxalate, amines, methanesulfonic acid (MSA) and water-soluble organic nitrogen (WSON) - were examined in great detail. Sea salt fluxes were estimated by the boundary layer box model and ranged from 0.3 to 3.5 ng m-2 s-1 over the wind speed range of 5-12 m s-1 and compared well with the derived fluxes from existing sea salt source parameterisations. The observed seasonal pattern of sea salt gradients was mainly driven by wind stress in addition to the yet unquantified effect of marine OM modifying fractional contributions of SS and OM in sea spray. WIOM gradients were a complex combination of rising and waning biological activity, especially in the flux footprint area, and wind-driven primary sea spray production supporting the coupling of recently developed sea spray and marine OM parameterisations.

  14. Free and combined amino acids in marine background atmospheric aerosols over the Eastern Mediterranean

    NASA Astrophysics Data System (ADS)

    Mandalakis, Manolis; Apostolaki, Maria; Tziaras, Thrasivoulos; Polymenakou, Paraskevi; Stephanou, Euripides G.

    2011-02-01

    During a six-week intensive field campaign at a background marine site of the Eastern Mediterranean, consecutive 24-h air samples were collected and analyzed for combined (CAA) and free amino acids (FAA), as well as for key chemical characteristics of aerosols. The total concentration of CAA (719 ± 326 pmol m -3) was on average four times higher than that of FAA (172 ± 147 pmol m -3), while glycine was the most abundant compound detected in both FAA and CAA. Back-trajectory analysis demonstrated that the geographical origin of the air masses did not have a significant influence on the atmospheric levels of amino acids. Wind speed was found to be the most important meteorological factor and it exhibited a negative correlation with both FAA and CAA. Moreover, FAA and CAA concentrations showed a more pronounced correlation with water-soluble organic carbon (WSOC) than elemental carbon. On average, FAA and CAA accounted for 0.3 ± 0.2% and 1.8 ± 0.8% of WSOC, respectively. The levels of anionic surfactants determined as methylene blue active substances did not show any positive correlation with CAA, while the corresponding correlation with FAA was only of marginal significance. The total protein concentration measured by NanoOrange assay was six times higher compared to that measured through CAA. It is suggested that the results from the application of commercially available protein quantitation kits should always be considered with caution, as these are more prone to matrix-related interferences.

  15. Latitudinal distributions of atmospheric dicarboxylic acids, oxocarboxylic acids, and α-dicarbonyls over the western North Pacific: Sources and formation pathways

    NASA Astrophysics Data System (ADS)

    Bikkina, Srinivas; Kawamura, Kimitaka; Miyazaki, Yuzo

    2015-05-01

    The present study aims to assess the molecular distributions of water-soluble dicarboxylic acids (diacids: C2-C12), oxocarboxylic acids (C2-C9), and α-dicarbonyls (glyoxal and methylglyoxal) in aerosols collected over the western North Pacific (WNP) during a summer cruise (August to September 2008). The measured water-soluble organics show pronounced latitudinal distributions with higher concentrations in the region of 30°N-45°N (average 63 ng m-3) than 10°N-30°N (18 ng m-3). Mass fraction of oxalic acid (C2) in total aliphatic diacids (ΣC2-C12) showed higher values (72 ± 10%) in lower latitude (10°N-30°N) than that (56 ± 16%) in higher latitude (30°N-45°N), suggesting a photochemical production of C2 due to an increased insolation over the tropical WNP. A similar trend was found in other diagnostic ratios such as oxalic to succinic (C2/C4) and oxalic to glyoxylic acid (C2/ωC2), which further corroborate an enhanced photochemical aging over the WNP. In addition, relative abundances of oxalic acid in total diacids showed a marked increase as a function of ambient temperature, supporting their photochemical production. Constantly low concentration ratios of adipic and phthalic acids relative to azelaic acid suggest a small contribution of anthropogenic sources and an importance of oceanic sources during the study period. Significant production of C2 through oxidation of biogenic volatile organic compounds emitted from the sea surface is also noteworthy, as inferred from the strong linear correlations among water-soluble organic carbon, methanesulphonic acid, and oxalic acid. Sea-to-air emission of unsaturated fatty acids also contributes to formation of diacids over the WNP.

  16. Oxalate: from the environment to kidney stones.

    PubMed

    Brzica, Hrvoje; Breljak, Davorka; Burckhardt, Birgitta C; Burckhardt, Gerhard; Sabolić, Ivan

    2013-12-01

    Oxalate urolithiasis (nephrolithiasis) is the most frequent type of kidney stone disease. Epidemiological research has shown that urolithiasis is approximately twice as common in men as in women, but the underlying mechanism of this sex-related prevalence is unclear. Oxalate in the organism partially originate from food (exogenous oxalate) and largely as a metabolic end-product from numerous precursors generated mainly in the liver (endogenous oxalate). Oxalate concentrations in plasma and urine can be modified by various foodstuffs, which can interact in positively or negatively by affecting oxalate absorption, excretion, and/or its metabolic pathways. Oxalate is mostly removed from blood by kidneys and partially via bile and intestinal excretion. In the kidneys, after reaching certain conditions, such as high tubular concentration and damaged integrity of the tubule epithelium, oxalate can precipitate and initiate the formation of stones. Recent studies have indicated the importance of the SoLute Carrier 26 (SLC26) family of membrane transporters for handling oxalate. Two members of this family [Sulfate Anion Transporter 1 (SAT-1; SLC26A1) and Chloride/Formate EXchanger (CFEX; SLC26A6)] may contribute to oxalate transport in the intestine, liver, and kidneys. Malfunction or absence of SAT-1 or CFEX has been associated with hyperoxaluria and urolithiasis. However, numerous questions regarding their roles in oxalate transport in the respective organs and male-prevalent urolithiasis, as well as the role of sex hormones in the expression of these transporters at the level of mRNA and protein, still remain to be answered. PMID:24384768

  17. Effects of breathing sulfur dioxide and an acidic sulfate aerosol during exercise on selected pulmonary function measurements

    SciTech Connect

    Jones, D.L.

    1985-01-01

    This study was undertaken to determine the effects of ambient air, acidic sulfate aerosol, sulfur dioxide, and the combination of sulfur dioxide and aerosol on selected pulmonary function measurements after 20 minutes of exercise at 75%-80% maximal heart rate in a hot (36-19/sup 0/C) and humid (70-90% RH) environment. Six male subjects between the ages 26 and 33 years with no pre-existing pulmonary or cardiovascular problems rode a stationary bicycle for 20 minutes during each exposure condition at a workload pre-set to assure that each subject would attain an average minute ventilation of 50-60 1/min (BTPS). Exposure to 2.5 ppm sulfur dioxide alone led to a significant lowering of FVC, FEV1, and FEF50. Exposure to sulfur dioxide plus aerosol led to a significant decrease of FVC. Baseline comparisons reflected a significant decline in FVC, FEV1, FEF25, FEF50, FEF75, and FEF25-75 between the pre-ambient and post-exposure. This decline suggests a residual effect of the air pollutant exposures. Significant differences were also observed between the pre-aerosol and pre-sulfur dioxide exposures for FVC, FEV1, FEF50, and FEF25-75.

  18. Hygroscopic Characteristics of Alkylaminium Carboxylate Aerosols.

    PubMed

    Gomez-Hernandez, Mario; McKeown, Megan; Secrest, Jeremiah; Marrero-Ortiz, Wilmarie; Lavi, Avi; Rudich, Yinon; Collins, Don R; Zhang, Renyi

    2016-03-01

    The hygroscopic growth factor (HGF) and cloud condensation nuclei (CCN) activity for a series of alkylaminium carboxylate aerosols have been measured using a hygroscopicity tandem differential mobility analyzer coupled to a condensation particle counter and a CCN counter. The particles, consisting of the mixtures of mono- (acetic, propanoic, p-toluic, and cis-pinonic acid) and dicarboxylic (oxalic, succinic, malic, adipic, and azelaic acid) acid with alkylamine (mono-, di-, and trimethylamines), represent those commonly found under diverse environmental conditions. The hygroscopicity parameter (κ) of the alkylaminium carboxylate aerosols was derived from the HGF and CCN results and theoretically calculated. The HGF at 90% RH is in the range of 1.3 to 1.8 for alkylaminium monocarboxylates and 1.1 to 2.2 for alkylaminium dicarboxylates, dependent on the molecular functionality (i.e., the carboxylic or OH functional group in organic acids and methyl substitution in alkylamines). The κ value for all alkylaminium carboxylates is in the range of 0.06-1.37 derived from the HGF measurements at 90% RH, 0.05-0.49 derived from the CCN measurements, and 0.22-0.66 theoretically calculated. The measured hygroscopicity of the alkylaminium carboxylates increases with decreasing acid to base ratio. The deliquescence point is apparent for several of the alkylaminium dicarboxylates but not for the alkylaminium monocarboxylates. Our results reveal that alkylaminium carboxylate aerosols exhibit distinct hygroscopic and deliquescent characteristics that are dependent on their molecular functionality, hence regulating their impacts on human health, air quality, and direct and indirect radiative forcing on climate. PMID:26794419

  19. Mechanisms leading to oligomers and SOA through aqueous photooxidation: insights from OH radical oxidation of acetic acid and methylglyoxal

    NASA Astrophysics Data System (ADS)

    Tan, Y.; Lim, Y. B.; Altieri, K. E.; Seitzinger, S. P.; Turpin, B. J.

    2012-01-01

    Previous experiments have demonstrated that the aqueous OH radical oxidation of methylglyoxal produces low volatility products including pyruvate, oxalate and oligomers. These products are found predominantly in the particle phase in the atmosphere, suggesting that methylglyoxal is a precursor of secondary organic aerosol (SOA). Acetic acid plays a central role in the aqueous oxidation of methylglyoxal and it is a ubiquitous product of gas phase photochemistry, making it a potential "aqueous" SOA precursor in its own right. However, the fate of acetic acid upon aqueous-phase oxidation is not well understood. In this research, acetic acid (20 μM-10 mM) was oxidized by OH radicals, and pyruvic acid and methylglyoxal experimental samples were analyzed using new analytical methods, in order to better understand the formation of SOA from acetic acid and methylglyoxal. Glyoxylic, glycolic, and oxalic acids formed from acetic acid and OH radicals. In contrast to the aqueous OH radical oxidation of methylglyoxal, the aqueous OH radical oxidation of acetic acid did not produce succinic acid and oligomers. This suggests that the methylgloxal-derived oligomers do not form through the acid catalyzed esterification pathway proposed previously. Using results from these experiments, radical mechanisms responsible for oligomer formation from methylglyoxal oxidation in clouds and wet aerosols are proposed. The importance of acetic acid/acetate as an SOA precursor is also discussed. We hypothesize that this and similar chemistry is central to the daytime formation of oligomers in wet aerosols.

  20. Hydroxy fatty acids in remote marine aerosols as microbial tracers: Long term study on β-hydroxy fatty acids from the remote marine Island, Chichi-Jima

    NASA Astrophysics Data System (ADS)

    Tyagi, P.

    2014-12-01

    To better understand the long-range atmospheric transport of microbial aerosols from Southeast Asia to the western North Pacific, marine aerosols were collected at a remote Island, Chichi-Jima on a biweekly basis during 1990-1993. These samples were investigated for the atmospheric abundances of hydroxy fatty acids (OH FAs). β-OH FAs are the major structural components of endotoxins in the outer membrane of Gram-negative bacteria (GNB) whereas w-OH FAs are present in cell walls of higher plants. Thus, we tested the applicability of the β-OH FAs (C10-C18) and ω-OH FAs (C16-C26) to assess the Gram-negative bacteria (GNB) and contribution of terrestrial higher plants, respectively. The average concentrations of β- and ω-OH FAs show pronounced seasonal variability with spring maximum (~301 ng/m-3 and ~ 272 ng/m-3, respectively). The concentrations of total OH FAs increased in winter/spring and decreased in summer/autumn, except for 1992-93. This seasonal trend can be interpreted by the atmospheric transport of microbial soil dust and higher plant metabolites from the Asian continent during winter/spring, when westerly winds dominate over the western North Pacific. The even carbon predominance of β- and ω-OH FAs (80 and 74 % of total) in marine aerosols could be explained by their significant contribution from GNB and terrestrial higher plants. These results have implications towards assessing the bacterial transport in the continental outflows. This study also confirms that β-OH FAs can be used as bacterial tracers in ambient aerosol samples.Keywords: β- and ω-hydroxy fatty acids, terrestrial biomarkers, marine aerosols, GC-MS

  1. On the composition of ammonia-sulfuric-acid ion clusters during aerosol particle formation

    NASA Astrophysics Data System (ADS)

    Schobesberger, S.; Franchin, A.; Bianchi, F.; Rondo, L.; Duplissy, J.; Kürten, A.; Ortega, I. K.; Metzger, A.; Schnitzhofer, R.; Almeida, J.; Amorim, A.; Dommen, J.; Dunne, E. M.; Ehn, M.; Gagné, S.; Ickes, L.; Junninen, H.; Hansel, A.; Kerminen, V.-M.; Kirkby, J.; Kupc, A.; Laaksonen, A.; Lehtipalo, K.; Mathot, S.; Onnela, A.; Petäjä, T.; Riccobono, F.; Santos, F. D.; Sipilä, M.; Tomé, A.; Tsagkogeorgas, G.; Viisanen, Y.; Wagner, P. E.; Wimmer, D.; Curtius, J.; Donahue, N. M.; Baltensperger, U.; Kulmala, M.; Worsnop, D. R.

    2015-01-01

    The formation of particles from precursor vapors is an important source of atmospheric aerosol. Research at the Cosmics Leaving OUtdoor Droplets (CLOUD) facility at CERN tries to elucidate which vapors are responsible for this new-particle formation, and how in detail it proceeds. Initial measurement campaigns at the CLOUD stainless-steel aerosol chamber focused on investigating particle formation from ammonia (NH3) and sulfuric acid (H2SO4). Experiments were conducted in the presence of water, ozone and sulfur dioxide. Contaminant trace gases were suppressed at the technological limit. For this study, we mapped out the compositions of small NH3-H2SO4 clusters over a wide range of atmospherically relevant environmental conditions. We covered [NH3] in the range from < 2 to 1400 pptv, [H2SO4] from 3.3 × 106 to 1.4 × 109 cm-3 (0.1 to 56 pptv), and a temperature range from -25 to +20 °C. Negatively and positively charged clusters were directly measured by an atmospheric pressure interface time-of-flight (APi-TOF) mass spectrometer, as they initially formed from gas-phase NH3 and H2SO4, and then grew to larger clusters containing more than 50 molecules of NH3 and H2SO4, corresponding to mobility-equivalent diameters greater than 2 nm. Water molecules evaporate from these clusters during sampling and are not observed. We found that the composition of the NH3-H2SO4 clusters is primarily determined by the ratio of gas-phase concentrations [NH3] / [H2SO4], as well as by temperature. Pure binary H2O-H2SO4 clusters (observed as clusters of only H2SO4) only form at [NH3] / [H2SO4] < 0.1 to 1. For larger values of [NH3] / [H2SO4], the composition of NH3-H2SO4 clusters was characterized by the number of NH3 molecules m added for each added H2SO4 molecule n (Δm/Δ n), where n is in the range 4-18 (negatively charged clusters) or 1-17 (positively charged clusters). For negatively charged clusters, Δ m/Δn saturated between 1 and 1.4 for [NH3] / [H2SO4] > 10. Positively

  2. On the composition of ammonia-sulfuric acid clusters during aerosol particle formation

    NASA Astrophysics Data System (ADS)

    Schobesberger, S.; Franchin, A.; Bianchi, F.; Rondo, L.; Duplissy, J.; Kürten, A.; Ortega, I. K.; Metzger, A.; Schnitzhofer, R.; Almeida, J.; Amorim, A.; Dommen, J.; Dunne, E. M.; Ehn, M.; Gagné, S.; Ickes, L.; Junninen, H.; Hansel, A.; Kerminen, V.-M.; Kirkby, J.; Kupc, A.; Laaksonen, A.; Lehtipalo, K.; Mathot, S.; Onnela, A.; Petäjä, T.; Riccobono, F.; Santos, F. D.; Sipilä, M.; Tomé, A.; Tsagkogeorgas, G.; Viisanen, Y.; Wagner, P. E.; Wimmer, D.; Curtius, J.; Donahue, N. M.; Baltensperger, U.; Kulmala, M.; Worsnop, D. R.

    2014-05-01

    The formation of particles from precursor vapors is an important source of atmospheric aerosol. Research at the Cosmics Leaving OUtdoor Droplets (CLOUD) facility at CERN tries to elucidate which vapors are responsible for this new particle formation, and how in detail it proceeds. Initial measurement campaigns at the CLOUD stainless-steel aerosol chamber focused on investigating particle formation from ammonia (NH3) and sulfuric acid (H2SO4). Experiments were conducted in the presence of water, ozone and sulfur dioxide. Contaminant trace gases were suppressed at the technological limit. For this study, we mapped out the compositions of small NH3-H2SO4 clusters over a wide range of atmospherically relevant environmental conditions. We covered [NH3] in the range from <2 to 1400 pptv, [H2SO4] from 3.3 × 106 to 1.4 × 109 cm-3, and a temperature range from -25 to +20 °C. Negatively and positively charged clusters were directly measured by an atmospheric pressure interface time-of-flight (APi-TOF) mass spectrometer, as they initially formed from gas-phase NH3 and H2SO4, and then grew to larger clusters containing more than 50 molecules of NH3 and H2SO4, corresponding to mobility-equivalent diameters greater than 2 nm. Water molecules evaporate from these clusters during sampling and are not observed. We found that the composition of the NH3-H2SO4 clusters is primarily determined by the ratio of gas-phase concentrations [NH3] / [H2SO4], as well as by temperature. Pure binary H2O-H2SO4 clusters (observed as clusters of only H2SO4) only form at [NH3] / [H2SO4]<0.1 to 1. For larger values of [NH3] / [H2SO4], the composition of NH3-H2SO4 clusters was characterized by the number of NH3 molecules m added for each added H2SO4 molecule n (Δm / Δn), where n is in the range 4-18 (negatively charged clusters) or 1-17 (positively charged clusters). For negatively charged clusters, Δm / Δn saturated between 1 and 1.4 for [NH3] / [H2SO4]>10. Positively charged clusters grew on

  3. Oxalobacter sp. reduces urinary oxalate excretion by promoting enteric oxalate secretion.

    PubMed

    Hatch, M; Cornelius, J; Allison, M; Sidhu, H; Peck, A; Freel, R W

    2006-02-01

    The primary goal of this study was to test the hypothesis that Oxalobacter colonization alters colonic oxalate transport thereby reducing urinary oxalate excretion. In addition, we examined the effects of intraluminal calcium on Oxalobacter colonization and tested the hypothesis that endogenously derived colonic oxalate could be degraded by lyophilized Oxalobacter enzymes targeted to this segment of the alimentary tract. Oxalate fluxes were measured across short-circuited, in vitro preparations of proximal and distal colon removed from Sprague-Dawley rats and placed in Ussing chambers. For these studies, rats were colonized with Oxalobacter either artificially or naturally, and urinary oxalate, creatinine and calcium excretions were determined. Colonized rats placed on various dietary treatment regimens were used to evaluate the impact of calcium on Oxalobacter colonization and whether exogenous or endogenous oxalate influenced colonization. Hyperoxaluric rats with some degree of renal insufficiency were also used to determine the effects of administering encapsulated Oxalobacter lysate on colonic oxalate transport and urinary oxalate excretion. We conclude that in addition to its intraluminal oxalate-degrading capacity, Oxalobacter interacts physiologically with colonic mucosa by inducing enteric oxalate secretion/excretion leading to reduced urinary excretion. Whether Oxalobacter, or products of Oxalobacter, can therapeutically reduce urinary oxalate excretion and influence stone disease warrants further investigation in long-term studies in various patient populations. PMID:16518326

  4. Association analysis for oxalate concentration in spinach

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Screening and breeding low-oxalate germplasm is a major objective in spinach breeding. This research aims to conduct association analysis and identify SNP markers associated with oxalate concentration in spinach germplasm. A total of 310 spinach genotypes including 300 USDA germplasm accessions and ...

  5. Engineering calcium oxalate crystal formation in Arabidopsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many plants accumulate crystals of calcium oxalate. Just how these crystals form remains unknown. To gain insight into the mechanisms regulating calcium oxalate crystal formation, a crystal engineering approach was initiated utilizing the non-crystal accumulating plant, Arabidopsis. The success of t...

  6. Aerosol Acidity in the New England Coastal Atmosphere During Summer 2002

    NASA Astrophysics Data System (ADS)

    Pszenny, A. A.; Keene, W. C.; Maben, J. R.; Stevenson, E.; Wall, A.

    2003-12-01

    Aerosol pH controls important multiphase chemical pathways in the atmosphere but absolute values are poorly constrained. As part of the New England Air Quality Study, aerosol pH was quantified based on multiple independent approaches and results were intercompared for consistency. Soluble, reactive trace gases with pH-dependent solubilities (HNO3, NH3, HCl, HCOOH, and CH3COOH) were sampled with mist chambers. Size-segregated aerosols were sampled in parallel with cascade impactors and analyzed for major ionic constituents. H+ was measured directly in minimally diluted, 5-μ L spots on surfaces of impaction substrates with a flat-surface, field-effect transistor. Aerosol liquid water contents (LWCs) were calculated with hygrospocity models. Aerosol pHs required to sustain the measured phase partitioning of each analyte were inferred based on corresponding thermodynamic properties and direct pH measurements were extrapolated to ambient LWCs. The ensemble of approaches yielded coherent results. Sea-salt pHs ranged from about 2 to the mid 4s and sub-μ m aerosol pHs ranged from <1 to the mid 3s. The H+ + SO42-<-> HSO4- equilibrium strongly buffered aerosol pH in all size fractions.

  7. Terpenylic acid and nine-carbon multifunctional compounds formed during the aging of β-pinene ozonolysis secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Sato, Kei; Jia, Tianyu; Tanabe, Kiyoshi; Morino, Yu; Kajii, Yoshizumi; Imamura, Takashi

    2016-04-01

    Recent field and laboratory studies suggest that forest aerosol particles contain more highly functionalized organic molecules than pinonic acid, a traditional molecular maker of secondary organic aerosol (SOA) particles. To investigate the reaction mechanisms during the aging of biogenic SOAs, the gases and particles formed from the ozonolysis of β- and α-pinene were exposed to OH radicals in a laboratory chamber. The particle samples were collected before and after OH exposure for analysis by liquid chromatography-negative electrospray ionization time-of-flight mass spectrometry. Pinic acid and terpenylic acid were abundant products in both β- and α-pinene ozonolysis SOA particles. Terpenylic acid and products with m/z 201.08 present in β-pinene SOA particles increased upon exposing SOA to OH radicals, whereas 3-methyl-1,2,3-butanetricarboxylic acid present in α-pinene SOA particles increased upon exposing SOA to OH radicals. The products with m/z 201.08 were suggested to be C9H14O5 compounds. Similar C9H14O5 compounds and terpenylic acid were also detected in SOA particles formed from the photooxidation of nopinone, a major first-generation product of β-pinene ozonolysis. The OH-initiated oxidation of nopinone will contribute to the formation of terpenylic acid and C9H14O5 compounds during the aging of β-pinene SOA. A formation mechanism for terpenylic acid via gas-phase diaterpenylic acid formation followed by self-dehydration in the condensed phase was suggested.

  8. Respiratory hospital admissions and summertime haze air pollution in Toronto, Ontario: consideration of the role of acid aerosols.

    PubMed

    Thurston, G D; Ito, K; Hayes, C G; Bates, D V; Lippmann, M

    1994-05-01

    A study of air pollution and daily hospital admissions for respiratory causes was conducted in Toronto, Ontario. Fine aerosol (da < 2.5 microns) samples were collected daily at a central city site during July and August 1986, 1987, and 1988 and were subsequently extracted and analyzed for daily particulate phase aerosol strong acidity (H+) and sulfates (SO4 =). Daily counts of respiratory admissions to 22 acute care hospitals and daily meteorological and environmental data (e.g. ozone [O3], total suspended particulate matter [TSP], and thoracic particle mass [PM10] were also obtained. Regression analyses indicated that only the O3, H+, and SO4 = associations with respiratory and asthma admissions remained consistently significant after controlling for temperature. Even after excluding days with maximum 1-hr O3 > 120 ppb, O3 was still strongly significant. In the various model specifications considered, the relative particle metric strengths of association with admissions were generally H+ > SO4 = > FP > PM10 > TSP, indicating that particle size and composition are of central importance in defining the adverse human health effects of particulate matter. On average, summertime haze air pollution was associated with 24% of all respiratory admissions (21% with O3, 3% with H+). On peak pollution days, however, aerosol acidity yielded the highest relative risk estimates (e.g., RR = 1.5 at 391 nmole/m3 H+), and summertime haze was associated with roughly half of all respiratory admissions.

  9. pH dependency of sclerotial development and pathogenicity revealed by using genetically defined oxalate-minus mutants of Sclerotinia sclerotiorum.

    PubMed

    Xu, Liangsheng; Xiang, Meichun; White, David; Chen, Weidong

    2015-08-01

    The devastating plant pathogen Sclerotinia sclerotiorum produces copious (up to 50 mM) amounts of oxalic acid, which, for over a quarter century, has been claimed as the pathogenicity determinant based on UV-induced mutants that concomitantly lost oxalate production and pathogenicity. Such a claim was made without fulfilling the molecular Koch's postulates because the UV mutants are genetically undefined and harbour a developmental defect in sclerotial production. Here, we generated oxalate-minus mutants of S. sclerotiorum using two independent mutagenesis techniques, and tested the resulting mutants for growth at different pHs and for pathogenicity on four host plants. The oxalate-minus mutants accumulated fumaric acid, produced functional sclerotia and have reduced ability to acidify the environment. The oxalate-minus mutants retained pathogenicity on plants, but their virulence varied depending on the pH and buffering capacity of host tissue. Acidifying the host tissue enhanced virulence of the oxalate-minus mutants, whereas supplementing with oxalate did not. These results suggest that it is low pH, not oxalic acid itself, that establishes the optimum conditions for growth, reproduction, pathogenicity and virulence expression of S. sclerotiorum. Exonerating oxalic acid as the primary pathogenicity determinant will stimulate research into identifying additional candidates as pathogenicity factors towards better understanding and managing Sclerotinia diseases. PMID:25720941

  10. Effect of Oxalate on the Recycle of Neptunium Filtrate Solution by Anion Exchange

    SciTech Connect

    Kyser, E

    2004-11-18

    A series of laboratory column runs has been performed that demonstrates the recovery of neptunium (Np) containing up to 0.05 M oxalate. Np losses were generally less than one percent to the raffinate for feed solutions that contained 2 to 10 g Np/L. Up to 16 percent Np losses were observed with lower Np feed concentrations, but those losses were attributed to the shortened residence times rather than the higher oxalate to Np ratios. Losses in the plant are expected to be significantly less due to the lower cross-section flowrate possible with existing plant pumps. Elimination of the permanganate treatment of filtrates appears to be reasonable since the amount of Np in those filtrates does not appear to be practical to recover. Combination of untreated filtrates with other actinide rich solutions is not advisable as precipitation problems are likely. If untreated filtrates are kept segregated from other actinide rich streams, the recovery of the remaining Np is probably still possible, but could be limited due to the excessively high oxalate to Np ratio. The persistence of hydrazine/hydrazoic acid in filtrate solutions dictates that the nitrite treatment be retained to eliminate those species from the filtrates prior to transfer to the canyon. Elimination of the permanganate treatment of precipitator flushes and recovery by anion exchange does not appear to be limited by the oxalate effect on anion exchange. Np from solutions with higher oxalate to Np molar ratios than expected in precipitator flushes was recovered with low to modest losses. Solubility problems appear to be unlikely when the moles of oxalate involved are less than the total number of moles of Np due to complexation effects. The presence of significant concentrations of iron (Fe) in the solutions will further decrease the probability of Np oxalate precipitation due the formation of Fe oxalate complexes. Np oxalate solubility data in 8 M HNO{sub 3} with from one to six times as much oxalate as Np have

  11. A Computational Study of Acid Catalyzed Aerosol Reactions of Atmospherically Relevant Epoxides

    EPA Science Inventory

    Epoxides are important intermediates of atmospheric isoprene oxidation. Their subsequent reactions in the particle phase lead to the production of organic compounds detected in ambient aerosols. We apply density functional theory to determine the important kinetic factors that ...

  12. The uptake of HO2 radicals to organic aerosols

    NASA Astrophysics Data System (ADS)

    Matthews, Pascale; Krapf, Manuel; Dommen, Josef; George, Ingrid; Whalley, Lisa; Ingham, Trevor; Baeza-Romero, Maria Teresa; Ammann, Markus; Heard, Dwayne

    2014-05-01

    , however, this was reduced to 0.008 ± 0.009 when EDTA was added in a 1:1 ratio with copper and 0.003 ± 0.004 when oxalic acid was added in a 10:1 ratio with copper. SOA aerosols were also investigated at PSI and HO2 uptake coefficients of γ < 0.004 and γ = 0.004 ± 0.003 were measured for alpha-pinene and trimethylbenzene derived SOA respectively. [1] Sommariva, R. et al. Atmos. Chem. Phys.2006, 6, 1135-1153. [2] Whalley, L.K. et al. Atmos. Chem. Phys. 2010, 10, 1555-1576. [3] Turpin, B.J. et al. Atmos. Environ. 2000, 34, 2983-3013 [4] Taketani, F. et al Int. J. Chem. Kin. 2013, 9, 560-565.

  13. Synthesis of labeled oxalic acid derivatives

    DOEpatents

    Martinez, Rodolfo A.; Unkefer, Clifford J.; Alvarez, Marc A.

    2004-06-22

    The present invention is directed to labeled compounds, specifically ##STR1## where each C* is selected from the group consisting of a carbon-12, i.e., .sup.12 C, or a carbon-13, i.e., .sup.13 C and at least one C* is .sup.13 C, R.sup.1 is selected from the group of C.sub.1 -C.sub.4 lower alkyl and aryl, and X is selected from the group of --NR.sup.2 R.sup.3 where R.sup.2 and R.sup.3 are each independently selected from the group of C.sub.1 -C.sub.4 lower alkyl, alkoxy and aryl, --SR.sup.4 where R.sup.4 is selected from the group of C.sub.1 -C.sub.4 lower alkyl, alkoxy and aryl, and --OR.sup.5 where R.sup.5 is selected from the group of C.sub.1 -C.sub.4 lower alkyl, alkoxy and aryl with the proviso that when R.sup.1 is methyl then R.sup.5 is other than methyl, when R.sup.1 is ethyl then R.sup.5 is other than ethyl, and when R.sup.1 is benzyl then R.sup.5 is other than benzyl.

  14. Effort to regulate acid aerosol pollution, based on new human health data, still up in the air

    SciTech Connect

    Goldsmith, M.F.

    1990-08-01

    Acid aerosols in the atmosphere are having acute short- and long-term respiratory effects. That is the view of David V. Bates, MD, who spoke recently at the World Conference on Lung Health in Boston, Mass. Bates, who is professor emeritus of medicine in the Department of Health Care and Epidemiology, University of British Columbia, Vancouver, has spent nearly 40 years in studies that make him, according to colleagues, the guru of respiratory physiology. Acid aerosols are colloidal suspensions of hydrogen ion-containing particles that form the misty air pollution called summer haze. They are generated commonly by sulfur dioxide and nitrogen dioxide emissions from coalfired industrial plants. The emissions are transformed into ammonium bisulfate or sulfuric acid and nitric acid, well-known air pollutants. In the ambient air they mix with ozone. Although researchers do not yet have the sort of massive and unidirectional proof that there is for cigarette smoking causing lung cancer, Bates says, if you want early detection and early action to ameliorate the situation, the kinds of indicators that are now positive are very important indeed.

  15. Reexamination of London, England, mortality in relation to exposure to acidic aerosols during 1963-1972 winters

    SciTech Connect

    Thurston, G.D.; Ito, K.; Lippmann, M.; Hayes, C.

    1989-02-01

    Air pollution epidemiology since the 1950s has been able to demonstrate that increases in daily mortality in London, England, were associated with elevated concentrations of index air pollutants, i.e., British Smoke (BS) and sulfur dioxide (SO/sub 2/). In this work, we reanalyze that portion of the 1958-1972 winter mortality-pollution record for which daily direct acid aerosol measurements were made at a central site in London (St. Bartholomew's Medical College). The purposes of these exploratory analyses are to examine the dataset for indications of a relationship between acid aerosol pollution and human mortality and to compare any noted associations with those for other pollution variables. It is found that the log of acid aerosol concentrations is more strongly associated with raw total mortality in bivariate analyses than is BS or SO2, despite the fact that acid data are available from only one central site (versus seven disperse sites for BS and SO/sub 2/). The logarithmic nature of the exposure side of the H/sub 2/SO/sub 4/-mortality relationship implies a saturation model of pollution effects, possibly due to multiday pollution harvesting influences on a susceptible subpopulation. Moreover, mortality-pollution cross-correlation analyses indicate that mortality effects usually follow pollution in time, supporting a causal relationship between the two. The apparent advantage of H/sub 2/SO/sub 4/ over BS in predicting total raw mortality is consistent with the hypothesis that it is the portion of particulate mass of greater health significance and may also allow the development of London mortality results which are more easily transferable to other environments than is the case for existing BS results.

  16. Reexamination of London, England, mortality in relation to exposure to acidic aerosols during 1963-1972 winters.

    PubMed

    Thurston, G D; Ito, K; Lippmann, M; Hayes, C

    1989-02-01

    Air pollution epidemiology since the 1950s has been able to demonstrate that increases in daily mortality in London, England, were associated with elevated concentrations of index air pollutants, i.e., British Smoke (BS) and sulfur dioxide (SO2). In this work, we reanalyze that portion of the 1958-1972 winter mortality-pollution record for which daily direct acid aerosol measurements were made at a central site in London (St. Bartholomew's Medical College). The purposes of these exploratory analyses are to examine the dataset for indications of a relationship between acid aerosol pollution and human mortality and to compare any noted associations with those for other pollution variables. It is found that the log of acid aerosol concentrations is more strongly associated with raw total mortality in bivariate analyses than is BS or SO2, despite the fact that acid data are available from only one central site (versus seven disperse sites for BS and SO2). The logarithmic nature of the exposure side of the H2SO4-mortality relationship implies a saturation model of pollution effects, possibly due to multiday pollution harvesting influences on a susceptible subpopulation. Moreover, mortality-pollution cross-correlation analyses indicate that mortality effects usually follow pollution in time, supporting a causal relationship between the two. The apparent advantage of H2SO4 over BS in predicting total raw mortality is consistent with the hypothesis that it is the portion of particulate mass of greater health significance and may also allow the development of London mortality results which are more easily transferable to other environments than is the case for existing BS results.