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Sample records for nitrogen 20

  1. 20-Kw nitrogen diluent chemical oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Yang, Tientsai T.; Bhowmik, Anup; Burde, David H.; Clark, Roy; Carroll, S.; Dickerson, Robert A.; Eblen, J.; Gylys, Vytas T.; Hsia, Y. C.; Humphreys, Richard H., Jr.; Moon, L. F.; Hurlock, Steve C.; Tomassian, A.

    2002-09-01

    A new Chemical Oxygen-Iodine Laser (COIL) has been developed and demonstrated at chlorine flow rates up to 1 gmol/s. The laser employs a cross flow jet oxygen generator operating with no diluent. The generator product flow enters the laser cavity at Mach 1 and is accelerated by mixing with 5 gmol/s, Mach 5 nitrogen diluent in an ejector nozzle array. The nitrogen also serves as the carrier for iodine. Vortex mixing is achieved through the use of mixing tabs at the nitrogen nozzle exit. Mixing approach design and analysis, including CFD analysis, led to the preferred nozzle configuration. The selected mixing enhancement design was tested in cold flow and the results are in good agreement with the CFD predictions. Good mixing was achieved within the desired cavity flow length of 20 cm and pressure recovery about 90 Torr was measured at the cavity exit. Finally, the design was incorporated into the laser and power extraction as high as 20 kw was measured at the best operating condition of 0.9 gmol/s. Stable resonator mode footprints showed desieable intensity profiles, which none of the sugar scoop profiles characteristic of the conventional COIL designs.

  2. Ab initio study of nitrogen-multisubstituted neutral and positively charged C{sub 20} fullerene

    SciTech Connect

    Rani, Anita; Kumar, Ranjan

    2014-04-24

    Ab initio investigation of structural and electronic properties of Nitrogen doped fullerenes, obtained from C{sub 20} by replacing up to 10 C atoms with N atoms, are studied by means of first principals density functional theory calculations using numerical orbitals as basis sets. We have obtained the ground state structures for C{sub 20−n}N{sub n} for n=1-10. While substituting nitrogen atoms, we cannot substitute more than 9 nitrogen atoms. Nitrogen doping in C20 shows a significant change in density of states. For a better comparison with experimental measurements, we have also considered some positively charged ions and report the differences between properties of these ions and the corresponding neutral molecules.

  3. Why isn't the N20 dodecahedron ideal for three-coordinate nitrogen?

    PubMed

    Strout, Douglas L

    2005-02-24

    Nitrogen molecules are the focus of much attention for their potential as high-energy density materials. The usefulness of such molecules as energy sources depends on the stability of the molecules with respect to dissociation. Many such molecules dissociate too easily to be a stable fuel, and the reasons for such instability are related to the details of structure and bonding of the molecule. Such details will be examined for isomers of the molecule N20. N20 has a highly symmetric isomer in which the 20 atoms occupy the vertexes of a dodecahedron. This isomer is a cage molecule in which all of the faces are regular pentagons that have interior angles of 108 degrees . These angles are very close to the known bond angles in very stable nitrogen compounds such as ammonia. Such a structure with only pentagons should provide an ideal bonding environment for three-coordinate nitrogen. However, by use of theoretical calculations including density-functional theory and fourth-order perturbation theory, along with the Dunning correlation-consistent basis sets, it will be shown that dodecahedral N20 is not the most stable cage for N20. The reasons why will be discussed in terms of the structure and bonding of the molecules.

  4. Nitrogen

    USGS Publications Warehouse

    Apodaca, Lori E.

    2013-01-01

    The article presents an overview of the nitrogen chemical market as of July 2013, including the production of ammonia compounds. Industrial uses for ammonia include fertilizers, explosives, and plastics. Other topics include industrial capacity of U.S. ammonia producers CF Industries Holdings Inc., Koch Nitrogen Co., PCS Nitrogen, Inc., and Agrium Inc., the impact of natural gas prices on the nitrogen industry, and demand for corn crops for ethanol production.

  5. DSMC simulations of Mach 20 nitrogen flows about a 70 degree blunted cone and its wake

    NASA Technical Reports Server (NTRS)

    Moss, James N.; Dogra, Virendra K.; Wilmoth, Richard G.

    1993-01-01

    Numerical results obtained with the direct simulation Monte Carlo (DSMC) method are presented for Mach 20 nitrogen flow about a 70-deg blunted cone. The flow conditions simulated are those that can be obtained in existing low-density hypersonic wind tunnels. Three sets of flow conditions are simulated with freestream Knudsen numbers ranging from 0.03 to 0.001. The focus is to characterize the wake flow under rarefied conditions. This is accomplished by calculating the influence of rarefaction on wake structure along with the impact that an afterbody has on flow features. This data report presents extensive information concerning flowfield features and surface quantities.

  6. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2006-01-01

    In 2005, ammonia was produced by 15 companies at 26 plants in 16 states in the United States. Of the total ammonia production capacity, 55% was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas. US producers operated at 66% of their rated capacity. In descending order, Koch Nitrogen, Terra Industries, CF Industries, Agrium and PCS Nitrogen accounted for 81% of the US ammonia production capacity.

  7. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2012-01-01

    Ammonia was produced by 12 companies at 27 plants in 15 states in the United States during 2011. Sixty-one percent of total U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock. In 2011, U.S. producers operated at about 84 percent of their rated capacity (excluding plants that were idle for the entire year). Four companies — CF Industries Holdings Inc.; Koch Nitrogen Co.; PCS Nitrogen Inc. and Agrium Inc., in descending order — accounted for 77 percent of the total U.S. ammonia production capacity.

  8. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2004-01-01

    Ammonia is the principal source of fixed nitrogen. It was produced by 17 companies at 34 plants in the United States during 2003. Fifty-three percent of U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas, the dominant domestic feedstock.

  9. Carbon, nitrogen, and oxygen abundances in main-sequence stars. II 20 F and G stars

    NASA Astrophysics Data System (ADS)

    Clegg, R. E. S.; Tomkin, J.; Lambert, D. L.

    1981-11-01

    High-resolution Reticon spectra of red and near-infrared C I, N I, and O I lines have been analyzed to determine C, N, and O abundances in a sample of 20 F and G main-sequence stars. Their iron abundances, which have been determined from analysis of additional Reticon spectra of red Fe I lines, cover the Fe/H range from -0.9 to 0.4. Sulfur abundances have also been obtained. It is found that the variations of the carbon and sulfur abundances closely follow those of iron. The oxygen abundance varies much more slowly than iron (O/Fe = 0.48 (+ or - 0.07) Fe/H). This result confirms an earlier conclusion that oxygen is overabundant in more metal-deficient stars. The behavior of the nitrogen abundance appears to be similar to that of iron (N/Fe = 0.0 + or - 0.2). However, the unavailability of nitrogen abundances for the most metal-deficient stars in the sample makes this result less certain than the results for the other elements. These results are discussed in the light of current theories of stellar nucleosynthesis of the elements.

  10. Nitrogen

    USGS Publications Warehouse

    Kramer, D.A.

    2007-01-01

    Ammonia was produced by 15 companies at 25 plants in 16 states in the United States during 2006. Fifty-seven percent of U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of their large reserves of natural gas, the dominant domestic feedstock. In 2006, U.S. producers operated at about 72 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies, Koch Nitrogen, Terra Industries, CF Industries, PCS Nitro-gen, and Agrium, in descending order, accounted for 79 percent U.S. ammonia production capacity. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  11. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2010-01-01

    Ammonia was produced by 13 companies at 23 plants in 16 states during 2009. Sixty percent of all U.S. ammonia production capacity was centered in Louisiana. Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock. In 2009, U.S. producers operated at about 83 percent of their rated capacity (excluding plants that were idle for the entire year). Five companies — Koch Nitrogen Co.; Terra Industries Inc.; CF Industries Inc.; PCS Nitrogen Inc. and Agrium Inc., in descending order — accounted for 80 percent of the total U.S. ammonia production capacity. U.S. production was estimated to be 7.7 Mt (8.5 million st) of nitrogen (N) content in 2009 compared with 7.85 Mt (8.65 million st) of N content in 2008. Apparent consumption was estimated to have decreased to 12.1 Mt (13.3 million st) of N, a 10-percent decrease from 2008. The United States was the world's fourth-ranked ammonia producer and consumer following China, India and Russia. Urea, ammonium nitrate, ammonium phosphates, nitric acid and ammonium sulfate were the major derivatives of ammonia in the United States, in descending order of importance.

  12. Wet atmospheric deposition of nitrogen: 20 years measurement in Shenzhen City, China.

    PubMed

    Huang, Yilong; Lu, XiXi; Chen, Kai

    2013-01-01

    We presented measurements of wet deposition of NH(4)(+)-N and NO(3)(-)-N from 1986 to 2006 in Shenzhen City, China. Over the past 20 years, NO(3)(-)-N concentration had significantly increased, but a reverse trend was found for NH(4)(+)-N. The main form of total inorganic nitrogen (TIN) was NH(4)(+)-N and the average NH(4)(+)-N/NO(3)(-)-N ratio was 1.57 in this area. The contribution of NO(3)(-)-N to TIN increased from 28-42% in the period of 1986-2000 to 50-63% during 2001-2006. The increased deposition flux of NO(3)(-)-N resulted in the increasing trend of TIN, although NH(4)(+)-N showed a decreasing trend over time. Average deposition flux of TIN during 1986-2006 was 13.24 kg/ha/year, with a minimum value of 6.03kg/ha/year in 1988 and a maximum value of 20.52 kg/ha/year in 1997. Wet deposition fluxes of N appeared to vary with season, 81% occurred in the warm season (from April to September). The wet deposition of TIN to the Shenzhen Reservoir reached 8,902 kg in 2006, which contributed 9.95% of the total nonpoint pollution to the reservoir and will be increased in the future.

  13. Changes in nitrogen budget and potential risk to the environment over 20years (1990-2010) in the agroecosystems of the Haihe Basin, China.

    PubMed

    Zheng, Mengmeng; Zheng, Hua; Wu, Yingxia; Xiao, Yi; Du, Yihua; Xu, Weihua; Lu, Fei; Wang, Xiaoke; Ouyang, Zhiyun

    2015-02-01

    The nitrogen balance can serve as an indicator of the risk to the environment of nitrogen loss from agricultural land. To investigate the temporal and spatial changes in agricultural nitrogen application and its potential threat to the environment of the Haihe Basin in China, we used a database of county-level agricultural statistics to calculate agricultural nitrogen input, output, surplus intensity, and use efficiency. Chemical fertilizer nitrogen input increased by 51.7% from 1990 to 2000 and by 37.2% from 2000 to 2010, concomitant with increasing crop yields. Simultaneously, the nitrogen surplus intensity increased by 53.5% from 1990 to 2000 and by 16.5% from 2000 to 2010, presenting a continuously increased environmental risk. Nitrogen use efficiency decreased from 0.46 in 1990 to 0.42 in 2000 and remained constant at 0.42 in 2010, partly due to fertilizer composition and type improvement. This level indicates that more than half of nitrogen inputs are lost in agroecosystems. Our results suggest that although the improvement in fertilizer composition and types has partially offset the decrease in nitrogen use efficiency, the environmental risk has still increased gradually over the past 20 years, along with the increase in crop yields and nitrogen application. It is important to achieve a better nitrogen balance through more effective management to significantly reduce the environmental risk, decrease nitrogen surplus intensity, and increase nitrogen use efficiency without sacrificing crop yields. Copyright © 2014. Published by Elsevier B.V.

  14. Vertical patterns of ecoenzyme activities in forest soils after 20 years of simulated nitrogen deposition

    NASA Astrophysics Data System (ADS)

    Forstner, Stefan J.; Kloss, Stefanie; Keiblinger, Katharina M.; Schleppi, Patrick; Hagedorn, Frank; Gundersen, Per; Wanek, Wolfgang; Gerzabek, Martin H.; Zechmeister-Boltenstern, Sophie

    2015-04-01

    The below-ground part of terrestrial carbon (C), nitrogen (N) and phosphorus (P) cycles are controlled by soil microorganisms. In order to meet their energy and nutrient requirements, soil microbes produce enzymes which catalyze the release of smaller molecules from decomposing organic matter. Recent work has shown that the potential activities of commonly measured enzymes for C-, N-, and P-acquisition can be related to microbial demand of these elements and link stoichiometry of soil microbes and their resources. Regulation of enzyme production might therefore be an important mechanism for microbes to adapt to different resource regimes. To investigate links between ecoenzyme activities, soil depth and N availability we make use of two long-term experiments where N has been added to two temperate forest stands for over 20 years. At both sites Norway spruce is the dominating tree whereas other site characteristics like soil type, climate, parent material and morphology differ. Increased N deposition was simulated by regularly applying NH4NO3 in the range of 35 kg N ha-1 y-1 (Klosterhede, Denmark; since 1992) and 25 kg N ha-1 y-1 (Alptal, Switzerland; since 1995), respectively. We hypothesize that ecoenzyme activities will decline exponentially with depth reflecting well-established similar trends in organic matter and microbial biomass. However, when normalized to microbial biomass we further hypothesize that activities will not change or even increase down the soil profile. Concerning microbial nutrient limitation, we expect to see a shift from N- to C-limitation with depth which should be reflected in increasing ratios of C- to N-acquiring enzymes. Preliminary results suggest that activity of hydrolytic enzymes generally decreases with depth, although this drop in activity is not so pronounced when normalized to microbial biomass. Oxidative enzymes, on the other hand, do not follow this pattern, often showing increased activities with depth. We further see site

  15. Enhanced Nitrogen in Morphologically Disturbed Blue Compact Galaxies at 0.20 < z < 0.35: Probing Galaxy Merging Features

    NASA Astrophysics Data System (ADS)

    Chung, Jiwon; Rey, Soo-Chang; Sung, Eon-Chang; Yeom, Bum-Suk; Humphrey, Andrew; Yi, Wonhyeong; Kyeong, Jaemann

    2013-04-01

    We present a study of correlations between the elemental abundances and galaxy morphologies of 91 blue compact galaxies (BCGs) at z = 0.20-0.35 with Sloan Digital Sky Survey (SDSS) DR7 data. We classify the morphologies of the galaxies as either "disturbed" or "undisturbed" by visual inspection of the SDSS images, and using the Gini coefficient and M 20. We derive oxygen and nitrogen abundances using the Te method. We find that a substantial fraction of BCGs with disturbed morphologies, indicative of merger remnants, show relatively high N/O and low O/H abundance ratios. The majority of the disturbed BCGs exhibit higher N/O values at a given O/H value compared to the morphologically undisturbed galaxies, implying more efficient nitrogen enrichment in disturbed BCGs. We detect Wolf-Rayet (WR) features in only a handful of the disturbed BCGs, which appears to contradict the idea that WR stars are responsible for high nitrogen abundance. Combining these results with Galaxy Evolution Explorer GR6 ultraviolet (UV) data, we find that the majority of the disturbed BCGs show systematically lower values of the Hα to near-UV star formation rate ratio. The equivalent width of the Hβ emission line is also systematically lower in the disturbed BCGs. Based on these results, we infer that disturbed BCGs have undergone star formation over relatively longer timescales, resulting in a more continuous enrichment of nitrogen. We suggest that this correlation between morphology and chemical abundances in BCGs is due to a difference in their recent star formation histories.

  16. Correlation Between Experimental and Calculated Phase Fractions in Aged 20Cr32Ni1Nb Austenitic Stainless Steels Containing Nitrogen

    NASA Astrophysics Data System (ADS)

    Dewar, Matthew P.; Gerlich, Adrian P.

    2013-02-01

    A centrifugally cast 20Cr32Ni1Nb stainless steel manifold in service for 16 years at temperatures ranging from 1073 K to 1123 K (800 °C to 850 °C) has been characterized using scanning electron microscopy (SEM), electron probe micro-analysis (EPMA), auger electron spectroscopy (AES), and X-ray diffraction (XRD). Nb(C,N), M23C6, and the silicide G-phases (Ni16Nb6Si7) were all identified in a conventional SEM, while the nitride Z-phase (CrNbN) was observed only in AES. M23C6, Z-phase and G-phase were characterized in XRD. Thermodynamic equilibrium calculations using ThermoCalc Version S, with the TCS Steel and Fe-alloys Database (TCFE6), and Thermotech Ni-based Superalloys Database (TTNI8) were validated by comparing experimental phase fraction results obtained from both EPMA and AES. A computational study looking at variations in the chemical composition of the alloy, and how they affect phase equilibria, was investigated. Increasing the nitrogen concentration is shown to decrease G-phase formation, where it is replaced by other intermetallic phases such as Z-phase and π-phase that do not experience liquation during pre-weld annealing treatments. Suppressing G-phase formation was ultimately determined to be a function of minimizing silicon content, and understabilizing the Nb/(C + 6/7N) ratio.

  17. Effects of soil and foliar applications of nitrogen fertilizers on a 20-year-old Douglas-fir stand

    Treesearch

    Richard E. Miller; Steve. Wert

    1979-01-01

    We compared growth and cone production of Douglas-fir treated 4 years earlier with ISO pounds N per acre applied as urea prill by hand and as a 32-percent N solution applied by helicopter. Nitrogen fertilization increased growth by 3 88 ft per acre during the 4 years after treatment; this 3S-percent gain was similar for both soil (prill) and foliar (solution)...

  18. Correlation between the granular structure and the mechanical properties of high-nitrogen austenitic 02Kh20AG10N4MFB steel after annealing

    NASA Astrophysics Data System (ADS)

    Bannykh, I. O.

    2016-10-01

    The effect of the annealing temperature and time on the formation of a granular structure in high-nitrogen austenitic 02Kh20AG10N4MFB steel has been studied. The hardness and the strength properties of the steel are shown to be related to the mean grain size by an inverse dependence, according to the Hall-Petch relation, and the impact toughness is proportional to the mean grain size. At annealing temperatures to 1100°C, structure formation is determined by the precipitation of secondary phases; at higher annealing temperatures, it is determined by the recrystallization of austenite grains.

  19. Technical note: Effect of determining baseline plasma urea nitrogen concentrations on subsequent posttreatment plasma urea nitrogen concentrations in 20- to 50-kilogram pigs.

    PubMed

    Waguespack, A M; Powell, S; Roux, M L; Frugé, E D; Bidner, T D; Payne, R L; Southern, L L

    2011-12-01

    Plasma urea N (PUN) has been used as an indicator of AA requirements and efficiency of AA utilization in swine. However, PUN concentrations vary among a population of pigs, even a population with a close range of BW and fed the same diet. Thus, pretreatment or baseline PUN concentrations are used as a covariate to reduce variation of posttreatment PUN. However, this procedure increases experimental costs and stress to the pigs. Data from 14 experiments (26 to 28 d in duration) conducted using PUN as a response variable were compiled into 1 data set. Each experiment had 4 to 6 treatments. The purpose of this technical report was to summarize the effect of determining pretreatment baseline PUN concentrations on subsequent posttreatment PUN concentrations in 20- to 50-kg pigs. In all experiments, pigs were fed corn- and soybean meal-based diets and low-CP diets with various AA additions; pigs were assigned to dietary treatments in a randomized complete block design with a minimum of 4 replicates of 3 to 5 pigs each. Before the start of each experiment, all pigs were fed a common diet for a minimum of 3 d. Blood samples were collected from each pig before allotment to dietary treatments (d 0) and at the end of each experiment. The baseline (d 0) PUN was analyzed as a covariate for posttreatment PUN. Data from each experiment were analyzed without and with baseline PUN in the statistical model. In all experiments combined, there were 768 possible treatment comparisons. The covariate baseline PUN was statistically significant (P < 0.10) in 9 of 14 experiments. However, only 8 treatment differences changed statistical significance as a result of analyzing the data with baseline PUN as a covariate. These 8 treatment differences were in 3 experiments. These results indicate that it is not always necessary to determine baseline PUN concentrations when feeding diets with large differences in AA content.

  20. [Profiles of the utilization of 20 amino acids as the only source of nitrogen and carbon in bacteria of the genera Klebsiella, Enterobacter, Serratia, Escherichia].

    PubMed

    Sivolodskiĭ, E P

    2005-01-01

    The profiles of the utilization of 20 protein amino acids in 118 Klebsiella pneumoniae sub- sp. pneumoniae, K. oxytoca, K. planticola, K. mobilis, Enterobacter cloacae, Serratia marscescens, S. liquefaciens, Escherichia coli strains isolated from clinical material were studied. The utilization of amino acids was determined on minimal saline agar containing amino acid as the only source of nitrogen and carbon; the results were evaluated after 72-hour incubation at 37 degrees C. 17 profiles of amino-acid utilization were thus determined, most of them genus-specific in enterobacteria: Klebsiella (profiles No. 1--6, 9, 10), Enterobacter (No. 11--13), Serratia (No. 14--16), Escherichia (No. 17). The full coincidence of amino-acid utilization profiles in bacteria of K. mobilis (No. 1, 6) and K. pneumoniae subsp. pneumoniae with out of such profiles in bacteria of the genera Enterobacter, Serratia, Escherichia was established, which confirmed that K. mobilis (formerly Enterobacter aerogenes) belonged to the genus Klebsiella.

  1. Genome Sequencing of Sulfolobus sp. A20 from Costa Rica and Comparative Analyses of the Putative Pathways of Carbon, Nitrogen, and Sulfur Metabolism in Various Sulfolobus Strains

    PubMed Central

    Dai, Xin; Wang, Haina; Zhang, Zhenfeng; Li, Kuan; Zhang, Xiaoling; Mora-López, Marielos; Jiang, Chengying; Liu, Chang; Wang, Li; Zhu, Yaxin; Hernández-Ascencio, Walter; Dong, Zhiyang; Huang, Li

    2016-01-01

    The genome of Sulfolobus sp. A20 isolated from a hot spring in Costa Rica was sequenced. This circular genome of the strain is 2,688,317 bp in size and 34.8% in G+C content, and contains 2591 open reading frames (ORFs). Strain A20 shares ~95.6% identity at the 16S rRNA gene sequence level and <30% DNA-DNA hybridization (DDH) values with the most closely related known Sulfolobus species (i.e., Sulfolobus islandicus and Sulfolobus solfataricus), suggesting that it represents a novel Sulfolobus species. Comparison of the genome of strain A20 with those of the type strains of S. solfataricus, Sulfolobus acidocaldarius, S. islandicus, and Sulfolobus tokodaii, which were isolated from geographically separated areas, identified 1801 genes conserved among all Sulfolobus species analyzed (core genes). Comparative genome analyses show that central carbon metabolism in Sulfolobus is highly conserved, and enzymes involved in the Entner-Doudoroff pathway, the tricarboxylic acid cycle and the CO2 fixation pathways are predominantly encoded by the core genes. All Sulfolobus species encode genes required for the conversion of ammonium into glutamate/glutamine. Some Sulfolobus strains have gained the ability to utilize additional nitrogen source such as nitrate (i.e., S. islandicus strain REY15A, LAL14/1, M14.25, and M16.27) or urea (i.e., S. islandicus HEV10/4, S. tokodaii strain7, and S. metallicus DSM 6482). The strategies for sulfur metabolism are most diverse and least understood. S. tokodaii encodes sulfur oxygenase/reductase (SOR), whereas both S. islandicus and S. solfataricus contain genes for sulfur reductase (SRE). However, neither SOR nor SRE genes exist in the genome of strain A20, raising the possibility that an unknown pathway for the utilization of elemental sulfur may be present in the strain. The ability of Sulfolobus to utilize nitrate or sulfur is encoded by a gene cluster flanked by IS elements or their remnants. These clusters appear to have become fixed at a

  2. Genome Sequencing of Sulfolobus sp. A20 from Costa Rica and Comparative Analyses of the Putative Pathways of Carbon, Nitrogen, and Sulfur Metabolism in Various Sulfolobus Strains.

    PubMed

    Dai, Xin; Wang, Haina; Zhang, Zhenfeng; Li, Kuan; Zhang, Xiaoling; Mora-López, Marielos; Jiang, Chengying; Liu, Chang; Wang, Li; Zhu, Yaxin; Hernández-Ascencio, Walter; Dong, Zhiyang; Huang, Li

    2016-01-01

    The genome of Sulfolobus sp. A20 isolated from a hot spring in Costa Rica was sequenced. This circular genome of the strain is 2,688,317 bp in size and 34.8% in G+C content, and contains 2591 open reading frames (ORFs). Strain A20 shares ~95.6% identity at the 16S rRNA gene sequence level and <30% DNA-DNA hybridization (DDH) values with the most closely related known Sulfolobus species (i.e., Sulfolobus islandicus and Sulfolobus solfataricus), suggesting that it represents a novel Sulfolobus species. Comparison of the genome of strain A20 with those of the type strains of S. solfataricus, Sulfolobus acidocaldarius, S. islandicus, and Sulfolobus tokodaii, which were isolated from geographically separated areas, identified 1801 genes conserved among all Sulfolobus species analyzed (core genes). Comparative genome analyses show that central carbon metabolism in Sulfolobus is highly conserved, and enzymes involved in the Entner-Doudoroff pathway, the tricarboxylic acid cycle and the CO2 fixation pathways are predominantly encoded by the core genes. All Sulfolobus species encode genes required for the conversion of ammonium into glutamate/glutamine. Some Sulfolobus strains have gained the ability to utilize additional nitrogen source such as nitrate (i.e., S. islandicus strain REY15A, LAL14/1, M14.25, and M16.27) or urea (i.e., S. islandicus HEV10/4, S. tokodaii strain7, and S. metallicus DSM 6482). The strategies for sulfur metabolism are most diverse and least understood. S. tokodaii encodes sulfur oxygenase/reductase (SOR), whereas both S. islandicus and S. solfataricus contain genes for sulfur reductase (SRE). However, neither SOR nor SRE genes exist in the genome of strain A20, raising the possibility that an unknown pathway for the utilization of elemental sulfur may be present in the strain. The ability of Sulfolobus to utilize nitrate or sulfur is encoded by a gene cluster flanked by IS elements or their remnants. These clusters appear to have become fixed at a

  3. Synthesis of Fe16N2 compound Free-Standing Foils with 20 MGOe Magnetic Energy Product by Nitrogen Ion-Implantation

    NASA Astrophysics Data System (ADS)

    Jiang, Yanfeng; Mehedi, Md Al; Fu, Engang; Wang, Yongqiang; Allard, Lawrence F.; Wang, Jian-Ping

    2016-05-01

    Rare-earth-free magnets are highly demanded by clean and renewable energy industries because of the supply constraints and environmental issues. A promising permanent magnet should possess high remanent magnetic flux density (Br), large coercivity (Hc) and hence large maximum magnetic energy product ((BH)max). Fe16N2 has been emerging as one of promising candidates because of the redundancy of Fe and N on the earth, its large magnetocrystalline anisotropy (Ku > 1.0 × 107 erg/cc), and large saturation magnetization (4πMs > 2.4 T). However, there is no report on the formation of Fe16N2 magnet with high Br and large Hc in bulk format before. In this paper, we successfully synthesize free-standing Fe16N2 foils with a coercivity of up to 1910 Oe and a magnetic energy product of up to 20 MGOe at room temperature. Nitrogen ion implantation is used as an alternative nitriding approach with the benefit of tunable implantation energy and fluence. An integrated synthesis technique is developed, including a direct foil-substrate bonding step, an ion implantation step and a two-step post-annealing process. With the tunable capability of the ion implantation fluence and energy, a microstructure with grain size 25–30 nm is constructed on the FeN foil sample with the implantation fluence of 5 × 1017/cm2.

  4. Nitrogen segregation in nanocarbons.

    PubMed

    Ewels, C P; Erbahar, D; Wagner, Ph; Rocquefelte, X; Arenal, R; Pochet, P; Rayson, M; Scardamaglia, M; Bittencourt, C; Briddon, P

    2014-01-01

    We explore the behaviour of nitrogen doping in carbon nanomaterials, notably graphene, nanotubes, and carbon thin films. This is initially via a brief review of the literature, followed by a series of atomistic density functional calculations. We show that at low concentrations, substitutional nitrogen doping in the sp(2)-C graphenic basal plane is favoured, however once the nitrogen concentration reaches a critical threshold there is a transition towards the formation of the more thermodynamically-favoured nitrogen terminated 'zigzag' type edges. These can occur either via formation of finite patches (polycyclic aromatic azacarbons), strips of sp(2) carbon with zigzag nitrogen edges, or internal nitrogen-terminated hole edges within graphenic planes. This transition to edge formation is especially favoured when the nitrogen can be partially functionalised with, e.g. hydrogen. By comparison with available literature results, notably from electron energy loss spectroscopy and X-ray spectroscopy, the current results suggest that much of the nitrogen believed to be incorporated into carbon nanoobjects is instead likely to be present terminating the edges of carbonaceous impurities attached to nanoobject's surface. By comparison to nitrogen-doped tetrahedrally amorphous carbon, we suggest that this transition at around 10-20% nitrogen concentration and above towards sp(2) coordination via internal nitrogen-terminated edge formation may be a general property of nitrogen-doped carbon materials.

  5. Synthesis of Fe16N2 compound Free-Standing Foils with 20 MGOe Magnetic Energy Product by Nitrogen Ion-Implantation

    PubMed Central

    Jiang, Yanfeng; Mehedi, Md Al; Fu, Engang; Wang, Yongqiang; Allard, Lawrence F.; Wang, Jian-Ping

    2016-01-01

    Rare-earth-free magnets are highly demanded by clean and renewable energy industries because of the supply constraints and environmental issues. A promising permanent magnet should possess high remanent magnetic flux density (Br), large coercivity (Hc) and hence large maximum magnetic energy product ((BH)max). Fe16N2 has been emerging as one of promising candidates because of the redundancy of Fe and N on the earth, its large magnetocrystalline anisotropy (Ku > 1.0 × 107 erg/cc), and large saturation magnetization (4πMs > 2.4 T). However, there is no report on the formation of Fe16N2 magnet with high Br and large Hc in bulk format before. In this paper, we successfully synthesize free-standing Fe16N2 foils with a coercivity of up to 1910 Oe and a magnetic energy product of up to 20 MGOe at room temperature. Nitrogen ion implantation is used as an alternative nitriding approach with the benefit of tunable implantation energy and fluence. An integrated synthesis technique is developed, including a direct foil-substrate bonding step, an ion implantation step and a two-step post-annealing process. With the tunable capability of the ion implantation fluence and energy, a microstructure with grain size 25–30 nm is constructed on the FeN foil sample with the implantation fluence of 5 × 1017/cm2. PMID:27145983

  6. Eighth international congress on nitrogen fixation

    SciTech Connect

    Not Available

    1990-01-01

    This volume contains the proceedings of the Eighth International Congress on Nitrogen Fixation held May 20--26, 1990 in Knoxville, Tennessee. The volume contains abstracts of individual presentations. Sessions were entitled Recent Advances in the Chemistry of Nitrogen Fixation, Plant-microbe Interactions, Limiting Factors of Nitrogen Fixation, Nitrogen Fixation and the Environment, Bacterial Systems, Nitrogen Fixation in Agriculture and Industry, Plant Function, and Nitrogen Fixation and Evolution.

  7. Indicators: Nitrogen

    EPA Pesticide Factsheets

    Nitrogen, like phosphorus, is a critical nutrient required for all life. Nitrogen can occur in rivers and streams, lakes, and coastal waters in several forms including ammonia (NH3), nitrates (NO3), and nitrites (NO2).

  8. [Effect of amino acid supplements to barley meal on the nitrogen metabolism of growing castrated male swine (20-65 kg live weight)].

    PubMed

    Wecke, C; Gebhardt, G

    1981-03-01

    In 56 N-balance experiments of the influence of differentiated amino acid supplements to coarse barley meal enriched with energy, minerals and additives on the nitrogen metabolism of castrated male pigs, was investigated. The joint supplement of lysine and methionine remained without result in comparison with the sole supplementation of lysine. Only the additional supplementation of threonine resulted in the further improvement of protein utilisation. The results corroborate the effect of the amino acid lysine limiting the performance in barley protein and prove that threonine takes the second place in the sequence of limitation.

  9. Greenhouse gas emissions and stocks of soil carbon and nitrogen from a 20-year fertilised wheat-maize intercropping system: A model approach.

    PubMed

    Zhang, Xubo; Xu, Minggang; Liu, Jian; Sun, Nan; Wang, Boren; Wu, Lianhai

    2016-02-01

    Accurate modelling of agricultural management impacts on greenhouse gas emissions and the cycling of carbon and nitrogen is complicated due to interactions between various processes and the disturbance caused by field management. In this study, a process-based model, the Soil-Plant-Atmosphere Continuum System (SPACSYS), was used to simulate the effects of different fertilisation regimes on crop yields, the dynamics of soil organic carbon (SOC) and total nitrogen (SN) stocks from 1990 to 2010, and soil CO2 (2007-2010) and N2O (2007-2008) emissions based on a long-term fertilisation experiment with a winter-wheat (Triticum Aestivum L.) and summer-maize (Zea mays L.) intercropping system in Eutric Cambisol (FAO) soil in southern China. Three fertilisation treatments were 1) unfertilised (Control), 2) chemical nitrogen, phosphorus and potassium (NPK), and 3) NPK plus pig manure (NPKM). Statistical analyses indicated that the SPACSYS model can reasonably simulate the yields of wheat and maize, the evolution of SOC and SN stocks and soil CO2 and N2O emissions. The simulations showed that the NPKM treatment had the highest values of crop yields, SOC and SN stocks, and soil CO2 and N2O emissions were the lowest from the Control treatment. Furthermore, the simulated results showed that manure amendment along with chemical fertiliser applications led to both C (1017 ± 470 kg C ha(-1) yr(-1)) and N gains (91.7 ± 15.1 kg N ha(-1) yr(-1)) in the plant-soil system, while the Control treatment caused a slight loss in C and N. In conclusion, the SPACSYS model can accurately simulate the processes of C and N as affected by various fertilisation treatments in the red soil. Furthermore, application of chemical fertilisers plus manure could be a suitable management for ensuring crop yield and sustaining soil fertility in the red soil region, but the ratio of chemical fertilisers to manure should be optimized to reduce C and N losses to the environment. Copyright © 2015

  10. Ammonium stability and nitrogen isotope fractionations for NH4+-NH3(aq)-NH3(gas) systems at 20-70 °C and pH of 2-13: Applications to habitability and nitrogen cycling in low-temperature hydrothermal systems

    NASA Astrophysics Data System (ADS)

    Li, Long; Lollar, Barbara Sherwood; Li, Hong; Wortmann, Ulrich G.; Lacrampe-Couloume, Georges

    2012-05-01

    Ammonium/ammonia is an essential nutrient and energy source to support life in oceanic and terrestrial hydrothermal systems. Thus the stability of ammonium is crucial to determine the habitability or ecological structure in hydrothermal environments, but still not well understood. To date, the lack of constraints on nitrogen isotope fractionations between ammonium and ammonia has limited the application of nitrogen isotopes to trace (bio)geochemical processes in such environments. In this study, we carried out laboratory experiments to (1) examine the stability of ammonium in an ammonium sulfate solution under temperature conditions from 20 to 70 °C and pH from 2.1 to 12.6 and (2) determine nitrogen isotope fractionation between ammonium and ammonia. Our experimental results show that ammonium is stable under the experimental temperatures when pH is less than 6. In experiments with starting pH greater than 8, significant ammonium was lost as a result of dissociation of ammonium and degassing of ammonia product. Nitrogen concentrations in the fluids decreased by more than 50% in the first two hours, indicating extremely fast effusion rates of ammonia. This implies that ammonium at high pH fluids (e.g., Lost City Hydrothermal Vents, Oman ophiolite hyperalkaline springs) may not be stable. Habitable environments may be more favorable at the leading edge of a pH gradient toward more acidic conditions, where the fluid can efficiently trap any ammonia transferred from a high pH vent. Although modeling shows that high temperature, low pH hydrothermal vents (e.g., Rainbow hydrothermal vent) may have the capability to retain ammonium, their high temperatures may limit habitability. The habitable zone associated with such a hydrothermal vent is likely at the lower front of a temperature gradient. In contrast, modeling of ammonium in deep terrestrial systems, suggests that saline fracture waters in crystalline rocks such as described in the Canadian Shield and in the

  11. Quarterly technical progress report No. 2, December 20-March 19, 1982. Second quarterly report on the effect of rapid heating rate on coal nitrogen and sulfur release

    SciTech Connect

    Gat, N.

    1982-04-26

    A laser pyrolysis technique is applied to the investigation of the effects of heating rate on release of coal-bound sulfur and nitrogen. An experimental system characterization and calibration has been completed. A detailed documentation was prepared describing the 3-color pyrometer and the data analysis technique. The coal particle feed system has been calibrated to provide accurate mass flow rate at pre-selected particle velocities. The first batch of samples submitted for chemical analysis will be used for the determination of kinetics parameters at a high heating rate (approximately equal to 10/sup 6/ K/s). The coal used presently is a Montana Rosebud. Two other coals are available; one is ILL No. 6 (through EERC) which will need to be pulverized and the second is a Pitt. hv-A (through KVB). It was confirmed that sieve and drag size distribution of coal differ significantly, and that particle shape effects may be significant in the modelling of particle dynamics.

  12. Nitrogen Index

    USDA-ARS?s Scientific Manuscript database

    There is a need to improve the management of nitrogen inputs to agricultural systems because they increase the potential for losses of reactive nitrogen to the environment, resulting in negative impacts to water and air resources. There is a need to reduce nitrate leaching, emissions of N2O from agr...

  13. Control and elimination of cracking in aluminum(0.20) gallium(0.80) nitrogen using aluminum(x) gallium(1-x) nitrogen interlayers and application toward a near ultraviolet vertical cavity surface emitting laser

    NASA Astrophysics Data System (ADS)

    Waldrip, Karen Elizabeth

    Thin film heterostructures based on aluminum gallium nitride and gallium nitride are of particular interest for applications such as ultraviolet light emitters and detectors. Due to the elastic mismatch strain between the materials, the AlGaN films tend to crack at thicknesses and aluminum compositions that are useful for device fabrication (e.g., 0.1 mum at 10% AlN mole fraction), and cracking has been shown to be deleterious to device performance. In this work, a method has been developed to control and eliminate cracking in 0.9-mum thick Al0.20Ga0.80N films grown on GaN by inserting a thin layer of AlxGa1-xN between the Al 0.20Ga0.80N and GaN films grown by metalorganic chemical vapor deposition. The strain state of the thin interlayers is determined through a combination of in situ and ex situ characterization techniques. It is shown that the interlayer partially relaxes through the nucleation and glide of misfit dislocations to the interlayer/GaN interface, and that although the edge dislocation content in AlGaN overlayers increases by a factor of 5--10, screw dislocations from GaN underlayers are filtered by the interlayer. The number of excess threading dislocations present in AlGaN overlayers can be manipulated by controlling the amount of relaxation of the AlGaN interlayers, which can in turn be controlled by the morphology of the interlayer. It has been found that the morphology of the interlayer is affected by a combination of the strain and the aluminum surface mobility during growth, which can be controlled by adjusting growth parameters such as interlayer composition, growth temperature, interlayer thickness, and V/III ratio. These parameters are explored and guidelines for choosing an interlayer composition, thickness, and morphology are outlined based on the chosen end application for the AlGaN overlayer. Finally, the interlayer technique is applied towards the development of the world's first (at time of announcement) room temperature, quasi

  14. Development of cooling system for 66/6.9kV-20MVA REBCO superconducting transformers with Ne turbo-Brayton refrigerator and subcooled liquid nitrogen

    NASA Astrophysics Data System (ADS)

    Iwakuma, M.; Adachi, K.; Yun, K.; Yoshida, K.; Sato, S.; Suzuki, Y.; Umeno, T.; Konno, M.; Hayashi, H.; Eguchi, T.; Izumi, T.; Shiohara, Y.

    2015-12-01

    We developed a turbo-Brayton refrigerator with Ne gas as a working fluid for a 3 ϕ- 66/6.9kV-2MVA superconducting transformer with coated conductors which was bath-cooled with subcooled LN2. The two-stage compressor and expansion turbine had non-contact magnetic bearings for a long maintenance interval. In the future, we intend to directly install a heat exchanger into the Glass-Fiber-Reinforced-Plastics cryostat of a transformer and make a heat exchange between the working fluid gas and subcooled LN2. In this paper we investigate the behaviour of subcooled LN2 in a test cryostat, in which heater coils were arranged side by side with a flat plate finned-tube heat exchanger. Here a He turbo-Brayton refrigerator was used as a substitute for a Ne turbo-Brayton one. The pressure at the surface of LN2 in the cryostat was one atmosphere. Just under the LN2 surface, a stationary layer of LN2 was created over the depth of 20 cm and temperature dropped from 77 K to 65 K with depth while, in the lower level than that, a natural convection flow of LN2 was formed and temperature was almost uniform over 1 m depth. The boundary plane between the stationary layer and the natural convection region was visible.

  15. Eighth international congress on nitrogen fixation. Final program

    SciTech Connect

    Not Available

    1990-12-31

    This volume contains the proceedings of the Eighth International Congress on Nitrogen Fixation held May 20--26, 1990 in Knoxville, Tennessee. The volume contains abstracts of individual presentations. Sessions were entitled Recent Advances in the Chemistry of Nitrogen Fixation, Plant-microbe Interactions, Limiting Factors of Nitrogen Fixation, Nitrogen Fixation and the Environment, Bacterial Systems, Nitrogen Fixation in Agriculture and Industry, Plant Function, and Nitrogen Fixation and Evolution.

  16. Nitrogen dioxide

    Integrated Risk Information System (IRIS)

    Nitrogen dioxide ; CASRN 10102 - 44 - 0 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogeni

  17. Phosphorus-nitrogen compounds. 20. Thiophosphorus hydrazones.

    PubMed

    Cates, L A; Cho, Y M; Smith, L K; Williams, L; Lemke, T L

    1976-09-01

    Six pyridine-2-carboxaldehyde, one pyridine N-oxide 2-carboxaldehyde, and five diketone thiophosphoric hydrazones, three thiophosphoric hydrazides, and two cupric chelates were synthesized. The chelates and nine of the hydrazones were tested against Ehrlich ascites carcinoma. Seven of these latter agents were administered concurrently with either cupric and/or ferrous salts to mice bearing this tumor. The greatest activity was found with the chelate, cimethyl pyridine-2-carboxyaldehyde phosphorothioic hydrazone-copper (1:1). The hydrazone portion of this chelate also formed a ligand-copper (2:1) complex. Although all of the hydrazones but one were inactive when evaluated alone, the concurrent injection of cupric ion increased survival times by an avoli alkaline phosphatase was found to be inhibited by two thiosemicarbazones in a manner similar to that previously reported by these agents against alkaline phosphatase derived from Sarcoma 180-6-thiopurine resistant ascites cells. None of the 14 hydrazides or hydrazones tested against E. coli enzyme displayed significant inhibition.

  18. Preprototype nitrogen supply subsystem development

    NASA Technical Reports Server (NTRS)

    Heppner, D. B.; Fort, J. H.; Schubert, F. H.

    1982-01-01

    The design and development of a test stand for the Nitrogen Generation Module (NGM) and a series of tests which verified its operation and performance capability are described. Over 900 hours of parametric testing were achieved. The results from this testing were then used to design an advanced NGM and a self contained, preprototype Nitrogen Supply Subsystem. The NGM consists of three major components: nitrogen generation module, pressure controller and hydrazine storage tank and ancillary components. The most important improvement is the elimination of all sealing surfaces, achieved with a total welded or brazed construction. Additionally, performance was improved by increasing hydrogen separating capability by 20% with no increase in overall packaging size.

  19. Nitrogen and Carbon Dynamics Across Trophic Levels Along an Atmospheric Nitrogen Deposition Gradient

    NASA Astrophysics Data System (ADS)

    Wissinger, B. D.; Bell, M. D.; Newingham, B. A.

    2011-12-01

    Atmospheric nitrogen deposition has altered soil biogeochemical processes and plant communities across the United States. Prior investigations have demonstrated these alterations; however, little is known about the effects of elevated nitrogen on higher trophic levels. Building upon previous research that revealed an atmospheric nitrogen deposition gradient from the San Bernardino Mountains through Joshua Tree National Park in California, we investigated atmospheric nitrogen and its effects on soils, plants, and harvester ants. We measured nitrogen and carbon concentrations, along with carbon and nitrogen stable isotopes, across trophic levels at eighteen urban and unpopulated sites along the deposition gradient. Carbon and nitrogen attributes were determined in atmospheric nitric acid, soil, Larrea tridentata and Ambrosia dumosa leaves, seeds from selected plant species, and ants. We predicted carbon and nitrogen ratios and isotopes to change in areas with higher nitrogen deposition and vary along the deposition gradient. Nitrogen (p=0.02) and carbon (p=0.05) concentrations, as well as C:N ratios (p=<0.001), significantly differed in Messor pergandei individuals among sites; however, no correlation was found between these carbon and nitrogen attributes and the nitrogen deposition gradient (%N r2=0.02, %C r2=0.007, C:N r2=0.02). The δ15N and δ13C values of the ants, leaf tissues, and seeds measured across the gradient follow similar patterns with r2 values all below 0.20. Our results suggest the current and previous rates of nitrogen deposition in this area are not enough to modify nitrogen and carbon concentrations and isotope values. Compensatory nitrogen cycling processes in the soil may reduce the effects of increased nitrogen on plants and thus higher trophic levels. Nitrogen and carbon dynamics across trophic levels might change after longer ecosystem exposure to elevated nitrogen; however, other abiotic and biotic factors are likely driving current

  20. Ice sheets and nitrogen.

    PubMed

    Wolff, Eric W

    2013-07-05

    Snow and ice play their most important role in the nitrogen cycle as a barrier to land-atmosphere and ocean-atmosphere exchanges that would otherwise occur. The inventory of nitrogen compounds in the polar ice sheets is approximately 260 Tg N, dominated by nitrate in the much larger Antarctic ice sheet. Ice cores help to inform us about the natural variability of the nitrogen cycle at global and regional scale, and about the extent of disturbance in recent decades. Nitrous oxide concentrations have risen about 20 per cent in the last 200 years and are now almost certainly higher than at any time in the last 800 000 years. Nitrate concentrations recorded in Greenland ice rose by a factor of 2-3, particularly between the 1950s and 1980s, reflecting a major change in NOx emissions reaching the background atmosphere. Increases in ice cores drilled at lower latitudes can be used to validate or constrain regional emission inventories. Background ammonium concentrations in Greenland ice show no significant recent trend, although the record is very noisy, being dominated by spikes of input from biomass burning events. Neither nitrate nor ammonium shows significant recent trends in Antarctica, although their natural variations are of biogeochemical and atmospheric chemical interest. Finally, it has been found that photolysis of nitrate in the snowpack leads to significant re-emissions of NOx that can strongly impact the regional atmosphere in snow-covered areas.

  1. Nitrogen metabolism in haloarchaea

    PubMed Central

    Bonete, María José; Martínez-Espinosa, Rosa María; Pire, Carmen; Zafrilla, Basilio; Richardson, David J

    2008-01-01

    The nitrogen cycle (N-cycle), principally supported by prokaryotes, involves different redox reactions mainly focused on assimilatory purposes or respiratory processes for energy conservation. As the N-cycle has important environmental implications, this biogeochemical cycle has become a major research topic during the last few years. However, although N-cycle metabolic pathways have been studied extensively in Bacteria or Eukarya, relatively little is known in the Archaea. Halophilic Archaea are the predominant microorganisms in hot and hypersaline environments such as salted lakes, hot springs or salted ponds. Consequently, the denitrifying haloarchaea that sustain the nitrogen cycle under these conditions have emerged as an important target for research aimed at understanding microbial life in these extreme environments. The haloarchaeon Haloferax mediterranei was isolated 20 years ago from Santa Pola salted ponds (Alicante, Spain). It was described as a denitrifier and it is also able to grow using NO3-, NO2- or NH4+ as inorganic nitrogen sources. This review summarizes the advances that have been made in understanding the N-cycle in halophilic archaea using Hfx mediterranei as a haloarchaeal model. The results obtained show that this microorganism could be very attractive for bioremediation applications in those areas where high salt, nitrate and nitrite concentrations are found in ground waters and soils. PMID:18593475

  2. Nitrogen metabolism in haloarchaea.

    PubMed

    Bonete, María José; Martínez-Espinosa, Rosa María; Pire, Carmen; Zafrilla, Basilio; Richardson, David J

    2008-07-01

    The nitrogen cycle (N-cycle), principally supported by prokaryotes, involves different redox reactions mainly focused on assimilatory purposes or respiratory processes for energy conservation. As the N-cycle has important environmental implications, this biogeochemical cycle has become a major research topic during the last few years. However, although N-cycle metabolic pathways have been studied extensively in Bacteria or Eukarya, relatively little is known in the Archaea. Halophilic Archaea are the predominant microorganisms in hot and hypersaline environments such as salted lakes, hot springs or salted ponds. Consequently, the denitrifying haloarchaea that sustain the nitrogen cycle under these conditions have emerged as an important target for research aimed at understanding microbial life in these extreme environments.The haloarchaeon Haloferax mediterranei was isolated 20 years ago from Santa Pola salted ponds (Alicante, Spain). It was described as a denitrifier and it is also able to grow using NO3(-), NO2(-) or NH4(+) as inorganic nitrogen sources. This review summarizes the advances that have been made in understanding the N-cycle in halophilic archaea using Hfx mediterranei as a haloarchaeal model. The results obtained show that this microorganism could be very attractive for bioremediation applications in those areas where high salt, nitrate and nitrite concentrations are found in ground waters and soils.

  3. Ice sheets and nitrogen

    PubMed Central

    Wolff, Eric W.

    2013-01-01

    Snow and ice play their most important role in the nitrogen cycle as a barrier to land–atmosphere and ocean–atmosphere exchanges that would otherwise occur. The inventory of nitrogen compounds in the polar ice sheets is approximately 260 Tg N, dominated by nitrate in the much larger Antarctic ice sheet. Ice cores help to inform us about the natural variability of the nitrogen cycle at global and regional scale, and about the extent of disturbance in recent decades. Nitrous oxide concentrations have risen about 20 per cent in the last 200 years and are now almost certainly higher than at any time in the last 800 000 years. Nitrate concentrations recorded in Greenland ice rose by a factor of 2–3, particularly between the 1950s and 1980s, reflecting a major change in NOx emissions reaching the background atmosphere. Increases in ice cores drilled at lower latitudes can be used to validate or constrain regional emission inventories. Background ammonium concentrations in Greenland ice show no significant recent trend, although the record is very noisy, being dominated by spikes of input from biomass burning events. Neither nitrate nor ammonium shows significant recent trends in Antarctica, although their natural variations are of biogeochemical and atmospheric chemical interest. Finally, it has been found that photolysis of nitrate in the snowpack leads to significant re-emissions of NOx that can strongly impact the regional atmosphere in snow-covered areas. PMID:23713125

  4. Virtual Nitrogen Losses from Organic Food Production

    NASA Astrophysics Data System (ADS)

    Cattell Noll, L.; Galloway, J. N.; Leach, A. M.; Seufert, V.; Atwell, B.; Shade, J.

    2015-12-01

    Reactive nitrogen (Nr) is necessary for crop and animal production, but when it is lost to the environment, it creates a cascade of detrimental environmental impacts. The nitrogen challenge is to maximize the food production benefits of Nr, while minimizing losses to the environment. The first nitrogen footprint tool was created in 2012 to help consumers learn about the Nr losses to the environment that result from an individual's lifestyle choices. The nitrogen lost during food production was estimated with virtual nitrogen factors (VNFs) that quantify the amount of nitrogen lost to the environment per unit nitrogen consumed. Alternative agricultural systems, such as USDA certified organic farms, utilize practices that diverge from conventional production. In order to evaluate the potential sustainability of these alternative agricultural systems, our team calculated VNFs that reflect organic production. Initial data indicate that VNFs for organic grains and organic starchy roots are comparable to, but slightly higher than conventional (+10% and +20% respectively). In contrast, the VNF for organic vegetables is significantly higher (+90%) and the VNF for organic legumes is significantly lower (-90%). Initial data on organic meat production shows that organic poultry and organic pigmeat are comparable to conventional production (both <5% difference), but that the organic beef VNF is significantly higher (+30%). These data show that in some cases organic and conventional production are comparable in terms of nitrogen efficiency. However, since conventional production relies heavily on the creation of new reactive nitrogen (Haber-Bosch, biological nitrogen fixation) and organic production primarily utilizes already existing reactive nitrogen (manure, crop residue, compost), the data also show that organic production contributes less new reactive nitrogen to the environment than conventional production (approximately 70% less). Therefore, we conclude that on a local

  5. Nitrogen removal from natural gas

    SciTech Connect

    1997-04-01

    According to a 1991 Energy Information Administration estimate, U.S. reserves of natural gas are about 165 trillion cubic feet (TCF). To meet the long-term demand for natural gas, new gas fields from these reserves will have to be developed. Gas Research Institute studies reveal that 14% (or about 19 TCF) of known reserves in the United States are subquality due to high nitrogen content. Nitrogen-contaminated natural gas has a low Btu value and must be upgraded by removing the nitrogen. In response to the problem, the Department of Energy is seeking innovative, efficient nitrogen-removal methods. Membrane processes have been considered for natural gas denitrogenation. The challenge, not yet overcome, is to develop membranes with the required nitrogen/methane separation characteristics. Our calculations show that a methane-permeable membrane with a methane/nitrogen selectivity of 4 to 6 would make denitrogenation by a membrane process viable. The objective of Phase I of this project was to show that membranes with this target selectivity can be developed, and that the economics of the process based on these membranes would be competitive. Gas permeation measurements with membranes prepared from two rubbery polymers and a superglassy polymer showed that two of these materials had the target selectivity of 4 to 6 when operated at temperatures below - 20{degrees}C. An economic analysis showed that a process based on these membranes is competitive with other technologies for small streams containing less than 10% nitrogen. Hybrid designs combining membranes with other technologies are suitable for high-flow, higher-nitrogen-content streams.

  6. 40 CFR 89.321 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Oxides of nitrogen analyzer calibration... Test Equipment Provisions § 89.321 Oxides of nitrogen analyzer calibration. (a) The chemiluminescent oxides of nitrogen analyzer shall receive the initial and periodic calibration described in this section...

  7. 40 CFR 90.318 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Oxides of nitrogen analyzer... Emission Test Equipment Provisions § 90.318 Oxides of nitrogen analyzer calibration. (a) Calibrate the chemiluminescent oxides of nitrogen analyzer as described in this section. (b) Initial and Periodic...

  8. 40 CFR 90.318 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Oxides of nitrogen analyzer... Emission Test Equipment Provisions § 90.318 Oxides of nitrogen analyzer calibration. (a) Calibrate the chemiluminescent oxides of nitrogen analyzer as described in this section. (b) Initial and Periodic...

  9. 40 CFR 90.318 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Oxides of nitrogen analyzer calibration... Emission Test Equipment Provisions § 90.318 Oxides of nitrogen analyzer calibration. (a) Calibrate the chemiluminescent oxides of nitrogen analyzer as described in this section. (b) Initial and Periodic...

  10. 40 CFR 91.318 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Oxides of nitrogen analyzer... Provisions § 91.318 Oxides of nitrogen analyzer calibration. (a) Calibrate the chemiluminescent oxides of nitrogen analyzer as described in this section. (b) Initial and periodic interference. Prior to...

  11. 40 CFR 91.318 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Oxides of nitrogen analyzer calibration... Provisions § 91.318 Oxides of nitrogen analyzer calibration. (a) Calibrate the chemiluminescent oxides of nitrogen analyzer as described in this section. (b) Initial and periodic interference. Prior to...

  12. 40 CFR 91.318 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Oxides of nitrogen analyzer... Provisions § 91.318 Oxides of nitrogen analyzer calibration. (a) Calibrate the chemiluminescent oxides of nitrogen analyzer as described in this section. (b) Initial and periodic interference. Prior to...

  13. Nitrogen dioxide detection

    DOEpatents

    Sinha, Dipen N.; Agnew, Stephen F.; Christensen, William H.

    1993-01-01

    Method and apparatus for detecting the presence of gaseous nitrogen dioxide and determining the amount of gas which is present. Though polystyrene is normally an insulator, it becomes electrically conductive in the presence of nitrogen dioxide. Conductance or resistance of a polystyrene sensing element is related to the concentration of nitrogen dioxide at the sensing element.

  14. Understanding Nitrogen Fixation

    SciTech Connect

    Paul J. Chirik

    2012-05-25

    synthesis of ammonia, NH{sub 3}, from its elements, H{sub 2} and N{sub 2}, via the venerable Haber-Bosch process is one of the most significant technological achievements of the past century. Our research program seeks to discover new transition metal reagents and catalysts to disrupt the strong N {triple_bond} N bond in N{sub 2} and create new, fundamental chemical linkages for the construction of molecules with application as fuels, fertilizers and fine chemicals. With DOE support, our group has discovered a mild method for ammonia synthesis in solution as well as new methods for the construction of nitrogen-carbon bonds directly from N{sub 2}. Ideally these achievements will evolve into more efficient nitrogen fixation schemes that circumvent the high energy demands of industrial ammonia synthesis. Industrially, atmospheric nitrogen enters the synthetic cycle by the well-established Haber-Bosch process whereby N{sub 2} is hydrogenated to ammonia at high temperature and pressure. The commercialization of this reaction represents one of the greatest technological achievements of the 20th century as Haber-Bosch ammonia is responsible for supporting approximately 50% of the world's population and serves as the source of half of the nitrogen in the human body. The extreme reaction conditions required for an economical process have significant energy consequences, consuming 1% of the world's energy supply mostly in the form of pollution-intensive coal. Moreover, industrial H{sub 2} synthesis via the water gas shift reaction and the steam reforming of methane is fossil fuel intensive and produces CO{sub 2} as a byproduct. New synthetic methods that promote this thermodynamically favored transformation ({Delta}G{sup o} = -4.1 kcal/mol) under milder conditions or completely obviate it are therefore desirable. Most nitrogen-containing organic molecules are derived from ammonia (and hence rely on the Haber-Bosch and H{sub 2} synthesis processes) and direct synthesis from

  15. Nitrogen spark denoxer

    DOEpatents

    Ng, Henry K.; Novick, Vincent J.; Sekar, Ramanujam R.

    1997-01-01

    A NO.sub.X control system for an internal combustion engine includes an oxygen enrichment device that produces oxygen and nitrogen enriched air. The nitrogen enriched air contains molecular nitrogen that is provided to a spark plug that is mounted in an exhaust outlet of an internal combustion engine. As the nitrogen enriched air is expelled at the spark gap of the spark plug, the nitrogen enriched air is exposed to a pulsating spark that is generated across the spark gap of the spark plug. The spark gap is elongated so that a sufficient amount of atomic nitrogen is produced and is injected into the exhaust of the internal combustion engine. The injection of the atomic nitrogen into the exhaust of the internal combustion engine causes the oxides of nitrogen to be reduced into nitrogen and oxygen such that the emissions from the engine will have acceptable levels of NO.sub.X. The oxygen enrichment device that produces both the oxygen and nitrogen enriched air can include a selectively permeable membrane.

  16. Flameless nitrogen skid unit

    SciTech Connect

    Loesch, S.B.; John, J.C.; Mints, D.K.

    1984-03-27

    A flameless nitrogen vaporizing unit includes a first internal combustion engine driving a nitrogen pump through a transmission. A second internal combustion engine drives three hydraulic oil pumps against a variable back pressure so that a variable load may be imposed upon the second engine. Liquid nitrogen is pumped from the nitrogen pump driven by the first engine into a first heat exchanger where heat is transferred from exhaust gases from the first and second internal combustion engines to the liquid nitrogen to cause the nitrogen to be transformed into a gaseous state. The gaseous nitrogen then flows into a second heat exchanger where it is superheated by an engine coolant fluid to heat the gaseous nitrogen to essentially an ambient temperature. The superheated nitrogen is then injected into the well. The engine coolant fluid flows in a coolant circulation system. Heat is transferred to the coolant fluid directly from the internal combustion engine. Heat is also provided to the coolant fluid from lubrication oil pumped by the three pumps attached to the second internal combustion engine. The coolant fluid circulating system includes a comingling chamber for comingling warmer coolant fluid flowing from the internal combustion engines to the second heat exchanger with cooler coolant fluids flowing from the second heat exchanger to the internal combustion engines. Methods of vaporizing nitrogen are also disclosed.

  17. Nitrogen In Saturn's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Sittler, E. C.; Johnson, R. E.; McComas, D. J.; Reisenfeld, D.; Shappirio, M. D.; Baragiola, R.; Michael, M.; Shematovich, V. I.; Crary, F.; Young, D. T.

    2004-12-01

    We are analyzing CAPS instrument data on Cassini to look for nitrogen ions in Saturn's magnetosphere. Because Voyager could not separate oxygen and nitrogen, there has been considerable controversy on nitrogen's presence and relative importance. Two principal sources have been suggested: Titan's atmosphere and nitrogen species trapped in Saturn's icy satellite surfaces (Sittler et al 2004). The latter may be primordial nitrogen, likely as NH3 in ice (Stevenson 1982; Squyers et al. 1983) or nitrogen ions that have been implanted in the surface (Delitsky and Lane 2002). We will present the results of Saturnian nitrogen cloud modeling and relevant CAPS observations. We recently described the Titan source (Michael, et al. 2004; Shematovich et al. 2003; Smith et al. 2004; Sittler et al. 2004) in preparation for Cassini's Saturnian plasma measurements. Two components were identified: energetic nitrogen ions formed near Titan and energized as they diffused inward (Sittler et al. 2004) and neutrals in orbits with small perigee that became ionized in the inner magnetosphere (Smith et al 2004). The latter component would be a source of lower energy, co-rotating nitrogen ions in the inner magnetosphere. Such a component would have an energy spectrum similar to nitrogen species sputtered from the icy satellite surfaces (Johnson and Sittler 1990). However, the mass spectrum would differ, likely containing NHx and NOx species also, and, hence, may be separated from the Titan source. Our preliminary analysis for nitrogen species in the CAPS data will be compared to our models. Of interest will be the energy spectra, which can indicate whether any nitrogen present is formed locally or near Titan's orbit and diffused inward. This work is supported by the NASA Planetary Atmospheres, NASA Graduate Student Research, Virginia Space Grant Consortium Graduate Research Fellowship and CAPS Cassini instrument team programs.

  18. Tribological characteristics of nitrogen (N+) implanted iron

    NASA Technical Reports Server (NTRS)

    Jones, W. R.; Ferrante, J.

    1982-01-01

    The effect of implantation of nitrogen ions (1.5 MeV) on the friction and wear characteristics of pure ion sliding against M-50 steel (unimplanted) was studied in a pin-on-disk sliding friction apparatus. Test conditions included room temperature (25 C), a dry air atmosphere, a load of 1/2 kg (4.9 N), sliding velocities of 0.043 to 0.078 m/sec (15 to 25 rpm), a pure hydrocarbon lubricant (n-hexadecane), or a U.S.P. mineral oil and nitrogen ion implantation doses of 5x10 to the 15th power and 5x10 to the 17th power ions/sq cm. No differences in wear rates were observed in the low dose experiments. In the high dose experiments, small reductions in initial (40 percent) and steady state (20 percent) wear rates were observed for nitrogen implanted iron riders as compared with unimplanted controls. No differences in average friction coefficients were noted for either dose. Auger electron spectroscopy combined with argon ion bombardment revealed a subsurface Gaussian nitrogen distribution with a maximum concentration of 6 atomic percent at a depth of 0.8 microns. Similar analysis within the wear scar of an implanted rider after 20 microns of wear yielded only background nitrogen concentration. No inward migration of nitrogen ions was observed.

  19. Tribological characteristics of nitrogen (N+) implanted iron

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.; Ferrante, J.

    1983-01-01

    The effect of implantation of nitrogen ions (1.5 MeV) on the friction and wear characteristics of pure ion sliding against M-50 steel (unimplanted) was studied in a pin-on-disk sliding friction apparatus. Test conditions included room temperature (25 C), a dry air atmosphere, a load of 1/2 kg (4.9 N), sliding velocities of 0.043 to 0.078 m/sec (15 to 25 rpm), a pure hydrocarbon lubricant (n-hexadecane), or a U.S.P. mineral oil and nitrogen ion implantation doses of 5x10 to the 15th power and 5x10 to the 17th power ions/sq cm. No differences in wear rates were observed in the low dose experiments. In the high dose experiments, small reductions in initial (40 percent) and steady state (20 percent) wear rates were observed for nitrogen implanted iron riders as compared with unimplanted controls. No differences in average friction coefficients were noted for either dose. Auger electron spectroscopy combined with argon ion bombardment revealed a subsurface Gaussian nitrogen distribution with a maximum concentration of 6 atomic percent at a depth of 0.8 microns. Similar analysis within the wear scar of an implanted rider after 20 microns of wear yielded only background nitrogen concentration. No inward migration of nitrogen ions was observed. Previously announced in STAR as N82-24322

  20. Climate change impacts of US reactive nitrogen.

    PubMed

    Pinder, Robert W; Davidson, Eric A; Goodale, Christine L; Greaver, Tara L; Herrick, Jeffrey D; Liu, Lingli

    2012-05-15

    Fossil fuel combustion and fertilizer application in the United States have substantially altered the nitrogen cycle, with serious effects on climate change. The climate effects can be short-lived, by impacting the chemistry of the atmosphere, or long-lived, by altering ecosystem greenhouse gas fluxes. Here we develop a coherent framework for assessing the climate change impacts of US reactive nitrogen emissions, including oxides of nitrogen, ammonia, and nitrous oxide (N(2)O). We use the global temperature potential (GTP), calculated at 20 and 100 y, in units of CO(2) equivalents (CO(2)e), as a common metric. The largest cooling effects are due to combustion sources of oxides of nitrogen altering tropospheric ozone and methane concentrations and enhancing carbon sequestration in forests. The combined cooling effects are estimated at -290 to -510 Tg CO(2)e on a GTP(20) basis. However, these effects are largely short-lived. On a GTP(100) basis, combustion contributes just -16 to -95 Tg CO(2)e. Agriculture contributes to warming on both the 20-y and 100-y timescales, primarily through N(2)O emissions from soils. Under current conditions, these warming and cooling effects partially offset each other. However, recent trends show decreasing emissions from combustion sources. To prevent warming from US reactive nitrogen, reductions in agricultural N(2)O emissions are needed. Substantial progress toward this goal is possible using current technology. Without such actions, even greater CO(2) emission reductions will be required to avoid dangerous climate change.

  1. Modeling Atmospheric Reactive Nitrogen

    EPA Science Inventory

    Nitrogen is an essential building block of all proteins and thus an essential nutrient for all life. Reactive nitrogen, which is naturally produced via enzymatic reactions, forest fires and lightning, is continually recycled and cascades through air, water, and soil media. Human ...

  2. Modeling Atmospheric Reactive Nitrogen

    EPA Science Inventory

    Nitrogen is an essential building block of all proteins and thus an essential nutrient for all life. Reactive nitrogen, which is naturally produced via enzymatic reactions, forest fires and lightning, is continually recycled and cascades through air, water, and soil media. Human ...

  3. Nitrogen trading tool

    USDA-ARS?s Scientific Manuscript database

    The nitrogen cycle is impacted by human activities, including those that increase the use of nitrogen in agricultural systems, and this impact can be seen in effects such as increased nitrate (NO3) levels in groundwater or surface water resources, increased concentration of nitrous oxide (N2O) in th...

  4. Update: Biological Nitrogen Fixation.

    ERIC Educational Resources Information Center

    Wiseman, Alan; And Others

    1985-01-01

    Updates knowledge on nitrogen fixation, indicating that investigation of free-living nitrogen-fixing organisms is proving useful in understanding bacterial partners and is expected to lead to development of more effective symbioses. Specific areas considered include biochemistry/genetics, synthesis control, proteins and enzymes, symbiotic systems,…

  5. The Fixation of Nitrogen.

    ERIC Educational Resources Information Center

    Andrew, S. P. S.

    1978-01-01

    Discusses the fixation of atmospheric nitrogen in the form of ammonia as one of the foundations of modern chemical industry. The article describes ammonia production and synthesis, purifying the hydrogen-nitrogen mix, nitric acid production, and its commericial plant. (HM)

  6. The Fixation of Nitrogen.

    ERIC Educational Resources Information Center

    Andrew, S. P. S.

    1978-01-01

    Discusses the fixation of atmospheric nitrogen in the form of ammonia as one of the foundations of modern chemical industry. The article describes ammonia production and synthesis, purifying the hydrogen-nitrogen mix, nitric acid production, and its commericial plant. (HM)

  7. Nitrogen in Chinese coals

    USGS Publications Warehouse

    Wu, D.; Lei, J.; Zheng, B.; Tang, X.; Wang, M.; Hu, Jiawen; Li, S.; Wang, B.; Finkelman, R.B.

    2011-01-01

    Three hundred and six coal samples were taken from main coal mines of twenty-six provinces, autonomous regions, and municipalities in China, according to the resource distribution and coal-forming periods as well as the coal ranks and coal yields. Nitrogen was determined by using the Kjeldahl method at U. S. Geological Survey (USGS), which exhibit a normal frequency distribution. The nitrogen contents of over 90% Chinese coal vary from 0.52% to 1.41% and the average nitrogen content is recommended to be 0.98%. Nitrogen in coal exists primarily in organic form. There is a slight positive relationship between nitrogen content and coal ranking. ?? 2011 Science Press, Institute of Geochemistry, CAS and Springer Berlin Heidelberg.

  8. The microbial nitrogen cycle.

    PubMed

    Jetten, Mike S M

    2008-11-01

    This special issue highlights several recent discoveries in the microbial nitrogen cycle including the diversity of nitrogen-fixing bacteria in special habitats, distribution and contribution of aerobic ammonium oxidation by bacteria and crenarchaea in various aquatic and terrestrial ecosystems, regulation of metabolism in nitrifying bacteria, the molecular diversity of denitrifying microorganisms and their enzymes, the functional diversity of freshwater and marine anammox bacteria, the physiology of nitrite-dependent anaerobic methane oxidation and the degradation of recalcitrant organic nitrogen compounds. Simultaneously the articles in this issue show that many questions still need to be addressed, and that the microbes involved in catalyzing the nitrogen conversions still harbour many secrets that need to be disclosed to fully understand the biogeochemical nitrogen cycle, and make future predictions and global modelling possible.

  9. Nitrogen Lewis Acids.

    PubMed

    Pogoreltsev, Alla; Tulchinsky, Yuri; Fridman, Natalia; Gandelman, Mark

    2017-03-22

    Being a major conception of chemistry, Lewis acids have found countless applications throughout chemical enterprise. Although many chemical elements can serve as the central atom of Lewis acids, nitrogen is usually associated with Lewis bases. Here, we report on the first example of robust and modifiable Lewis acids centered on the nitrogen atom, which provide stable and well-characterized adducts with various Lewis bases. On the basis of the reactivity of nitrogen Lewis acids, we prepared, for the first time, cyclic triazanes, a class of cyclic organic compounds sequentially bearing three all-saturated nitrogen atoms (N-N-N motif). Reactivity abilities of these N-Lewis acids were explained by theoretical calculations. Properties and future applications of nitrogen Lewis acids are intriguing.

  10. NITROGEN REMOVAL FROM NATURAL GAS

    SciTech Connect

    K.A. Lokhandwala; M.B. Ringer; T.T. Su; Z. He; I. Pinnau; J.G. Wijmans; A. Morisato; K. Amo; A. DaCosta; R.W. Baker; R. Olsen; H. Hassani; T. Rathkamp

    1999-12-31

    The objective of this project was to develop a membrane process for the denitrogenation of natural gas. Large proven reserves in the Lower-48 states cannot be produced because of the presence of nitrogen. To exploit these reserves, cost-effective, simple technology able to reduce the nitrogen content of the gas to 4-5% is required. Technology applicable to treatment of small gas streams (below 10 MMscfd) is particularly needed. In this project membranes that selectively permeate methane and reject nitrogen in the gas were developed. Preliminary calculations show that a membrane with a methane/nitrogen selectivity of 3 to 5 is required to make the process economically viable. A number of polymer materials likely to have the required selectivities were evaluated as composite membranes. Polyacetylenes such as poly(1-trimethylsilyl-1-propyne) [PTMSP] and poly(4-methyl-2-pentyne) [PMP] had high selectivities and fluxes, but membranes prepared from these polymers were not stable, showing decreasing flux and selectivity during tests lasting only a few hours. Parel, a poly(propylene oxide allyl glycidyl ether) had a selectivity of 3 at ambient temperatures and 4 or more at temperatures of {minus}20 C. However, Parel is no longer commercially available, and we were unable to find an equivalent material in the time available. Therefore, most of our experimental work focused on silicone rubber membranes, which have a selectivity of 2.5 at ambient temperatures, increasing to 3-4 at low temperatures. Silicone rubber composite membranes were evaluated in bench-scale module tests and with commercial-scale, 4-inch-diameter modules in a small pilot plant. Over six days of continuous operation at a feed gas temperature of {minus}5 to {minus}10 C, the membrane maintained a methane/nitrogen selectivity of about 3.3. Based on the pilot plant performance data, an analysis of the economic potential of the process was prepared. We conclude that a stand-alone membrane process is the lowest

  11. Demonstrating Paramagnetism Using Liquid Nitrogen.

    ERIC Educational Resources Information Center

    Simmonds, Ray; And Others

    1994-01-01

    Describes how liquid nitrogen is attracted to the poles of neodymium magnets. Nitrogen is not paramagnetic, so the attraction suggests that the liquid nitrogen contains a small amount of oxygen, which causes the paramagnetism. (MVL)

  12. Molecular Biology of Nitrogen Fixation

    ERIC Educational Resources Information Center

    Shanmugam, K. T.; Valentine, Raymond C.

    1975-01-01

    Reports that as a result of our increasing knowledge of the molecular biology of nitrogen fixation it might eventually be possible to increase the biological production of nitrogenous fertilizer from atmospheric nitrogen. (GS)

  13. Demonstrating Paramagnetism Using Liquid Nitrogen.

    ERIC Educational Resources Information Center

    Simmonds, Ray; And Others

    1994-01-01

    Describes how liquid nitrogen is attracted to the poles of neodymium magnets. Nitrogen is not paramagnetic, so the attraction suggests that the liquid nitrogen contains a small amount of oxygen, which causes the paramagnetism. (MVL)

  14. Molecular Biology of Nitrogen Fixation

    ERIC Educational Resources Information Center

    Shanmugam, K. T.; Valentine, Raymond C.

    1975-01-01

    Reports that as a result of our increasing knowledge of the molecular biology of nitrogen fixation it might eventually be possible to increase the biological production of nitrogenous fertilizer from atmospheric nitrogen. (GS)

  15. Electrical Properties of Nitrogen Doped Float Zone Silicon.

    DTIC Science & Technology

    1985-07-01

    examination from Shin - Etsu Handotai Co. throuqh Dr. T. Abe. The boule is typical of such material grown by Shin - Etsu and nitrogen doping was accomplished... Shin - Etsu FZ Nitrogen n 10 3 Handotai Hughes FZ residual p105 Aircraft Boron Monsanto CZ Phosphorus n 200 Monsanto CZ Phosphorus n 2.0 Several 3/8" x 3

  16. [Effects of chlorimuron-ethyl and urea on soil microbial biomass carbon and nitrogen and soil inorganic nitrogen].

    PubMed

    Tan, Huan-Bo; Li, Xin-Yu; Zhang, Hui-Wen; Li, Xu; Xu, Ming-Kai

    2012-08-01

    A microcosm experiment was conducted to study the effects of different concentration chlorimuron-ethyl (20, 200, and 2000 microg x kg(-1) soil) and its combination with urea (120 mg x kg(-1) soil) on the dynamic changes of soil microbial biomass carbon and nitrogen and soil nitrate nitrogen and ammonium nitrogen. Applying chlorimuron-ethyl alone decreased the soil microbial biomass carbon and nitrogen throughout the experiment period (60 days), and the decrement increased with increasing chlorimuron-ethyl concentration. Chlorimuron-ethyl had little effects on the soil ammonium nitrogen and nitrite nitrogen in the early period of the experiment, but increased the soil ammonium nitrogen in the mid-period (15 d) and the soil nitrate nitrogen in the late period (after 30 days) significantly. Both urea addition and its combination with chlorimuron-ethyl increased the soil microbial biomass carbon and nitrogen obviously in a short time, but the effect of combined addition of urea and chlorimuron-ethyl weakened then. Applying urea and its combination with chlorimuron-ethyl resulted in a lasting increase of soil nitrate nitrogen and ammonium nitrogen.

  17. [Effects of elevated atmospheric CO2 and nitrogen application on cotton biomass, nitrogen utilization and soil urease activity].

    PubMed

    Lyu, Ning; Yin, Fei-hu; Chen, Yun; Gao, Zhi-jian; Liu, Yu; Shi, Lei

    2015-11-01

    under the ambient CO2- (360 µmol · mol(-1)) treatment. The order of nitrogen accumulation content in organs was bud > leaf > stem > root. Soil urease activity of both layers increased significantly with the elevation of CO2 concentration in all the nitrogen treatments. Under each CO2 concentration treatment, the soil urease activity in the upper layer (0-20 cm) increased significantly with nitrogen application, while the urease activity under the application of 300 kg · hm(-2) nitrogen was highest in the lower layer (20- 40 cm). The average soil urease activity in the upper layer (0-20 cm) was significantly higher than that in the lower layer (20-40 cm). This study suggested that the cotton dry matter accumulation and nitrogen absorption content were significantly increased in response to the elevated CO2 concentration (540 µmol · mol(-1)) and higher nitrogen addition (300 kg · hm(-2)).

  18. The nitrogen cycle.

    PubMed

    Stein, Lisa Y; Klotz, Martin G

    2016-02-08

    Nitrogen is the fourth most abundant element in cellular biomass, and it comprises the majority of Earth's atmosphere. The interchange between inert dinitrogen gas (N2) in the extant atmosphere and 'reactive nitrogen' (those nitrogen compounds that support, or are products of, cellular metabolism and growth) is entirely controlled by microbial activities. This was not the case, however, in the primordial atmosphere, when abiotic reactions likely played a significant role in the inter-transformation of nitrogen oxides. Although such abiotic reactions are still important, the extant nitrogen cycle is driven by reductive fixation of dinitrogen and an enzyme inventory that facilitates dinitrogen-producing reactions. Prior to the advent of the Haber-Bosch process (the industrial fixation of N2 into ammonia, NH3) in 1909, nearly all of the reactive nitrogen in the biosphere was generated and recycled by microorganisms. Although the Haber-Bosch process more than quadrupled the productivity of agricultural crops, chemical fertilizers and other anthropogenic sources of fixed nitrogen now far exceed natural contributions, leading to unprecedented environmental degradation.

  19. Fertilizer nitrogen isotope signatures.

    PubMed

    Bateman, Alison S; Kelly, Simon D

    2007-09-01

    There has been considerable recent interest in the potential application of nitrogen isotope analysis in discriminating between organically and conventionally grown crops. A prerequisite of this approach is that there is a difference in the nitrogen isotope compositions of the fertilizers used in organic and conventional agriculture. We report new measurements of delta15N values for synthetic nitrogen fertilizers and present a compilation of the new data with existing literature nitrogen isotope data. Nitrogen isotope values for fertilizers that may be permitted in organic cultivation systems are also reported (manures, composts, bloodmeal, bonemeal, hoof and horn, fishmeal and seaweed based fertilizers). The delta15N values of the synthetic fertilizers in the compiled dataset fall within a narrow range close to 0 per thousand with 80% of samples lying between-2 and 2 per thousand and 98.5% of the data having delta15N values of less than 4 per thousand (mean=0.2 per thousand n=153). The fertilizers that may be permitted in organic systems have a higher mean delta15N value of 8.5 per thousand and exhibit a broader range in delta15N values from 0.6 to 36.7 per thousand (n=83). The possible application of the nitrogen isotope approach in discriminating between organically and conventionally grown crops is discussed in light of the fertilizer data presented here and with regard to other factors that are also important in determining crop nitrogen isotope values.

  20. Nitrogen Backbone Oligomers.

    PubMed

    Wang, Hongbo; Eremets, Mikhail I; Troyan, Ivan; Liu, Hanyu; Ma, Yanming; Vereecken, Luc

    2015-08-19

    We found that nitrogen and hydrogen directly react at room temperature and pressures of ~35 GPa forming chains of single-bonded nitrogen atom with the rest of the bonds terminated with hydrogen atoms - as identified by IR absorption, Raman, X-ray diffraction experiments and theoretical calculations. At releasing pressures below ~10 GPa, the product transforms into hydrazine. Our findings might open a way for the practical synthesis of these extremely high energetic materials as the formation of nitrogen-hydrogen compounds is favorable already at pressures above 2 GPa according to the calculations.

  1. Nitrogen Backbone Oligomers

    PubMed Central

    Wang, Hongbo; Eremets, Mikhail I.; Troyan, Ivan; Liu, Hanyu; Ma, Yanming; Vereecken, Luc

    2015-01-01

    We found that nitrogen and hydrogen directly react at room temperature and pressures of ~35 GPa forming chains of single-bonded nitrogen atom with the rest of the bonds terminated with hydrogen atoms - as identified by IR absorption, Raman, X-ray diffraction experiments and theoretical calculations. At releasing pressures below ~10 GPa, the product transforms into hydrazine. Our findings might open a way for the practical synthesis of these extremely high energetic materials as the formation of nitrogen-hydrogen compounds is favorable already at pressures above 2 GPa according to the calculations. PMID:26286836

  2. PVT gauging with liquid nitrogen

    NASA Astrophysics Data System (ADS)

    Van Dresar, Neil T.

    2006-02-01

    Experimental results are presented for pressure-volume-temperature (PVT) liquid quantity gauging of a 0.17 m 3 liquid nitrogen tank pressured with ambient temperature helium in the normal gravity environment. A previously reported PVT measurement procedure has been improved to include helium solubility in liquid nitrogen. Gauging data was collected at nominal tank fill levels of 80%, 50% and 20% and at nominal tank pressures of 0.3, 1.0, and 1.7 MPa. The test tank was equipped with a liquid pump and spray manifold to circulate and mix the fluid contents and therefore create near-isothermal conditions throughout the tank. Silicon diode sensors were distributed throughout the tank to monitor temperatures. Close-spaced arrays of silicon diode point sensors were utilized to precisely detect the liquid level at the nominal 80%, 50%, and 20% fill levels. The tests simulated the cryogenic tank-side conditions only; helium mass added to the tank was measured by gas flowmeters rather than using pressure and temperature measurements from a dedicated helium supply bottle. Equilibrium data for cryogenic nitrogen and helium mixtures from numerous sources was correlated to predict soluble helium mole fractions. Results show that solubility should be accounted for in the PVT gauging calculations. Mole fractions predicted by Dalton's Law were found to be in good agreement with the compiled equilibrium data within the temperature-pressure range of interest. Therefore, Dalton's Law was deemed suitable for calculating ullage composition. Gauging results from the PVT method agreed with the reference liquid level measurements to within 3%.

  3. Mineral commodity profiles: nitrogen

    USGS Publications Warehouse

    Kramer, Deborah A.

    2004-01-01

    Overview -- Nitrogen (N) is an essential element of life and a part of all animal and plant proteins. As a part of the DNA and RNA molecules, nitrogen is an essential constituent of each individual's genetic blueprint. As an essential element in the chlorophyll molecule, nitrogen is vital to a plant's ability to photosynthesize. Some crop plants, such as alfalfa, peas, peanuts, and soybeans, can convert atmospheric nitrogen into a usable form by a process referred to as 'fixation.' Most of the nitrogen that is available for crop production, however, comes from decomposing animal and plant waste or from commercially produced fertilizers. Commercial fertilizers contain nitrogen in the form of ammonium and/or nitrate or in a form that is quickly converted to the ammonium or nitrate form once the fertilizer is applied to the soil. Ammonia is generally the source of nitrogen in fertilizers. Anhydrous ammonia is commercially produced by reacting nitrogen with hydrogen under high temperatures and pressures. The source of nitrogen is the atmosphere, which is almost 80 percent nitrogen. Hydrogen is derived from a variety of raw materials, which include water, and crude oil, coal, and natural gas hydrocarbons. Nitrogen-based fertilizers are produced from ammonia feedstocks through a variety of chemical processes. Small quantities of nitrates are produced from mineral resources principally in Chile. In 2002, anhydrous ammonia and other nitrogen materials were produced in more than 70 countries. Global ammonia production was 108 million metric tons (Mt) of contained nitrogen. With 28 percent of this total, China was the largest producer of ammonia. Asia contributed 46 percent of total world ammonia production, and countries of the former U.S.S.R. represented 13 percent. North America also produced 13 percent of the total; Western Europe, 9 percent; the Middle East, 7 percent; Central America and South America, 5 percent; Eastern Europe, 3 percent; and Africa and Oceania

  4. The Liquid Nitrogen Fountain

    NASA Astrophysics Data System (ADS)

    McRae, Robin; Rahn, Jeffrey A.; Beamer, Timothy W.; Lebret, Norm

    2002-10-01

    Details of a demonstration using liquid nitrogen are presented. The demonstration is based on a 500-mL transparent polyethylene soft-drink bottle with a screw-on pop-up drink top. Prior to the demonstration, a balloon is placed over the popped-up spout of the bottle top. The bottle is filled with liquid nitrogen and the top, with the balloon affixed, is quickly put in place and screwed on tightly. As the liquid nitrogen in the bottle boils, the balloon inflates. When the balloon bursts the noise produced is far greater than would ordinarily be expected, and a fountain of liquid nitrogen and condensing water vapor shoots into the air above the bottle.

  5. The effects of deep zones on wetland nitrogen processing.

    PubMed

    Kadlec, R H

    2007-01-01

    Twelve research wetlands were operated under varying conditions at a site west of the city of Phoenix. These were constructed as a triplicated design, with zero, one, two and three internal deep zones, all containing an inlet distribution and an outlet collection deep zone, together comprising 12.5-35% of the wetland areas. The water supply was partially nitrified effluent from a city wastewater treatment plant. Total nitrogen was reduced by about 50%, from inflow concentrations between 6 and 8 mg/L. Speciation of the inflow was approximately 25% organic nitrogen, 25% ammonium nitrogen and 50% nitrate nitrogen. Typical outflow concentrations were about 1.2 mg/L organic, 0.5 mg/L ammonium and 0.0-2.5 mg/L nitrate. Rate constants for total nitrogen were 15-20 m/year at 20 degrees C, and 20-30 m/year for nitrate, which agree well with other project reports. Temperature factors averaged 1.100 for total nitrogen, and 1.184 for nitrate. There were no differences in the internal hydraulics with deep zone numbers. Deep zone numbers in the wetlands did not affect nitrogen treatment performance. No differences with deep zone numbers were found for temperature, dissolved oxygen, pH, or nitrogen removals or rate constants. In conjunction with other reported results, there appears to be no large treatment benefit or detriment of incorporating internal deep zones in free water surface wetlands.

  6. Protein Nitrogen Determination

    NASA Astrophysics Data System (ADS)

    Nielsen, S. Suzanne

    The protein content of foods can be determined by numerous methods. The Kjeldahl method and the nitrogen combustion (Dumas) method for protein analysis are based on nitrogen determination. Both methods are official for the purposes of nutrition labeling of foods. While the Kjeldahl method has been used widely for over a hundred years, the recent availability of automated instrumentation for the Dumas method in many cases is replacing use of the Kjeldahl method.

  7. Atmospheric Nitrogen Fluorescence Yield

    NASA Technical Reports Server (NTRS)

    Adams, J. H., Jr.; Christl, M. J.; Fountain, W. F.; Gregory, J. C.; Martens, K. U.; Sokolsky, Pierre; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Several existing and planned experiments estimate the energies of ultra-high energy cosmic rays from air showers using the atmospheric nitrogen fluorescence. The nitrogen fluorescence yield from air shower electrons depends on the atmospheric composition. We will discuss the uncertainties in the fluorescence yield form electrons in the real atmosphere and describe a concept for a small balloon payload to measure the atmospheric fluorescence yield as a function of attitude.

  8. Brucella, nitrogen and virulence.

    PubMed

    Ronneau, Severin; Moussa, Simon; Barbier, Thibault; Conde-Álvarez, Raquel; Zuniga-Ripa, Amaia; Moriyon, Ignacio; Letesson, Jean-Jacques

    2016-08-01

    The brucellae are α-Proteobacteria causing brucellosis, an important zoonosis. Although multiplying in endoplasmic reticulum-derived vacuoles, they cause no cell death, suggesting subtle but efficient use of host resources. Brucellae are amino-acid prototrophs able to grow with ammonium or use glutamate as the sole carbon-nitrogen source in vitro. They contain more than twice amino acid/peptide/polyamine uptake genes than the amino-acid auxotroph Legionella pneumophila, which multiplies in a similar vacuole, suggesting a different nutritional strategy. During these two last decades, many mutants of key actors in nitrogen metabolism (transporters, enzymes, regulators, etc.) have been described to be essential for full virulence of brucellae. Here, we review the genomic and experimental data on Brucella nitrogen metabolism and its connection with virulence. An analysis of various aspects of this metabolism (transport, assimilation, biosynthesis, catabolism, respiration and regulation) has highlighted differences and similarities in nitrogen metabolism with other α-Proteobacteria. Together, these data suggest that, during their intracellular life cycle, the brucellae use various nitrogen sources for biosynthesis, catabolism and respiration following a strategy that requires prototrophy and a tight regulation of nitrogen use.

  9. Nitrogen loss from Titan

    NASA Astrophysics Data System (ADS)

    Shematovich, V. I.; Johnson, R. E.; Michael, M.; Luhmann, J. G.

    2003-08-01

    Dissociation and dissociative ionization of molecular nitrogen by solar UV radiation and by photoelectrons and sputtering by the magnetospheric ions and pickup ions are the main sources of translationally excited (hot) nitrogen atoms and molecules in the upper atmosphere of Titan. As Titan does not posses an intrinsic magnetic field, Saturn's magnetospheric ions can penetrate Titan's exobase and sputter atoms and molecules from it. The sputtering of nitrogen from Titan's upper atmosphere by the corotating nitrogen ions and by photodissociation was addressed earlier [Lammer and Bauer, 1993; Shematovich et al., 2001]. Here penetration of slowed and deflected magnetospheric N+ and carbon-containing pickup ions is described using a Monte Carlo model. The interaction of these ions with the atmospheric neutrals leads to the production of fast neutrals that collide with other atmospheric neutrals producing heating and ejection of atoms and molecules. Results from Brecht et al. [2000] are used to estimate the net flux and energy spectra of the magnetospheric and pickup ions onto the exobase. Sputtering is primarily responsible for any ejected molecular nitrogen, and, for the ion fluxes used, we show that the total sputtering contribution is comparable to or larger than the dissociation contribution giving a total loss rate of ~3.6 × 1025 nitrogen neutrals per second.

  10. Nitrogen recycling from fuel-extracted algal biomass: residuals as the sole nitrogen source for culturing Scenedesmus acutus.

    PubMed

    Gu, Huiya; Nagle, Nick; Pienkos, Philip T; Posewitz, Matthew C

    2015-05-01

    In this study, the reuse of nitrogen from fuel-extracted algal residues was investigated. The alga Scenedesmus acutus was found to be able to assimilate nitrogen contained in amino acids, yeast extracts, and proteinaceous alga residuals. Moreover, these alternative nitrogen resources could replace nitrate in culturing media. The ability of S. acutus to utilize the nitrogen remaining in processed algal biomass was unique among the promising biofuel strains tested. This alga was leveraged in a recycling approach where nitrogen is recovered from algal biomass residuals that remain after lipids are extracted and carbohydrates are fermented to ethanol. The protein-rich residuals not only provided an effective nitrogen resource, but also contributed to a carbon "heterotrophic boost" in subsequent culturing, improving overall biomass and lipid yields relative to the control medium with only nitrate. Prior treatment of the algal residues with Diaion HP20 resin was required to remove compounds inhibitory to algal growth.

  11. 40 CFR Table 1 to Subpart Cb of... - Nitrogen Oxides Guidelines for Designated Facilities

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 7 2012-07-01 2012-07-01 false Nitrogen Oxides Guidelines for... September 20, 1994 Pt. 60, Subpt. Cb, Table 1 Table 1 to Subpart Cb of part 60—Nitrogen Oxides Guidelines for Designated Facilities Municipal waste combustor technology Before April 28, 2009,nitrogen oxides...

  12. 40 CFR Table 1 to Subpart Cb of... - Nitrogen Oxides Guidelines for Designated Facilities

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 7 2014-07-01 2014-07-01 false Nitrogen Oxides Guidelines for... September 20, 1994 Pt. 60, Subpt. Cb, Table 1 Table 1 to Subpart Cb of Part 60—Nitrogen Oxides Guidelines for Designated Facilities Municipal waste combustor technology Before April 28, 2009,nitrogen oxides...

  13. 40 CFR Table 2 to Subpart Fff of... - Nitrogen Oxides Requirements for Affected Facilities

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 9 2013-07-01 2013-07-01 false Nitrogen Oxides Requirements for... Before September 20, 1994 Pt. 62, Subpt. FFF, Table 2 Table 2 to Subpart FFF of Part 62—Nitrogen Oxides Requirements for Affected Facilities Municipal waste combustor technology Nitrogen oxides emission limit (parts...

  14. 40 CFR Table 2 to Subpart Fff of... - Nitrogen Oxides Requirements for Affected Facilities

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 8 2010-07-01 2010-07-01 false Nitrogen Oxides Requirements for... Before September 20, 1994 Pt. 62, Subpt. FFF, Table 2 Table 2 to Subpart FFF of Part 62—Nitrogen Oxides Requirements for Affected Facilities Municipal waste combustor technology Nitrogen oxides emission limit (parts...

  15. 40 CFR 92.121 - Oxides of nitrogen analyzer calibration and check.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Oxides of nitrogen analyzer... Procedures § 92.121 Oxides of nitrogen analyzer calibration and check. (a) Quench checks; NO X analyzer. (1... performed in step in paragraph (a)(3)(i) this section. (b) Oxides of nitrogen analyzer calibration. (1...

  16. 40 CFR Table 1 to Subpart Cb of... - Nitrogen Oxides Guidelines for Designated Facilities

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Nitrogen Oxides Guidelines for... September 20, 1994 Pt. 60, Subpt. Cb, Table 1 Table 1 to Subpart Cb of part 60—Nitrogen Oxides Guidelines for Designated Facilities Municipal waste combustor technology Before April 28, 2009,nitrogen oxides...

  17. 40 CFR Table 1 to Subpart Cb of... - Nitrogen Oxides Guidelines for Designated Facilities

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 6 2011-07-01 2011-07-01 false Nitrogen Oxides Guidelines for... September 20, 1994 Pt. 60, Subpt. Cb, Table 1 Table 1 to Subpart Cb of part 60—Nitrogen Oxides Guidelines for Designated Facilities Municipal waste combustor technology Before April 28, 2009,nitrogen oxides...

  18. 40 CFR Table 1 to Subpart Cb of... - Nitrogen Oxides Guidelines for Designated Facilities

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 7 2013-07-01 2013-07-01 false Nitrogen Oxides Guidelines for... September 20, 1994 Pt. 60, Subpt. Cb, Table 1 Table 1 to Subpart Cb of Part 60—Nitrogen Oxides Guidelines for Designated Facilities Municipal waste combustor technology Before April 28, 2009,nitrogen oxides...

  19. 40 CFR Table 2 to Subpart Fff of... - Nitrogen Oxides Requirements for Affected Facilities

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 9 2012-07-01 2012-07-01 false Nitrogen Oxides Requirements for... Before September 20, 1994 Pt. 62, Subpt. FFF, Table 2 Table 2 to Subpart FFF of Part 62—Nitrogen Oxides Requirements for Affected Facilities Municipal waste combustor technology Nitrogen oxides emission limit (parts...

  20. 40 CFR 92.121 - Oxides of nitrogen analyzer calibration and check.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Oxides of nitrogen analyzer... Procedures § 92.121 Oxides of nitrogen analyzer calibration and check. (a) Quench checks; NO X analyzer. (1... performed in step in paragraph (a)(3)(i) this section. (b) Oxides of nitrogen analyzer calibration....

  1. 40 CFR 92.121 - Oxides of nitrogen analyzer calibration and check.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Oxides of nitrogen analyzer calibration... Procedures § 92.121 Oxides of nitrogen analyzer calibration and check. (a) Quench checks; NO X analyzer. (1... performed in step in paragraph (a)(3)(i) this section. (b) Oxides of nitrogen analyzer calibration....

  2. 40 CFR Table 2 to Subpart Fff of... - Nitrogen Oxides Requirements for Affected Facilities

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 9 2014-07-01 2014-07-01 false Nitrogen Oxides Requirements for... Before September 20, 1994 Pt. 62, Subpt. FFF, Table 2 Table 2 to Subpart FFF of Part 62—Nitrogen Oxides Requirements for Affected Facilities Municipal waste combustor technology Nitrogen oxides emission limit...

  3. 40 CFR Table 2 to Subpart Fff of... - Nitrogen Oxides Requirements for Affected Facilities

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 8 2011-07-01 2011-07-01 false Nitrogen Oxides Requirements for... Before September 20, 1994 Pt. 62, Subpt. FFF, Table 2 Table 2 to Subpart FFF of Part 62—Nitrogen Oxides Requirements for Affected Facilities Municipal waste combustor technology Nitrogen oxides emission limit...

  4. Increasing importance of deposition of reduced nitrogen in the United States

    Treesearch

    Yi Li; Bret A. Schichtel; John T. Walker; Donna B. Schwede; Xi Chen; Christopher M. B. Lehmann; Melissa A. Puchalski; David A. Gay; Jeffrey L. Collett

    2016-01-01

    Rapid development of agriculture and fossil fuel combustion greatly increased US reactive nitrogen emissions to the atmosphere in the second half of the 20th century, resulting in excess nitrogen deposition to natural ecosystems. Recent efforts to lower nitrogen oxides emissions have substantially decreased nitrate wet deposition. Levels of wet ammonium...

  5. Nitrogen Uptake in Spinach

    NASA Astrophysics Data System (ADS)

    Ramirez, J.; VanBenthem, P.

    2013-12-01

    A plant's absorption of nitrogen can be encouraged by a variety of environmental factors, especially the application of fertilizers. As a common limiting factor in plant growth, not up taking enough nitrogen can be a result of an unhealthy plant. Moreover, as farmers seek out methods to increase growth of plants, fertilizers are used as a solution to the issue of nitrogen deficiency to incorporate additional nitrogen from chemical or organic sources, by not using the right fertilizer can greatly affect the plats. The point of this research project is to determine the effect of various fertilizers on the plant growth, and to correlate the measured nitrogen, water and chlorophyll content in spinach leaves. Spinach leaves were used because they are known to quickly uptake chemicals in the environment. The spinach plants were exposed to four different growing parameters, which are referred to as control, ammonium nitrate, MiracleGro , and organic. The spinach was originally placed in nitrogen deficient soil with only 2.2x10 4 weight percent (wt. %) nitrogen. The leaves in the control group were grown in this nitrogen deficient soil without any fertilizer added. Ammomium nitrate and MiracleGro were added to the spinach in the A and MG groups, respectively, and organic chicken stool was used for the O group. By using a spectral imaging system and flame combustion techniques, the chlorophyll content can be related to the nitrogen content in the spinach leaves. In these spinach leaves, nitrogen and chlorophyll content were measured, chlorophyll is a green pigment that plays a crucial role in producing nutrients for green plants. The lack of chlorophyll will allow the plant to become susceptible to diseases, so it is extremely important that the plants have a high content of chlorophyll. The role of nitrogen in chlorophyll is very important and helps in the creation of chlorophyll; therefore it is necessary that an appropriate amount of nitrogen is added for optimal growth

  6. Fuel nitrogen release during black liquor pyrolysis; Part 2: Comparisons between different liquors

    SciTech Connect

    Aho, K.; Nikkanen, S. ); Hupa, M. . Chemical Engineering Dept.)

    1994-08-01

    This continuation of earlier work reports fuel nitrogen release for black liquors at two temperatures during pyrolysis of single droplets in an oxygen-free environment. Approximately half of the 20--60% fuel nitrogen released was ammonia and half was molecular nitrogen. The total amount of fixed nitrogen released during pyrolysis was almost linearly proportional to the liquor nitrogen content. The yield of fixed nitrogen for birch liquors was significantly higher than for pine liquors, and the yield for bagasse liquor was extremely high.

  7. Nitrogen transformations and balance in constructed wetlands for slightly polluted river water treatment using different macrophytes.

    PubMed

    Wu, Haiming; Zhang, Jian; Wei, Rong; Liang, Shuang; Li, Cong; Xie, Huijun

    2013-01-01

    Nitrogen removal processing in different constructed wetlands treating different kinds of wastewater often varies, and the contribution to nitrogen removal by various pathways remains unclear. In this study, the seasonal nitrogen removal and transformations as well as nitrogen balance in wetland microcosms treating slightly polluted river water was investigated. The results showed that the average total nitrogen removal rates varied in different seasons. According to the mass balance approach, plant uptake removed 8.4-34.3 % of the total nitrogen input, while sediment storage and N(2)O emission contributed 20.5-34.4 % and 0.6-1.9 % of nitrogen removal, respectively. However, the percentage of other nitrogen loss such as N(2) emission due to nitrification and denitrification was estimated to be 2.0-23.5 %. The results indicated that plant uptake and sediment storage were the key factors limiting nitrogen removal besides microbial processes in surface constructed wetland for treating slightly polluted river water.

  8. The 20-20-20 Airship Challenge

    NASA Astrophysics Data System (ADS)

    Kiessling, Alina; Diaz, Ernesto; Miller, Sarah; Rhodes, Jason

    2014-06-01

    A NASA Centennial Challenge; (http://www.nasa.gov/directorates/spacetech/centennial_challenges/index.html) is in development to spur innovation in stratospheric airships as a science platform. We anticipate a million dollar class prize for the first organization to fly a powered airship that remains stationary at 20km (65,000 ft) altitude for over 20 hours with a 20kg payload. The design must be scalable to longer flights with more massive payloads.In NASA’s constrained budget environment, there are few opportunities for space missions in astronomy and Earth science, and these have very long lead times. We believe that airships (powered, maneuverable, lighter-than-air vehicles) could offer significant gains in observing time, sky and ground coverage, data downlink capability, and continuity of observations over existing suborbital options at competitive prices. We seek to spur private industry (or non-profit institutions, including FFRDCs and Universities) to demonstrate the capability for sustained airship flights as astronomy and Earth science platforms. This poster will introduce the challenge in development and provide details of who to contact for more information.

  9. [XPS and Raman spectral analysis of nitrogenated tetrahedral amorphous carbon (ta-C : N) films with different nitrogen content].

    PubMed

    Chen, Wang-Shou; Zhu, Jia-Qi; Han, Jie-Cai; Tian, Gui; Tan, Man-Lin

    2009-01-01

    Nitrogenated tetrahedral amorphous carbon (ta-C : N) films were prepared on the polished C--Si substrates by introducing highly pure nitrogen gas into the cathode region and the depositing chamber synchronously using filtered cathodic vacuum arc (FCVA) technology. The nitrogen content in the films was controlled by changing the flow rate of nitrogen gas. The configuration of ta-C : N films was investigated by means of X-ray photoelectron spectroscopy (XPS) and visible Raman spectroscopy. It was shown that the nitrogen content in the films increased from 0.84 at% to 5.37 at% monotonously when the nitrogen flow rate was varied from 2 seem to 20 sccm. The peak position of C (1s) core level moved towards higher binding energy with the increase in nitrogen content. The shift of C (1s) peak position could be ascribed to the chemical bonding between carbon and nitrogen atoms even though more three-fold coordinated sp2 configuration as in graphite was formed when the films were doped with more nitrogen atoms. Additionally, the half width of C(1s) peak gradually was also broadened with increasing nitrogen content. In order to discover clearly the changing regularities of the microstructure of the films, the XPS C(1s) spectra and Raman spectra were deconvoluted using a Gaussian-Lorentzian mixed lineshape. It was shown that the tetrahedral hybridization component was still dominant even though the ratio of sp2/sp3 obtained from C(1s) spectra rose with the increase in nitrogen content. The Raman measurements demonstrated that the G peak position shifted towards higher frequency from 1,561 to 1,578 cm(-1) and the ratio of ID/IG also rose with the increase in nitrogen content. Both results indicated that the graphitizing tendency could occur with the increase in nitrogen content in the films.

  10. Nitrogen Inputs via Nitrogen Fixation in Northern Plants and Soils

    NASA Astrophysics Data System (ADS)

    Thorp, N. R.; Wieder, R. K.; Vile, M. A.

    2015-12-01

    Dominated by cold and often acidic water logged environments, mineralization of organic matter is slow in the majority of northern ecosystems. Measures of extractable ammonium and nitrate are generally low and can be undetectable in peat pore waters. Despite this apparent nitrogen limitation, many of these environments produce deep deposits of soil organic matter. Biological nitrogen fixation carried out by autotrophic and heterotrophic diazotrophs associated with cryptograms provides the majority of known nitrogen inputs in these northern ecosystems. Nitrogen fixation was assessed in a variety of northern soils within rhizospheres of dominant plant communities. We investigated the availability of this newly fixed nitrogen to the vascular plant community in nitrogen limited northern plant communities. We tracked nitrogen flow from 15N2 gas fixed in Sphagnum mosses into tissues of two native vascular plant species, boreal cranberry (Vaccinium oxycoccus) and black spruce (Picea mariana). 15N-labeled Sphagnum microcosms were grown within variable mesh size exclusion/inclusion fabrics in a nitrogen addition experiment in situ in order to investigate the role of mycorrhizal fungi in the uptake of newly fixed nitrogen. Up to 24% of daily fixed 15N label was transferred to vascular plant tissues during 2 months. Nitrogen addition resulted in decreased N2 fixation rates; however, with higher nitrogen availability there was a higher rate of 15N label uptake into the vascular plants, likely the result of increased production of dissolved organic nitrogen. Reliance on mycorrhizal networks for nitrogen acquisition was indicated by nitrogen isotope fractionation patterns. Moreover, N2 fixation activities in mosses were stimulated when vascular plants were grown in moss microcosms versus "moss only" treatments. Results indicate that bog vascular plants may derive considerable nitrogen from atmospheric N2 biologically fixed within Sphagnum mosses. This work demonstrates that

  11. Trichodesmium and nitrogen fixation in the Kuroshio

    NASA Astrophysics Data System (ADS)

    Shiozaki, T.; Takeda, S.; Itoh, S.; Kodama, T.; Liu, X.; Hashihama, F.; Furuya, K.

    2015-07-01

    Nitrogen fixation in the Kuroshio influences nitrogen balance in the North Pacific Ocean. The genus Trichodesmium is recognized as a major diazotroph in the Kuroshio. Although its abundance is higher in the Kuroshio than in adjacent waters, the reason for this difference remains unclear. The present study investigated the abundance of Trichodesmium spp. and nitrogen fixation together with concentrations of dissolved iron and phosphate, whose availabilities potentially control diazotrophy, in the Kuroshio and its marginal seas. We performed the observations near the Miyako Islands, which form part of the Ryukyu Islands, situated along the Kuroshio, since satellite analysis suggested that material transport could occur from the islands to the Kuroshio. Trichodesmium spp. bloomed (> 20 000 filaments L-1) near the Miyako Islands, and the abundance was high in the Kuroshio and the Kuroshio bifurcation region of the East China Sea, but was low in the Philippine Sea. The abundance of Trichodesmium spp. was significantly correlated with the total nitrogen fixation activity. The surface concentrations of dissolved iron (0.19-0.89 nM) and phosphate (< 3-36 nM) were similar for all of the study areas, indicating that the nutrient distribution could not explain the spatial differences in Trichodesmium spp. abundance and nitrogen fixation. We used a numerical model to simulate the transportation of water around the Ryukyu Islands to the Kuroshio. Our results indicate that Trichodesmium growing around the islands situated along the Kuroshio is potentially important for determining diazotrophy in this region.

  12. Nitrogen release from rock and soil under simulated field conditions

    USGS Publications Warehouse

    Holloway, J.M.; Dahlgren, R.A.; Casey, W.H.

    2001-01-01

    A laboratory study was performed to simulate field weathering and nitrogen release from bedrock in a setting where geologic nitrogen has been suspected to be a large local source of nitrate. Two rock types containing nitrogen, slate (1370 mg N kg-1) and greenstone (480 mg N kg-1), were used along with saprolite and BC horizon sand from soils derived from these rock types. The fresh rock and weathered material were used in batch reactors that were leached every 30 days over 6 months to simulate a single wet season. Nitrogen was released from rock and soil materials at rates between 10-20 and 10-19 mo1 N cm-2 s-1. Results from the laboratory dissolution experiments were compared to in situ soil solutions and available mineral nitrogen pools from the BC horizon of both soils. Concentrations of mineral nitrogen (NO3- + NH4+) in soil solutions reached the highest levels at the beginning of the rainy season and progressively decreased with increased leaching. This seasonal pattern was repeated for the available mineral nitrogen pool that was extracted using a KCl solution. Estimates based on these laboratory release rates bracket stream water NO3-N fluxes and changes in the available mineral nitrogen pool over the active leaching period. These results confirm that geologic nitrogen, when present, may be a large and reactive pool that may contribute as a non-point source of nitrate contamination to surface and ground waters. ?? 2001 Elsevier Science B.V. All rights reserved.

  13. The nitrogen cycle: Atmosphere interactions

    NASA Technical Reports Server (NTRS)

    Levine, J. S.

    1984-01-01

    Atmospheric interactions involving the nitrogen species are varied and complex. These interactions include photochemical reactions, initiated by the absorption of solar photons and chemical kinetic reactions, which involve both homogeneous (gas-to-gas reactions) and heterogeneous (gas-to-particle) reactions. Another important atmospheric interaction is the production of nitrogen oxides by atmospheric lightning. The nitrogen cycle strongly couples the biosphere and atmosphere. Many nitrogen species are produced by biogenic processes. Once in the atmosphere nitrogen oxides are photochemically and chemically transformed to nitrates, which are returned to the biosphere via precipitation, dry deposition and aerosols to close the biosphere-atmosphere nitrogen cycle. The sources, sinks and photochemistry/chemistry of the nitrogen species; atmospheric nitrogen species; souces and sinks of nitrous oxide; sources; sinks and photochemistry/chemistry of ammonia; seasonal variation of the vertical distribution of ammonia in the troposphere; surface and atmospheric sources of the nitrogen species, and seasonal variation of ground level ammonia are summarized.

  14. The nitrogen index as a tool to reduce nitrogen loss to the environment

    USDA-ARS?s Scientific Manuscript database

    Continued population growth creates a need for increased productivity of agricultural systems around the world. Increased agricultural productivity will be needed to support a population that is anticipated to have an additional 2.5 billion people by the year 2050. Nitrogen was part of the 20th cent...

  15. Plasticity of nitrogen allocation in the leaves of the invasive wetland grass, Phalaris arundinacea and co-occurring Carex species determines the photosynthetic sensitivity to nitrogen availability.

    PubMed

    Holaday, A Scott; Schwilk, Dylan W; Waring, Elizabeth F; Guvvala, Hasitha; Griffin, Chelsea M; Lewis, O Milo

    2015-04-01

    Phalaris arundinacea displaces the slower-growing, native sedge, Carex stricta, where nitrogen availability is high. Our aim was to address whether morphological and physiological traits associated with carbon gain for P. arundinacea and C. stricta responded to nitrogen supply differently and if the species exhibited different degrees of plasticity in these traits. The plants were grown in gravel and provided modified Hoagland's solution containing four nitrogen concentrations from 0.15 to 15 mM for 6 to 7 weeks. Supplied nitrogen affected the leaf nitrogen content to the same degree for both species. Increasing supplied nitrogen strongly increased CO2 assimilation (A), photosynthetic nitrogen use efficiency (PNUE), and respiration for P. arundinacea but had only a small effect on these parameters for C. stricta. Relative to growth at 15 mM nitrogen, growth at 0.15 mM for young leaves decreased carboxylation capacity and efficiency and the capacity for electron transport for P. arundinacea and a larger, stouter Carex species, Carex lacustris, by 53 to 70% but only 20 to 24% for C. stricta. Leaf nitrogen decreased approximately 50% for all species, but vacuolar nitrate did not decrease for P. arundinacea and C. stricta, suggesting that it does not serve as a nitrogen reserve for use during nitrogen deprivation in these species. After 4 months of nitrogen deprivation, P. arundinacea doubled A in 12 days after being supplied 15 mM nitrogen, whereas A for C. stricta increased only 22%. We propose that one factor linking P. arundinacea abundance to nitrogen availability involves this species' plastic response of carbon gain to nitrogen supply. C. stricta appears to be adapted to tolerate low nitrogen availability but cannot respond as rapidly and extensively as P. arundinacea when nitrogen supply is high.

  16. Saturn - Tropospheric ammonia and nitrogen

    NASA Technical Reports Server (NTRS)

    Atreya, S. K.; Kuhn, W. R.; Donahue, T. M.

    1980-01-01

    Photochemical calculations based on recent data on the Saturn temperature structure and Lyman-alpha albedo indicate that detectable amounts of gaseous ammonia may exist between 20 and 35 km above the cloud tops. An instrument that might be able to observe this gas is the spectrometer on board the International Ultraviolet Explorer satellite. The calculations also yield a maximum nitrogen mixing ratio at the cloud tops between 1.8 x 10 to the -10th to 6 x 10 to the -8th by volume, depending upon the degree of supersaturation of ammonia and hydrazine. Even the lower limit could produce intense emissions if electrical discharges such as those observed on Jupiter by Voyager are also present on Saturn, or if high energy particles penetrate to the Saturnian troposphere.

  17. Ruminant nitrogen usage

    SciTech Connect

    Not Available

    1985-01-01

    This book brings together the latest research on protein absorption by ruminants and takes a look at the calculation of optimum nutrient requirements, including bacterial digestion, in the calculations. It also describes the parameters of nitrogen conversion in the ruminant and examines the different kinds of protein found in animal feedstuffs.

  18. Nitrogen Trading Tool (NTT)

    USDA-ARS?s Scientific Manuscript database

    The Natural Resources Conservation Service (NRCS) recently developed a prototype web-based nitrogen trading tool to facilitate water quality credit trading. The development team has worked closely with the Agriculture Research Service Soil Plant Nutrient Research Unit (ARS-SPNR) and the Environmenta...

  19. Nitrogen recommendation systems

    USDA-ARS?s Scientific Manuscript database

    Nitrogen fertilization for corn production is complicated by soil and weather variability, yet has far-reaching economic and environmental implications. To address this challenge, alternative N management strategies have been explored extensively in recent years by both public and private groups for...

  20. Commercial Nitrogen Fertilizer Purchased

    EPA Pesticide Factsheets

    Amounts of fertilizer nitrogen (N) purchased by states in individual years 2003, 2005, 2007, 2009 and 2011, and the % change in average amounts purchased per year from 2002-2006 to 2007-2011. Fertilizer information is reported by state fertilizer control offices and excludes livestock manure, liming materials, peat, potting soils, soil amendments, soil additives, and soil conditioners.

  1. The nitrogen cascade

    SciTech Connect

    Galloway J.N.; Aber J.D.; Erisman J.W.; Seitzinger S.P.; Howarth R.W.; Cowling E.B.; Cosby B.J.

    2003-04-01

    Human production of food and energy is the dominant continental process that breaks the triple bond in molecular nitrogen (N{sub 2}) and creates reactive nitrogen (Nr) species. Circulation of anthropogenic Nr in Earth's atmosphere, hydrosphere, and biosphere has a wide variety of consequences, which are magnified with time as Nr moves along its biogeochemical pathway. The same atom of Nr can cause multiple effects in the atmosphere, in terrestrial ecosystems, in freshwater and marine systems, and on human health. We call this sequence of effects the nitrogen cascade. As the cascade progresses, the origin of Nr becomes unimportant. Reactive nitrogen does not cascade at the same rate through all environmental systems; some systems have the ability to accumulate Nr, which leads to lag times in the continuation of the cascade. These lags slow the cascade and result in Nr accumulation in certain reservoirs, which in turn can enhance the effects of Nr on that environment. The only way to eliminate Nr accumulation and stop the cascade is to convert Nr back to nonreactive N{sub 2}.

  2. High Nitrogen Stainless Steel

    DTIC Science & Technology

    2011-07-19

    Hydrogen Embrittlement in Steel by the Increment Loading Technique. Fractography: After the stress-life fatigue tests, the fracture surface morphology...study was conducted to clarify the mechanical properties and stress corrosion cracking (SCC) resistance of high nitrogen stainless steel (HNSS) plates...Corrosion Cracking 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON

  3. ODD NITROGEN PROCESSES

    SciTech Connect

    Johnston, Harold S.

    1980-01-01

    This chapter is in three parts. The first concerns interpretations that can be made from atmospheric observations regarding nitrogen compounds and ozone, the second reviews some predictions made by atmospheric models, and the third compares between certain model results and atmospheric measurements with an emphasis on detecting evidence of significant disagreements.

  4. Nitrogen in aquatic ecosystems.

    PubMed

    Rabalais, Nancy N

    2002-03-01

    Aquatic ecosystems respond variably to nutrient enrichment and altered nutrient ratios, along a continuum from fresh water through estuarine, coastal, and marine systems. Although phosphorus is considered the limiting nutrient for phytoplankton production in freshwater systems, the effects of atmospheric nitrogen and its contribution to acidification of fresh waters can be detrimental. Within the estuarine to coastal continuum, multiple nutrient limitations occur among nitrogen, phosphorus, and silicon along the salinity gradient and by season, but nitrogen is generally considered the primary limiting nutrient for phytoplankton biomass accumulation. There are well-established, but nonlinear, positive relationships among nitrogen and phosphorus flux, phytoplankton primary production, and fisheries yield. There are thresholds, however, where the load of nutrients to estuarine, coastal and marine systems exceeds the capacity for assimilation of nutrient-enhanced production, and water-quality degradation occurs. Impacts can include noxious and toxic algal blooms, increased turbidity with a subsequent loss of submerged aquatic vegetation, oxygen deficiency, disruption of ecosystem functioning, loss of habitat, loss of biodiversity, shifts in food webs, and loss of harvestable fisheries.

  5. Nitrogen use efficiency revisited.

    PubMed

    Hirose, Tadaki

    2011-08-01

    Nitrogen use efficiency (NUE) was originally defined as the dry mass productivity per unit N taken up from soil. The term was subsequently redefined as the product of nitrogen productivity (NP) and mean residence time of nitrogen (MRT). However, this redefinition was found to contradict the original definition under certain conditions, and confusion arose when the MRT defined for a steady-state system was applied to a system that was actually not at steady state. As MRT is the expected length of time that a unit of N newly taken up from soil is retained before being lost, it can be translated into the plant nitrogen duration (PND) divided by the total N uptake. This MRT is determined equally well for a steady state- and a non-steady state system and is in accordance with the original definition of NUE. It can be applied to a herbaceous perennial stand (that was at a steady state) and to an annual stand (that was not at a steady state) to determine NUE. NUE is also applicable when plant growth and reproduction are analyzed in relation to N use.

  6. Nitrogen catch crops

    USDA-ARS?s Scientific Manuscript database

    High costs of nitrogen (N) fertilizer and the potential for N losses to ground and surface water have resulted in increased interest in using catch crops to recover this N. Research on potatoes has shown that the amount of N lost to leaching can be as much as the amount of N removed from the field ...

  7. The Global Nitrogen Cycle

    NASA Astrophysics Data System (ADS)

    Galloway, J. N.

    2003-12-01

    Once upon a time nitrogen did not exist. Today it does. In the intervening time the universe was formed, nitrogen was created, the Earth came into existence, and its atmosphere and oceans were formed! In this analysis of the Earth's nitrogen cycle, I start with an overview of these important events relative to nitrogen and then move on to the more traditional analysis of the nitrogen cycle itself and the role of humans in its alteration.The universe is ˜15 Gyr old. Even after its formation, there was still a period when nitrogen did not exist. It took ˜300 thousand years after the big bang for the Universe to cool enough to create atoms; hydrogen and helium formed first. Nitrogen was formed in the stars through the process of nucleosynthesis. When a star's helium mass becomes great enough to reach the necessary pressure and temperature, helium begins to fuse into still heavier elements, including nitrogen.Approximately 10 Gyr elapsed before Earth was formed (˜4.5 Ga (billion years ago)) by the accumulation of pre-assembled materials in a multistage process. Assuming that N2 was the predominate nitrogen species in these materials and given that the temperature of space is -270 °C, N2 was probably a solid when the Earth was formed since its boiling point (b.p.) and melting point (m.p.) are -196 °C and -210 °C, respectively. Towards the end of the accumulation period, temperatures were probably high enough for significant melting of some of the accumulated material. The volcanic gases emitted by the resulting volcanism strongly influenced the surface environment. Nitrogen was converted from a solid to a gas and emitted as N2. Carbon and sulfur were probably emitted as CO and H2S (Holland, 1984). N2 is still the most common nitrogen volcanic gas emitted today at a rate of ˜2 TgN yr-1 (Jaffee, 1992).Once emitted, the gases either remained in the atmosphere or were deposited to the Earth's surface, thus continuing the process of biogeochemical cycling. The rate of

  8. Nitrogen-incorporation induced changes in the microstructure of nanocrystalline WO3 thin films

    SciTech Connect

    Vemuri, Venkata Rama Sesha R.; Noor-A-Alam, M.; Gullapalli, Satya K.; Engelhard, Mark H.; Ramana, C.V.

    2011-12-30

    Nitrogen doped tungsten oxide (WO3) films were grown by reactive magnetron sputter-deposition by varying the nitrogen content in the reactive gas mixture keeping the deposition temperature fixed at 400 C. The crystal structure, surface morphology, chemical composition, and electrical resistivity of nitrogen doped WO3 films were evaluated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and electrical conductivity measurements. The results indicate that the nitrogen-doping induced changes in the microstructure and electrical properties of WO3 films are significant. XRD measurements coupled with SEM analysis indicates that the increasing nitrogen content decreases the grain size and crystal quality. The nitrogen concentration increases from 0 at.% to 1.35 at.% with increasing nitrogen flow rate from 0 to 20 sccm. The corresponding dc electrical conductivity of the films had shown a decreasing trend with increasing nitrogen content.

  9. Aqueous phase removal of nitrogen from nitrogen compounds

    DOEpatents

    Fassbender, Alex G.

    1993-01-01

    A method is disclosed for denitrification of compounds containing nitrogen present in aqueous waste streams. The method comprises the steps of (1) identifying the types of nitrogen compounds present in a waste stream, (2) determining the concentrations of nitrogen compounds, (3) balancing oxidized and reduced form of nitrogen by adding a reactant, and (4) heating the mixture to a predetermined reaction temperature from about 300.degree. C. to about 600.degree. C., thereby resulting in less harmful nitrogen and oxygen gas, hydroxides, alcohols, and hydrocarbons.

  10. Apollo 20

    ERIC Educational Resources Information Center

    Houston Independent School District, 2013

    2013-01-01

    The Apollo 20 project was launched during the 2010-2011 school year to accelerate Houston Independent School District's (HISD's) efforts to improve student performance in every school and close the achievement gap districtwide. This partnership with EdLabs at Harvard University incorporates best practices from successful public and charter schools…

  11. Bacteria and the Nitrogen Economy.

    ERIC Educational Resources Information Center

    Ayanaba, A.

    1982-01-01

    Biological nitrogen fixation accounts for almost 70 percent of nitrogen for plant growth. If food is to keep abreast of population growth, even more nitrogen must be fixed. For this international research institutes continue the search for natural variants in the bacterial population while also pursuing novel genetic engineering methods. (Author)

  12. Bacteria and the Nitrogen Economy.

    ERIC Educational Resources Information Center

    Ayanaba, A.

    1982-01-01

    Biological nitrogen fixation accounts for almost 70 percent of nitrogen for plant growth. If food is to keep abreast of population growth, even more nitrogen must be fixed. For this international research institutes continue the search for natural variants in the bacterial population while also pursuing novel genetic engineering methods. (Author)

  13. The nitrogen and sulphur cycles

    SciTech Connect

    Cole, J.A.; Ferguson, S.J.

    1988-01-01

    This book contains 17 selections. Some of the titles are: Genetic regulation of nitrogen fixation; On the analysis of symbiotic genes of Rhizobium; Regulation of nitrogen assimilation by bacteria; Alternative and conventional nitrogenases; and The role of oxygen and hydrogen in nitrogen fixation.

  14. Foliar uptake of nitrogen oxides: A nitrogen source for forests

    SciTech Connect

    Hanson, P.J.; Taylor, G.E. Jr.; Gunderson, C.A. )

    1989-04-01

    Non-urban concentrations of nitrogen oxide gases are insufficient to directly impede plant growth processes, but foliar uptake of these gases may represent a significant N source. Measurements of NO{sub 2} and HNO{sub 3} vapor uptake by elements representative of a forest landscape (e.g. foliage, bark, forest floor) were conducted in an open gas exchange system. Under daylight conditions using a mean NO{sub 2} level of 33 ml l{sup {minus}1}, NO{sub 2} uptake by foliage of forest tree species ranged from 0.35 to 5.75 nmol m{sup {minus}2} s{sup {minus}1}. Uptake of NO{sub 2} by broadleaf species was greater than by conifers. Dry bark surfaces showed about half the conductance to NO{sub 2} than did plant shoots. Forest floor samples had a disproportionately high conductance to NO{sub 2} when compared to bark or foliage surfaces. At similar concentrations, uptake of HNO{sub 3} vapor exceeded that for NO{sub 2}. Foliar NO{sub 2} uptake, under stomatal control, was principally to leaf interiors, but HNO{sub 3} uptake occurred to leaf interiors and surfaces. Based on ambient NO{sub 2} concentrations and conductance data scaled to the forest canopy, NO{sub 2} deposition provides from 0.1 to 2.0 kg ha{sup {minus}1} y{sup {minus}1} of nitrogen to natural forests (0.1 to 3% of annual needs). Conversely, deposition to urban forests may supply >10% of a forest's annual need.

  15. Chemical Conversion of PON to Nitrous Oxide for Nitrogen Isotopic Analysis : High- Sensitivity Tracer Assay for Nitrogen Fixation

    NASA Astrophysics Data System (ADS)

    Tsunogai, U.; Kido, T.; Hirota, A.; Ohkubo, S.; Komatsu, D. D.; Nakagawa, F.

    2006-12-01

    We present a method for high-sensitivity nitrogen isotopic analysis of particulate organic nitrogen (PON) in seawater and freshwater, for the aim of measuring the rate of nitrogen fixation through 15N2 tracer technique for samples that contain low numeric abundance of organisms. The method composed of the traditional oxidation/reduction methods: such as oxidation of PON to nitrate using persulfate, the reduction of nitrate to nitrite using spongy cadmium, and further reduction of nitrite to nitrous oxide using sodium azide in an acetic acid buffer. Then, Nitrous oxide is purged from the water and trapped cryogenically with subsequent release into a gas chromatography column to analyze stable nitrogen isotopic compositions using a continuous-flow isotope ratio mass spectrometer. A standard deviation less than 0.3 ‰ for nitrogen was found for PON samples containing more than 80 nmolN, with a blank nitrogen of 20 nmolN. Nitrogen isotopic fractionation were consistent within each batch of analysis. Besides, we found that we can also determine nitrogen isotopic compositions of total dissolved nitrogen (TDN, sum of NO3-, NO2-, ammonium, and DON), by applying the method for filtrate samples. Our method may prove to obtain isotopic information for lower quantities of PON and TDN than other methods, so that we can reduce quantities of water samples needed for incubation to determine the nitrogen fixation rate in both seawater and freshwater. Besides, the method is also useful to determine the rate of nitrogen fixation by the small size fraction in ocean. We will also present the results obtained at western subtropical North Pacific to support our conclusions.

  16. Methane/nitrogen separation process

    DOEpatents

    Baker, R.W.; Lokhandwala, K.A.; Pinnau, I.; Segelke, S.

    1997-09-23

    A membrane separation process is described for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. The authors have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen. 11 figs.

  17. Methane/nitrogen separation process

    DOEpatents

    Baker, Richard W.; Lokhandwala, Kaaeid A.; Pinnau, Ingo; Segelke, Scott

    1997-01-01

    A membrane separation process for treating a gas stream containing methane and nitrogen, for example, natural gas. The separation process works by preferentially permeating methane and rejecting nitrogen. We have found that the process is able to meet natural gas pipeline specifications for nitrogen, with acceptably small methane loss, so long as the membrane can exhibit a methane/nitrogen selectivity of about 4, 5 or more. This selectivity can be achieved with some rubbery and super-glassy membranes at low temperatures. The process can also be used for separating ethylene from nitrogen.

  18. Sealing Nitrogen Tetroxide Leaks

    NASA Technical Reports Server (NTRS)

    Garrard, George G.; Houston, Donald W.; Scott, Frank D.

    1990-01-01

    Use of Furmanite FSC-N-6B sealant in clam-shell sealing device makes it possible to stop leaks of nitrogen tetroxide through defective or improperly-seated plumbing fittings. Devised to stop leaks in vent line of small rocket motor on Space Shuttle. Also used on plumbing containing hydrazine and other hazardous fluids, and repair withstands severe temperature, vibration, and shock. Leaks stopped in place, without draining or replacement of leaking parts.

  19. The evolution of nitrogen cycling

    NASA Technical Reports Server (NTRS)

    Mancinelli, Rocco L.; Mckay, Christopher P.

    1988-01-01

    The energetics of nitrogen transformation reactions and the evolution of nitrogen cycling are examined. It is suggested that meteor impact-produced fixed nitrogen could have caused the entire reservoir of the earth's N2 to convert into fixed nitrogen at the end of accretion. The abiotic fixation rate on the early earth by lightning is estimated at about 1-3 X 10 to the 16th molecules of NO/J. It is found that biological nitrogen fixation may have evolved after the development of an aerobic atmosphere. It is shown that HNO could eventually become NO2(-) and NO3(-) after reaching the earth's surface. It is concluded that the evolutionary sequence for the biological transformation of nitrogen compounds is ammonification - denitrification - nitrification - nitrogen fixation.

  20. 40 CFR 89.112 - Oxides of nitrogen, carbon monoxide, hydrocarbon, and particulate matter exhaust emission standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Oxides of nitrogen, carbon monoxide....112 Oxides of nitrogen, carbon monoxide, hydrocarbon, and particulate matter exhaust emission... emissions of oxides of nitrogen, carbon monoxide, hydrocarbon, and nonmethane hydrocarbon are measured...

  1. 40 CFR 89.112 - Oxides of nitrogen, carbon monoxide, hydrocarbon, and particulate matter exhaust emission standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Oxides of nitrogen, carbon monoxide....112 Oxides of nitrogen, carbon monoxide, hydrocarbon, and particulate matter exhaust emission... emissions of oxides of nitrogen, carbon monoxide, hydrocarbon, and nonmethane hydrocarbon are measured...

  2. 40 CFR 89.112 - Oxides of nitrogen, carbon monoxide, hydrocarbon, and particulate matter exhaust emission standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Oxides of nitrogen, carbon monoxide....112 Oxides of nitrogen, carbon monoxide, hydrocarbon, and particulate matter exhaust emission... emissions of oxides of nitrogen, carbon monoxide, hydrocarbon, and nonmethane hydrocarbon are measured...

  3. Influence of nitrogen loading and plant nitrogen assimilation on nitrogen leaching and N₂O emission in forage rice paddy fields fertilized with liquid cattle waste.

    PubMed

    Riya, Shohei; Zhou, Sheng; Kobara, Yuso; Sagehashi, Masaki; Terada, Akihiko; Hosomi, Masaaki

    2015-04-01

    Livestock wastewater disposal onto rice paddy fields is a cost- and labor-effective way to treat wastewater and cultivate rice crops. We evaluated the influence of nitrogen loading rates on nitrogen assimilation by rice plants and on nitrogen losses (leaching and N2O emission) in forage rice fields receiving liquid cattle waste (LCW). Four forage rice fields were subjected to nitrogen loads of 107, 258, 522, and 786 kg N ha(-1) (N100, N250, N500, and N750, respectively) using basal fertilizer (chemical fertilizer) (50 kg N ha(-1)) and three LCW topdressings (each 57-284 kg N ha(-1)). Nitrogen assimilated by rice plants increased over time. However, after the third topdressing, the nitrogen content of the biomass did not increase in any treatment. Harvested aboveground biomass contained 93, 60, 33, and 31 % of applied nitrogen in N100, N250, N500, and N750, respectively. The NH4 (+) concentration in the pore water at a depth of 20 cm was less than 1 mg N L(-1) in N100, N250, and N500 throughout the cultivation period, while the NH4 (+) concentration in N750 increased to 3 mg N L(-1) after the third topdressing. Cumulative N2O emissions ranged from -0.042 to 2.39 kg N ha(-1); the highest value was observed in N750, followed by N500. In N750, N2O emitted during the final drainage accounted for 80 % of cumulative N2O emissions. This study suggested that 100-258 kg N ha(-1) is a recommended nitrogen loading rate for nitrogen recovery by rice plants without negative environmental impacts such as groundwater pollution and N2O emission.

  4. Nitrogen and Oxygen Isotopic Studies of the Marine Nitrogen Cycle

    NASA Astrophysics Data System (ADS)

    Casciotti, Karen L.

    2016-01-01

    The marine nitrogen cycle is a complex web of microbially mediated reactions that control the inventory, distribution, and speciation of nitrogen in the marine environment. Because nitrogen is a major nutrient that is required by all life, its availability can control biological productivity and ecosystem structure in both surface and deep-ocean communities. Stable isotopes of nitrogen and oxygen in nitrate and nitrite have provided new insights into the rates and distributions of marine nitrogen cycle processes, especially when analyzed in combination with numerical simulations of ocean circulation and biogeochemistry. This review highlights the insights gained from dual-isotope studies applied at regional to global scales and their incorporation into oceanic biogeochemical models. These studies represent significant new advances in the use of isotopic measurements to understand the modern nitrogen cycle, with implications for the study of past ocean productivity, oxygenation, and nutrient status.

  5. Nitrogen and Oxygen Isotopic Studies of the Marine Nitrogen Cycle.

    PubMed

    Casciotti, Karen L

    2016-01-01

    The marine nitrogen cycle is a complex web of microbially mediated reactions that control the inventory, distribution, and speciation of nitrogen in the marine environment. Because nitrogen is a major nutrient that is required by all life, its availability can control biological productivity and ecosystem structure in both surface and deep-ocean communities. Stable isotopes of nitrogen and oxygen in nitrate and nitrite have provided new insights into the rates and distributions of marine nitrogen cycle processes, especially when analyzed in combination with numerical simulations of ocean circulation and biogeochemistry. This review highlights the insights gained from dual-isotope studies applied at regional to global scales and their incorporation into oceanic biogeochemical models. These studies represent significant new advances in the use of isotopic measurements to understand the modern nitrogen cycle, with implications for the study of past ocean productivity, oxygenation, and nutrient status.

  6. Effect of ruthenium on nitrogen fixation by some nitrogen fixers.

    PubMed

    Bahadur, K; Gaur, N

    1979-01-01

    The effect of ruthenium chloride in the culture media on the nitrogen-fixing ability of the three nitrogen fixers (unidentified species of Azotobacter, designated here as D3, B3, and B), isolated from Allahabad soil, was studied. It was observed that the nitrogen-fixing ability of the organisms is much increased in presence of 25-75 micro M concentration of ruthenium chloride in the culture media, while sugar consumption remains more or less steady. Also, if mg nitrogen fixed/g carbon consumed in two culture media with successive increasing concentrations of ruthenium chloride is compared by calculating the difference in increase of the amount of nitrogen fixed and carbon consumed in these two culture media, it was observed that high amounts of nitrogen are fixed by B3 and B between 25-50 micro M, and between 50-75 micro M concentration of ruthenium chloride by D3.

  7. 21 CFR 862.1515 - Nitrogen (amino-nitrogen) test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Systems § 862.1515 Nitrogen (amino-nitrogen) test system. (a) Identification. A nitrogen (amino-nitrogen) test system is a device intended to measure amino acid nitrogen levels in serum, plasma, and urine... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Nitrogen (amino-nitrogen) test system. 862.1515...

  8. 21 CFR 862.1515 - Nitrogen (amino-nitrogen) test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Systems § 862.1515 Nitrogen (amino-nitrogen) test system. (a) Identification. A nitrogen (amino-nitrogen) test system is a device intended to measure amino acid nitrogen levels in serum, plasma, and urine... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nitrogen (amino-nitrogen) test system. 862.1515...

  9. 21 CFR 862.1515 - Nitrogen (amino-nitrogen) test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Systems § 862.1515 Nitrogen (amino-nitrogen) test system. (a) Identification. A nitrogen (amino-nitrogen) test system is a device intended to measure amino acid nitrogen levels in serum, plasma, and urine... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Nitrogen (amino-nitrogen) test system. 862.1515...

  10. 21 CFR 862.1515 - Nitrogen (amino-nitrogen) test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Systems § 862.1515 Nitrogen (amino-nitrogen) test system. (a) Identification. A nitrogen (amino-nitrogen) test system is a device intended to measure amino acid nitrogen levels in serum, plasma, and urine... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nitrogen (amino-nitrogen) test system. 862.1515...

  11. Background nitrogen concentrations in fresh waters in Denmark

    NASA Astrophysics Data System (ADS)

    Windolf, Jørgen; Bøgestrand, Jens; Blicher-Mathiesen, Gitte; Kronvang, Brian

    2013-04-01

    Quantitative information on the background loading of nitrogen is important when establishing the pressure-impact pathway for Danish springs, streams, lakes and estuaries The background nitrogen loading thus determines present day lowest nitrogen loadings without influence from point sources and agriculture but includes present day atmospheric deposition of nitrogen compounds. We have mapped the background concentration of nitrogen in Danish soil water, springs and streams based on monitoring in one soil water station (1990-2010), 11 springs, 7 small streams draining undisturbed catchments (1990-2010) and 19 streams draining small undisturbed catchments (2004-11). The concentration of ammonium-N (NH4+) and organic N was found to be nearly constant within six major landscape types in Denmark, respectively, 0.05 mg ± 0.06 mg N L-1 and 0.53 mg ± 0.29 mg N L-1. On contrary, the concentration of nitrate-nitrite-N (NO3- + NO2-) was found to vary between 0.06-0.83 mg N L-1 within the six landscape types. We have also time series of background total nitrogen concentrations from 7 small undisturbed catchments covering the period 1990-2010. No significant trends have been observed for total nitrogen concentrations from these streams during the period 1990-2010. The measured average nitrate-N concentrations in streams has been modelled against dominant landscape geology and a 5x5 km grid map of Denmark showing background concentrations of nitrate-N and total N has been produced. This map has been used during the implementation of the EU Water Framework Directive as a baseline for estimating background nitrogen losses to surface waters in Denmark. Thus, the average annual background loss of total nitrogen amounts to 13,000 tonnes N or 20% of the total loading of nitrogen from the Danish land to sea during the period 2005-2009.

  12. Biotic Nitrogen Enrichment Regulates Calcium Sources to Forests

    NASA Astrophysics Data System (ADS)

    Pett-Ridge, J. C.; Perakis, S. S.; Hynicka, J. D.

    2015-12-01

    Calcium is an essential nutrient in forest ecosystems that is susceptible to leaching loss and depletion. Calcium depletion can affect plant and animal productivity, soil acid buffering capacity, and fluxes of carbon and water. Excess nitrogen supply and associated soil acidification are often implicated in short-term calcium loss from soils, but the long-term role of nitrogen enrichment on calcium sources and resupply is unknown. Here we use strontium isotopes (87Sr/86Sr) as a proxy for calcium to investigate how soil nitrogen enrichment from biological nitrogen fixation interacts with bedrock calcium to regulate both short-term available supplies and the long-term sources of calcium in montane conifer forests. Our study examines 22 sites in western Oregon, spanning a 20-fold range of bedrock calcium on sedimentary and basaltic lithologies. In contrast to previous studies emphasizing abiotic control of weathering as a determinant of long-term ecosystem calcium dynamics and sources (via bedrock fertility, climate, or topographic/tectonic controls) we find instead that that biotic nitrogen enrichment of soil can strongly regulate calcium sources and supplies in forest ecosystems. For forests on calcium-rich basaltic bedrock, increasing nitrogen enrichment causes calcium sources to shift from rock-weathering to atmospheric dominance, with minimal influence from other major soil forming factors, despite regionally high rates of tectonic uplift and erosion that can rejuvenate weathering supply of soil minerals. For forests on calcium-poor sedimentary bedrock, we find that atmospheric inputs dominate regardless of degree of nitrogen enrichment. Short-term measures of soil and ecosystem calcium fertility are decoupled from calcium source sustainability, with fundamental implications for understanding nitrogen impacts, both in natural ecosystems and in the context of global change. Our finding that long-term nitrogen enrichment increases forest reliance on atmospheric

  13. Controls over nitrogen cycling in California chaparral

    NASA Astrophysics Data System (ADS)

    Hanan, E. J.; Schimel, J.

    2013-12-01

    Chaparral landscapes of southern California and other Mediterranean-type ecosystems are structured by fire. They exist in environments that typically do not receive rain for 6 months or more at a time, making combustion inevitable. The heavy winter rains following fire can erode soil and leach nutrients such as nitrogen into streams and reservoirs, particularly along slopes that have been denuded. The extent to which nitrogen is cycled and redistributed following fire is a function of the rate at which soil microbes metabolize nitrogen into mobile forms such as nitrate. However, the specific mechanisms controlling nitrogen metabolism in chaparral are not fully understood. We measured mineralization and nitrification rates in ecosystems dominated by species typical of southern and central California chaparral, and conducted a laboratory incubation to experimentally examine the influence of pH, charcoal, and ammonium supply on nitrogen dynamics. Nitrate production was significantly enhanced in recently burned chaparral, which correlated with elevated soil pH. Enhanced pH can both raise the solubility of soil organic matter, and stimulate nitrification, while fires simultaneously release nitrifying bacteria from competition with vegetation for ammonium. To further explore these processes, we applied ammonium, pH, and charcoal treatments to samples from 4 chaparral stands, which burned 1, 4, 20 and 40 years ago, using a factorial design. Treated soils were incubated in mason jars at 50% water holding capacity for 8 weeks. Soil respiration, substrate induced respiration, mineralization, nitrification, and nitrification potential were measured periodically to evaluate whether ammonium addition, pH and the presence of charcoal influence substrate production and nitrification. The threat nitrate of leaching following fire grows with climate change, because fire and precipitation regimes are expected to become both increasingly variable and punctuated by more intense events

  14. Nitrogen fixation and nitrogen transformations in marine symbioses.

    PubMed

    Fiore, Cara L; Jarett, Jessica K; Olson, Nathan D; Lesser, Michael P

    2010-10-01

    Many marine organisms have coevolved symbiotic relationships with nitrogen-fixing bacteria in nitrogen limited environments such as coral reefs. In addition, some of these organisms also harbor microbes that carry out nitrification and denitrification. Prokaryotes involved in nitrogen fixation and other nitrogen transformations are symbionts in a range of eukaryotic hosts in the marine environment including shipworms, diatoms, corals and sponges. Molecular genetic approaches, and other analytical techniques, have provided exciting new insights into symbiont diversity and the relationship between host and symbiont. We review the current state of knowledge of these symbioses and highlight important avenues for future studies. Copyright © 2010 Elsevier Ltd. All rights reserved.

  15. The microchannel heatsink with liquid nitrogen cooling

    SciTech Connect

    Riddle, R.A.; Bernhardt, A.F.

    1992-06-09

    Excellent thermal performance of a silicon microchannel heatsink is demonstrated using liquid nitrogen as the coolant over a wide range of heat loads up to 1 kW/cm[sup 2]. This performance is partly due to the order of magnitude increase in the thermal conductivity of silicon near 77 [degree]K compared to room temperature. Subcooled boiling of the liquid nitrogen in the microchannel heatsink further enhances the thermal performance but makes the thermal resistance a nonlinear function of heat load. For a 500 W/cm[sup 2] heat load, a thermal resistances of 0.052 cm[sup 2*0]C/W for a 9:1 aspect ratio heatsink was measured.

  16. The microchannel heatsink with liquid nitrogen cooling

    SciTech Connect

    Riddle, R.A.; Bernhardt, A.F.

    1992-06-09

    Excellent thermal performance of a silicon microchannel heatsink is demonstrated using liquid nitrogen as the coolant over a wide range of heat loads up to 1 kW/cm{sup 2}. This performance is partly due to the order of magnitude increase in the thermal conductivity of silicon near 77 {degree}K compared to room temperature. Subcooled boiling of the liquid nitrogen in the microchannel heatsink further enhances the thermal performance but makes the thermal resistance a nonlinear function of heat load. For a 500 W/cm{sup 2} heat load, a thermal resistances of 0.052 cm{sup 2*0}C/W for a 9:1 aspect ratio heatsink was measured.

  17. Nitrogen fixation apparatus

    DOEpatents

    Chen, Hao-Lin

    1984-01-01

    A method and apparatus for achieving nitrogen fixation includes a volumetric electric discharge chamber. The volumetric discharge chamber provides an even distribution of an electron beam, and enables the chamber to be maintained at a controlled energy to pressure (E/p) ratio. An E/p ratio of from 5 to 15 kV/atm of O.sub.2 /cm promotes the formation of vibrationally excited N.sub.2. Atomic oxygen interacts with vibrationally excited N.sub.2 at a much quicker rate than unexcited N.sub.2, greatly improving the rate at which NO is formed.

  18. Nitrogen Control in VIM Melts

    NASA Astrophysics Data System (ADS)

    Jablonski, P. D.; Hawk, J. A.

    NETL has developed a design and control philosophy for the addition of nitrogen to austenitic and ferritic steels. The design approach uses CALPHAD as the centerpiece to predict the level to which nitrogen is soluble in both the melt and the solid. Applications of this technique have revealed regions of "exclusion" in which the alloy, while within specification limits of prescribed, cannot be made by conventional melt processing. Furthermore, other investigations have found that substantial retrograde solubility of nitrogen exists, which can become problematic during subsequent melt processing and/or other finishing operations such as welding. Additionally, the CALPHAD method has been used to adjust primary melt conditions. To that end, nitrogen additions have been made using chrome nitride, silicon nitride, high-nitrogen ferrochrome as well as nitrogen gas. The advantages and disadvantages of each approach will be discussed and NETL experience in this area will be summarized with respect to steel structure.

  19. Nitrogen doping in carbon nanotubes.

    PubMed

    Ewels, C P; Glerup, M

    2005-09-01

    Nitrogen doping of single and multi-walled carbon nanotubes is of great interest both fundamentally, to explore the effect of dopants on quasi-1D electrical conductors, and for applications such as field emission tips, lithium storage, composites and nanoelectronic devices. We present an extensive review of the current state of the art in nitrogen doping of carbon nanotubes, including synthesis techniques, and comparison with nitrogen doped carbon thin films and azofullerenes. Nitrogen doping significantly alters nanotube morphology, leading to compartmentalised 'bamboo' nanotube structures. We review spectroscopic studies of nitrogen dopants using techniques such as X-ray photoemission spectroscopy, electron energy loss spectroscopy and Raman studies, and associated theoretical models. We discuss the role of nanotube curvature and chirality (notably whether the nanotubes are metallic or semiconducting), and the effect of doping on nanotube surface chemistry. Finally we review the effect of nitrogen on the transport properties of carbon nanotubes, notably its ability to induce negative differential resistance in semiconducting tubes.

  20. Nitrogen abundance in Comet Halley

    NASA Technical Reports Server (NTRS)

    Wyckoff, Susan; Tegler, Stephen C.; Engel, Lisa

    1991-01-01

    Data on the nitrogen-containing compounds that observed spectroscopically in the coma of Comet Halley are summarized, and the elemental abundance of nitrogen in the Comet Halley nucleus is derived. It is found that 90 percent of elemental nitrogen is in the dust fraction of the coma, while in the gas fraction, most of the nitrogen is contained in NH3 and CN. The elemental nitrogen abundance in the ice component of the nucleus was found to be deficient by a factor of about 75, relative to the solar photosphere, indicating that the chemical partitioning of N2 into NH3 and other nitrogen compounds during the evolution of the solar nebula cannot account completely for the low abundance ratio N2/NH3 = 0.1, observed in the comet. It is suggested that the low N2/NH3 ratio in Comet Halley may be explained simply by physical fractionation and/or thermal diffusion.

  1. Preprototype nitrogen supply subsystem development

    NASA Technical Reports Server (NTRS)

    Heppner, D. B.; Hallick, T. M.; Schubert, F. H.

    1981-01-01

    A nitrogen supply subsystem based on the dissociation of hydrazine into a mixture of hydrogen and nitrogen is developed. The latter is separated to provide makeup nitrogen to control the composition of spacecraft atmospheres. Specific hardware developments resulted in the design and fabrication of a nominal 3.6 kg/d nitrogen generation module. The design integrates a hydrazine catalytic dissociator, three ammonia dissociation stages and four hydrogen separation stages into a 33 kg, 14 cu dm module. A technique was devised to alternate the ammonia dissociation and hydrogen separation stages to give high nitrogen purity in the end product stream. Tests show the product stream to contain less than 0.5 percent hydrogen and 10 parts per million ammonia. The design and development of a test stand for the nitrogen generation module and a series of tests which verified its operation and performance capability are described.

  2. Inorganic nitrogen reduction and stability under simulated hydrothermal conditions.

    PubMed

    Brandes, Jay A; Hazen, Robert M; Yoder, Hatten S

    2008-12-01

    Availability of reduced nitrogen is considered a prerequisite for the genesis of life from prebiotic precursors. Most atmospheric and oceanic models for the Hadean Earth predict a mildly oxidizing environment that is conducive to the formation and stability of only oxidized forms of nitrogen. A possible environment where reduction of oxidized nitrogen to ammonium has been speculated to occur is aqueous hydrothermal systems. We examined a suite of transition metal oxides and sulfides for their ability to reduce nitrate and nitrite, as well as oxidize ammonia, under hot (300 degrees C) high-pressure (50-500 MPa) aqueous conditions. In general, iron sulfides exhibited the most rapid and complete conversion noted, followed by nickel and copper sulfides to a much lower degree. Of the oxides examined, only magnetite exhibited any ability to reduce NO(3)(-) or NO(2)(-). Ammonium was stable or exhibited small losses (<20%) in contact with all the mineral phases and conditions tested. The results support the idea that hydrothermal systems could have provided significant amounts of reduced nitrogen to their immediate environments. The enhanced availability of reduced nitrogen in hydrothermal systems also has important implications for prebiotic metabolic pathways where nitrogen availability is critical to the production of amino acids and other nitrogenous compounds.

  3. Nitrogen In Saturn's Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Smith, H. T.; Sittler, E. C.; Johnson, R. E.; McComas, D.; Reisenfeld, D.; Shappirio, M.; Michael, M.; Shematovich, V. I.; Baragiola, R. A.; Crary, F.; Young, D.

    2004-11-01

    We are analyzing CAPS instrument data on Cassini to look for nitrogen ions in Saturn's magnetosphere. Because Voyager could not separate oxygen and nitrogen, there has been considerable controversy on nitrogen's presence and relative importance. Two principal sources have been suggested: Titan's atmosphere and nitrogen species trapped in Saturn's icy satellite surfaces (Sittler et al 2004). The latter may be primordial nitrogen, likely as NH3 in ice (Stevenson 1982; Squyers et al. 1983) or nitrogen ions that have been implanted in the surface (Delitsky and Lane 2002). We will present the results of Saturnian nitrogen cloud modeling and relevant CAPS observations. We recently described the Titan source (Michael, et al. 2004; Shematovich et al. 2003; Smith et al. 2004; Sittler et al. 2004) in preparation for Cassini's Saturnian plasma measurements. Two components were identified: energetic nitrogen ions formed near Titan and energized as they diffused inward (Sittler et al. 2004) and neutrals in orbits with small perigee that became ionized in the inner magnetosphere (Smith et al 2004). The latter component would be a source of lower energy, co-rotating nitrogen ions to the inner magnetosphere. Such a component would have an energy spectrum similar to nitrogen species sputtered from the icy satellite surfaces (Johnson and Sittler 1990). However, the mass spectrum would differ, likely containing NHx and NOx species also, and, hence, may be separated from the Titan source. Our preliminary analysis for nitrogen species in the CAPS data will be compared to the models. Of interest will be the energy spectra, which can indicate whether any nitrogen present is formed locally or near Titan's orbit and diffused inward. This work is supported by the NASA Planetary Atmospheres, NASA Graduate Student Research, Virginia Space Grant Consortium Graduate Research Fellowship and the CAPS Cassini instrument team programs.

  4. Redistribution of nitrogen implanted in the crystals of synthetic diamond

    NASA Astrophysics Data System (ADS)

    Cherepov, E. I.; Tishkovsky, E. G.; Obodnikov, V. I.; Pal'yanov, Ju. N.; Sokol, A. G.; Sobolev, N. V.

    2001-10-01

    The redistribution of nitrogen atoms implanted in synthetic diamond crystals was investigated by secondary ion mass-spectrometry in course of an isothermal annealing program at 1400°C during 1, 5 and 20 h. It was shown that the nitrogen profiles spread at a macroscopic scale, and the broadening is well described in terms of the diffusion movement of impurity atoms. The preliminary estimates of diffusion coefficients were obtained: 2.3×10 -15 cm2/ s for 1 h annealing, 8.5×10 -16 cm2/ s for 5 h annealing and 3.7×10 -16 cm2/ s for 20 h annealing.

  5. Diurnal variation of atomic nitrogen. [in upper atmosphere

    NASA Technical Reports Server (NTRS)

    Mauersberger, K.; Engebretson, M. J.; Kayser, D. C.; Potter, W. E.

    1976-01-01

    When the perigee of the Atmospheric Explorer C satellite reached the northern latitudes (68 deg) by mid-April 1974, descending and ascending portions of the orbits stretched symmetrically across the Northern Hemisphere. Corresponding local solar times at altitudes above 400 km were 1700 hours and 0200 hours, respectively, thus providing the opportunity to study the diurnal variation of the neutral constituents. Atomic nitrogen densities, measured with the open-source neutral mass spectrometer, show a pronounced diurnal variation. At 400 km, the density ratios derived from measurements of the descending and ascending portions are 5.2 for N, 4.9 for N2, and 2.0 for O. Absolute densities of atomic nitrogen agree within a factor of 2 or 3 with densities derived from neutral-ion reactions. Measurements taken close to the geomagnetic pole show a decrease in atomic nitrogen densities when an increase in molecular nitrogen is observed.

  6. Orchard nitrogen management: Which nitrogen source is best?

    USDA-ARS?s Scientific Manuscript database

    Suboptimal management of nitrogen fertility in pecan orchards leads to a loss of nutmeat yield and quality, but also a waste of natural resources and money. This article reviews several basic guiding principles useful to orchard managers when developing nitrogen management strategies, and determini...

  7. An Expanded Analysis of Nitrogen Ice Convection in Sputnik Planum

    NASA Astrophysics Data System (ADS)

    Umurhan, Orkan M.; Lyra, Wladimir; Wong, Teresa; McKinnon, William B.; Nimmo, Francis; Howard, Alan D.; Moore, Jeffrey M.; Binzel, Richard; White, Oliver; Stern, S. Alan; Ennico, Kimberly; Olkin, Catherine B.; Weaver, Harold A.; Young, Leslie; New Horizons Geology and Geophysics Science Team

    2016-10-01

    The New Horizons close-encounter flyby of Pluto revealed 20-35 km scale ovoid patterns on the informally named Sputnik Planum. These features have been recently interpreted and shown to arise from the action of solid-state convection of (predominantly) nitrogen ice driven by Pluto's geothermal gradient. One of the major uncertainties in the convection physics centers on the temperature and grain-size dependency of nitrogen ice rheology, which has strong implications for the overturn times of the convecting ice. Assuming nitrogen ice in Sputnik Planum rests on a passive water ice bedrock that conducts Pluto's interior heat flux, and, given the uncertainty of the grain-size distribution of the nitrogen ice in Sputnik Planum, we examine a suite of two-dimensional convection models that take into account the thermal contact between the nitrogen ice layer and the conducting water-ice bedrock for a given emergent geothermal flux. We find for nitrogen ice layers several km deep, the emerging convection efficiently cools the nitrogen-ice water-ice bedrock interface resulting in temperature differences across the convecting layer of 10-20 K (at most) regardless of layer depth. For grain sizes ranging from 0.01 mm to 5 mm the resulting horizontal size to depth ratios of the emerging convection patterns go from 4:1 up to 6:1, suggesting that the nitrogen ice layer in Sputnik Planum may be anywhere between 3.5 and 8 km deep. Such depths are consistent with Sputnik Planum being a large impact basin (in a relative sense) analogous to Hellas on Mars. In this grain-size range we also find, (i) the calculated cell overturn times are anywhere from 1e4 to 5e5 yrs and, (ii) there is a distinct transition from steady state to time dependent convection.

  8. Hydraulic studies of drilling microbores with supercritical steam, nitrogen and carbon dioxide

    SciTech Connect

    Ken Oglesby

    2010-01-01

    Hydraulic studies of drilling microbores at various depths and with various hole sizes, tubing, fluids and rates showed theoretical feasibility. WELLFLO SIMULATIONS REPORT STEP 4: DRILLING 10,000 FT WELLS WITH SUPERCRITICAL STEAM, NITROGEN AND CARBON DIOXIDE STEP 5: DRILLING 20,000 FT WELLS WITH SUPERCRITICAL STEAM, NITROGEN AND CARBON DIOXIDE STEP 6: DRILLING 30,000 FT WELLS WITH SUPERCRITICAL STEAM, NITROGEN AND CARBON DIOXIDE Mehmet Karaaslan, MSI

  9. Nitrogen release during coal combustion

    SciTech Connect

    Baxter, L.L.; Mitchell, R.E.; Fletcher, T.H.; Hurt, R.H.

    1995-02-01

    Experiments in entrained flow reactors at combustion temperatures are performed to resolve the rank dependence of nitrogen release on an elemental basis for a suite of 15 U.S. coals ranging from lignite to low-volatile bituminous. Data were obtained as a function of particle conversion, with overall mass loss up to 99% on a dry, ash-free basis. Nitrogen release rates are presented relative to both carbon loss and overall mass loss. During devolatilization, fractional nitrogen release from low-rank coals is much slower than fractional mass release and noticeably slower than fractional carbon release. As coal rank increases, fractional nitrogen release rate relative to that of carbon and mass increases, with fractional nitrogen release rates exceeding fractional mass and fractional carbon release rates during devolatilization for high-rank (low-volatile bituminous) coals. At the onset of combustion, nitrogen release rates increase significantly. For all coals investigated, cumulative fractional nitrogen loss rates relative to those of mass and carbon passes through a maximum during the earliest stages of oxidation. The mechanism for generating this maximum is postulated to involve nascent thermal rupture of nitrogen-containing compounds and possible preferential oxidation of nitrogen sites. During later stages of oxidation, the cumulative fractional loss of nitrogen approaches that of carbon for all coals. Changes in the relative release rates of nitrogen compared to those of both overall mass and carbon during all stages of combustion are attributed to a combination of the chemical structure of coals, temperature histories during combustion, and char chemistry.

  10. Investigating Nitrogen Pollution: Activities and Models.

    ERIC Educational Resources Information Center

    Green Teacher, 2000

    2000-01-01

    Introduces activities on nitrogen, nitrogen pollution from school commuters, nitrogen response in native and introduced species, and nutrient loading models. These activities help students determine the nitrogen contribution from their parents' cars, test native plant responses to nitrogen, and experiment with the results of removing water from…

  11. Investigating Nitrogen Pollution: Activities and Models.

    ERIC Educational Resources Information Center

    Green Teacher, 2000

    2000-01-01

    Introduces activities on nitrogen, nitrogen pollution from school commuters, nitrogen response in native and introduced species, and nutrient loading models. These activities help students determine the nitrogen contribution from their parents' cars, test native plant responses to nitrogen, and experiment with the results of removing water from…

  12. Nitrogen and phosphorus intake by phytoplankton in the Xiamen Bay

    NASA Astrophysics Data System (ADS)

    Lin, Cai; Li, Hui; He, Qing; Xu, Kuncan; Wu, Shengsan; Zhang, Yuanbiao; Chen, Jinmin; Chen, Baohong; Lin, Libin; Lu, Meiluan; Chen, Weifen; Tang, Rongkun; Ji, Weidong

    2010-01-01

    This paper describes a time series experiment examining the nitrogen and phosphorus intake of natural phytoplankton communities by a microcosms approach. Seawater samples containing natural phytoplankton communities were collected from waters around Baozhu Islet in inner Xiamen Bay and around Qingyu Islet in the outer bay. The goal was to elucidate the relationship between phytoplankton population enhancement, the biological removal of nitrogen and phosphorus from the seawater, and the phytoplankton nitrogen and phosphorus intake ratio based on nitrogen and phosphorus removal from seawater by phytoplankton, to provide a basis for detecting prewarning conditions for red tide and the assessment of red tide events. Two key results were obtained: 1. During the experiment, the nitrogen and phosphorus seawater concentrations in samples from these two sites were negatively and closely correlated to the logarithm of the phytoplankton cell concentration and to the value of the apparent oxygen increment. The ratio of the intake coefficients was 3.5:1 for phosphorus and 1.1:1 for nitrogen for the phytoplankton between these samples from around Baozhu Islet and Qingyu Islet, respectively. This indicates that the intake capabilities of phytoplankton for nitrogen in the two waters are essentially identical. However, for phosphorus, the capability was much higher in the Baozhu Islet waters than the Qingyu Islet waters. In other words, the phytoplankton in Qingyu Islet waters produced more biomass while consuming the same amount of phosphorus as the other waters; 2. The phytoplankton nitrogen and phosphorus intake ratio from the Baozhu Islet and Qingyu Islet waters was 20:1 and 36:1, respectively. The latter waters had a significantly higher ratio than the former and both were higher than the Redfield Ratio. These results indicate that nitrogen and phosphorus intake ratios by phytoplankton can vary significantly from region to region.

  13. Alternative nitrogen sources for cotton

    USDA-ARS?s Scientific Manuscript database

    Several alternative nitrogen (N) sources, rates of N, and amendments were evaluated at Prattville, Alabama, on cotton in 2008. Nitrogen rates reported are for sidedress application only. Dry urea produced the highest yield, averaging 1100 pounds lint per acre. Ammonia volatilization was measured fr...

  14. Nitrogen chiller acceptance test procedure

    SciTech Connect

    Kostelnik, A.J.

    1995-03-07

    This document includes the inspection and testing requirements for the Nitrogen Chiller unit. The Chiller will support the Rotary Mode core Sampling System during the summer. The Chiller cools the Nitrogen Purge Gas that is used when drilling in tank wastes to cool the drill bit.

  15. Seasonal Nitrogen Cycles on Pluto

    NASA Technical Reports Server (NTRS)

    Hansen, C. J.; Paige, D. A.

    1994-01-01

    A thermal model, developed to predict seasonal nitrogen cycles on Triton, has been modified and applied to Pluto. The model is used to calculate the partitioning of nitrogen between surface frost deposits and the atmosphere, as a function of time for various sets of input parameters.

  16. Seasonal Nitrogen Cycles on Pluto

    NASA Technical Reports Server (NTRS)

    Hansen, C. J.; Paige, D. A.

    1994-01-01

    A thermal model, developed to predict seasonal nitrogen cycles on Triton, has been modified and applied to Pluto. The model is used to calculate the partitioning of nitrogen between surface frost deposits and the atmosphere, as a function of time for various sets of input parameters.

  17. Swivel Joint For Liquid Nitrogen

    NASA Technical Reports Server (NTRS)

    Milner, James F.

    1988-01-01

    Swivel joint allows liquid-nitrogen pipe to rotate through angle of 100 degree with respect to mating pipe. Functions without cracking hard foam insulation on lines. Pipe joint rotates on disks so mechanical stress not transmitted to thick insulation on pipes. Inner disks ride on fixed outer disks. Disks help to seal pressurized liquid nitrogen flowing through joint.

  18. Effects of acute exposure to nitrogen dioxide on primary antibody response

    SciTech Connect

    Hidekazu, F.; Fujio, S.

    1981-01-01

    The effects of acute exposure to nitrogen dioxide on primary humoral antibody response to sheep red blood cells in mice were studied. Mice were exposed to 5 ppm, 20 ppm, and 40 ppm nitrogen dioxide for 12 hr. An exposure of 20 ppm or 40 ppm resulted in a significant suppression of antibody responses, but 5 ppm did not affect antibody response. This immunosuppression resulting from nitrogen dioxide exposure was more apparent in males than females. Exposures to 20 ppm nitrogen dioxide for various time intervals revealed that the strongest suppression effect was observed in the group exposed 2 days after antigen injection. A decreased total cell number in the spleen, and more strikingly, in the thymus, was also caused by acute exposure to nitrogen dioxide.

  19. Effects of acute exposure to nitrogen dioxide on primary antibody response

    SciTech Connect

    Hidekazu, F.; Fujio, S.

    1981-05-01

    The effects of acute exposure to nitrogen dioxide on primary humoral antibody response to sheep red blood cells in mice were studied. Mice were exposed to 5 ppM, 20 ppM, and 40 ppM nitrogen dioxide for 12 h. An exposure of 20 ppM or 40 ppM resulted in a significant suppression of antibody responses, but 5 ppM did not affect antibody response. This immunosuppression resulting from nitrogen dioxide exposure was more apparent in males than females. Exposures to 20 ppM nitrogen dioxide for various time intervals revealed that the strongest suppression effect was observed in the group exposed 2 days after antigen injection. A decreased total cell number in the spleen, and more strikingly, in the thymus, was also caused by acute exposure to nitrogen dioxide.

  20. Shelf life study of fresh celery (Apium graveolens L.) grown under different nitrogen fertilization treatments.

    PubMed

    Rizzo, Valeria; Muratore, Giuseppe; Russo, Marco Antonio; Belligno, Adalgisa

    2011-05-01

    Nitrogen fertilization is useful for obtaining higher growth and quality of productions, and the use of nitrogen fertilization is widespread. To evaluate the influence of nitrogen-rich fertilizers on quality characteristics of celery, shelf life tests of celery grown with 2 levels of nitrogen and 2 different nitrogen fertilizers were performed. The treatments of the celery samples were identified as follows: T1, mineral nitrogen (80 kg ha(-1)); T2, mineral nitrogen (120 kg ha(-1)); T3, organic nitrogen (80 kg ha(-1)); T4, organic nitrogen (120 kg ha(-1)); R4, residual organic nitrogen (120 kg ha(-1)); and C, untreated control. Celery plants were selected and packaged in either of the following 2 plastic films: antifog polyolefin (AFP) film or microperforated polypropylene (MPP) film. The nitrate contents, weight loss, hardness, changes in color parameters, and total phenols were studied for both packaging types during storage. The results demonstrated that celery fertilized with organic nitrogen and packaged in AFP film reached a shelf life of 37 d. The control sample packaged in MPP film was not marketable after 20 d, but the same untreated sample packaged in AFP film reached a shelf life of 30 d.

  1. Effect of 21 different nitrogen sources on global gene expression in the yeast Saccharomyces cerevisiae.

    PubMed

    Godard, Patrice; Urrestarazu, Antonio; Vissers, Stéphan; Kontos, Kevin; Bontempi, Gianluca; van Helden, Jacques; André, Bruno

    2007-04-01

    We compared the transcriptomes of Saccharomyces cerevisiae cells growing under steady-state conditions on 21 unique sources of nitrogen. We found 506 genes differentially regulated by nitrogen and estimated the activation degrees of all identified nitrogen-responding transcriptional controls according to the nitrogen source. One main group of nitrogenous compounds supports fast growth and a highly active nitrogen catabolite repression (NCR) control. Catabolism of these compounds typically yields carbon derivatives directly assimilable by a cell's metabolism. Another group of nitrogen compounds supports slower growth, is associated with excretion by cells of nonmetabolizable carbon compounds such as fusel oils, and is characterized by activation of the general control of amino acid biosynthesis (GAAC). Furthermore, NCR and GAAC appear interlinked, since expression of the GCN4 gene encoding the transcription factor that mediates GAAC is subject to NCR. We also observed that several transcriptional-regulation systems are active under a wider range of nitrogen supply conditions than anticipated. Other transcriptional-regulation systems acting on genes not involved in nitrogen metabolism, e.g., the pleiotropic-drug resistance and the unfolded-protein response systems, also respond to nitrogen. We have completed the lists of target genes of several nitrogen-sensitive regulons and have used sequence comparison tools to propose functions for about 20 orphan genes. Similar studies conducted for other nutrients should provide a more complete view of alternative metabolic pathways in yeast and contribute to the attribution of functions to many other orphan genes.

  2. Nitrogen mass balance across pilot-scale algae and duckweed-based wastewater stabilisation ponds.

    PubMed

    Zimmo, O R; van der Steen, N P; Gijzen, H J

    2004-02-01

    Nitrogen removal processes and nitrogen mass balances in algae-based ponds (ABPs) and duckweed (Lemna gibba)-based ponds (DBPs) were assessed during periods of 4 months, each under different operational conditions. During periods 1 and 2, the effect of cold and warm temperature was studied. During periods 2 and 3, the effect of low- and high-system organic loading (OL) was studied in warm seasons operation. The pilot-scale systems consisted of four similar ponds in series fed with domestic sewage with hydraulic retention time of 7 days in each pond. Overall nitrogen removal was higher during warm temperature in both ABPs and DBPs, but similar during periods 2 and 3. Nitrogen removal in DBPs was lower than in ABPs by 20%, 12% and 8% during cold temperature, warm temperature and high-OL periods, respectively. Depending on temperature and OL rate, ABPs showed higher nitrogen removal via sedimentation (46-245% higher) compared to DBPs. Also, ABPs also showed higher nitrogen removal via denitrification (7-37% higher) compared to DBPs. Ammonia volatilisation in both systems did not exceed 1.1% of influent total nitrogen during the entire experimental period. N uptake by duckweed corresponds to 30% of the influent nitrogen during warm/low OL period and decreased to 10% and 19% during the cold and warm/high OL period, respectively. Predictive models for nitrogen removal presented a good reflection of nitrogen fluxes on overall nitrogen balance under the prevailing experimental conditions.

  3. Cationic Nitrogen Doped Helical Nanographenes.

    PubMed

    Xu, Kun; Feng, Xinliang; Berger, Reinhard; Popov, Alexey A; Weigand, Jan J; Vincon, Ilka; Machata, Peter; Hennersdorf, Felix; Zhou, Youjia; Fu, Yubin

    2017-09-13

    Herein, we report on the synthesis of a series of novel cationic nitrogen doped nanographenes (CNDN) by rhodium catalyzed annulation reactions. This powerful method allows for the synthesis of cationic nanographenes with non-planar, axial chiral geometries. Single-crystal X-ray analysis reveals helical and cove-edged structures. Compared to their all-carbon analogues, the CNDN exhibit energetically lower lying frontier orbitals with a reduced optical energy gap and an electron accepting behavior. All derivatives show quasi reversible reductions in cyclic voltammetry. Depending on the number of nitrogen dopant, in situ spectroelectrochemistry proves the formation of neutral radicals (one nitrogen dopant) or radical cations (two nitrogen dopants) upon reduction. The developed synthetic protocol paves the way for the design and synthesis of expanded nanographenes or even graphene nanoribbons containing cationic nitrogen doping. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Advanced nitrogen elimination by encapsulated nitrifiers.

    PubMed

    Sievers, M; Vorlop, K D; Hahne, J; Schlieker, M; Schäfer, S

    2003-01-01

    By introducing a mixed population of nitrifiers encapsulated in gel lens beads a more selective nitrification process was found in treatment of settled sewage in lab scale at a hydraulic retention time (HRT) of about 30 to 60 minutes. The reaction rates for oxidation of soluble chemical oxygen demand (SCOD) were found to vary between 25 to 150 mg/L x h while nitrification takes place around 50 mg nitrogen per hour and litre reaction volume. However, based on this SCOD removal in the nitrification step, a consequent post-denitrification process without nitrate recycle and dosage of external carbon sources has been proven to reach substantial nitrate elimination of up to 20 mg nitrogen per litre at COD/N-ratios of approx. 6 in settled sewage. At such COD/N-ratios, suitable nitrogen elimination seems to be possible, because the bioflocs of settled sewage, produced so far by SCOD oxidation and entrapment of particulate COD, are passing through the nitrification process having a substantial contribution to the denitrification rate additionally to the remaining SCOD.

  5. 20 CFR 625.20 - [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 3 2012-04-01 2012-04-01 false 625.20 Section 625.20 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR DISASTER UNEMPLOYMENT ASSISTANCE § 625.20...

  6. 20 CFR 625.20 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false 625.20 Section 625.20 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR DISASTER UNEMPLOYMENT ASSISTANCE § 625.20 ...

  7. Bounding salt marsh nitrogen fluxes: development of an ecohydrological salt marsh model

    EPA Science Inventory

    A mass-balance approach to characterize nitrogen flux in a 2-hectare, meso-haline saltmarsh yielded extensive flow and water chemistry data. However, a significant, unevenly distributed population of the nitrogen fixer Alnus rubra (red alder) in the 20-hectare upland catchment l...

  8. Five Years of Nitrogen Fertilization in a Sweetgum-Oak Stand

    Treesearch

    W. M. Broadfoot

    1966-01-01

    Diameter and height growth were significantly increased in a 20-year-old sweetgum-oak stand by annual surface application of ammonium nitrate and of complete N-P-K fertilizer. Nitrogen fertilization significantly increased the nitrogen content of foliage. With increasing nitrate application, exchangeable potassium in the soil 1 year after treatment decreased.

  9. 40 CFR 86.1323-2007 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 20 2012-07-01 2012-07-01 false Oxides of nitrogen analyzer... (CONTINUED) Emission Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines; Gaseous and Particulate Exhaust Test Procedures § 86.1323-2007 Oxides of nitrogen analyzer calibration. This section describes...

  10. 40 CFR 86.1323-84 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 20 2013-07-01 2013-07-01 false Oxides of nitrogen analyzer... (CONTINUED) Emission Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines; Gaseous and Particulate Exhaust Test Procedures § 86.1323-84 Oxides of nitrogen analyzer calibration. The chemiluminescent...

  11. 40 CFR 86.1323-2007 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 20 2013-07-01 2013-07-01 false Oxides of nitrogen analyzer... (CONTINUED) Emission Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines; Gaseous and Particulate Exhaust Test Procedures § 86.1323-2007 Oxides of nitrogen analyzer calibration. This section describes...

  12. 40 CFR 86.1323-84 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 20 2012-07-01 2012-07-01 false Oxides of nitrogen analyzer... (CONTINUED) Emission Regulations for New Otto-Cycle and Diesel Heavy-Duty Engines; Gaseous and Particulate Exhaust Test Procedures § 86.1323-84 Oxides of nitrogen analyzer calibration. The chemiluminescent...

  13. Bounding salt marsh nitrogen fluxes: development of an ecohydrological salt marsh model

    EPA Science Inventory

    A mass-balance approach to characterize nitrogen flux in a 2-hectare, meso-haline saltmarsh yielded extensive flow and water chemistry data. However, a significant, unevenly distributed population of the nitrogen fixer Alnus rubra (red alder) in the 20-hectare upland catchment l...

  14. Do foliar endophytic bacteria fix nitrogen?

    NASA Astrophysics Data System (ADS)

    Kueppers, L. M.; Moyes, A. B.; Frank, C.; Pett-Ridge, J.; Carper, D.; Vandehey, N.; O'Neil, J.; Dekas, A.

    2015-12-01

    Endophytic microorganisms - bacteria and fungi that live inside healthy plant tissue - are a relatively unexplored source of functional diversity in natural ecosystems. Prior to modern sequencing technology, detecting uncultured endophytic bacteria and assessing their putative functions was challenging. However, recent work has revealed a remarkable diversity of as yet non-culturable endophytic taxa and is beginning to identify functional roles within plant microbiomes. We recently examined bacterial communities in the foliage of a long-lived, high-elevation conifer species, limber pine (Pinus flexilis), and discovered a community strongly dominated by acetic acid bacteria (Acetobacteraceae), with several taxa closely related to known nitrogen fixers. Given limber pine's status as a pioneer species that is able to grow in low fertility soils, we hypothesized that this bacterial community has a potential functional role in fixing atmospheric nitrogen, providing a source of this limiting nutrient to the host tree. We used the radioisotope 13N2 to confirm that N2 rapidly diffuses into pine needles, where it could potentially be fixed. With an acetylene reduction assay we confirmed nitrogenase enzyme activity inside excised twigs 4 times over a growing season, and estimate potential rates of N2 fixation at 0.1 nmol N2 g needle-1 hr-1. Scaled to the stand level, this N input could be on the order of ~20 mg N m-2 d-1 over a growing season. While these rates are low, the long lifespan of individual trees (~1000 years) makes them biologically meaningful. Still, measured rates of acetylene reduction and bulk 15N2 incorporation are quite variable in space and time. Much work remains to better characterize the plant-microbial interactions in this system, including the rates of nitrogen fixation and their variability over the growing season, across edaphic conditions, among host species, and through plant development; and to determine which community members are responsible

  15. Continuous Monitoring of Nitrogen Retention in an Urban Stormwater Detention Pond

    NASA Astrophysics Data System (ADS)

    Rosenzweig, B.; Jaffe, P. R.

    2009-12-01

    Stormwater detention ponds have become ubiquitous in urbanized areas and have been suggested as potential ‘hotspots’ of nitrogen transformation within urban watersheds. As a result, there is a great deal of interest in the use of detention ponds as structural ‘best mangagement practices’ to reduce the excessive nitrogen export from these watersheds. We conducted continuous monitoring of the influent and effluent nitrogen loads of a stormwater detention pond located on the Princeton University campus in Princeton, New Jersey, USA. Our monitoring was conducted during 4, 21-day periods representing the 4 seasons of the northeastern United States. Laboratory incubations of sediments and surface water from the detention pond were also conducted to provide insight on the mechanisms of nitrogen retention and removal. The results of our monitoring show considerable seasonal variation in nitrogen retention within the detention pond. While retention of nitrate, the most dominant form of nitrogen in the influent stormwater, was observed during the spring and summer sampling periods, no significant nitrate retention was observed during the two cold-weather sampling periods. The initial results of our laboratory experiments suggest that the observed nitrate retention arises both from permanent removal by denitrification as well as temporary uptake by nuisance algae present in the detention pond during warmer months. Also, we observed that particulate nitrogen, which is often neglected in urban stormwater monitoring, was found to make up a significant fraction of the stormwater nitrogen load entering this detention pond (20-40% of the cumulative influent nitrogen load). A net retention of particulate nitrogen was observed during all 4 sampling periods, resulting in the retention of up to 20% of the total influent nitrogen load within the 21-day timeframe of our sampling periods. The results of this study provide important initial data on the role of stormwater detention

  16. Soluble carbohydrate allocation to roots, photosynthetic rate of leaves, and nitrate assimilation as affected by nitrogen stress and irradiance

    NASA Technical Reports Server (NTRS)

    Henry, L. T.; Raper, C. D. Jr

    1991-01-01

    Upon resupply of exogenous nitrogen to nitrogen-stressed plants, uptake rate of nitrogen is enhanced relative to nonstressed plants. Absorption of nitrogen presumably is dependent on availability of carbohydrates in the roots. A buildup in soluble carbohydrates thus should occur in roots of nitrogen-stressed plants, and upon resupply of exogenous nitrogen the increased uptake rate should be accompanied by a rapid decline in carbohydrates to prestress levels. To evaluate this relationship, three sets of tobacco plants growing in a complete hydroponic solution containing 1.0 mM NO3- were either continued in the complete solution for 21 d, transferred to a minus-nitrogen solution for 21 d, or transferred to a minus-nitrogen solution for 8-9 d and then returned to the 1.0 mM NO3- solution. These nitrogen treatments were imposed upon plants growing at photosynthetic photon flux densities of 700 and 350 micromoles m-2 s-1. Soluble carbohydrate levels in roots increased during onset of nitrogen stress to levels that were fourfold greater than in roots of non-stressed plants. Following resupply of external nitrogen, a rapid resumption of nitrogen uptake was accompanied by a decline in soluble carbohydrates in roots to levels characteristic of nonstressed plants. This pattern of soluble carbohydrate levels in roots during onset of and recovery from nitrogen stress occurred at both irradiance levels. The response of net photosynthetic rate to nitrogen stress could be expressed as a nonlinear function of concentration of reduced nitrogen in leaves. The net photosynthetic rate at a given concentration of reduced nitrogen, however, averaged 10% less at the lower than at the higher irradiance. The decline in net photosynthetic rate per unit of reduced nitrogen in leaves at the lower irradiance was accompanied by an increase in the nitrate fraction of total nitrogen in leaves from 20% at the higher irradiance to 38% at the lower irradiance.

  17. Soluble carbohydrate allocation to roots, photosynthetic rate of leaves, and nitrate assimilation as affected by nitrogen stress and irradiance

    NASA Technical Reports Server (NTRS)

    Henry, L. T.; Raper, C. D. Jr

    1991-01-01

    Upon resupply of exogenous nitrogen to nitrogen-stressed plants, uptake rate of nitrogen is enhanced relative to nonstressed plants. Absorption of nitrogen presumably is dependent on availability of carbohydrates in the roots. A buildup in soluble carbohydrates thus should occur in roots of nitrogen-stressed plants, and upon resupply of exogenous nitrogen the increased uptake rate should be accompanied by a rapid decline in carbohydrates to prestress levels. To evaluate this relationship, three sets of tobacco plants growing in a complete hydroponic solution containing 1.0 mM NO3- were either continued in the complete solution for 21 d, transferred to a minus-nitrogen solution for 21 d, or transferred to a minus-nitrogen solution for 8-9 d and then returned to the 1.0 mM NO3- solution. These nitrogen treatments were imposed upon plants growing at photosynthetic photon flux densities of 700 and 350 micromoles m-2 s-1. Soluble carbohydrate levels in roots increased during onset of nitrogen stress to levels that were fourfold greater than in roots of non-stressed plants. Following resupply of external nitrogen, a rapid resumption of nitrogen uptake was accompanied by a decline in soluble carbohydrates in roots to levels characteristic of nonstressed plants. This pattern of soluble carbohydrate levels in roots during onset of and recovery from nitrogen stress occurred at both irradiance levels. The response of net photosynthetic rate to nitrogen stress could be expressed as a nonlinear function of concentration of reduced nitrogen in leaves. The net photosynthetic rate at a given concentration of reduced nitrogen, however, averaged 10% less at the lower than at the higher irradiance. The decline in net photosynthetic rate per unit of reduced nitrogen in leaves at the lower irradiance was accompanied by an increase in the nitrate fraction of total nitrogen in leaves from 20% at the higher irradiance to 38% at the lower irradiance.

  18. Oxygen-Nitrogen Relationships in Autotrophic Nitrification

    PubMed Central

    Wezernak, C. T.; Gannon, J. J.

    1967-01-01

    Oxygen utilization by the autotrophic nitrifiers Nitrosomonas and Nitrobacter was studied. Experimental evidence is presented which reflects the effect of carbon dioxide fixation on overall oxygen utilization in autotrophic nitrification. Measurement of dissolved oxygen and inorganic nitrogen changes indicates that oxygen-nitrogen ratios in inorganic nitrogen oxidation are equal to 3.22 parts (expressed in milligrams per liter) of oxygen per part of ammonia nitrogen oxidized to nitrite nitrogen and 1.11 parts of oxygen per part of nitrite nitrogen oxidized to nitrate nitrogen. These values rather than the stoichiometric ratios should be used in nitrogenous oxygen demand calculations. PMID:6077417

  19. Testing of Colorimetric Tubes for Nitrogen Dioxide and Monomethylhydrazine.

    ERIC Educational Resources Information Center

    Diamond, Philip

    Colorimetric tubes for nitrogen dioxide (NO2) and monomethylhydrazine (MMH) were tested for accuracy and results indicate that at the levels checked the tubes' average deviation was plus or minus 20 percent. Tube NO2 concentrations all read lower than the analyzed concentrations. MMH tubes read much higher than the analyzed concentration of 0.28…

  20. 40 CFR 90.318 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... chemiluminescent oxides of nitrogen analyzer as described in this section. (b) Initial and Periodic Interference... and periodic calibration. Prior to its initial use and monthly thereafter, or within one month prior... following table). Example calibration points (%) Acceptable for calibration? 20, 30, 40, 50, 60, 70...

  1. 40 CFR 90.318 - Oxides of nitrogen analyzer calibration.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... chemiluminescent oxides of nitrogen analyzer as described in this section. (b) Initial and Periodic Interference... and periodic calibration. Prior to its initial use and monthly thereafter, or within one month prior... following table). Example calibration points (%) Acceptable for calibration? 20, 30, 40, 50, 60, 70 No...

  2. Wort free amino nitrogen analysis adapted to a microplate format

    USDA-ARS?s Scientific Manuscript database

    The standard method for determining wort free amino nitrogen content calls for the use of test tubes and glass marbles, as well as boiling and 20°C water baths. In this paper we describe how the standard method can be updated and streamlined by replacing water baths, test tubes and marbles with a th...

  3. Nitrogen isotope effects on glutamate decarboxylase from Escherichia coli

    SciTech Connect

    Abell, L.M.; O'Leary, M.H.

    1988-05-03

    The nitrogen isotope effect on the decarboxylation of glutamic acid by glutamate decarboxylase from Escherichia coli has been measured by comparison of the isotopic composition of the amino nitrogen of the product ..gamma..-aminobutyric acid isolated after 10-20% reaction with that of the starting glutamic acid. At pH 4.7, 37 /sup 0/C, the isotope effect is k/sup 14//k/sup 15/ = 0.9855 +/- 0.0006 when compared to unprotonated glutamic acid. Interpretation of this result requires knowledge of the equilibrium nitrogen isotope effect for Schiff base formation. This equilibrium isotope effect is K/sup 14//K/sup 15/ - 0.9824 for the formation of the unprotonated Schiff base between unprotonated valine and salicylaldehyde. Analysis of the nitrogen isotope effect on decarboxylation of glutamic acid and of the previously measured carbon isotope effect on this same reaction shows that decarboxylation and Schiff base formation are jointly rate limiting. The enzyme-bound Schiff base between glutamate and pyridoxal 5'-phosphate partitions approximately 2:1 between decarboxylation and return to the starting state. The nitrogen isotope effect also reveals that the Schiff base nitrogen is protonated in this intermediate.

  4. High-nitrogen explosives

    SciTech Connect

    Naud, D.; Hiskey, M. A.; Kramer, J. F.; Bishop, R. L.; Harry, H. H.; Son, S. F.; Sullivan, G. K.

    2002-01-01

    The syntheses and characterization of various tetrazine and furazan compounds offer a different approach to explosives development. Traditional explosives - such as TNT or RDX - rely on the oxidation of the carbon and hydrogen atoms by the oxygen carrying nitro group to produce the explosive energy. High-nitrogen compounds rely instead on large positive heats of formation for that energy. Some of these high-nitrogen compounds have been shown to be less sensitive to initiation (e.g. by impact) when compared to traditional nitro-containing explosives of similar performances. Using the precursor, 3,6-bis-(3,5-dimethylpyrazol-1-yl)-s-tetrazine (BDT), several useful energetic compounds based on the s-tetrazine system have been synthesized and studied. The compound, 3,3{prime}-azobis(6-amino-s-tetrazine) or DAAT, detonates as a half inch rate stick despite having no oxygen in the molecule. Using perfluoroacetic acid, DAAT can be oxidized to give mixtures of N-oxide isomers (DAAT03.5) with an average oxygen content of about 3.5. This energetic mixture burns at extremely high rates and with low dependency on pressure. Another tetrazine compound of interest is 3,6-diguanidino-s-tetrazine(DGT) and its dinitrate and diperchlorate salts. DGT is easily synthesized by reacting BDT with guanidine in methanol. Using Caro's acid, DGT can be further oxidized to give 3,6-diguanidino-s-tetrazine-1,4-di-N-oxide (DGT-DO). Like DGT, the di-N-oxide can react with nitric acid or perchloric acid to give the dinitrate and the diperchlorate salts. The compounds, 4,4{prime}-diamino-3,3{prime}-azoxyfurazan (DAAF) and 4,4{prime}-diamino-3,3{prime}-azofurazan (DAAzF), may have important future roles in insensitive explosive applications. Neither DAAF nor DAAzF can be initiated by laboratory impact drop tests, yet both have in some aspects better explosive performances than 1,3,5-triamino-2,4,6-trinitrobenzene TATB - the standard of insensitive high explosives. The thermal stability of DAAzF is

  5. Helium tube separates nitrogen gas from liquid nitrogen

    NASA Technical Reports Server (NTRS)

    Stephens, J. B.

    1964-01-01

    To prevent a boiloff problem, liquid nitrogen flowing from a storage tank to a container, is separated into liquid and gaseous components. This is accomplished by centrifugal and venting action, using a section of perforated helical aluminum tubing.

  6. Melting line of polymeric nitrogen

    NASA Astrophysics Data System (ADS)

    Yakub, L. N.

    2013-05-01

    We made an attempt to predict location of the melting line of polymeric nitrogen using two equations for Helmholtz free energy: proposed earlier for cubic gauche-structure and developed recently for liquid polymerized nitrogen. The P-T relation, orthobaric densities and latent heat of melting were determined using a standard double tangent construction. The estimated melting temperature decreases with increasing pressure, alike the temperature of molecular-nonmolecular transition in solid. We discuss the possibility of a triple point (solid-molecular fluid-polymeric fluid) at ˜80 GPa and observed maximum of melting temperature of nitrogen.

  7. Molybdenum Trafficking for Nitrogen Fixation†

    PubMed Central

    Hernandez, Jose A.; George, Simon J.; Rubio, Luis M.

    2009-01-01

    The molybdenum nitrogenase is responsible for most biological nitrogen fixation, a prokaryotic metabolic process that determines the global biogeochemical cycles of nitrogen and carbon. Here we describe the trafficking of molybdenum for nitrogen fixation in the model diazotrophic bacterium Azotobacter vinelandii. The genes and proteins involved in molybdenum uptake, homeostasis, storage, regulation, and nitrogenase cofactor biosynthesis are reviewed. Molybdenum biochemistry in A. vinelandii reveals unexpected mechanisms and a new role for iron-sulfur clusters in the sequestration and delivery of molybdenum. PMID:19772354

  8. Aphids alter host-plant nitrogen isotope fractionation

    PubMed Central

    Wilson, Alex C. C.; Sternberg, Leonel da S. L.; Hurley, Katherine B.

    2011-01-01

    Plant sap-feeding insects and blood-feeding parasites are frequently depleted in 15N relative to their diet. Unfortunately, most fluid-feeder/host nitrogen stable-isotope studies simply report stable-isotope signatures, but few attempt to elucidate the mechanism of isotopic trophic depletion. Here we address this deficit by investigating the nitrogen stable-isotope dynamics of a fluid-feeding herbivore-host plant system: the green peach aphid, Myzus persicae, feeding on multiple brassicaceous host plants. M. persicae was consistently more than 6‰ depleted in 15N relative to their hosts, although aphid colonized plants were 1.5‰ to 2.0‰ enriched in 15N relative to uncolonized control plants. Isotopic depletion of aphids relative to hosts was strongly related to host nitrogen content. We tested whether the concomitant aphid 15N depletion and host 15N enrichment was coupled by isotopic mass balance and determined that aphid 15N depletion and host 15N enrichment are uncoupled processes. We hypothesized that colonized plants would have higher nitrate reductase activity than uncolonized plants because previous studies had demonstrated that high nitrate reductase activity under substrate-limiting conditions can result in increased plant δ15N values. Consistent with our hypothesis, nitrate reductase activity in colonized plants was twice that of uncolonized plants. This study offers two important insights that are likely applicable to understanding nitrogen dynamics in fluid-feeder/host systems. First, isotopic separation of aphid and host depends on nitrogen availability. Second, aphid colonization alters host nitrogen metabolism and subsequently host nitrogen stable-isotope signature. Notably, this work establishes a metabolic framework for future hypothesis-driven studies focused on aphid manipulation of host nitrogen metabolism. PMID:21646532

  9. Quantifying atmospheric nitrogen outflow from the Front Range of Colorado

    NASA Astrophysics Data System (ADS)

    Neuman, J. A.; Eilerman, S. J.; Brock, C. A.; Brown, S. S.; Dube, W. P.; Herndon, S. C.; Holloway, J. S.; Nowak, J. B.; Roscioli, J. R.; Ryerson, T. B.; Sjostedt, S. J.; Thompson, C. R.; Trainer, M.; Veres, P. R.; Wild, R. J.

    2015-12-01

    Reactive nitrogen emitted to the atmosphere from urban, industrial, and agricultural sources can be transported and deposited far from the source regions, affecting vegetation, soils, and water of sensitive ecosystems. Mitigation of atmospheric nitrogen deposition requires emissions characterization and quantification. Ammonia (NH3), a full suite of gas-phase oxidized nitrogen compounds, and particulate matter were measured from an aircraft that flew downwind from concentrated animal feeding operations, oil and gas extraction facilities, and urban areas along the Colorado Front Range in March and April 2015, as part of the Shale Oil and Natural Gas Nexus (SONGNEX) field study. Additionally, NH3 measurements from a fully instrumented aircraft that flew over the same region in July and August 2014 as part of the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) are used to examine atmospheric nitrogen emission and transport. Cross-wind plume transects and altitude profiles were performed over the source regions and 60-240 km downwind. Plumes were transported in the boundary layer with large NH3 mixing ratios (typically 20-100 ppbv) and were tens of km wide. The NH3 in these plumes provided an atmospheric nitrogen burden greater than 0.2 kg N/ha. Nitrogen oxides and their oxidation products and particulate matter were also enhanced in the plumes, but with concentrations substantially less than NH3. With efficient transport followed by wet deposition, these plumes have the potential to provide a large nitrogen input to the neighboring Rocky Mountain National Park, where nitrogen deposition currently exceeds the ecological critical load of 1.5 kg N/ha/yr.

  10. Nitrogen metabolism meets phytopathology.

    PubMed

    Fagard, Mathilde; Launay, Alban; Clément, Gilles; Courtial, Julia; Dellagi, Alia; Farjad, Mahsa; Krapp, Anne; Soulié, Marie-Christine; Masclaux-Daubresse, Céline

    2014-10-01

    Nitrogen (N) is essential for life and is a major limiting factor of plant growth. Because soils frequently lack sufficient N, large quantities of inorganic N fertilizers are added to soils for crop production. However, nitrate, urea, and ammonium are a major source of global pollution, because much of the N that is not taken up by plants enters streams, groundwater, and lakes, where it affects algal production and causes an imbalance in aquatic food webs. Many agronomical data indicate that the higher use of N fertilizers during the green revolution had an impact on the incidence of crop diseases. In contrast, examples in which a decrease in N fertilization increases disease severity are also reported, indicating that there is a complex relationship linking N uptake and metabolism and the disease infection processes. Thus, although it is clear that N availability affects disease, the underlying mechanisms remain unclear. The aim of this review is to describe current knowledge of the mechanisms that link plant N status to the plant's response to pathogen infection and to the virulence and nutritional status of phytopathogens. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  11. Environmental friendly nitrogen fertilization.

    PubMed

    Shaviv, Avi

    2005-09-01

    With the huge intensification of agriculture and the increasing awareness to human health and natural resources sustainability, there was a shift towards the development of environmental friendly N application approaches that support sustainable use of land and sustain food production. The effectiveness of such approaches depends on their ability to synchronize plant nitrogen demand with its supply and the ability to apply favored compositions and dosages of N-species. They are also influenced by farming scale and its sophistication, and include the following key concepts: (i) Improved application modes such as split or localized ("depot") application; (ii) use of bio-amendments like nitrification and urease inhibitors and combinations of (i) and (ii); (iii) use of controlled and slow release fertilizers; (iv) Fertigation-fertilization via irrigation systems including fully automated and controlled systems; and (v) precision fertilization in large scale farming systems. The paper describes the approaches and their action mechanisms and examines their agronomic and environmental significance. The relevance of the approaches for different farming scales, levels of agronomic intensification and agro-technical sophistication is examined as well.

  12. Relationship between site-specific nitrogen concentrations in mosses and measured wet bulk atmospheric nitrogen deposition across Europe.

    PubMed

    Harmens, Harry; Schnyder, Elvira; Thöni, Lotti; Cooper, David M; Mills, Gina; Leblond, Sébastien; Mohr, Karsten; Poikolainen, Jarmo; Santamaria, Jesus; Skudnik, Mitja; Zechmeister, Harald G; Lindroos, Antti-Jussi; Hanus-Illnar, Andrea

    2014-11-01

    To assess the relationship between nitrogen concentrations in mosses and wet bulk nitrogen deposition or concentrations in precipitation, moss tissue and deposition were sampled within a distance of 1 km of each other in seven European countries. Relationships for various forms of nitrogen appeared to be asymptotic, with data for different countries being positioned at different locations along the asymptotic relationship and saturation occurring at a wet bulk nitrogen deposition of ca. 20 kg N ha(-1) yr(-1). The asymptotic behaviour was more pronounced for ammonium-N than nitrate-N, with high ammonium deposition at German sites being most influential in providing evidence of the asymptotic behaviour. Within countries, relationships were only significant for Finland and Switzerland and were more or less linear. The results confirm previous relationships described for modelled total deposition. Nitrogen concentration in mosses can be applied to identify areas at risk of high nitrogen deposition at European scale. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Energy, industry and nitrogen: strategies for decreasing reactive nitrogen emissions.

    PubMed

    Moomaw, William R

    2002-03-01

    Nitrogen oxides are released during atmospheric combustion of fossil fuels and biomass, and during the production of certain chemicals and products. They can react with natural or man-made volatile organic compounds to produce smog, or else can be further oxidized to produce particulate haze, or acid rain that can eutrophy land and water. The reactive nitrogen that begins in the energy sector thus cascades through the atmosphere, the hydrosphere and soils before being eventually partially denitrifed to the global warming and stratospheric ozone-depleting gas nitrous oxide or molecular nitrogen. This paper will suggest how an economic analysis of the nitrogen cycle can identify the most cost-effective places to intervene. Nitrogen oxides released during fossil-fuel combustion in vehicles, power plants and heating boilers can either be controlled by add-on emission control technology, or can be eliminated by many of the same technical options that lead to carbon dioxide reduction. These integrated strategies also address sustainability, economic development and national security issues. Similarly in industrial production, it is more effective to focus on redesigning industrial processes rather than on nitrogen oxide pollution elimination from the current system. This paper will suggest which strategies might be utilized to address multiple benefits rather than focusing on single pollutants.

  14. 75 FR 14116 - Approval of Implementation Plans of Wisconsin: Nitrogen Oxides Reasonably Available Control...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-24

    ... Annealing Furnace. Asphalt Plants =>65 mmBtu/hr... Gaseous fuel, 0.15 lbs/mmBtu. Distillate oil, 0.20 lbs/mm... relations, Nitrogen oxides, Ozone, Particulate matter, Reporting and recordkeeping requirements, Sulfur...

  15. An analytical study of nitrogen oxides and carbon monoxide emissions in hydrocarbon combustion with added nitrogen - Preliminary results

    NASA Technical Reports Server (NTRS)

    Bittker, D. A.

    1980-01-01

    The influence of ground-based gas turbine combustor operating conditions and fuel-bound nitrogen (FBN) found in coal-derived liquid fuels on the formation of nitrogen oxides and carbon monoxide is investigated. Analytical predictions of NOx and CO concentrations are obtained for a two-stage, adiabatic, perfectly-stirred reactor operating on a propane-air mixture, with primary equivalence ratios from 0.5 to 1.7, secondary equivalence ratios of 0.5 or 0.7, primary stage residence times from 12 to 20 msec, secondary stage residence times of 1, 2 and 3 msec and fuel nitrogen contents of 0.5, 1.0 and 2.0 wt %. Minimum nitrogen oxide but maximum carbon monoxide formation is obtained at primary zone equivalence ratios between 1.4 and 1.5, with percentage conversion of FBN to NOx decreasing with increased fuel nitrogen content. Additional secondary dilution is observed to reduce final pollutant concentrations, with NOx concentration independent of secondary residence time and CO decreasing with secondary residence time; primary zone residence time is not observed to affect final NOx and CO concentrations significantly. Finally, comparison of computed results with experimental values shows a good semiquantitative agreement.

  16. An analytical study of nitrogen oxides and carbon monoxide emissions in hydrocarbon combustion with added nitrogen - Preliminary results

    NASA Technical Reports Server (NTRS)

    Bittker, D. A.

    1980-01-01

    The influence of ground-based gas turbine combustor operating conditions and fuel-bound nitrogen (FBN) found in coal-derived liquid fuels on the formation of nitrogen oxides and carbon monoxide is investigated. Analytical predictions of NOx and CO concentrations are obtained for a two-stage, adiabatic, perfectly-stirred reactor operating on a propane-air mixture, with primary equivalence ratios from 0.5 to 1.7, secondary equivalence ratios of 0.5 or 0.7, primary stage residence times from 12 to 20 msec, secondary stage residence times of 1, 2 and 3 msec and fuel nitrogen contents of 0.5, 1.0 and 2.0 wt %. Minimum nitrogen oxide but maximum carbon monoxide formation is obtained at primary zone equivalence ratios between 1.4 and 1.5, with percentage conversion of FBN to NOx decreasing with increased fuel nitrogen content. Additional secondary dilution is observed to reduce final pollutant concentrations, with NOx concentration independent of secondary residence time and CO decreasing with secondary residence time; primary zone residence time is not observed to affect final NOx and CO concentrations significantly. Finally, comparison of computed results with experimental values shows a good semiquantitative agreement.

  17. BUN (Blood Urea Nitrogen) Test

    MedlinePlus

    ... nitrogen and creatinine. Emerg Med Clin North Am [Internet]. 1986 May 4 [cited 2017 Jan 30]; 4( ... ncbi.nlm.nih.gov/pubmed/3516645 Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998- ...

  18. Reduced atmospheric CO2 inhibits nitrogen mobilization in Festuca rubra.

    PubMed

    Thornton, Barry; Paterson, Eric; Kingston-Smith, Alison H; Bollard, Andrea L; Pratt, Shona M; Sim, Allan

    2002-09-01

    In defoliated grasses, where photosynthesis is reduced due to removal of leaf material, it is well established that remobilization of nitrogen occurs from both older remaining leaves and roots towards the younger growing leaves. In contrast, little is known about the movement of nitrogen within intact grass plants experiencing prolonged inhibition of photosynthesis. We tested the following hypotheses in Festuca rubra L. ssp. rubra cv. Boreal: that both reduction of the atmospheric CO2 concentration and defoliation (1) induce mobilization of nitrogen from roots and older leaves towards growing leaves and (2) elicit similar directional change in the abundance of proteins in roots and older leaves relevant to the process of nitrogen mobilization including, glutamine synthetase (GS), EC 6.3.1.2; papain, EC 3.4.22.2; chymopapain, EC 3.4.22.6; ribulose bisphosphate carboxylase/oxygenase (Rubisco), EC 4.1.1.39; and the light harvesting complex of photosystem II (LHCPII). After growth at ambient atmospheric CO2 concentration, plants of F. rubra were subject to atmospheres containing either ambient (350 micro l l-1) or deplete (< 20 micro l l-1) CO2. Concurrently, plants were either left intact or defoliated on one occasion. Steady state 15N labelling coupled with a series of destructive harvests over a 7-day period enabled changes in the nitrogen dynamics of the plants to be established. Proteins pertinent to the process of nitrogen mobilization were quantified by immunoblotting. Irrespective of defoliation, plants in ambient CO2 mobilized nitrogen from older to growing leaves. This mobilization was inhibited by deplete CO2. Greater concentration of Rubisco and reduced chymopapain abundance in older remaining leaves of intact plants, in deplete compared with ambient CO2, suggested the inhibition of mobilization was due to inhibition of protein degradation, rather than to the export of degradation products. Both deplete CO2 and defoliation induced nitrogen mobilization from

  19. Effect of salinity on the critical nitrogen concentration of Spartina alterniflora Loisel

    USGS Publications Warehouse

    Bradley, P.M.; Morris, J.T.

    1992-01-01

    Nitrogen was withheld from the salt marsh grass Spartina alterniflora Loisel., in order to determine the effect of salinity (sea salts) on critical tissue nitrogen concentrations (defined here as the minimum tissue concentration required to sustain biomass accumulation). The critical nitrogen concentration per kilogram dry weight of above-ground tissue increased non-linearly from a mean of 8.2 g kg-1 at 5 g l-1 and 20 g l-1 salinity to 13.6 g kg-1 and 22.9 g kg-1 at salinities of 40 g l-1 and 50 g l-1, respectively. Below-ground tissue nitrogen concentrations averaged 62% of the above-ground values irrespective of salinity treatment. These results suggest that the critical nitrogen concentration is a function of salinity and indicate that the internal nitrogen supply required in support of growth increases with salinity. Above-ground tissue nitrogen concentrations reported in the literature and the relationship between salinity and critical nitrogen concentration observed in this study were used to evaluate the nitrogen status of S. alterniflora over a wide range of geographical locations. Comparisons suggest that both short and tall forms of S. alterniflora are nitrogen limited in the majority of marshes along the Gulf and Atlantic Coasts of the US. ?? 1992.

  20. Increasing importance of deposition of reduced nitrogen in the United States

    PubMed Central

    Li, Yi; Schichtel, Bret A.; Walker, John T.; Schwede, Donna B.; Chen, Xi; Lehmann, Christopher M. B.; Puchalski, Melissa A.; Gay, David A.; Collett, Jeffrey L.

    2016-01-01

    Rapid development of agriculture and fossil fuel combustion greatly increased US reactive nitrogen emissions to the atmosphere in the second half of the 20th century, resulting in excess nitrogen deposition to natural ecosystems. Recent efforts to lower nitrogen oxides emissions have substantially decreased nitrate wet deposition. Levels of wet ammonium deposition, by contrast, have increased in many regions. Together these changes have altered the balance between oxidized and reduced nitrogen deposition. Across most of the United States, wet deposition has transitioned from being nitrate-dominated in the 1980s to ammonium-dominated in recent years. Ammonia has historically not been routinely measured because there are no specific regulatory requirements for its measurement. Recent expansion in ammonia observations, however, along with ongoing measurements of nitric acid and fine particle ammonium and nitrate, permit new insight into the balance of oxidized and reduced nitrogen in the total (wet + dry) US nitrogen deposition budget. Observations from 37 sites reveal that reduced nitrogen contributes, on average, ∼65% of the total inorganic nitrogen deposition budget. Dry deposition of ammonia plays an especially key role in nitrogen deposition, contributing from 19% to 65% in different regions. Future progress toward reducing US nitrogen deposition will be increasingly difficult without a reduction in ammonia emissions. PMID:27162336

  1. Increasing importance of deposition of reduced nitrogen in the United States.

    PubMed

    Li, Yi; Schichtel, Bret A; Walker, John T; Schwede, Donna B; Chen, Xi; Lehmann, Christopher M B; Puchalski, Melissa A; Gay, David A; Collett, Jeffrey L

    2016-05-24

    Rapid development of agriculture and fossil fuel combustion greatly increased US reactive nitrogen emissions to the atmosphere in the second half of the 20th century, resulting in excess nitrogen deposition to natural ecosystems. Recent efforts to lower nitrogen oxides emissions have substantially decreased nitrate wet deposition. Levels of wet ammonium deposition, by contrast, have increased in many regions. Together these changes have altered the balance between oxidized and reduced nitrogen deposition. Across most of the United States, wet deposition has transitioned from being nitrate-dominated in the 1980s to ammonium-dominated in recent years. Ammonia has historically not been routinely measured because there are no specific regulatory requirements for its measurement. Recent expansion in ammonia observations, however, along with ongoing measurements of nitric acid and fine particle ammonium and nitrate, permit new insight into the balance of oxidized and reduced nitrogen in the total (wet + dry) US nitrogen deposition budget. Observations from 37 sites reveal that reduced nitrogen contributes, on average, ∼65% of the total inorganic nitrogen deposition budget. Dry deposition of ammonia plays an especially key role in nitrogen deposition, contributing from 19% to 65% in different regions. Future progress toward reducing US nitrogen deposition will be increasingly difficult without a reduction in ammonia emissions.

  2. The nitrogen cycle on Mars

    NASA Technical Reports Server (NTRS)

    Mancinelli, Rocco L.

    1989-01-01

    Nirtogen is an essential element for the evolution of life, because it is found in a variety of biologically important molecules. Therefore, N is an important element to study from a exobiological perspective. In particular, fixed nitrogen is the biologically useful form of nitrogen. Fixed nitrogen is generally defines as NH3, NH4(+), NO(x), or N that is chemically bound to either inorganic or organic molecules, and releasable by hydrolysis to NH3 or NH4(+). On Earth, the vast majority of nitrogen exists as N2 in the atmosphere, and not in the fixes form. On early Mars the same situations probably existed. The partial pressure of N2 on early Mars was thought to be 18 mb, significantly less than that of Earth. Dinitrogen can be fixed abiotically by several mechanisms. These mechanisms include thernal shock from meteoritic infall and lightning, as well as the interaction of light and sand containing TiO2 which produces NH3 that would be rapidly destroyed by photolysis and reaction with OH radicals. These mechanisms could have been operative on primitive Mars.The chemical processes effecting these compounds and possible ways of fixing or burying N in the Martian environment are described. Data gathered in this laboratory suggest that the low abundance of nitrogen along (compared to primitive Earth) may not significantly deter the origin and early evolution of a nitrogen utilizing organisms. However, the conditions on current Mars with respect to nitrogen are quite different, and organisms may not be able to utilize all of the available nitrogen.

  3. Input of urban nitrogen to coastal waters

    NASA Astrophysics Data System (ADS)

    Sorensen, L. L.; Barthelmie, R.; Pryor, S.; Bilde, M.; Ingemansson, O.

    2003-04-01

    The project described is a pilot study to make first estimates of the contribution of urban emissions to nitrogen (N) deposition to coastal waters. The overall objective is to estimate the transport and deposition of N gases emitted in the city of Copenhagen to the coastal waters of the Øresund. Traffic emissions are increasingly recognised as a source of nitrogen gases which contribute to urban pollution affecting human health and visibility by contributing both reduced and oxidised forms of nitrogen where co-emitted pollutants (such as ammonia NH3 and nitric acid HNO3) may react to increase the aerosol burden. While net agricultural emissions of NH3 are larger, they are mainly concentrated in spring and summer whereas urban emissions are a year-round phenomena and in winter mixed layer depths are lower concentrating pollutants in the boundary-layer. First estimates are that emissions from Copenhagen are up to 2.5% of Denmark's total NH3 emissions. Detailed NH3 measurements are being conducted on the Chemistry Building at Copenhagen University using Risø's Wet Effluent Diffusion Denuders which have very low detection limits (~0.1 ppb) and provide good time resolution (~ minutes). The measurements indicate a strong correlation between NH3 and nitrogen oxides (NOx), with diurnal emission patterns strongly indicative of traffic emissions. Measurements are also being conducted at Barseback approximately 20 km from Copenhagen across the Øresund. Measurements from a mast installed just outside (2 km) of Copenhagen harbour are being used to characterise the wind and turbulence conditions of the Øresund. The presence of the city can be detected in the turbulence intensity. Sector average turbulence intensity at 10 m height is up to 17% in easterly sectors and around 10% from overwater directions. This implies that the presence of Copenhagen increases turbulence potentially increasing deposition to coast waters. The data collected will be used to provide first

  4. Anaerobic Nitrogen Fixers on Mars

    NASA Astrophysics Data System (ADS)

    Lewis, B. G.

    2000-07-01

    The conversion of atmospheric nitrogen gas to the protein of living systems is an amazing process of nature. The first step in the process is biological nitrogen fixation, the transformation of N2 to NH3. The phenomenon is crucial for feeding the billions of our species on Earth. On Mars, the same process may allow us to discover how life can adapt to a hostile environment, and render it habitable. Hostile environments also exist on Earth. For example, nothing grows in coal refuse piles due to the oxidation of pyrite and marcasite to sulfuric acid. Yet, when the acidity is neutralized, alfalfa and soybean plants develop root nodules typical of symbiotic nitrogen fixation with Rhizobium species possibly living in the pyritic material. When split open, these nodules exhibited the pinkish color of leghemoglobin, a protein in the nodule protecting the active nitrogen-fixing enzyme nitrogenase against the toxic effects of oxygen. Although we have not yet obtained direct evidence of nitrogenase activity in these nodules (reduction of acetylene to ethylene, for example), these findings suggested the possibility that nitrogen fixation was taking place in this hostile, non-soil material. This immediately raises the possibility that freeliving anaerobic bacteria which fix atmospheric nitrogen on Earth, could do the same on Mars.

  5. [Nitrogen flow in Huizhou region].

    PubMed

    Ma, Xiaobo; Wang, Zhaoyin; Koenig, Albert; Deng, Jiaquan

    2006-06-01

    Eutrophication is a serious problem of water body pollution. By the method of material flow accounting, this paper studied the human activities- related nitrogen flow in the system of environment and anthroposphere in Huizhou region. The non-point source pollution was quantified by export coefficient method, and the domestic discharge was estimated by demand-supply method. The statistic and dynamic analyses based on the investigation data of 1998 showed that the major nitrogen flows in this region were river loads, fertilizer and feedstuff imports, atmospheric deposition, animal excretes' degradation and volatilization, and the processes relating to burning and other emissions. In 1998, about 40% of nitrogen was detained in the system, which could be accumulated and yield potential environmental problems. The nitrogen export in this region was mainly by rivers, accounted for about 57%. A comparison of Huizhou region with the Danube and Changjiang basins showed that the unit area nitrogen exports in these three regions were of the same magnitude, and the per capita nitrogen exports were comparable.

  6. [Nitrogen balance assessment in burn patients].

    PubMed

    Beça, Andreia; Egipto, Paula; Carvalho, Davide; Correia, Flora; Oliveira, Bruno; Rodrigues, Acácio; Amarante, José; Medina, J Luís

    2010-01-01

    The burn injury probably represents the largest stimulus for muscle protein catabolism. This state is characterized by an accelerated catabolism of the lean or skeletal mass that results in a clinical negative balance of nitrogen and muscle wasting. The determination of an appropriate value for protein intake is essential, since it is positively related to the nitrogen balance (NB) and accordingly several authors argue that a positive NB is the key parameter associated with nutritional improvement of a burn patient. Evaluation of the degree of protein catabolism by assessment of the Nitrogen Balance; Defining of nutritional support (protein needs) to implement in patients with burned surface area (BSA) = 10%. We prospectively evaluated the clinical files and scrutinized the clinical variables of interest. The NB was estimated according to three formulae. Each gram of nitrogen calculated by the NB was then converted into grams of protein, subtracted or added to protein intake (or administered enteric or parenterically) and divided by kg of reference Weight (kg Rweight), in an attempt to estimate the daily protein needs. The cohort consisted of 10 patients, 6 females, with average age of 58(23) years old, a mean of BSA of 21.4(8.4)%, ranging from a minimum of 10.0% and máximum of 35.0%. On average, patients were 58 (23) years old. The average number of days of hospitalization in the burn unit was 64.8(36.5) days. We observed significant differences between the 3 methods used for calculating the NB (p = 0.004), on average the NB was positive. When the formula A was used the average value of NB was higher. Regarding the attempt to estimate the needs of g prot/kg Rweight/day most of the values did not exceed, on average, 2.6 g Prot/kg Rweight/day and no significant differences between patients with a BSA% of 10-20% and with BSA% > 20% were found. Despite being able to estimate the protein catabolism through these formulas and verifying that most values were above zero

  7. Evaluation of a spacecraft nitrogen generator

    NASA Technical Reports Server (NTRS)

    Marshall, R. D.; Powell, J. D.

    1976-01-01

    A method is discussed of generating nitrogen for cabin leakage makeup aboard space vehicles having longer duration missions. The nitrogen generation concept is based on using liquid hydrazine as the stored form of nitrogen to reduce the higher tankage and expendables weight associated with high pressure gaseous or cryogenic liquid nitrogen storage. The hydrazine is catalytically dissociated to yield a mixture of nitrogen and hydrogen. The nitrogen/hydrogen mixture is then separated to yield the makeup nitrogen. The excess supply of hydrogen would be available for use in the reduction of metabolic carbon dioxide. A detailed comparison was completed of Palladium/Silver and Polymer Electrochemical-based Nitrogen Generation Systems. The palladium/silver-based system was judged better than the Polymer Electrochemical Nitrogen Generation System because of lower expendable weight and palladium/silver nitrogen/hydrogen separation represents 'off-the-shelf' technology.

  8. 20 CFR 602.20 - Organization.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 3 2014-04-01 2014-04-01 false Organization. 602.20 Section 602.20 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR QUALITY CONTROL IN THE FEDERAL-STATE UNEMPLOYMENT INSURANCE SYSTEM State Responsibilities § 602.20 Organization. Each State shall establish a...

  9. 20 CFR 602.20 - Organization.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Organization. 602.20 Section 602.20 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR QUALITY CONTROL IN THE FEDERAL-STATE UNEMPLOYMENT INSURANCE SYSTEM State Responsibilities § 602.20 Organization. Each State shall establish a...

  10. 20 CFR 602.20 - Organization.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false Organization. 602.20 Section 602.20 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR QUALITY CONTROL IN THE FEDERAL-STATE UNEMPLOYMENT INSURANCE SYSTEM State Responsibilities § 602.20 Organization. Each State shall establish a...

  11. 20 CFR 602.20 - Organization.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 3 2013-04-01 2013-04-01 false Organization. 602.20 Section 602.20 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR QUALITY CONTROL IN THE FEDERAL-STATE UNEMPLOYMENT INSURANCE SYSTEM State Responsibilities § 602.20 Organization. Each State shall establish a...

  12. 20 CFR 602.20 - Organization.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 3 2012-04-01 2012-04-01 false Organization. 602.20 Section 602.20 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR QUALITY CONTROL IN THE FEDERAL-STATE UNEMPLOYMENT INSURANCE SYSTEM State Responsibilities § 602.20 Organization. Each State shall establish a...

  13. 20 CFR 656.20 - Audit procedures.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 3 2013-04-01 2013-04-01 false Audit procedures. 656.20 Section 656.20... FOR PERMANENT EMPLOYMENT OF ALIENS IN THE UNITED STATES Labor Certification Process § 656.20 Audit procedures. (a) Review of the labor certification application may lead to an audit of the...

  14. Water quality improvement through bioretention media: nitrogen and phosphorus removal.

    PubMed

    Davis, Allen P; Shokouhian, Mohammad; Sharma, Himanshu; Minami, Christie

    2006-03-01

    High nutrient inputs and eutrophication continue to be one of the highest priority water quality problems. Bioretention is a low-impact development technology that has been advocated for use in urban and other developed areas. This work provides an in-depth analysis on removal of nutrients from a synthetic stormwater runoff by bioretention. Results have indicated good removal of phosphorus (70 to 85%) and total Kjeldahl nitrogen (55 to 65%). Nitrate reduction was poor (< 20%) and, in several cases, nitrate production was noted. Variations in flowrate (intensity) and duration had a moderate affect on nutrient removal. Mass balances demonstrate the importance of water attenuation in the facility in reducing mass nutrient loads. Captured nitrogen can be converted to nitrate between storm events and subsequently washed from the system. Analysis on the fate of nutrients in bioretention suggests that accumulation of phosphorus and nitrogen may be controlled by carefully managing growing and harvesting of vegetation.

  15. Vibrational properties of cagelike diamondoid nitrogen at high pressure

    NASA Astrophysics Data System (ADS)

    Wang, Hui

    2013-08-01

    Under high pressure, a cagelike diamondoid nitrogen structure was lately discovered by first-principles structure researches. This newly proposed structure is very unique and has not been observed in any other element. Using density-functional calculations, we study the pressure effect on its vibrational properties. The Born effective charges are calculated, and the resulting LO—TO splittings of certain infrared active modes are beyond 20 cm-1. We depict the Γ-point vibrational modes and find the breathing mode, rotational mode, and shearing mode. Frequencies of all the optical modes increase with pressure increasing. Moreover, the relation between the breathing mode frequency and the nitrogen cage diameter is discussed in detail. Our calculation results give a deeper insight into the vibrational properties of the cagelike diamondoid nitrogen.

  16. Predominantly non-solar origin of nitrogen in lunar soils

    NASA Astrophysics Data System (ADS)

    Mortimer, J.; Verchovsky, A. B.; Anand, M.

    2016-11-01

    Simultaneous static-mode mass spectrometric measurements of nitrogen, carbon, helium, neon, and argon, extracted from the same aliquot of sample by high-resolution stepped combustion, have been made for a suite of five lunar soils. Noble gas isotope ratios show that the majority of noble gases are derived from a solar wind source; for example, at peak release temperatures of 500-600 °C, 21Ne/22Ne = 0.0313 ± 0.0007 to 0.0333 ± 0.0007, and 20Ne/22Ne = 11.48 ± 0.05 to 12.43 ± 0.07, with values at the lowest temperature steps less fractionated during implantation from, and therefore even closer to, solar values (21Ne/22NeSW = 0.03361 ± 0.00018 and 20Ne/22NeSW = 14.001 ± 0.042 (Pepin et al., 2012)). Despite the co-release of nitrogen and solar wind argon, measured nitrogen isotopic signatures at each temperature step, whilst variable, are significantly more enriched in 15N compared to the measured solar wind nitrogen value from the Genesis mission. Therefore, mixing between a 15N-enriched non-solar planetary nitrogen source with solar wind nitrogen is required to explain the measured isotopic values from the stepped combustion analysis of lunar soils. Binary mixing calculations, made under different assumptions about the degree of loss of solar wind 36Ar, reveal that the majority (up to 98%) of the nitrogen released is derived from a non-solar source. The range of modelled non-solar end-member nitrogen compositions required to satisfy the measured δ15N values varies between samples and temperature steps from +5‰ up to +300‰, or between +87‰ and +160‰ for bulk samples. This range of modelled isotopic compositions for the non-solar source of nitrogen encompasses measured values for several different groups of carbonaceous chondrite, as well as IDPs.

  17. The carbon bonus of organic nitrogen enhances nitrogen use efficiency of plants

    PubMed Central

    Cambui, Camila Aguetoni; Gruffman, Linda; Palmroth, Sari; Oren, Ram; Näsholm, Torgny

    2016-01-01

    Abstract The importance of organic nitrogen (N) for plant nutrition and productivity is increasingly being recognized. Here we show that it is not only the availability in the soil that matters, but also the effects on plant growth. The chemical form of N taken up, whether inorganic (such as nitrate) or organic (such as amino acids), may significantly influence plant shoot and root growth, and nitrogen use efficiency (NUE). We analysed these effects by synthesizing results from multiple laboratory experiments on small seedlings (Arabidopsis, poplar, pine and spruce) based on a tractable plant growth model. A key point is that the carbon cost of assimilating organic N into proteins is lower than that of inorganic N, mainly because of its carbon content. This carbon bonus makes it more beneficial for plants to take up organic than inorganic N, even when its availability to the roots is much lower – up to 70% lower for Arabidopsis seedlings. At equal growth rate, root:shoot ratio was up to three times higher and nitrogen productivity up to 20% higher for organic than inorganic N, which both are factors that may contribute to higher NUE in crop production. PMID:27241731

  18. Connecting the dots: linking nitrogen cycle gene expression to nitrogen fluxes in marine sediment mesocosms

    PubMed Central

    Bowen, Jennifer L.; Babbin, Andrew R.; Kearns, Patrick J.; Ward, Bess B.

    2014-01-01

    Connecting molecular information directly to microbial transformation rates remains a challenge, despite the availability of molecular methods to investigate microbial biogeochemistry. By combining information on gene abundance and expression for key genes with quantitative modeling of nitrogen fluxes, we can begin to understand the scales on which genetic signals vary and how they relate to key functions. We used quantitative PCR of DNA and cDNA, along with biogeochemical modeling to assess how the abundance and expression of microbes responsible for two steps in the nitrogen cycle changed over time in estuarine sediment mesocosms. Sediments and water were collected from coastal Massachusetts and maintained in replicated 20 L mesocosms for 45 days. Concentrations of all major inorganic nitrogen species were measured daily and used to derive rates of nitrification and denitrification from a Monte Carlo-based non-negative least-squares analysis of finite difference equations. The mesocosms followed a classic regeneration sequence in which ammonium released from the decomposition of organic matter was subsequently oxidized to nitrite and then further to nitrate, some portion of which was ultimately denitrified. Normalized abundances of ammonia oxidizing archaeal ammonia monoxoygenase (amoA) transcripts closely tracked rates of ammonia oxidation throughout the experiment. No such relationship, however, was evident between denitrification rates and the normalized abundance of nitrite reductase (nirS and nirK) transcripts. These findings underscore the complexity of directly linking the structure of the microbial community to rates of biogeochemical processes. PMID:25191309

  19. Insulating geothermal well casings from thermal stress with nitrogen gas or nitrogen foam

    SciTech Connect

    Dreesen, D.S.; Murphy, H.D.; Zyvoloski, G.; McEligot, D.M.; Dash, Z.; Nicholson, R.N.

    1984-08-26

    Fenton Hill Hot Dry Rock Geothermal Site Well EE-3 was designed and completed to function as a completion of the reservoirs with the injection well, EE-2, progressed it become evident that it would be desirable to fracture in EE-3 as well to obtain a flow connection between the wells. Unfortunately, the 9-5/8'' od production casing in EE-3 had been pretensioned to 885,000 lbs to accommodate its intended service as a hot water production well. Cool-down of the casing was thus limited to only 11/sup 0/C (20/sup 0/F) to keep the stress in the top joints of the casing below the minimum yield stress, or else the pretension had to be released. Before incurring the risk and expense required to release the tension, fracturing experiments were performed to evaluate the use gaseous nitrogen and 75% quality nitrogen-gel foam as insulating media in an annular wellbore configuration, i.e., the nitrogen gas or foam was placed in the annular gap between the tubing string and the casing.

  20. Membrane rejection of nitrogen compounds

    NASA Technical Reports Server (NTRS)

    Lee, S.; Lueptow, R. M.

    2001-01-01

    Rejection characteristics of nitrogen compounds were examined for reverse osmosis, nanofiltration, and low-pressure reverse osmosis membranes. The rejection of nitrogen compounds is explained by integrating experimental results with calculations using the extended Nernst-Planck model coupled with a steric hindrance model. The molecular weight and chemical structure of nitrogen compounds appear to be less important in determining rejection than electrostatic properties. The rejection is greatest when the Donnan potential exceeds 0.05 V or when the ratio of the solute radius to the pore radius is greater than 0.8. The transport of solute in the pore is dominated by diffusion, although convective transport is significant for organic nitrogen compounds. Electromigration contributes negligibly to the overall solute transport in the membrane. Urea, a small organic compound, has lower rejection than ionic compounds such as ammonium, nitrate, and nitrite, indicating the critical role of electrostatic interaction in rejection. This suggests that better treatment efficiency for organic nitrogen compounds can be obtained after ammonification of urea.

  1. Membrane rejection of nitrogen compounds

    NASA Technical Reports Server (NTRS)

    Lee, S.; Lueptow, R. M.

    2001-01-01

    Rejection characteristics of nitrogen compounds were examined for reverse osmosis, nanofiltration, and low-pressure reverse osmosis membranes. The rejection of nitrogen compounds is explained by integrating experimental results with calculations using the extended Nernst-Planck model coupled with a steric hindrance model. The molecular weight and chemical structure of nitrogen compounds appear to be less important in determining rejection than electrostatic properties. The rejection is greatest when the Donnan potential exceeds 0.05 V or when the ratio of the solute radius to the pore radius is greater than 0.8. The transport of solute in the pore is dominated by diffusion, although convective transport is significant for organic nitrogen compounds. Electromigration contributes negligibly to the overall solute transport in the membrane. Urea, a small organic compound, has lower rejection than ionic compounds such as ammonium, nitrate, and nitrite, indicating the critical role of electrostatic interaction in rejection. This suggests that better treatment efficiency for organic nitrogen compounds can be obtained after ammonification of urea.

  2. Improved clinical facility for in vivo nitrogen measurement.

    PubMed

    Krishnan, S S; McNeill, K G; Mernagh, J R; Bayley, A J; Harrison, J E

    1990-04-01

    The design and construction of a hospital clinical facility for in vivo prompt gamma neutron activation analysis for total body nitrogen (TBN) measurement is described. The use of 252Cf neutron sources gives a better signal-to-background ratio compared with 238Pu-Be sources of equal strength, thus yielding better reproducibility of measurements. By measuring the hydrogen and nitrogen signals separately using appropriate gating circuits, signal-to-background ratio is further improved. Measurements using a urea phantom (5.63 kg nitrogen as urea in 34.53 kg of water) show that 2 x 6 micrograms 252Cf sources gives a nitrogen signal-to-background ratio of 5.6 (compared with 3.4 in the case of a 2 x 10 Ci 238Pu-Be source) and a reproducibility for nitrogen signal of +/- 1.1% (CV) and for hydrogen signal (internal standard) of +/- 2.33% (CV). Approximately 30 minutes of patient's time is required for each TBN measurement with an estimated reproducibility of +/- 3.8% (CV). The radiation dose to the patient is about 0.2 mSv (effective dose equivalent; QF = 10) per 20 min measurement. A report for the clinician is produced within a few minutes after the measurement by a dedicated IBM-PC computer. The entire facility is clean, comfortable and the electronics and computer processing are simple and economical.

  3. Characteristics of Nitrogen Balances of Large-scale Stock Farms and Reduction of Environmental Nitrogen Loads

    NASA Astrophysics Data System (ADS)

    Hattori, Toshihiro; Takamatsu, Rieko

    We calculated nitrogen balances on farm gate and soil surface on large-scale stock farms and discussed methods for reducing environmental nitrogen loads. Four different types of public stock farms (organic beef, calf supply and daily cows) were surveyed in Aomori Prefecture. (1) Farm gate and soil surface nitrogen inflows were both larger than the respective outflows on all types of farms. Farm gate nitrogen balance for beef farms were worse than that for dairy farms. (2) Soil surface nitrogen outflows and soil nitrogen retention were in proportion to soil surface nitrogen inflows. (3) Reductions in soil surface nitrogen retention were influenced by soil surface nitrogen inflows. (4) In order to reduce farm gate nitrogen retention, inflows of formula feed and chemical fertilizer need to be reduced. (5) In order to reduce soil surface nitrogen retention, inflows of fertilizer need to be reduced and nitrogen balance needs to be controlled.

  4. NITROGEN OUTPUTS OF SMALL MAMMALS FROM FECAL AND URINE DEPOSITION: IMPLICATIONS FOR NITROGEN CYCLING

    EPA Science Inventory

    The contribution of small mammals in nitrogen cycling is poorly understood and could have reverberations back to the producer community by maintaining or even magnifying increased nitrogen availability. Our objective was to model nitrogen outputs (deposition of feces and urine) ...

  5. NITROGEN OUTPUTS OF SMALL MAMMALS FROM FECAL AND URINE DEPOSITION: IMPLICATIONS FOR NITROGEN CYCLING

    EPA Science Inventory

    The contribution of small mammals in nitrogen cycling is poorly understood and could have reverberations back to the producer community by maintaining or even magnifying increased nitrogen availability. Our objective was to model nitrogen outputs (deposition of feces and urine) ...

  6. Modelling the nitrogen loadings from large yellow croaker (Larimichthys crocea) cage aquaculture.

    PubMed

    Cai, Huiwen; Ross, Lindsay G; Telfer, Trevor C; Wu, Changwen; Zhu, Aiyi; Zhao, Sheng; Xu, Meiying

    2016-04-01

    Large yellow croaker (LYC) cage farming is a rapidly developing industry in the coastal areas of the East China Sea. However, little is known about the environmental nutrient loadings resulting from the current aquaculture practices for this species. In this study, a nitrogenous waste model was developed for LYC based on thermal growth and bioenergetic theories. The growth model produced a good fit with the measured data of the growth trajectory of the fish. The total, dissolved and particulate nitrogen outputs were estimated to be 133, 51 and 82 kg N tonne(-1) of fish production, respectively, with daily dissolved and particulate nitrogen outputs varying from 69 to 104 and 106 to 181 mg N fish(-1), respectively, during the 2012 operational cycle. Greater than 80 % of the nitrogen input from feed was predicted to be lost to the environment, resulting in low nitrogen retention (<20 %) in the fish tissues. Ammonia contributed the greatest proportion (>85 %) of the dissolved nitrogen generated from cage farming. This nitrogen loading assessment model is the first to address nitrogenous output from LYC farming and could be a valuable tool to examine the effects of management and feeding practices on waste from cage farming. The application of this model could help improve the scientific understanding of offshore fish farming systems. Furthermore, the model predicts that a 63 % reduction in nitrogenous waste production could be achieved by switching from the use of trash fish for feed to the use of pelleted feed.

  7. Terrestrial nitrogen cycles: Some unanswered questions

    NASA Technical Reports Server (NTRS)

    Vitousek, P.

    1984-01-01

    Nitrogen is generally considered to be the element which most often limits the growth of plants in both natural and agricultural ecosystems. It regulates plant growth because photosynthetic rates are strongly dependent on the concentration of nitrogen in leaves, and because relatively large mounts of protein are required for cell division and growth. Yet nitrogen is abundant in the biosphere - the well-mixed pool in the atmosphere is considered inexhaustible compared to biotic demand, and the amount of already fixed organic nitrogen in soils far exceeds annual plant uptake in terrestrial ecosystems. In regions where natural vegetation is not nitrogen limited, continuous cultivation induces nitrogen deficiency. Nitrogen loss from cultivated lands is more rapid than that of other elements, and nitrogen fertilization is generally required to maintain crop yield under any continuous system. The pervasiveness of nitrogen deficiency in many natural and most managed sites is discussed.

  8. Missing nitrogen fixation in the Benguela region

    NASA Astrophysics Data System (ADS)

    Wasmund, Norbert; Struck, Ulrich; Hansen, Anja; Flohr, Anita; Nausch, Günther; Grüttmüller, Annett; Voss, Maren

    2015-12-01

    Opposing opinions on the importance of nitrogen fixation in the northern Benguela upwelling region provoked us to investigate the magnitude of nitrogen fixation in front of northern Namibia and southern Angola. Measurements of nitrogen fixation rates using the 15N method at 66 stations during seven cruises from 2008 to 2014 showed that, in general, the 15N content in the biomass did not increase after tracer incubation with 15N2, indicating that no nitrogen fixation occurred. Correspondingly, the filamentous nitrogen-fixing cyanobacterium Trichodesmium was almost not present. The abundant picocyanobacteria did obviously not perform nitrogen fixation to a significant degree. The artificial improvement of conditions for nitrogen fixation in mesocosm experiments, including phosphate and iron additions and a warmer temperature, failed to induce nitrogen fixation. A plausible explanation of these findings is a lack of conditioned cells for nitrogen fixation in the Benguela region.

  9. Managing nitrogen for sustainable development.

    PubMed

    Zhang, Xin; Davidson, Eric A; Mauzerall, Denise L; Searchinger, Timothy D; Dumas, Patrice; Shen, Ye

    2015-12-03

    Improvements in nitrogen use efficiency in crop production are critical for addressing the triple challenges of food security, environmental degradation and climate change. Such improvements are conditional not only on technological innovation, but also on socio-economic factors that are at present poorly understood. Here we examine historical patterns of agricultural nitrogen-use efficiency and find a broad range of national approaches to agricultural development and related pollution. We analyse examples of nitrogen use and propose targets, by geographic region and crop type, to meet the 2050 global food demand projected by the Food and Agriculture Organization while also meeting the Sustainable Development Goals pertaining to agriculture recently adopted by the United Nations General Assembly. Furthermore, we discuss socio-economic policies and technological innovations that may help achieve them.

  10. Managing nitrogen for sustainable development

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Davidson, Eric A.; Mauzerall, Denise L.; Searchinger, Timothy D.; Dumas, Patrice; Shen, Ye

    2015-12-01

    Improvements in nitrogen use efficiency in crop production are critical for addressing the triple challenges of food security, environmental degradation and climate change. Such improvements are conditional not only on technological innovation, but also on socio-economic factors that are at present poorly understood. Here we examine historical patterns of agricultural nitrogen-use efficiency and find a broad range of national approaches to agricultural development and related pollution. We analyse examples of nitrogen use and propose targets, by geographic region and crop type, to meet the 2050 global food demand projected by the Food and Agriculture Organization while also meeting the Sustainable Development Goals pertaining to agriculture recently adopted by the United Nations General Assembly. Furthermore, we discuss socio-economic policies and technological innovations that may help achieve them.

  11. Insects as a Nitrogen Source for Plants.

    PubMed

    Behie, Scott W; Bidochka, Michael J

    2013-07-31

    Many plants have evolved adaptations in order to survive in low nitrogen environments. One of the best-known adaptations is that of plant symbiosis with nitrogen-fixing bacteria; this is the major route by which nitrogen is incorporated into plant biomass. A portion of this plant-associated nitrogen is then lost to insects through herbivory, and insects represent a nitrogen reservoir that is generally overlooked in nitrogen cycles. In this review we show three specialized plant adaptations that allow for the recovery of insect nitrogen; that is, plants gaining nitrogen from insects. First, we show specialized adaptations by carnivorous plants in low nitrogen habitats. Insect carnivorous plants such as pitcher plants and sundews (Nepenthaceae/Sarraceniaceae and Drosera respectively) are able to obtain substantial amounts of nitrogen from the insects that they capture. Secondly, numerous plants form associations with mycorrhizal fungi that can provide soluble nitrogen from the soil, some of which may be insect-derived nitrogen, obtained from decaying insects or insect frass. Finally, a specialized group of endophytic, insect-pathogenic fungi (EIPF) provide host plants with insect-derived nitrogen. These soil-inhabiting fungi form a remarkable symbiosis with certain plant species. They can infect a wide range of insect hosts and also form endophytic associations in which they transfer insect-derived nitrogen to the plant. Root colonizing fungi are found in disparate fungal phylogenetic lineages, indicating possible convergent evolutionary strategies between taxa, evolution potentially driven by access to carbon-containing root exudates.

  12. Insects as a Nitrogen Source for Plants

    PubMed Central

    Behie, Scott W.; Bidochka, Michael J.

    2013-01-01

    Many plants have evolved adaptations in order to survive in low nitrogen environments. One of the best-known adaptations is that of plant symbiosis with nitrogen-fixing bacteria; this is the major route by which nitrogen is incorporated into plant biomass. A portion of this plant-associated nitrogen is then lost to insects through herbivory, and insects represent a nitrogen reservoir that is generally overlooked in nitrogen cycles. In this review we show three specialized plant adaptations that allow for the recovery of insect nitrogen; that is, plants gaining nitrogen from insects. First, we show specialized adaptations by carnivorous plants in low nitrogen habitats. Insect carnivorous plants such as pitcher plants and sundews (Nepenthaceae/Sarraceniaceae and Drosera respectively) are able to obtain substantial amounts of nitrogen from the insects that they capture. Secondly, numerous plants form associations with mycorrhizal fungi that can provide soluble nitrogen from the soil, some of which may be insect-derived nitrogen, obtained from decaying insects or insect frass. Finally, a specialized group of endophytic, insect-pathogenic fungi (EIPF) provide host plants with insect-derived nitrogen. These soil-inhabiting fungi form a remarkable symbiosis with certain plant species. They can infect a wide range of insect hosts and also form endophytic associations in which they transfer insect-derived nitrogen to the plant. Root colonizing fungi are found in disparate fungal phylogenetic lineages, indicating possible convergent evolutionary strategies between taxa, evolution potentially driven by access to carbon-containing root exudates. PMID:26462427

  13. Nitrogen and protein components of human milk.

    PubMed

    Hambraeus, L; Lönnerdal, B; Forsum, E; Gebre-Medhin, M

    1978-09-01

    The true protein content of human milk is 0.9%, in well-nourished as well as malnourished mothers. Casein constitutes only about 20% of the protein nitrogen in human milk. The remaining 80% is derived from the whey proteins, the three dominant components being alpha-lactalbumin, lactoferrin and secretory IgA. alpha-lactalbumin is a subunit of lactose synthetase. Lactoferrin is an iron-binding glycoprotein which plays a role in the defence against gastro-intestinal infections and is probably also involved in iron transport in the gut. Secretory IgA is comparatively stable at low pH; it is resistant to proteolytic enzymes and plays an essential role in the immunological defence against gastro-intestinal infections. Lysozyme is a minor component of the whey proteins and represents an active enzyme with a bactericidal effect. The nutritional and immunological significance of the marked differences with respect to the nitrogen and protein compositions of human milk and cow's milk should not be underestimated, but need further elucidation.

  14. Bioretention Design to Improve Nitrogen Removal | Science ...

    EPA Pesticide Factsheets

    Bioretention has been shown to effectively remove a variety of stormwater stressors, including oil/grease, heavy metals, phosphorus, and ammonium. However, reported nitrate and total nitrogen removal performance is highly variable. The media typically used in bioretention installation is coarse-grained with low organic matter content, which facilitates high infiltration rates but fails to provide the anaerobic conditions and carbon availability necessary to promote nitrate removal by denitrification. EPA's research at the Urban Watershed Research Facility investigates the effects of media carbon amendments, introduced internal storage zones, plant type, and media volume on nitrogen removal. Initial bench-scale tests informed media and carbon amendment choices. A locally-available, sandy media with low organic matter content was added to eight experimental, pilot-scale rain gardens above a shallow pea gravel drainage layer. The media was separated from the pea gravel with a nonwoven geotextile. Double-shredded hardwood wood chips were chosen as a carbon amendment and added as a 20-cm layer 10 cm above the geotextile in four of the eight pilot-scale rain gardens; the other four did not receive the mulch layer. Four rain gardens were constructed with an elevated outlet pipe to create an internal storage zone; the other four drain freely. Pilot-scale rain gardens were constructed in tanks of two sizes to test the effects of media volume. After initial hydrologic

  15. Bioretention Design to Improve Nitrogen Removal | Science ...

    EPA Pesticide Factsheets

    Bioretention has been shown to effectively remove a variety of stormwater stressors, including oil/grease, heavy metals, phosphorus, and ammonium. However, reported nitrate and total nitrogen removal performance is highly variable. The media typically used in bioretention installation is coarse-grained with low organic matter content, which facilitates high infiltration rates but fails to provide the anaerobic conditions and carbon availability necessary to promote nitrate removal by denitrification. EPA's research at the Urban Watershed Research Facility investigates the effects of media carbon amendments, introduced internal storage zones, plant type, and media volume on nitrogen removal. Initial bench-scale tests informed media and carbon amendment choices. A locally-available, sandy media with low organic matter content was added to eight experimental, pilot-scale rain gardens above a shallow pea gravel drainage layer. The media was separated from the pea gravel with a nonwoven geotextile. Double-shredded hardwood wood chips were chosen as a carbon amendment and added as a 20-cm layer 10 cm above the geotextile in four of the eight pilot-scale rain gardens; the other four did not receive the mulch layer. Four rain gardens were constructed with an elevated outlet pipe to create an internal storage zone; the other four drain freely. Pilot-scale rain gardens were constructed in tanks of two sizes to test the effects of media volume. After initial hydrologic

  16. Estimating the social costs of nitrogen pollution

    NASA Astrophysics Data System (ADS)

    Gourevitch, J.; Keeler, B.; Polasky, S.

    2014-12-01

    Agricultural expansion can degrade water quality and related ecosystem services through increased export of nutrients. Such damages to water quality can negatively affect recreation, property values, and human health. While the relationship between agricultural production and nitrogen export is well-studied, the economic costs of nitrogen loss are less well understood. We present a comprehensive assessment of the full costs associated with nitrate pollution from agricultural sources in Minnesota. We found that the most significant economic costs are likely from groundwater contamination of nitrate in public and private wells. For example, we estimated that loss of grassland to corn cultivation in Minnesota between 2007 and 2012 is expected to increase the future number of domestic wells exceeding nitrate concentrations of 10 ppm by 31%. This increase in contamination is estimated to cost well owners $1.4 to 19 million (present values over a 20 year horizon) through remediation, avoidance, and replacement. Our findings demonstrate linkages between changes in land use, water quality, and human well-being.

  17. Nitrogen control of chloroplast differentiation

    SciTech Connect

    Schmidt, G.W.

    1994-11-01

    This project was directed toward understanding how the availability of nitrogen affects the accumulation of chloroplast pigments and proteins that function in energy transduction and carbon metabolism. The availability of this nutrient most pervasively limits plant growth and agricultural productivity but the molecular and physiological consequences of nitrogen-deficiency are poorly understood. The model system for our studies of nitrogen-dependent regulation of chloroplast differentiation is the unicellular green alga Chlamydomonas reinhardtii which is grown phototrophically in a continuous culture system. When 150 {mu}M nitrogen is provided at a dilution rate of 0.25 volumes of the growth medium per day, the cultures are sustained at a density of less than 10{sup 5} cells/ml and chlorophyll deficiency, the classical symptom of nitrogen-deficiency, becomes quite pronounced. We found that there is a concomitant loss of light-harvesting complexes and reduced levels of Photosystem II reaction center complexes while ATP synthetase and Photosystem I reaction centers are maintained at high levels. Moreover, reduced rates of chloroplast protein synthesis are due to differential effects on mRNA translation. In contrast, the deficiency of light-harvesting genes is due to marked reductions of the nuclear-encoded cab mRNAs. Although there is no significant reduction of the amounts of RuBPCase, we also detected substantial changes in the mRNA abundance of the alga`s two small subunit genes. All of the effects of nitrogen-limitation are readily reversible: greening of cells is completed within 24 hours after provision of 10 mM ammonium. During this time, the plastid translational constraints are disengaged and progressive changes in the abundance of nuclear transcripts occur, including a transient 30-fold elevation of {und cab} mRNAs.

  18. Membrane Separation Of Nitrogen Tetroxide

    NASA Technical Reports Server (NTRS)

    Castro, R. C.; Kaschemekat, J.; Helm, V. D.; Shrock, P. H.; Wijmans, J. G.

    1993-01-01

    Pilot plant reduces N2O4 content to one-hundredth of inlet value. Permeable-membrane process removes nitrogen tetroxide from stream of nitrogen or helium gas. Operates in conjunction with scrubbing process removing N2O4 from He or N2 after He or N2 used as gas blanket in N2O4-storage tank. First stage of separator divided into two steps for efficiency. Permeate from second step of first stage and residue from second stage returned to inlet of first stage. Each module contains spiral-wound interleaved permeable membranes and spacer sheets.

  19. The role of nitrogen uptake on the competition ability of three vineyard Saccharomyces cerevisiae strains.

    PubMed

    Vendramini, Chiara; Beltran, Gemma; Nadai, Chiara; Giacomini, Alessio; Mas, Albert; Corich, Viviana

    2017-10-03

    Three vineyard strains of Saccharomyces cerevisiae, P301.4, P304.4 and P254.12, were assayed in comparison with a commercial industrial strain, QA23. The aim was to understand if nitrogen availability could influence strain competition ability during must fermentation. Pairwise-strain fermentations and co-fermentations with the simultaneous presence of the four strains were performed in synthetic musts at two nitrogen levels: control nitrogen condition (CNC) that assured the suitable assimilable nitrogen amount required by the yeast strains to complete the fermentation and low nitrogen condition (LNC) where nitrogen is present at very low level. Results suggested a strong involvement of nitrogen availability, as the frequency in must of the vineyard strains, respect to QA23, in LNC was always higher than that found in CNC. Moreover, in CNC only strain P304.4 reached the same strain frequency as QA23. P304.4 competition ability increased during the fermentation, indicating better performance when nitrogen availability was dropping down. P301.4 was the only strain sensitive to QA23 killer toxin. In CNC, when it was co-inoculated with the industrial strain QA23, P301.4 was never detected. In LNC, P301.4 after 12h accounted for 10% of the total population. This percentage increased after 48h (20%). Single-strain fermentations were also run in both conditions and the nitrogen metabolism further analyzed. Fermentation kinetics, ammonium and amino-acid consumptions and the expression of genes under nitrogen catabolite repression evidenced that vineyard yeasts, and particularly strain P304.4, had higher nitrogen assimilation rate than the commercial control. In conclusion, the high nitrogen assimilation rate seems to be an additional strategy that allowed vineyard yeasts successful competition during the growth in grape musts. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. METHOD OF FIXING NITROGEN FOR PRODUCING OXIDES OF NITROGEN

    DOEpatents

    Harteck, P.; Dondes, S.

    1959-08-01

    A method is described for fixing nitrogen from air by compressing the air, irradiating the compressed air in a nuclear reactor, cooling to remove NO/ sub 2/, compressing the cooled gas, further cooling to remove N/sub 2/O and recirculating the cooled compressed air to the reactor.

  1. Evaluation of a spacecraft nitrogen generator

    NASA Technical Reports Server (NTRS)

    Marshall, R. D.; Lee, M. K.; Schubert, F. H.

    1978-01-01

    A research and development program was successfully completed towards the development of a method of generating nitrogen for cabin leakage makeup aboard space vehicles. The nitrogen generation concept used liquid hydrazine as the stored form of nitrogen. This reduced tankage and expendables weight associated with high pressure gaseous and cryogenic liquid nitrogen storage. The hydrazine was catalytically dissociated to yield a mixture of nitrogen and hydrogen. The latter was separated to provide the makeup nitrogen. The hydrogen will be used in the reduction of metabolic carbon dioxide.

  2. Sodium Pentazolate: a Nitrogen Rich Energetic Material

    NASA Astrophysics Data System (ADS)

    Oleynik, Ivan; Steele, Brad

    Sodium pentazolates NaN5 and Na2N5, new energetic materials, are discovered using first principles crystal structure search for the compounds of varying amounts of elemental sodium and nitrogen. The pentazole anion (N5-s)i stabilized in the condensed phase by sodium Na+ cations at pressures exceeding 20 GPa, and becomes metastable upon release of pressure, i.e. at ambient conditions. The sodium azide (NaN3) precursor for the new compounds is predicted to undergo a chemical transformation above 50 GPa into sodium pentazolates NaN5 and Na2N5. The calculated Raman spectrum of NaN5 is in agreement with the experimental Raman spectrum of a previously unidentified substance appearing upon compression and heating of NaN3 precursor, thus confirming the appearance of the new compound.

  3. Ambient Ammonium Contribution to total Nitrogen Deposition ...

    EPA Pesticide Factsheets

    There has been a wealth of evidence over the last decade illustrating the rising importance of reduced inorganic nitrogen (NHx = ammonia gas, NH3, plus particulate ammonium, p-NH4) in the overall atmospheric mass balance and deposition of nitrogen as emissions of oxidized nitrogen have decreased throughout a period of stable or increasing NH3 emissions. In addition, the fraction of ambient ammonia relative to p-NH4 generally has risen as a result of decreases in both oxides of nitrogen and sulfur emissions. EPA plans to consider ecological effects related to deposition of nitrogen, of which NHx is a contributing component, in the review of secondary National Ambient Air Quality Standards (NAAQS) for oxides of nitrogen and sulfur (NOx/SOx standard). Although these ecological effects are associated with total nitrogen deposition, it will be important to understand the emissions sources contributing to the total nitrogen deposition and to understand how much of the total nitrogen deposition is from deposition of NHx versus other nitrogen species. Because p-NH4 contributes to nitrogen deposition and can also be a significant component of particulate matter, there is a potential overlap in addressing nitrogen based deposition effects in the secondary PM and NOx/SOx NAAQS. Consequently, there is a policy interest in quantifying the contribution of p-NH4 to total nitrogen deposition. While dry deposition of p-NH4 is calculated through a variety of modeling app

  4. Sequestration of Carbon in Mycorrhizal Fungi Under Nitrogen Fertilization

    NASA Astrophysics Data System (ADS)

    Treseder, K. K.; Turner, K. M.

    2005-12-01

    Mycorrhizal fungi are root symbionts that facilitate plant uptake of soil nutrients in exchange for plant carbohydrates. They grow in almost every terrestrial ecosystem on earth, form relationships with about 80% of plant species, and receive 10 to 20% of the carbon fixed by their host plants. As such, they could potentially sequester a significant amount of carbon in ecosystems. We hypothesized that nitrogen fertilization would decrease carbon storage in mycorrhizal fungi, because plants should reduce investment of carbon in mycorrhizal fungi when nitrogen availability is high. We measured the abundance of two major groups of mycorrhizal fungi, arbuscular mycorrhizal (AM) and ectomycorrhizal (ECM) fungi, in control and nitrogen-fertilized plots within three boreal ecosystems of inland Alaska. The ecosystems represented different recovery stages following severe fire, and comprised a young site dominated by AM fungi, an old site dominated by ECM fungi, and an intermediate site co-dominated by both groups. Pools of mycorrhizal carbon included root-associated AM and ECM structures, soil-associated AM hyphae, and soil-associated glomalin. Glomalin is a glycoprotein produced only by AM fungi. It is present in the cell walls of AM hyphae, and then is deposited in the soil as the hyphae senesce. Nitrogen significantly altered total mycorrhizal carbon pools, but its effect varied by site (site * N interaction, P = 0.05). Under nitrogen fertilization, mycorrhizal carbon was reduced from 99 to 50 g C m2 in the youngest site, was increased from 124 to 203 g C m2 in the intermediate-aged site, and remained at 35 g C m2 in the oldest site. The changes in total mycorrhizal carbon stocks were driven mostly by changes in glomalin (site * N interaction, P = 0.05), and glomalin stocks were strongly correlated with AM hyphal abundance (P < 0.01). Nevertheless, it is not clear why AM hyphae responded differently to nitrogen fertilization in the different sites. Carbon stocks within

  5. Replenishment and mobilization of intracellular nitrogen pools decouples wine yeast nitrogen uptake from growth.

    PubMed

    Gutiérrez, Alicia; Sancho, Marta; Beltran, Gemma; Guillamon, José Manuel; Warringer, Jonas

    2016-04-01

    Wine yeast capacity to take up nitrogen from the environment and catabolize it to support population growth, fermentation, and aroma production is critical to wine production. Under nitrogen restriction, yeast nitrogen uptake is believed to be intimately coupled to reproduction with nitrogen catabolite repression (NCR) suggested mediating this link. We provide a time- and strain-resolved view of nitrogen uptake, population growth, and NCR activity in wine yeasts. Nitrogen uptake was found to be decoupled from growth due to early assimilated nitrogen being used to replenish intracellular nitrogen pools rather than being channeled directly into reproduction. Internally accumulated nitrogen was later mobilized to support substantial population expansion after external nitrogen was depleted. On good nitrogen sources, the decoupling between nitrogen uptake and growth correlated well with relaxation of NCR repression, raising the potential that the latter may be triggered by intracellular build-up of nitrogen. No link between NCR activity and nitrogen assimilation or growth on poor nitrogen sources was found. The decoupling between nitrogen uptake and growth and its influence on NCR activity is of relevance for both wine production and our general understanding of nitrogen use.

  6. Foliage nitrogen turnover: differences among nitrogen absorbed at different times by Quercus serrata saplings

    PubMed Central

    Ueda, Miki U.; Mizumachi, Eri; Tokuchi, Naoko

    2011-01-01

    Background and Aims Nitrogen turnover within plants has been intensively studied to better understand nitrogen use strategies. However, differences among the nitrogen absorbed at different times are not completely understood and the fate of nitrogen absorbed during winter is largely uncharacterized. In the present study, nitrogen absorbed at different times of the year (growing season, winter and previous growing season) was traced, and the within-leaf nitrogen turnover of a temperate deciduous oak Quercus serrata was investigated. Methods The contributions of nitrogen absorbed at the three different times to leaf construction, translocation during the growing season, and the leaf-level resorption efficiency during leaf senescence were compared using 15N. Key Results Winter- and previous growing season-absorbed nitrogen significantly contributed to leaf construction, although the contribution was smaller than that of growing season-absorbed nitrogen. On the other hand, the leaf-level resorption efficiency of winter- and previous growing season-absorbed nitrogen was higher than that of growing season-absorbed nitrogen, suggesting that older nitrogen is better retained in leaves than recently absorbed nitrogen. Conclusions The results demonstrate that nitrogen turnover in leaves varies with nitrogen absorption times. These findings are important for understanding plant nitrogen use strategies and nitrogen cycles in forest ecosystems. PMID:21515608

  7. PROCESS DESIGN MANUAL: NITROGEN CONTROL

    EPA Science Inventory

    This manual is an update and revision of the original 1975 edition. Given the experience of the past 18 years, the focus of this edition is directed to those biological/mechanical systems that have found widespread use for nitrification and nitrogen,removal. The primary audience ...

  8. Nitrogen Fixation: An Interdisciplinary Frontier

    ERIC Educational Resources Information Center

    Schneller, Stewart W.

    1972-01-01

    Research has progressed from three major directions--biological, chemical, and non-enzymatic. Hopefully all three will converge and will explain not only the process, but also introduce new means for modifying the molecule to meet the nutritional needs of man in areas now incapable of self support without fixed nitrogen. (DF)

  9. Artificial wetlands performance: nitrogen removal.

    PubMed

    Durán-de-Bazúa, Carmen; Guido-Zárate, Alejandro; Huanosta, Thalía; Padrón-López, Rosa Martha; Rodríguez-Monroy, Jesús

    2008-01-01

    Artificial wetlands (AW) are a promising option for wastewater treatment in small communities due to their high performance in nutrients removal and low operation and maintenance costs. Nitrogen can favour the growth of algae in water bodies causing eutrophication when present at high concentrations. Nitrogen can be removed through different mechanisms (e.g. nitrification-denitrification, adsorption and plant uptake). Environmental conditions such as temperature and relative humidity can play an important role in the performance of these systems by promoting the growth of macrophytes such as reeds and cattails (e.g. Phragmites australis, Typha latifolia respectively). In this paper, two AW systems were compared, one located in Mexico City, Mexico at an altitude higher than 2,000 m above the sea level, and the second one located in Villahermosa, Tabasco, Mexico at an a altitude near the sea level (27 m). Both systems comprised five reactors (147-L plastic boxes) filled with volcanic slag and gravel and intermittently fed with synthetic water. The removal nitrogen efficiency found for the system located in Mexico City was higher than that of the Tabasco system (90 and 80% as TKN respectively). The higher temperatures in the Tabasco system did not enhanced the nitrogen removal as expected.

  10. Adaptive Management Tools for Nitrogen: Nitrogen Index, Nitrogen Trading Tool and Nitrogen Losses Environmental Assessment Package (NLEAP-GIS)

    USDA-ARS?s Scientific Manuscript database

    Average nitrogen (N) use efficiencies are approximately fifty percent and can be even lower for shallower rooted systems grown on irrigated sandy soils. These low N use efficiencies need to be increased if reactive N losses to the environmental are to be reduced. Recently, USDA-NRCS identified Adapt...

  11. Nitrogen Fixation: An Interdisciplinary Frontier

    ERIC Educational Resources Information Center

    Schneller, Stewart W.

    1972-01-01

    Research has progressed from three major directions--biological, chemical, and non-enzymatic. Hopefully all three will converge and will explain not only the process, but also introduce new means for modifying the molecule to meet the nutritional needs of man in areas now incapable of self support without fixed nitrogen. (DF)

  12. Nitrogen deposition and terrestrial biodiversity

    Treesearch

    Christopher M. Clark; Yongfei Bai; William D. Bowman; Jane M. Cowles; Mark E. Fenn; Frank S. Gilliam; Gareth K. Phoenix; Ilyas Siddique; Carly J. Stevens; Harald U. Sverdrup; Heather L. Throop

    2013-01-01

    Nitrogen deposition, along with habitat losses and climate change, has been identified as a primary threat to biodiversity worldwide (Butchart et al., 2010; MEA, 2005; Sala et al., 2000). The source of this stressor to natural systems is generally twofold: burning of fossil fuels and the use of fertilizers in modern intensive agriculture. Each of these human...

  13. The Origin of Planetary Nitrogen

    NASA Technical Reports Server (NTRS)

    Owen, T.; Niemann, H.; Mahaffy, P.; Atreya, S.

    2006-01-01

    The nitrogen found today in planetary atmospheres appears to come from two sources: N2 and condensed, nitrogen-containing compounds. On Jupiter and thus presumably on the other giant planets, the nitrogen is present mainly as ammonia but was apparently delivered primarily in the form of N2, whereas on the inner planets and Titan, the nitrogen is present as N2 but was delivered as condensed compounds, dominated by ammonia. This analysis is consistent with abundance data from the Interstellar Medium and models for the solar nebula. For Jupiter and the inner planets, it is substantiated by measurements of N-l5/N-14 and is supported by investigations of comets and meteorites, soon to be supplemented by solar wind data from the Genesis Mission. The Cassini-Huygens Mission may be able to constrain models for Saturn s ammonia abundance that could test the proportion of N2 captured by the planet. The Titan story is less direct, depending on studies of noble gases. These studies in turn suggest an evolutionary stage of the early Earth s atmosphere that included the ammonia and methane postulated by S. L. Miller (1953) in his classical experiments on the production of biogenic compounds.

  14. PROCESS DESIGN MANUAL: NITROGEN CONTROL

    EPA Science Inventory

    This manual is an update and revision of the original 1975 edition. Given the experience of the past 18 years, the focus of this edition is directed to those biological/mechanical systems that have found widespread use for nitrification and nitrogen,removal. The primary audience ...

  15. The Joys of Liquid Nitrogen.

    ERIC Educational Resources Information Center

    Nolan, William T.; Gish, Thaddeus J.

    1996-01-01

    Presents 6 short experiments with liquid nitrogen that 12- and 13-year-old students can safely perform under close supervision. Helps the students in learning a number of basic chemical principles while spurring their curiosity and showing them how much fun chemistry can be. (JRH)

  16. Nitrogen trailer acceptance test report

    SciTech Connect

    Kostelnik, A.J.

    1996-02-12

    This Acceptance Test Report documents compliance with the requirements of specification WHC-S-0249. The equipment was tested according to WHC-SD-WM-ATP-108 Rev.0. The equipment being tested is a portable contained nitrogen supply. The test was conducted at Norco`s facility.

  17. The Origin of Planetary Nitrogen

    NASA Technical Reports Server (NTRS)

    Owen, T.; Niemann, H.; Mahaffy, P.; Atreya, S.

    2006-01-01

    The nitrogen found today in planetary atmospheres appears to come from two sources: N2 and condensed, nitrogen-containing compounds. On Jupiter and thus presumably on the other giant planets, the nitrogen is present mainly as ammonia but was apparently delivered primarily in the form of N2, whereas on the inner planets and Titan, the nitrogen is present as N2 but was delivered as condensed compounds, dominated by ammonia. This analysis is consistent with abundance data from the Interstellar Medium and models for the solar nebula. For Jupiter and the inner planets, it is substantiated by measurements of N-l5/N-14 and is supported by investigations of comets and meteorites, soon to be supplemented by solar wind data from the Genesis Mission. The Cassini-Huygens Mission may be able to constrain models for Saturn s ammonia abundance that could test the proportion of N2 captured by the planet. The Titan story is less direct, depending on studies of noble gases. These studies in turn suggest an evolutionary stage of the early Earth s atmosphere that included the ammonia and methane postulated by S. L. Miller (1953) in his classical experiments on the production of biogenic compounds.

  18. Nitrogen Availability in Proterozoic Seawater

    NASA Astrophysics Data System (ADS)

    Koehler, M.; Stüeken, E. E.; Buick, R.

    2014-12-01

    Recent bulk δ15N measurements transecting the Mesoproterozoic Belt Supergroup basin by Stüeken (2013) showed a trend of heavier δ15N values in shallow and peritidal environments to lighter δ15N values in deep water environments. This indicates a gradient in nitrogen metabolisms from quantitative nitrification, partial denitrification, and assimilation of the residual NO3- onshore (with most δ15N values greater than 2‰), to nitrogen fixation offshore (δ15N values less than 2‰). Here we present nitrogen isotope data from the roughly contemporaneous Bangemall Group in northwestern Australia and the Roper Group in northern Australia, both showing an average ~1‰ enrichment from deep to shallow facies. A maximum range from 0.9‰ (deep) to 5.8‰ (shallow) and 1.4‰ (deep) to 4.8‰ (shallow) is observed in the Bangemall and Roper Groups respectively. Viewed together with the maximum 7‰ basinal trend of the Belt Supergroup, these results suggest (a) that bioavailable nitrate limitation offshore may have been widespread in the Mesoproterozoic, and (b) that there was significant variability between basins in the degree of onshore-offshore nitrogen speciation. Prolonged nitrate limitation in offshore environments may have globally prevented the radiation of eukaryotes into deeper waters. Differences between the isotope profiles of the Belt Supergroup and the Bangemall Group may be attributed to varying degrees of restriction of each basin to the ocean.

  19. Effect of ambient temperature on losses of volatile nitrogen compounds from stored laying hen manure.

    PubMed

    Pratt, E V; Rose, S P; Keeling, A A

    2002-09-01

    Eight one tonne lots of laying hen manure were stored in individual, environmentally controlled chambers for 18-weeks at one of four constant temperatures: 12, 15, 20 and 25 degrees C. The losses of volatile nitrogen compounds, ammonia, and changes in dry matter and pH were measured during the storage period. There was a linear (P < 0.001) loss of nitrogen from the manure over the 18-week storage period. This loss represented approximately 60% of the initial nitrogen present in the manure. The rate of nitrogen loss increased non-linearly (P < 0.05) with increasing storage temperature. Poultry housing systems that provide low temperature storage of manure are recommended to reduce the volatile nitrogen losses from egg-laying enterprises.

  20. Spectroscopic determination of the phase composition and temperature of nitrogen ice on Triton

    NASA Technical Reports Server (NTRS)

    Tryka, Kimberly A.; Brown, Robert H.; Anicich, Vincent; Cruikshank, Dale P.; Owen, Tobias C.

    1993-01-01

    Laboratory spectra of the first overtone band (2.1480 microns, 4655.4 reciprocal cm) of solid nitrogen show additional structure at 2.1618 microns (4625.8 reciprocal cm) over a limited temperature range. The spectrum of Neptune's satellite Triton shows the nitrogen overtone band as well as the temperature-sensitive component. The temperature dependence of this band may be used in conjunction with ground-based observations of Triton as an independent means of determining the temperature of surface deposits of nitrogen ice. The surface temperature of Triton is found to be 38.0 +2.0 or -1.0 K, in agreement with previous temperature estimates and measurements. There is no spectral evidence for the presence of alpha-nitrogen on Triton's surface, indicating that there is less than 10 percent carbon monoxide in solid solution with the nitrogen on the surface.

  1. TiO2 doped with nitrogen: synthesis and characterization.

    PubMed

    Abazović, Nadica D; Montone, Amelia; Mirenghi, Luciana; Janković, Ivana A; Comor, Mirjana I

    2008-02-01

    In this study, nitrogen-doped titanium dioxide (TiO2) powders were synthesized in two ways: by heating of titanium hydroxide with urea and by direct hydrolysis of titanium tetraisopropoxide (TTIP) with ammonium hydroxide. The samples were characterized by structural (XRD), analytical (XPS), optical (UV/Vis absorption/reflection and Raman spectroscopy) and morphological (SEM, TEM) techniques. The characterization suggested that the doped materials have anatase crystalline form without any detectable peaks that correspond to dopants. The absorption threshold of titanium dioxide was moved in the visible range of optical spectrum from 3.2 eV to 2.20 eV. Particle sizes of synthesized powders were obtained from XRD measurements and from TEM data ranging from 6-20 nm. XPS and Raman spectroscopy were used for detection of nitrogen in doped samples.

  2. Recent studies of the ocean nitrogen cycle

    NASA Technical Reports Server (NTRS)

    Eppley, R. W.

    1984-01-01

    The nitrogen cycle in the ocean is dominated by the activities of organisms. External nitrogen inputs from land and from the atmosphere are small compared with rates of consumption and production by organisms and with rates of internal rearrangements of nitrogen pools within the ocean. The chief reservoirs of nitrogen are, in decreasing order of size: nitrogen in sediments, dissolved N2, nitrate, dissolved organic nitrogen (DON), particulate organic nitrogen (PON) (mostly organisms and their by-products). The biogenic fluxes of nitrogen were reviewed. The rate of PON decomposition in the surface layer must be comparable to the rate of ammonium consumption; and at the same time the nitrate consumption rate will be similar to the rates of: (1) sinking of PON out of the surface layer and its decompositon at depth, (2) the rate of nitrification at depth, and (3) the rate of nitrate return to the surface layer by upwelling.

  3. Nitrogen: It Always Needs a Fix

    NASA Astrophysics Data System (ADS)

    Williams, Kathryn R.

    2005-02-01

    The fixation of nitrogen was a popular topic in early issues of the Journal of Chemical Education . This column, From Past Issues, briefly summarizes articles on the nonbiological methods for nitrogen fixation.

  4. Determination of nitrogen balance in agroecosystems

    USDA-ARS?s Scientific Manuscript database

    Nitrogen balance in agroecosystems provides a quantitative framework of N inputs and outputs and retention in the soil that examine sustainability of agricultural productivity and soil and environmental quality. Nitrogen inputs include N additions from manures and fertilizers, atmospheric deposition...

  5. Nitrogen Dioxide's Impact on Indoor Air Quality

    EPA Pesticide Factsheets

    The two most prevalent oxides of nitrogen are nitrogen dioxide (NO2) and nitric oxide (NO). Both are toxic gases with NO2 being a highly reactive oxidant and corrosive. The primary sources indoors are combustion processes.

  6. Method of preparing nitrogen containing semiconductor material

    SciTech Connect

    Barber, Greg D.; Kurtz, Sarah R.

    2004-09-07

    A method of combining group III elements with group V elements that incorporates at least nitrogen from a nitrogen halide for use in semiconductors and in particular semiconductors in photovoltaic cells.

  7. Determination of nitrogen in titanium nitride

    NASA Technical Reports Server (NTRS)

    Philipp, W. H.; Tetzlaff, J. E.

    1970-01-01

    Quantitative determination of nitrogen in titanium nitride involves dissolution of TiN in 10M hydrofluoric acid containing an oxidant. Released nitrogen is determined as ammonia. Best oxidizers are ferric chloride, potassium iodate, and potassium dichromate.

  8. Nitrogen control of chloroplast differentiation

    SciTech Connect

    Schmidt, G.W.

    1992-07-01

    This project is directed toward understanding how the availability of nitrogen affects the accumulation of chloroplast pigments and proteins functioning in energy transduction and carbon metabolism. Molecular analyses performed with Chlamydomonas reinhardtii grown in a continuous culture system such that ammonium concentration is maintained at a low steady-state concentration so as to limit cell division. As compared to chloroplasts from cells of non-limiting nitrogen provisions, chloroplasts of N-limited cells are profoundly chlorophyll-deficient but still assimilate carbon for deposition of as starch and as storage lipids. Chlorophyll deficiency arises by limiting accumulation of appropriate nuclear-encoded mRNAs of and by depressed rates of translation of chloroplast mRNAs for apoproteins of reaction centers. Chloroplast translational effects can be partially ascribed to diminished rates of chlorophyll biosynthesis in N-limited cells, but pigment levels are not determinants for expression of the nuclear light-harvesting protein genes. Consequently, other signals that are responsive to nitrogen availability mediate transcriptional or post-transcriptional processes for accumulation of the mRNAs for LHC apoproteins and other mRNAs whose abundance is dependent upon high nitrogen levels. Conversely, limited nitrogen availability promotes accumulation of other proteins involved in carbon metabolism and oxidative electron transport in chloroplasts. Hence, thylakoids of N-limited cells exhibit enhanced chlororespiratory activities wherein oxygen serves as the electron acceptor in a pathway that involves plastoquinone and other electron carrier proteins that remain to be thoroughly characterized. Ongoing and future studies are also outlined.

  9. The 20-20-20 Airships NASA Centennial Challenge

    NASA Astrophysics Data System (ADS)

    Kiessling, Alina; Diaz, Ernesto; Rhodes, Jason; Ortega, Sam; Eberly, Eric

    2015-08-01

    A 2013 Keck Institute for Space Studies (KISS) study examined airships as a possible platform for Earth and space science. Airships, lighter than air, powered, maneuverable vehicles, could offer significant gains in observing time, sky and ground coverage, data downlink capability, and continuity of observations over existing suborbital options at competitive prices. The KISS study recommended three courses of action to spur the development and use of airships as a science platform. One of those recommendations was that a prize competition be developed to demonstrate a stratospheric airship. Consequently, we have been developing a NASA Centennial Challenge; (www.nasa.gov/challenges) to spur innovation in stratospheric airships as a science platform. We anticipate a multi-million dollar class prize for the first organization to fly a powered airship that remains stationary at 20km (65,000 ft) altitude for over 20 hours with a 20kg payload. The design must be scalable to longer flights with more massive payloads. A second prize tier, for a 20km flight lasting 200 hours with a 200kg payload would incentivize a further step toward a scientifically compelling and viable new platform. This technology would also have broad commercial applications including communications, asset tracking, and surveillance. Via the 20-20-20 Centennial Challenge, we are seeking to spur private industry (or non-profit institutions, including Universities) to demonstrate the capability for sustained airship flights as astronomy and Earth science platforms.

  10. Chemically Reactive Nitrogen Trace Species in the Planetary Boundary Layer

    DTIC Science & Technology

    1996-01-01

    solution, containing equal parts of urea , ammonia, and nitrate, that was broadcast across the field after planting. The final addition of fertilizer...102 kg N per hectare, was applied on May 20, 1995, also as a 30% N solution 5 of equal parts urea , ammonia, and nitrate. This final sidedressing was...Lobroue L. and Chassin P., Nitrogen compound emissions from fertilized soils in a maize field pine tree forest agrosystem in the southwest of France

  11. Soil biochemical responses to nitrogen addition in a bamboo forest.

    PubMed

    Tu, Li-hua; Chen, Gang; Peng, Yong; Hu, Hong-ling; Hu, Ting-xing; Zhang, Jian; Li, Xian-wei; Liu, Li; Tang, Yi

    2014-01-01

    Many vital ecosystem processes take place in the soils and are greatly affected by the increasing active nitrogen (N) deposition observed globally. Nitrogen deposition generally affects ecosystem processes through the changes in soil biochemical properties such as soil nutrient availability, microbial properties and enzyme activities. In order to evaluate the soil biochemical responses to elevated atmospheric N deposition in bamboo forest ecosystems, a two-year field N addition experiment in a hybrid bamboo (Bambusa pervariabilis × Dendrocalamopsis daii) plantation was conducted. Four levels of N treatment were applied: (1) control (CK, without N added), (2) low-nitrogen (LN, 50 kg N ha(-1) year(-1)), (3) medium-nitrogen (MN, 150 kg N ha(-1) year(-1)), and (4) high-nitrogen (HN, 300 kg N ha(-1) year(-1)). Results indicated that N addition significantly increased the concentrations of NH4(+), NO3(-), microbial biomass carbon, microbial biomass N, the rates of nitrification and denitrification; significantly decreased soil pH and the concentration of available phosphorus, and had no effect on the total organic carbon and total N concentration in the 0-20 cm soil depth. Nitrogen addition significantly stimulated activities of hydrolytic enzyme that acquiring N (urease) and phosphorus (acid phosphatase) and depressed the oxidative enzymes (phenol oxidase, peroxidase and catalase) activities. Results suggest that (1) this bamboo forest ecosystem is moving towards being limited by P or co-limited by P under elevated N deposition, (2) the expected progressive increases in N deposition may have a potential important effect on forest litter decomposition due to the interaction of inorganic N and oxidative enzyme activities, in such bamboo forests under high levels of ambient N deposition.

  12. Dietary protein effects on hen performance and nitrogen excretion.

    PubMed

    Latshaw, J D; Zhao, L

    2011-01-01

    Because dietary nitrogen intake affects nitrogen content in manure, diet management has been recognized as a means to reduce ammonia emissions from poultry operations. The objectives of the present research were 1) to determine the extent to which the CP content of laying diets can be reduced, based on performance criteria, and 2) to determine how ash:nitrogen ratios of manure, eggs, and hens are affected by dietary protein changes. Egg-type hens were fed equal daily amounts of essential amino acids in diets that provided 13, 15, or 17 g of protein/d. Each diet was fed to 20 hens, with 2 hens/cage. The planned digestible lysine intake was 0.71 g/hen per day. Ratios of other digestible amino acids to lysine were methionine plus cysteine, 0.83; threonine, 0.68; and isoleucine, 0.94. The experiment began when hens were 29 wk old and continued until they were 57 wk old. Egg production averaged approximately 90%, and daily protein intake caused no effects on egg production or grams of egg per hen per day. Feed intake was higher for hens fed 13 g of protein than for hens in the other 2 treatments (P < 0.01). Average feed intake for the experiment was approximately 95 g/d. Composition of the eggs was not affected by protein intake. Average values were DM, 30.5%; ash, 31.0% of DM; and nitrogen, 6.31% of DM. The average manure DM production was 25.9 g/hen per day, with an ash content of 25.5% of DM. Manure nitrogen content ranged from 3.98% of DM for hens fed 13 g of protein to 5.68% for those fed 17 g of protein (P < 0.01). A method is outlined that uses the analysis of fresh manure and manure leaving the poultry operation to estimate the loss of nitrogen as ammonia.

  13. Research on the Iron-Nitrogen System

    DTIC Science & Technology

    1949-01-01

    Micro- Kjeldahl Methods 101 XIV Results of Preliminary Nitrogenizing Experiments 104 𔃾 -vii- Table Number Pae XV Influence of Cooling Atmosphere on the...Several iso-fugacity and isothermal sections are presented. -95- Appendix I DETEBMINATION OF NITROGEN IN IRON- NITROGEN ALLOYS The micro- Kjeldahl method...scription of the apparatus and procedure and the results of s’,.me trial determinations are presented below. The micro- Kjeldahl method used for nitrogen

  14. 2005 AG20/20 Annual Review

    NASA Technical Reports Server (NTRS)

    Ross, Kenton W.; McKellip, Rodney D.

    2005-01-01

    Topics covered include: Implementation and Validation of Sensor-Based Site-Specific Crop Management; Enhanced Management of Agricultural Perennial Systems (EMAPS) Using GIS and Remote Sensing; Validation and Application of Geospatial Information for Early Identification of Stress in Wheat; Adapting and Validating Precision Technologies for Cotton Production in the Mid-Southern United States - 2004 Progress Report; Development of a System to Automatically Geo-Rectify Images; Economics of Precision Agriculture Technologies in Cotton Production-AG 2020 Prescription Farming Automation Algorithms; Field Testing a Sensor-Based Applicator for Nitrogen and Phosphorus Application; Early Detection of Citrus Diseases Using Machine Vision and DGPS; Remote Sensing of Citrus Tree Stress Levels and Factors; Spectral-based Nitrogen Sensing for Citrus; Characterization of Tree Canopies; In-field Sensing of Shallow Water Tables and Hydromorphic Soils with an Electromagnetic Induction Profiler; Maintaining the Competitiveness of Tree Fruit Production Through Precision Agriculture; Modeling and Visualizing Terrain and Remote Sensing Data for Research and Education in Precision Agriculture; Thematic Soil Mapping and Crop-Based Strategies for Site-Specific Management; and Crop-Based Strategies for Site-Specific Management.

  15. 2005 AG20/20 Annual Review

    NASA Technical Reports Server (NTRS)

    Ross, Kenton W.; McKellip, Rodney D.

    2005-01-01

    Topics covered include: Implementation and Validation of Sensor-Based Site-Specific Crop Management; Enhanced Management of Agricultural Perennial Systems (EMAPS) Using GIS and Remote Sensing; Validation and Application of Geospatial Information for Early Identification of Stress in Wheat; Adapting and Validating Precision Technologies for Cotton Production in the Mid-Southern United States - 2004 Progress Report; Development of a System to Automatically Geo-Rectify Images; Economics of Precision Agriculture Technologies in Cotton Production-AG 2020 Prescription Farming Automation Algorithms; Field Testing a Sensor-Based Applicator for Nitrogen and Phosphorus Application; Early Detection of Citrus Diseases Using Machine Vision and DGPS; Remote Sensing of Citrus Tree Stress Levels and Factors; Spectral-based Nitrogen Sensing for Citrus; Characterization of Tree Canopies; In-field Sensing of Shallow Water Tables and Hydromorphic Soils with an Electromagnetic Induction Profiler; Maintaining the Competitiveness of Tree Fruit Production Through Precision Agriculture; Modeling and Visualizing Terrain and Remote Sensing Data for Research and Education in Precision Agriculture; Thematic Soil Mapping and Crop-Based Strategies for Site-Specific Management; and Crop-Based Strategies for Site-Specific Management.

  16. Compost and manure effects on sugarbeet nitrogen uptake, nitrogen recovery, and nitrogen use efficiency

    USDA-ARS?s Scientific Manuscript database

    To maximize recoverable sucrose from sugarbeet (Beta vulgaris L.), producers must effectively manage added nitrogen (N), whether it be from urea or organic sources such as manure or composted manure. Our multi-site study’s objective was to determine the effects of a one-time application of stockpil...

  17. 21 CFR 184.1540 - Nitrogen.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Nitrogen. 184.1540 Section 184.1540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) DIRECT FOOD....1540 Nitrogen. (a) Nitrogen (empirical formula N2, CAS Reg. No. 7727-37-9) is a colorless, odorless...

  18. 46 CFR 154.1755 - Nitrogen.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Nitrogen. 154.1755 Section 154.1755 Shipping COAST GUARD... Nitrogen. Except for deck tanks and their piping systems, cargo containment systems and piping systems carrying nitrogen must be specially approved by the Commandant (CG-OES). ...

  19. 21 CFR 582.1540 - Nitrogen.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Nitrogen. 582.1540 Section 582.1540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Nitrogen. (a) Product. Nitrogen. (b) Conditions of use. This substance is generally recognized as safe when...

  20. 46 CFR 154.1755 - Nitrogen.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Nitrogen. 154.1755 Section 154.1755 Shipping COAST GUARD... Nitrogen. Except for deck tanks and their piping systems, cargo containment systems and piping systems carrying nitrogen must be specially approved by the Commandant (CG-522). ...

  1. 46 CFR 154.1755 - Nitrogen.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Nitrogen. 154.1755 Section 154.1755 Shipping COAST GUARD... Nitrogen. Except for deck tanks and their piping systems, cargo containment systems and piping systems carrying nitrogen must be specially approved by the Commandant (CG-522). ...

  2. 21 CFR 184.1540 - Nitrogen.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Nitrogen. 184.1540 Section 184.1540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1540 Nitrogen. (a) Nitrogen (empirical formula N2, CAS Reg. No. 7727-37-9...

  3. 21 CFR 184.1540 - Nitrogen.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Nitrogen. 184.1540 Section 184.1540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1540 Nitrogen. (a) Nitrogen (empirical formula N2, CAS Reg. No. 7727-37-9...

  4. 21 CFR 582.1540 - Nitrogen.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Nitrogen. 582.1540 Section 582.1540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Nitrogen. (a) Product. Nitrogen. (b) Conditions of use. This substance is generally recognized as safe when...

  5. 46 CFR 154.1755 - Nitrogen.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Nitrogen. 154.1755 Section 154.1755 Shipping COAST GUARD... Nitrogen. Except for deck tanks and their piping systems, cargo containment systems and piping systems carrying nitrogen must be specially approved by the Commandant (CG-OES). ...

  6. 21 CFR 582.1540 - Nitrogen.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Nitrogen. 582.1540 Section 582.1540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Nitrogen. (a) Product. Nitrogen. (b) Conditions of use. This substance is generally recognized as safe when...

  7. 21 CFR 184.1540 - Nitrogen.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Nitrogen. 184.1540 Section 184.1540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1540 Nitrogen. (a) Nitrogen (empirical formula N2, CAS Reg. No. 7727-37-9...

  8. 21 CFR 184.1540 - Nitrogen.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Nitrogen. 184.1540 Section 184.1540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Substances Affirmed as GRAS § 184.1540 Nitrogen. (a) Nitrogen (empirical formula N2, CAS Reg. No. 7727-37-9...

  9. 21 CFR 582.1540 - Nitrogen.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Nitrogen. 582.1540 Section 582.1540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Nitrogen. (a) Product. Nitrogen. (b) Conditions of use. This substance is generally recognized as safe when...

  10. 21 CFR 582.1540 - Nitrogen.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Nitrogen. 582.1540 Section 582.1540 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS... Nitrogen. (a) Product. Nitrogen. (b) Conditions of use. This substance is generally recognized as safe when...

  11. 46 CFR 154.1755 - Nitrogen.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Nitrogen. 154.1755 Section 154.1755 Shipping COAST GUARD... Nitrogen. Except for deck tanks and their piping systems, cargo containment systems and piping systems carrying nitrogen must be specially approved by the Commandant (CG-OES). ...

  12. Biochemical Approaches to Improved Nitrogen Fixation

    USDA-ARS?s Scientific Manuscript database

    Improving symbiotic nitrogen fixation by legumes has emerged again as an important topic on the world scene due to the energy crisis and lack of access to nitrogen fertilizer in developing countries. We have taken a biochemical genomics approach to improving symbiotic nitrogen fixation in legumes. L...

  13. The anaerobic potentially mineralizable nitrogen test as a tool for nitrogen management in the Midwest

    USDA-ARS?s Scientific Manuscript database

    The anaerobic potentially mineralizable nitrogen (PMNan) test is a tool that can improve estimations of mineralizable nitrogen (N) and enhance nitrogen use efficiency. This tool may also help improve predictions of N uptake, grain yield, and the economic optimum nitrogen rate (EONR) of corn (Zea ma...

  14. Climate change, agricultural adaptation and mitigation, and using the nitrogen index to increase nitrogen use efficiency

    USDA-ARS?s Scientific Manuscript database

    Nitrogen is needed to maximize productivity of agricultural systems in Mexico. However, when these systems receive more nitrogen than necessary, losses of nitrogen to the environment can occur and negatively impact water bodies. Additionally, it has been reported across the literature that nitrogen ...

  15. Can the anaerobic potentially mineralizable nitrogen test improve predictions of fertilizer nitrogen rates in the Cornbelt?

    USDA-ARS?s Scientific Manuscript database

    Correctly estimating the amount of mineralizable nitrogen (N) can enhance nitrogen use efficiency. The anaerobic potentially mineralizable nitrogen (PMNAn) test is a tool that may help improve predictions of N uptake, grain yield, and the economical optimum nitrogen rate (EONR) of corn (Zea mays L...

  16. Modeling nitrogen fluxes in Germany - where does the nitrogen go?

    NASA Astrophysics Data System (ADS)

    Klement, Laura; Bach, Martin; Breuer, Lutz

    2016-04-01

    According to the latest inventory of the EU Water Framework Directive, 26.3% of German groundwater bodies are in a poor chemical state regarding nitrate. Additionally, the EU initiated infringement proceedings against Germany for not meeting the quality standards of the EU Nitrate Directive. Agriculture has been determined as the main source of nitrate pollution due to over-fertilization and regionally high density of livestock farming. The nitrogen balance surplus is commonly used as an indicator characterizing the potential of nitrate leaching into groundwater bodies and thus also serves as a foundation to introduce legislative restrictions or to monitor the success of mitigation measures. Currently, there is an ongoing discussion which measures are suitable for reducing the risk of nitrate leaching and also to what extent. However, there is still uncertainty about just how much the nitrogen surplus has to be reduced to meet the groundwater quality standards nationwide. Therefore, the aims of our study were firstly to determine the level of the nitrogen surplus that would be acceptable at the utmost and secondly whether the currently discussed target value of 30 kg N per hectare agricultural land for the soil surface nitrogen balance would be sufficient. The models MONERIS (Modeling Nutrient Emissions in River System) and MoRE (Modelling of Regionalized Emissions), the latter based on the first, are commonly used for estimating nitrogen loads into the river system in Germany at the mesoscale, as well as the effect of mitigation measures in the context of the EU directive 2008/105/EC (Environmental quality standards applicable to surface water). We used MoRE to calculate nitrate concentration for 2759 analytical units in Germany. Main factors are the surplus of the soil surface nitrogen balance, the percolation rate and an exponent representing the denitrification in the vadose zone. The modeled groundwater nitrate concentrations did not correspond to the regional

  17. Total body nitrogen in health and disease: effects of age, weight, height, and sex

    SciTech Connect

    Ellis, K.J.; Yasumura, S.; Vartsky, D.; Vaswani, A.N.; Cohn, S.H.

    1982-06-01

    Total body levels of nitrogen were measured by prompt-gamma neutron activation analysis in 136 healthy adults in the general population (age 20 to 80 years), in 55 cancer patients, and in 20 obese subjects. In order to evaluate the TBN values for the patients, it was necessary to normalize the data for possible differences due to body habitus. This normalization was defined as the ratio of the measured nitrogen level to a predicted nitrogen level derived from the normal population. The parameters of sex, age, height, weight, and fat were used to calculate expected normal values of nitrogen. For the cancer patients, an average TBN deficit of less than 10% was observed. Individual patients, however, showed deviations from the TBN/sub p/ value as large as 28%. For obese patients, the TBN values were normal to slightly high. When adjusted for body size, the deficit of TBN in the cancer patients was approximately half that observd for TBK.

  18. Evaluation of radiative transfer models for estimation of foliar nitrogen content at leaf and canopy level

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Skidmore, A. K.; Wang, T.; Darvishzadeh, R.; Hearne, J.

    2016-12-01

    Foliar nitrogen is often a limiting factor for plant growth, and is a primary regulator of physiological processes such as photosynthesis, leaf respiration, and transpiration. Foliar nitrogen has been recently proposed as one of the key ecosystem biodiversity variables. Estimation of foliar nitrogen using hyperspectral data will further improve our understanding of the photosynthetic process and net primary productivity and will be beneficial to the assessment of biodiversity, ecosystem services and carbon sequestration. Empirical approaches have dominated the retrieval of nitrogen using hyperspectral data; physically based approaches using radiative transfer models remain elusive. This study aimed to evaluate radiative transfer models for estimating foliar nitrogen at the leaf and canopy level. A leaf-level optical properties model PROSPECT-5 was first recalibrated, and then linked with a canopy reflectance model for canopy level analysis. Our results confirmed the feasibility of retrieving foliar nitrogen from fresh leaf spectra by inversion of the recalibrated PROSPECT-5. Moderate accuracies were obtained for the previously published LOPEX agricultural data set (R2 = 0.47, NRMSE = 0.17) and a Bavarian forest data set (R2 = 0.49, NRMSE = 0.20). At the canopy level, foliar nitrogen content was estimated with a lower accuracy (R2 = 0.38, NRMSE = 0.20) when using canopy spectra extracted from airborne hyperspectral imagery.

  19. Supramolecular architecture of photosynthetic membrane in red algae in response to nitrogen starvation.

    PubMed

    Zhao, Long-Sheng; Su, Hai-Nan; Li, Kang; Xie, Bin-Bin; Liu, Lu-Ning; Zhang, Xi-Ying; Chen, Xiu-Lan; Huang, Feng; Zhou, Bai-Cheng; Zhang, Yu-Zhong

    2016-11-01

    The availability of nitrogen is one of the most important determinants that can limit the growth of photosynthetic organisms including plants and algae; however, direct observations on the supramolecular architecture of photosynthetic membranes in response to nitrogen stress are still lacking. Red algae are an important evolutionary group of algae which contain phycobilisomes (PBSs) on their thylakoid membranes, as do cyanobacteria. PBSs function not only as light-harvesting antennae but also as nitrogen storage. In this report, alterations of the supramolecular architecture of thylakoid membranes from red alga Porphyridium cruentum during nitrogen starvation were characterized. The morphology of the intact thylakoid membrane was observed to be round vesicles. Thylakoid membranes were reduced in content and PBSs were degraded during nitrogen starvation. The size and density of PBSs were both found to be reduced. PBS size decreased by less than one-half after 20days of nitrogen starvation, but their hemispherical morphology was retained. The density of PBSs on thylakoid membranes was more seriously affected as time proceeded. Upon re-addition of nitrogen led to increasing of PBSs on thylakoid membranes. This work reports the first direct observation on alterations in the supramolecular architecture of thylakoid membranes from a photosynthetic organism in response to nitrogen stress. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. [Proteomics of rice leaf and grain at late growth stage under different nitrogen fertilization levels].

    PubMed

    Ning, Shu-ju; Zhao, Min; Xiang, Xiao-liang; Wei, Dao-zhi

    2010-10-01

    Taking super-rice Liangyoupeijiu as test material, and by the method of two-dimensional gel electrophoresis (2-DE), this paper studied the changes in the leaf and grain proteomics of the variety at its late growth stage under different levels of nitrogen fertilization (1/2 times of normal nitrogen level, 20 mg x L(-1); normal nitrogen level, 40 mg x L(-1); 2 times of normal nitrogen level, 80 mg x L(-1)), with the biological functions of 16 leaf proteins, 9 inferior grain proteins, and 4 superior grain proteins identified and analyzed. Nitrogen fertilization could affect and regulate the plant photosynthesis via affecting the activation of photosynthesis-related enzymes and of CO2, the light system unit, and the constitution of electron transfer chain at the late growth stage of the variety. It could also promote the expression of the enzymes related to the energy synthesis and growth in inferior grains. High nitrogen fertilization level was not beneficial to the synthesis of starch in superior grain, but sufficient nitrogen supply was still important for the substance accumulation and metabolism. Therefore, rational nitrogen fertilization could increase the photosynthesis rate of flag leaves, enhance the source function, delay the functional early ageing, and promote the grain-filling at late growth stage.

  1. The appearance of nitrate reductase activity in nitrogen-starved cells of Ankistrodesmus braunii.

    PubMed

    Syrett, P J; Hipkin, C R

    1973-03-01

    Nitrate reductase activity was detectable in ammonium-grown cells of Ankistrodesmus braunii after 50 minutes of nitrogen starvation. The rate of formation of nitrate reductase was stimulated by addition of nitrate and inhibited completely by cycloheximide (20 μg/ml). Nitrogen-starved cells assimilated added nitrate or nitrite rapidly and no nitrite or nitrate was detectable in either cells or culture medium from cultures subjected to nitrogen starvation. It is concluded that nitrate is not obligatory for the formation of nitrate reductase.

  2. Humus and nitrogen in soddy-podzolic soils of different agricultural lands in Perm region

    NASA Astrophysics Data System (ADS)

    Zav'yalova, N. E.

    2016-11-01

    Heavy loamy soddy-podzolic soils (Eutric Albic Retisols (Abruptic, Loamic, Cutanic)) under a mixed forest, a grass-herb meadow, a perennial legume crop (fodder galega, Galéga orientalis), and an eightcourse crop rotation (treatment without fertilization) have been characterized by the main fertility parameters. Differences have been revealed in the contents of humus and essential nutrients in the 0- to 20- and 20- to 40-cm layers of soils of the studied agricultural lands. The medium acid reaction and the high content of ash elements and nitrogen in stubble-root residues of legume grasses favor the accumulation of humic acids in the humus of soil under fodder galega; the CHA/CFA ratio is 0.95 in the 0- to 20-cm layer and 0.81 in the 20- to 40-cm layer (under forest, 0.61 and 0.41, respectively). The nitrogen pool in the upper horizon of the studied soddy-podzolic soil includes 61-76% nonhydrolyzable nitrogen and 17-25% difficultly hydrolyzable nitrogen. The content of easily hydrolyzable nitrogen varies depending on the type of agricultural land from 6% in the soil under mixed forest to 10% under crop rotation; the content of mineral nitrogen varies from 0.9 to 1.9%, respectively. The long-term use of plowland in crop rotation and the cultivation of perennial legume crop have increased the content of hydrolyzable nitrogen forms but have not changed the proportions of nitrogen fractions characteristic of this soil type.

  3. 28 CFR 20.20 - Applicability.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL JUSTICE INFORMATION SYSTEMS State and Local Criminal History Record Information Systems § 20.20 Applicability. (a) The regulations in this subpart apply to all... information processed by manual or automated operations where such collection, storage, or dissemination...

  4. 28 CFR 20.20 - Applicability.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL JUSTICE INFORMATION SYSTEMS State and Local Criminal History Record Information Systems § 20.20 Applicability. (a) The regulations in this subpart apply to all... information processed by manual or automated operations where such collection, storage, or dissemination...

  5. 28 CFR 20.20 - Applicability.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL JUSTICE INFORMATION SYSTEMS State and Local Criminal History Record Information Systems § 20.20 Applicability. (a) The regulations in this subpart apply to all... information processed by manual or automated operations where such collection, storage, or dissemination...

  6. 28 CFR 20.20 - Applicability.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL JUSTICE INFORMATION SYSTEMS State and Local Criminal History Record Information Systems § 20.20 Applicability. (a) The regulations in this subpart apply to all... information processed by manual or automated operations where such collection, storage, or dissemination...

  7. 28 CFR 20.20 - Applicability.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Judicial Administration DEPARTMENT OF JUSTICE CRIMINAL JUSTICE INFORMATION SYSTEMS State and Local Criminal History Record Information Systems § 20.20 Applicability. (a) The regulations in this subpart apply to all... information processed by manual or automated operations where such collection, storage, or dissemination...

  8. The effect of atmospheric nitrogen deposition on marine nitrogen cycling throughout the global ocean

    NASA Astrophysics Data System (ADS)

    Somes, Christopher; Oschlies, Andreas

    2014-05-01

    The rapidly increasing rate of anthropogenic nitrogen deposition has the potential to perturb marine ecosystems and biogeochemical cycles because nitrogen is one of the major limiting nutrients in the ocean. We use an Earth System Climate Model that includes ocean biogeochemistry to assess the impact of atmospheric nitrogen deposition. Experiments are conducted where we artificially add nitrogen to nearly all locations individually throughout the global surface ocean using a nitrogen deposition rate of 700 mg N m-2 yr-1, which is consistent with modern estimates near industrial areas. We identify oceanic "biomes" that respond differently to atmospheric nitrogen deposition. (1) When nitrogen is deposited near oxygen minimum zones where water column denitrification occurs, locally increased primary production stimulates additional denitrification. Since water column denitrification removes 7 mol N for every mol N of newly formed organic matter respired, the global oceanic nitrogen inventory declines in response to nitrogen deposition in these areas. This slow, but steady decline persists for at least 1,000 years. (2) When nitrogen is deposited above shallow continental shelves where benthic denitrification occurs, our benthic denitrification model predicts an increase that is nearly equal to the nitrogen deposited and thus no net change in the global nitrogen inventory. (3) When nitrogen is deposited into the high latitude open ocean far removed from nitrogen fixation and denitrification, all of this deposited nitrogen initially accumulates in the ocean. This nitrogen eventually circulates into the tropical oxygen minimum zones where it fuels additional primary production and denitrification, which removes nitrogen at a rate equal to the deposition after 1,000 years and leads to a stable, but increased nitrogen inventory in our model. (4) When nitrogen is deposited into the open ocean where nitrogen fixation occurs, nitrogen fixation decreases due to less nitrogen

  9. Enzymology and ecology of the nitrogen cycle.

    PubMed

    Martínez-Espinosa, Rosa María; Cole, Jeffrey A; Richardson, David J; Watmough, Nicholas J

    2011-01-01

    The nitrogen cycle describes the processes through which nitrogen is converted between its various chemical forms. These transformations involve both biological and abiotic redox processes. The principal processes involved in the nitrogen cycle are nitrogen fixation, nitrification, nitrate assimilation, respiratory reduction of nitrate to ammonia, anaerobic ammonia oxidation (anammox) and denitrification. All of these are carried out by micro-organisms, including bacteria, archaea and some specialized fungi. In the present article, we provide a brief introduction to both the biochemical and ecological aspects of these processes and consider how human activity over the last 100 years has changed the historic balance of the global nitrogen cycle.

  10. Nucleobases in Space: Laboratory Studies of Polycyclic Aromatic Nitrogen Heterocycles

    NASA Technical Reports Server (NTRS)

    Elsila, Jamie; Mattioda, Andy; Bernstein, Max; Sandford, Scott; Hudgins, Doug

    2005-01-01

    Polycyclic Aromatic Nitrogen Heterocycles (PANHs) are heterocyclic aromatics Le., PAHs with carbon atoms replaced by a nitrogen atom. These molecules have been detected in meteorite extracts, and in general these nitrogen heterocycles are of astrobiological interest since this class of molecules include nucleobases, basic components of our nucleic acids. These compounds are predicted to be present in the interstellar medium and in Titan tholin, but have received relatively little attention. We will present spectra and reactions of PANHs, frozen in solid H2O at 12 K, conditions germane to astronomical observations. In contrast to simple PAHs, that do not interact strongly with solid H2O, the nitrogen atoms in PANHs are potentially capable of hydrogen bonding with H20 changing their spectra, complicating their remote detection on the surfaces of icy bodies. Moreover, we have studied the photo-chemistry of these interesting compounds under astrophysical conditions and will use our lab studies to assess a potential interstellar heritage of these compounds in carbonaceous chondrites.

  11. thermodynamics of nitrogen in BaO-TiOx melts

    NASA Astrophysics Data System (ADS)

    Tomioka, Katsutomo; Suito, Hideaki

    1993-02-01

    Using a gas-slag-metal equilibration technique, nitrogen contents in BaO-TiO^ slags and nitrogen and titanium contents in liquid Cu were measured at 1823, 1873, and 1923 K under controlled partial pressures of oxygen (@#@ PO 2 = 10-11.5 ≈ 10-13.7 atm) and nitrogen (@#@ PN 2 = 0.9 atm). The nitride capacity, C(N) [=(mass pct N) · PO2/3/4, (mass pct Ti3+)/(mass pct Ti4+) ratio, and solubility of TiN in BaO-TiO2-TiO1.5 slags were obtained as a function of slag com-position (@#@ XBaO = 0.20 = 0.43) and temperature. Activity coefficients of TiN were estimated, using the values for activity coefficients of Ti in liquid Cu which were calculated from the results of a TiN saturation experiment. Free energy of dissolution of nitrogen into liquid Cu was derived as °GGN o = 32,400 + 46.17 ± 1400 (J/g · atom).

  12. Nucleobases in Space: Laboratory Studies of Polycyclic Aromatic Nitrogen Heterocycles

    NASA Technical Reports Server (NTRS)

    Elsila, Jamie; Mattioda, Andy; Bernstein, Max; Sandford, Scott; Hudgins, Doug

    2005-01-01

    Polycyclic Aromatic Nitrogen Heterocycles (PANHs) are heterocyclic aromatics Le., PAHs with carbon atoms replaced by a nitrogen atom. These molecules have been detected in meteorite extracts, and in general these nitrogen heterocycles are of astrobiological interest since this class of molecules include nucleobases, basic components of our nucleic acids. These compounds are predicted to be present in the interstellar medium and in Titan tholin, but have received relatively little attention. We will present spectra and reactions of PANHs, frozen in solid H2O at 12 K, conditions germane to astronomical observations. In contrast to simple PAHs, that do not interact strongly with solid H2O, the nitrogen atoms in PANHs are potentially capable of hydrogen bonding with H20 changing their spectra, complicating their remote detection on the surfaces of icy bodies. Moreover, we have studied the photo-chemistry of these interesting compounds under astrophysical conditions and will use our lab studies to assess a potential interstellar heritage of these compounds in carbonaceous chondrites.

  13. Imaging carbon and nitrogen concentrations for narcotics and explosives screening

    SciTech Connect

    Trower, W.P.

    1993-12-31

    The author describes a nuclear technique for imaging carbon and nitrogen concentrations with surface densities characteristics of bulk narcotics and concealed explosives, the Carbon and the Nitrogen Camera. The physics is rooted in the tightly bound carbon-12 nucleus to which its neighboring isobars, nitrogen-12 and boron-12, decay rapidly (11 and 20 ms), mostly to its ground state, by emitting energetic beta particles (E{sub {beta}}{sup max} {approximately} 13 and 17 MeV) all of which produce bremsstrahlung and some yield annihilate radiation. The signal, photons detected in the multiscalar mode, results from the reactions {sup 13}C({gamma},p){sup 12}{Beta} for the bulk narcotics application and {sup 14}N({gamma},2n){sup 12}N and 14N({gamma},2p){sup 12}{Beta} for explosives detection and are initiated by a stepped pulsed electron beam with energy of {approximately} 30 and {approximately} 50 MeV, respectively. Images of 180 {approximately} 5 cm{sup 2} pixels taken in {approximately} 7 seconds will be presented of the carbon in a kilo of cocaine and the nitrogen in 125 grams of SEMTEX.

  14. Ecology of the nitrogen cycle

    SciTech Connect

    Sprent, J.J.

    1987-01-01

    This book consists of two parts, approximately equal in size. The first part covers the general features of the nitrogen cycle, while the second part consists of case histories from particular environments. These include arid and semi-arid areas, tundras, peat soils, lakes, marshes, and such saline systems as salt marshes, coral reefs, intertidal zones, and the open sea. The last chapter discusses the human impact on the cycle through agriculture, forestry, and acidification.

  15. Nitrogen in Ancient Mud: A Biosignature?

    PubMed

    Stüeken, Eva E

    2016-09-01

    Nitrogen is an essential nutrient for all life on Earth and possibly elsewhere. Burial of nitrogen bound to organic matter constitutes the major flux of nitrogen into sediments today, which has led to the inference that nitrogen enrichments in sedimentary rocks may be a biosignature. However, abiotic processes such as lightning or volcanism can fix atmospheric N2 and contribute to sedimentary nitrogen burial in the absence of life. It is therefore uncertain whether observed nitrogen enrichments of up to 430 ppm in Paleoarchean metasedimentary biotite grains are indeed biogenic. This study seeks to address that problem with a numerical model. The NH4(+) concentration of an abiotic ocean is modeled as a function of source fluxes, pH-dependent NH3 volatilization, and equilibrated adsorption of NH4(+) onto clay particles. The results suggest that the observed nitrogen concentrations in Paleoarchean biotite can only be reconciled with purely abiotic processes if the ocean was more acidic (pH <6) and/or if the source fluxes from lightning and volcanism were at least an order of magnitude higher (≥10(12) mol/yr) than previously thought. The bulk of the nitrogen is thus most likely of biological origin. While this does not necessitate a particular metabolism such as biological N2 fixation, the data provide evidence of nitrogen utilization back to 3.8 Gyr. Nitrogen abundances could thus provide useful information in extraterrestrial missions. Early Earth-Biosignatures-Nitrogen fixation. Astrobiology 16, 730-735.

  16. Newly Recognized Vital Nitrogen Cycle

    PubMed Central

    Johnston, Harold

    1972-01-01

    Soil and sea bacteria produce a small amount of nitrous oxide (N2O); a small part of this N2O is photochemically converted to nitric oxide (NO) in the stratosphere. This process has recently been shown to be the principal source of the active oxides of nitrogen (NO and NO2) in the stratosphere. The active oxides of nitrogen catalytically destroy ozone, and NO and NO2 appear to be a principal factor in the natural ozone balance. Stratospheric ozone is the only effective shield for the surface of the Earth against the harsh ultraviolet radiation between 300 and 250 nm. Thus, soil bacteria indirectly control the intensity of ultraviolet radiation reaching the Earth's surface. This subcycle of the major nitrogen cycle involves a relatively small amount of nitric oxide, estimated to be between 0.26 and 1.2 × 109 kg of NO per year on a worldwide basis. A recent estimate of the future nitric oxide emission in the stratosphere by the Concord supersonic transport is 0.37 × 109 kg/year on a world-wide basis, which is similar to the amount estimated from the natural source. PMID:4506756

  17. Liquid nitrogen energy storage unit

    NASA Astrophysics Data System (ADS)

    Afonso, J.; Catarino, I.; Patrício, R.; Rocaboy, A.; Linder, M.; Bonfait, G.

    2011-11-01

    An energy storage unit is a device able to store thermal energy with a limited temperature drift. After precooling such unit with a cryocooler it can be used as a temporary cold source if the cryocooler is stopped or as a thermal buffer to attenuate temperature fluctuations due to heat bursts. In this article, after a brief study of the possible solutions for such devices, we show that a low temperature cell filled with liquid nitrogen and coupled to a room temperature expansion volume offers the most compact and light solution in the temperature range 60-80 K. For instance, a low temperature cell as small as 23 cm 3 allows the storage of 3.7 kJ between 76 K and 81 K. Experimental results were obtained varying the expansion volume size, the filling pressure and the temperature range. These results agree with our simple model based on thermodynamical properties of nitrogen. A cell filled with porous material was tested to confine the liquid in the cell independently of the gravity. This material enhances the thermal exchange for high liquid filling ratio whereas below ≈16% a solution must be found to improve the heat exchange coefficient between the fluid and the cell walls. Our calculations are extended to the 80-120 K temperature range for nitrogen and argon in order to clarify the various parameters to take into account for an energy storage unit dimensioning.

  18. Pelagic nitrogen cycle in an Arctic lake

    SciTech Connect

    Whalen, S.C.

    1986-01-01

    A mass balance for nitrogen was developed for the water column of Toolik Lake and the isotope tracers /sup 15/N and /sup 14/C were used to examine the phytoplankton ecology with respect to dissolved inorganic nitrogen (ammonium and nitrate). The nutrient budget showed an oligotrophic ecosystem with important flux terms few and small in magnitude. Nitrogen input was primarily from inflowing rivers and was dominated by the dissolved organic fraction. Ammonium release from sediment provided the only other major source of nitrogen to the lake water. Toolik acted as a nitrogen sink, trapping 18% of the annual input. Retention was almost exclusively (98%) as dissolved organic nitrogen. Tracer experiments suggested chronic nitrogen deficiency in the phytoplankton, but indigenous populations were well-adapted for utilizing characteristically low levels of nutrient.

  19. Nitrogen as a friendly addition to steel

    SciTech Connect

    Rawers, J.C.

    2006-01-01

    Interstitial alloying with nitrogen or carbon is a common means of enhancing properties of iron-based alloys. Interstitial nitrogen addition to fcc-phase Fe-Cr-Mn/Ni alloys results in improved mechanical properties, whereas addition of carbon can result in the formation of unwanted carbides. Carbon addition to low alloy, bcc-phase iron alloys significantly improves strength through the formation of carbides, whereas addition of nitrogen in bcc-phase iron alloys can result in porous casting and reduced mechanical properties. This study will show that alloying iron-based alloys with both nitrogen and carbon can produce positive results. Nitrogen addition to Fe-C and Fe-Cr-C alloys, and both nitrogen and nitrogen-carbon additions to Fe-Cr-Mn/Ni alloys altered the microstructure, improved mechanical properties, increased hardness, and reduced wear by stabilizing the fcc-phase and altering (possibly eliminating) precipitate formation.

  20. Nitrogen loss in chicken litter compost as affected by carbon to nitrogen ratio and turning frequency.

    PubMed

    Ogunwande, G A; Osunade, J A; Adekalu, K O; Ogunjimi, L A O

    2008-11-01

    The study was undertaken to investigate the effects of carbon to nitrogen (C:N) ratio and turning frequency (TF) on the loss of total nitrogen (TN) during composting of chicken litter (a mixture of chicken manure, waste feed, feathers and sawdust) with a view to producing good quality compost. Carbon to nitrogen ratios of 20:1, 25:1 and 30:1 and TF of 2, 4 and 6 days were experimented. The initial physico-chemical properties of the litter were determined. During the composting process, moisture level in the piles was periodically replenished to 55% and the temperature, pH and TN of the chicken litter were periodically monitored. Also, the dry matter (DM), total carbon (TC), total phosphorus (P) and total potassium (K) were examined at the end of composting. The results showed that both C:N ratio and TF had significant (p < or = 0.05) effect on pile temperature, pH changes, TN, TC, P and K losses while DM was only affected (p < or = 0.05) by C:N ratio. All treatments reached maturation at about 87 days as indicated by the decline of pile temperatures to near ambient temperature. Losses of TN, which were largely attributed to volatilization of ammonia (NH3), were highest within the first 28 days when the pile temperatures and pH values were above 33 degrees C and 7.7, respectively. Moisture loss increased as C:N ratio and TF increased. In conclusion, the treatment with a combination of 4 days TF and C:N ratio 25:1 (T4R25) had the minimum TN loss (70.73% of the initial TN) and this indicated the most efficient combination.

  1. Evaluation of the relationship between nitrogen dry deposition and wildfire in a boreal forest of interior Alaska

    NASA Astrophysics Data System (ADS)

    Nagano, H.; Iwata, H.; Harazono, Y.

    2014-12-01

    In the boreal forests of interior Alaska, wildfires may play an important role in nitrogen dry deposition, which is one of the major input pathways affecting nitrogen availability. In order to examine the relationship between nitrogen dry deposition and wildfire, we applied regression analysis to the annual dry deposition of an Alaska boreal forest and annual burned area in Alaska for the 1999-2013 period. Furthermore, we estimated long-term nitrogen dry deposition for the past 54 years (1950-2013) at the same Alaska boreal forest, using an obtained regression equation and annual burned area. We used the data for annual nitrogen dry deposition (nitric acid, particulate nitrate, and particulate ammonium) measured at the CASTNET station (DEN417) in Denali National Park, available for 1999-2013. The annual burned area data for Alaska were referred to in previous reports (Todd and Jewkes, 2006; AICC, 2013). Nitrogen dry depositions at DEN417 were strongly correlated with the annual burned area in Alaska, where that area explained more than 68 % of the variation in annual nitrogen dry deposition. The background dry depositions defined as intercepts in the regression equations were 4.70, 0.24, and 2.15 mg m-2 year-1 for nitric acid, particulate nitrate, and particulate ammonium, respectively. Assuming that the increase in observed dry deposition above the background level (7.09 mg N m-2 year-1) was equal to nitrogen dry deposition originated from wildfire, we estimated that wildfire contributions to nitrogen dry deposition were 14 ± 20 % in 1999-2013. The long-term reproduction of nitrogen dry deposition revealed an increase in wildfire enhanced nitrogen dry deposition of up to 20 % for the 2000s, compared to the previous decadal age. The regression analysis and long-term reproduction in this study showed that the increase of wildfires in Alaska since 2000 has significantly enhanced the nitrogen dry deposition at DEN417.

  2. Inactivation of Campylobacter jejuni with dielectric barrier discharge plasma using air and nitrogen gases.

    PubMed

    Kim, Joo-Sung; Lee, Eun-Jung; Kim, Yun-Ji

    2014-08-01

    Air and nitrogen gas are commonly used feed gases for plasma generation and are economically useful in industrial applications. The two gases were compared in dielectric barrier discharge plasma for the inactivation of Campylobacter jejuni on an agar surface. Plasma treatment with nitrogen gas for 20 s did not yield any reduction (p>0.05) in viable cell count. However, a 0.8-log reduction (p<0.05) in colony-forming units (CFU) occurred when the nitrogen gas was supplemented with 2% (vol/vol) air. The use of air only, air supplemented with 2% (vol/vol) nitrogen, or oxygen only further decreased the viable cell counts by 0.7-1.7-log CFU (p<0.05). These results suggest that oxygen in plasma generation is critically important for the increased inactivation effect. Scanning electron microscopy analysis showed much cell debris including fragmented flagella in the sample exposed to air plasma, while no cell debris was found in the sample exposed to nitrogen plasma. In transmission electron microscopy analysis, many C. jejuni cells exposed to air plasma had truncated flagella with sharp bends, while the cells exposed to nitrogen plasma were normal, strongly suggesting that the air plasma can reduce the virulence of C. jejuni. A BacLight assay showed that air plasma damaged the cellular membrane (p<0.05), whereas nitrogen plasma did not after 5- or 20-s treatment. The damage to the membrane was consistent with the reduced viable cell count. Based on confocal microscopic analysis, the similar results were found by visualizing the fluorescent-dye-stained cells. In addition, the prolonged nitrogen plasma for 2 min also damaged many cellular membranes. This study shows that air, especially oxygen, is more effective and destructive than nitrogen and provides evidence that membrane damage may be a major mechanism for the inactivation of C. jejuni exposed to plasma.

  3. Pre- and post-impoundment nitrogen in the lower Missouri River

    USGS Publications Warehouse

    Blevins, Dale W.; Wilkison, Donald H.; Niesen, Shelley L.

    2013-01-01

    Large water-sample sets collected from 1899 through 1902, 1907, and in the early 1950s allow comparisons of pre-impoundment and post-impoundment (1969 through 2008) nitrogen concentrations in the lower Missouri River. Although urban wastes were not large enough to detectably increase annual loads of total nitrogen at the beginning of the 20th century, carcass waste, stock-yard manure, and untreated human wastes measurably increased ammonia and organic-nitrogen concentrations during low flows. Average total-nitrogen concentrations in both periods were about 2.5 mg/l, but much of the particulate-organic nitrogen, which was the dominant form of nitrogen around 1900, has been replaced by nitrate. This change in speciation was caused by the nearly 80% decrease in suspended-sediment concentrations that occurred after impoundment, modern agriculture, drainage of riparian wetlands, and sewage treatment. Nevertheless, bioavailable nitrogen has not been low enough to limit primary production in the Missouri River since the beginning of the 20th century. Nitrate concentrations have increased more rapidly from 2000 through 2008 (5 to 12% per year), thus increasing bioavailable nitrogen delivered to the Mississippi River and affecting Gulf Coast hypoxia. The increase in nitrate concentrations with distance downstream is much greater during the post-impoundment period. If strategies to decrease total-nitrogen loads focus on particulate N, substantial decreases will be difficult because particulate nitrogen is now only 23% of total nitrogen in the Missouri River. A strategy aimed at decreasing particulates also could further exacerbate land loss along the Gulf of Mexico, which has been sediment starved since Missouri River impoundment. In contrast, strategies or benchmarks aimed at decreasing nitrate loads could substantially decrease nitrogen loadings because nitrates now constitute over half of the Missouri's nitrogen input to the Mississippi. Ongoing restoration and creation

  4. Increased Precipitation and Nitrogen Alter Shrub Architecture in a Desert Shrubland: Implications for Primary Production

    PubMed Central

    She, Weiwei; Zhang, Yuqing; Qin, Shugao; Wu, Bin; Bai, Yuxuan

    2016-01-01

    Shrublands are one of the major types of ecosystems in the desert regions of northern China, which is expected to be substantially more sensitive to global environmental changes, such as widespread nitrogen enrichment and precipitation changes, than other ecosystem types. However, the interactive effects of nitrogen and precipitation on them remain poorly understood. We conducted a fully factorial field experiment simulating three levels of precipitation (ambient, +20%, +40%) and with two levels of nitrogen deposition (ambient, 60 kg N ha-1 yr-1) in a desert shrubland in the Mu Us Desert of northern China. We used plant architectural traits (plant cover, volume, twig size and number) as proxies to predict aboveground net primary productivity (ANPP) of the dominant shrub (Artemisia ordosica Krasch), and assessed the responses of plant productivity and architectural traits to water and nitrogen addition. We found significant differences in twig size and number of A. ordosica under water and nitrogen treatments but not in shrub cover/volume, which suggest that twig size and number of the shrub species were more sensitive to environmental changes. The productivity of the overall community was sensitive to increased precipitation and nitrogen, and shrubs played a more important role than herbaceous plants in driving productivity in this ecosystem. Precipitation- and nitrogen-induced increases in vegetation production were positively associated with increases in twig size and number of the dominant shrub. Water addition enhanced the twig length of A. ordosica, while nitrogen addition resulted in increased twig density (the number of twigs per square meter). Water and nitrogen interacted to affect twig length, but not twig number and shrub ANPP. The trade-off, defined as negative covariance between twig size and number, was likely the mechanism underlying the responses of twig length and shrub ANPP to water and nitrogen interactions. Our results highlight the sensitivity

  5. Carbon Accumulation and Nitrogen Pool Recovery during Transitions from Savanna to Forest in Central Brazil

    NASA Astrophysics Data System (ADS)

    Pellegrini, A.; Hoffmann, W. A.; Franco, A. C.

    2014-12-01

    The expansion of tropical forest into savanna may potentially be a large carbon sink, but little is known about the patterns of carbon sequestration during transitional forest formation. Moreover, it is unclear how nutrient limitation, due to extended exposure to firedriven nutrient losses, may constrain carbon accumulation. Here, we sampled plots that spanned a woody biomass gradient from savanna to transitional forest in response to differential fire protection in central Brazil. These plots were used to investigate how the process of transitional forest formation affects the size and distribution of carbon (C) and nitrogen (N) pools. This was paired with a detailed analysis of the nitrogen cycle to explore possible connections between carbon accumulation and nitrogen limitation. An analysis of carbon pools in the vegetation, upper soil, and litter shows that the transition from savanna to transitional forest can result in a fourfold increase in total carbon (from 43 to 179 Mg C/ha) with a doubling of carbon stocks in the litter and soil layers. Total nitrogen in the litter and soil layers increased with forest development in both the bulk (+68%) and plant-available (+150%) pools, with the most pronounced changes occurring in the upper layers. However, the analyses of nitrate concentrations, nitrate : ammonium ratios, plant stoichiometry of carbon and nitrogen, and soil and foliar nitrogen isotope ratios suggest that a conservative nitrogen cycle persists throughout forest development, indicating that nitrogen remains in low supply relative to demand. Furthermore, the lack of variation in underlying soil type (>20 cm depth) suggests that the biogeochemical trends across the gradient are driven by vegetation. Our results provide evidence for high carbon sequestration potential with forest encroachment on savanna, but nitrogen limitation may play a large and persistent role in governing carbon sequestration in savannas or other equally fire-disturbed tropical

  6. Carbon accumulation and nitrogen pool recovery during transitions from savanna to forest in central Brazil.

    PubMed

    Pellegrini, Adam F A; Hoffmann, William A; Franco, Augusto C

    2014-02-01

    The expansion of tropical forest into savanna may potentially be a large carbon sink, but little is known about the patterns of carbon sequestration during transitional forest formation. Moreover, it is unclear how nutrient limitation, due to extended exposure to fire-driven nutrient losses, may constrain carbon accumulation. Here, we sampled plots that spanned a woody biomass gradient from savanna to transitional forest in response to differential fire protection in central Brazil. These plots were used to investigate how the process of transitional forest formation affects the size and distribution of carbon (C) and nitrogen (N) pools. This was paired with a detailed analysis of the nitrogen cycle to explore possible connections between carbon accumulation and nitrogen limitation. An analysis of carbon pools in the vegetation, upper soil, and litter shows that the transition from savanna to transitional forest can result in a fourfold increase in total carbon (from 43 to 179 Mg C/ha) with a doubling of carbon stocks in the litter and soil layers. Total nitrogen in the litter and soil layers increased with forest development in both the bulk (+68%) and plant-available (+150%) pools, with the most pronounced changes occurring in the upper layers. However, the analyses of nitrate concentrations, nitrate:ammonium ratios, plant stoichiometry of carbon and nitrogen, and soil and foliar nitrogen isotope ratios suggest that a conservative nitrogen cycle persists throughout forest development, indicating that nitrogen remains in low supply relative to demand. Furthermore, the lack of variation in underlying soil type (>20 cm depth) suggests that the biogeochemical trends across the gradient are driven by vegetation. Our results provide evidence for high carbon sequestration potential with forest encroachment on savanna, but nitrogen limitation may play a large and persistent role in governing carbon sequestration in savannas or other equally fire-disturbed tropical

  7. Nitrogen incorporation in carbon nitride films produced by direct and dual ion-beam sputtering

    SciTech Connect

    Abrasonis, G.; Gago, R.; Jimenez, I.; Kreissig, U.; Kolitsch, A.; Moeller, W.

    2005-10-01

    Carbon (C) and carbon nitride (CN{sub x}) films were grown on Si(100) substrates by direct ion-beam sputtering (IBS) of a carbon target at different substrate temperatures (room temperature-450 deg. C) and Ar/N{sub 2} sputtering gas mixtures. Additionally, the effect of concurrent nitrogen-ion assistance during the growth of CN{sub x} films by IBS was also investigated. The samples were analyzed by elastic recoil detection analysis (ERDA) and x-ray absorption near-edge spectroscopy (XANES). The ERDA results showed that significant nitrogen amount (up to 20 at. %) was incorporated in the films, without any other nitrogen source but the N{sub 2}-containing sputtering gas. The nitrogen concentration is proportional to the N{sub 2} content in the sputtering beam and no saturation limit is reached under the present working conditions. The film areal density derived from ERDA revealed a decrease in the amount of deposited material at increasing growth temperature, with a correlation between the C and N losses. The XANES results indicate that N atoms are efficiently incorporated into the carbon network and can be found in different bonding environments, such as pyridinelike, nitrilelike, graphitelike, and embedded N{sub 2} molecules. The contribution of molecular and pyridinelike nitrogen decreases when the temperature increases while the contribution of the nitrilelike nitrogen increases. The concurrent nitrogen ion assistance resulted in the significant increase of the nitrogen content in the film but it induced a further reduction of the deposited material. Additionally, the assisting ions inhibited the formation of the nitrilelike configurations while promoting nitrogen environments in graphitelike positions. The nitrogen incorporation and release mechanisms are discussed in terms of film growth precursors, ion bombardment effects, and chemical sputtering.

  8. Responses to simulated nitrogen deposition by the neotropical epiphytic orchid Laelia speciosa.

    PubMed

    Díaz-Álvarez, Edison A; Lindig-Cisneros, Roberto; de la Barrera, Erick

    2015-01-01

    Potential ecophysiological responses to nitrogen deposition, which is considered to be one of the leading causes for global biodiversity loss, were studied for the endangered endemic Mexican epiphytic orchid, Laelia speciosa, via a shadehouse dose-response experiment (doses were 2.5, 5, 10, 20, 40, and 80 kg N ha(-1) yr(-1)) in order to assess the potential risk facing this orchid given impending scenarios of nitrogen deposition. Lower doses of nitrogen of up to 20 kg N ha yr(-1), the dose that led to optimal plant performance, acted as fertilizer. For instance, the production of leaves and pseudobulbs were respectively 35% and 36% greater for plants receiving 20 kg N ha yr(-1) than under any other dose. Also, the chlorophyll content and quantum yield peaked at 0.66 ± 0.03 g m(-2) and 0.85 ± 0.01, respectively, for plants growing under the optimum dose. In contrast, toxic effects were observed at the higher doses of 40 and 80 kg N ha yr(-1). The δ (13)C for leaves averaged -14.7 ± 0.2‰ regardless of the nitrogen dose. In turn, δ (15)N decreased as the nitrogen dose increased from 0.9 ± 0.1‰ under 2.5 kg N ha(-1)yr(-1) to -3.1 ± 0.2‰ under 80 kg N ha(-1)yr(-1), indicating that orchids preferentially assimilate NH4 (+) rather than NO3 (-) of the solution under higher doses of nitrogen. Laelia speciosa showed a clear response to inputs of nitrogen, thus, increasing rates of atmospheric nitrogen deposition can pose an important threat for this species.

  9. Responses to simulated nitrogen deposition by the neotropical epiphytic orchid Laelia speciosa

    PubMed Central

    Díaz-Álvarez, Edison A.; Lindig-Cisneros, Roberto

    2015-01-01

    Potential ecophysiological responses to nitrogen deposition, which is considered to be one of the leading causes for global biodiversity loss, were studied for the endangered endemic Mexican epiphytic orchid, Laelia speciosa, via a shadehouse dose-response experiment (doses were 2.5, 5, 10, 20, 40, and 80 kg N ha−1 yr−1) in order to assess the potential risk facing this orchid given impending scenarios of nitrogen deposition. Lower doses of nitrogen of up to 20 kg N ha yr−1, the dose that led to optimal plant performance, acted as fertilizer. For instance, the production of leaves and pseudobulbs were respectively 35% and 36% greater for plants receiving 20 kg N ha yr−1 than under any other dose. Also, the chlorophyll content and quantum yield peaked at 0.66 ± 0.03 g m−2 and 0.85 ± 0.01, respectively, for plants growing under the optimum dose. In contrast, toxic effects were observed at the higher doses of 40 and 80 kg N ha yr−1. The δ13C for leaves averaged −14.7 ± 0.2‰ regardless of the nitrogen dose. In turn, δ15N decreased as the nitrogen dose increased from 0.9 ± 0.1‰ under 2.5 kg N ha−1yr−1 to −3.1 ± 0.2‰ under 80 kg N ha−1yr−1, indicating that orchids preferentially assimilate NH4+ rather than NO3− of the solution under higher doses of nitrogen. Laelia speciosa showed a clear response to inputs of nitrogen, thus, increasing rates of atmospheric nitrogen deposition can pose an important threat for this species. PMID:26131375

  10. Nitrogen in Ancient Mud: A Biosignature?

    NASA Astrophysics Data System (ADS)

    Stüeken, Eva E.

    2016-09-01

    Nitrogen is an essential nutrient for all life on Earth and possibly elsewhere. Burial of nitrogen bound to organic matter constitutes the major flux of nitrogen into sediments today, which has led to the inference that nitrogen enrichments in sedimentary rocks may be a biosignature. However, abiotic processes such as lightning or volcanism can fix atmospheric N2 and contribute to sedimentary nitrogen burial in the absence of life. It is therefore uncertain whether observed nitrogen enrichments of up to 430 ppm in Paleoarchean metasedimentary biotite grains are indeed biogenic. This study seeks to address that problem with a numerical model. The NH4+ concentration of an abiotic ocean is modeled as a function of source fluxes, pH-dependent NH3 volatilization, and equilibrated adsorption of NH4+ onto clay particles. The results suggest that the observed nitrogen concentrations in Paleoarchean biotite can only be reconciled with purely abiotic processes if the ocean was more acidic (pH <6) and/or if the source fluxes from lightning and volcanism were at least an order of magnitude higher (≥1012 mol/yr) than previously thought. The bulk of the nitrogen is thus most likely of biological origin. While this does not necessitate a particular metabolism such as biological N2 fixation, the data provide evidence of nitrogen utilization back to 3.8 Gyr. Nitrogen abundances could thus provide useful information in extraterrestrial missions.

  11. Nitrogen Flow Analysis in Huizhou, South China

    NASA Astrophysics Data System (ADS)

    Ma, Xiaobo; Wang, Zhaoyin; Yin, Zegao; Koenig, Albert

    2008-03-01

    Eutrophication due to uncontrolled discharges of nitrogen and phosphorus has become a serious pollution problem in many Chinese rivers. This article analyzes the nitrogen flow in Huizhou City in the East River watershed in south China. The material accounting method was applied to investigate the nitrogen flows related to human activities, which consist of the natural and anthropogenic systems. In Huizhou City, the nonpoint source pollution was quantified by the export coefficient method and the domestic discharge was estimated as the product of per capita nitrogen contribution and population. This research was conducted based on statistical information and field data from 1998 in the Huizhou City. The results indicated that the major nitrogen flows in this area were river loads, fertilizer and feedstuff imports, atmospheric deposition, animal manure volatilization, and processes related to burning and other emissions. In 1998, about 40% of the nitrogen was retained in the system and could result in potential environmental problems. Nitrogen export was mainly by rivers, which account for about 57% of the total nitrogen exported. Comparisons made between the East River and the Danube and Yangtze Rivers show that the unit area nitrogen export was of the same magnitude and the per capita nitrogen export was comparable.

  12. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2011-01-01

    Ammonia was produced by 12 companies at 24 plants in 16 states in the United States during 2010. Sixty percent of total U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of those states' large reserves of natural gas, the dominant domestic feedstock.

  13. Nitrogen

    USGS Publications Warehouse

    Apodaca, L.E.

    2013-01-01

    Ammonia was produced by 13 companies at 25 plants in 16 states during 2012. Sixty-one percent of total U.S. ammonia production capacity was centered in Louisiana, Oklahoma and Texas because of those states’ large reserves of natural gas, the dominant domestic feedstock.

  14. Nitrogen

    USGS Publications Warehouse

    Kramer, D.

    2003-01-01

    The ammonia industry partially recovered from the effects of high natural gas prices that had closed a significant portion of the industry in 2001. Ammonia production capacity in the United States in 2002 was about 17.1 Mt (18.8 million st). About 53 percent of this capacity was centered in Louisiana, Oklahoma and Texas where there are large reserves of natural gas.

  15. Spatial pattern of nitrogen deposition flux over Czech forests: a novel approach accounting for unmeasured nitrogen species

    NASA Astrophysics Data System (ADS)

    Hůnová, Iva; Stoklasová, Petra; Kurfürst, Pavel; Vlček, Ondřej; Schovánková, Jana; Stráník, Vojtěch

    2015-04-01

    atmospheric nitrogen deposition flux over the Czech forests collating all available data and model results. The aim of the presented study is to provide an improved, more reliable and more realistic estimate of spatial pattern of nitrogen deposition flux over one country. This has so far been based standardly on measurements of ambient N/NOx concentrations as dry deposition proxy, and N/NH4+ and N/NO3- as wet deposition proxy. For estimate of unmeasured species contributing to dry deposition, we used an Eulerian photochemical dispersion model CAMx, the Comprehensive Air Quality Model with extensions (ESSS, 2011), coupled with a high resolution regional numeric weather prediction model Aladin (Vlček, Corbet, 2011). Contribution of fog was estimated using a geostatistical data driven model. Final maps accounting for unmeasured species clearly indicate, that so far used approach results in substantial underestimation of nitrogen deposition flux. Substitution of unmeasured nitrogen species by modeled values seems to be a plausible way for approximation of total nitrogen deposition, and getting more realistic spatial pattern as input for further studies of likely nitrogen impacts on ecosystems. Acknowledgements: We would like to acknowledge the grants GA14-12262S - Effects of changing growth conditions on tree increment, stand production and vitality - danger or opportunity for the Central-European forestry?, and NAZV QI112A168 (ForSoil) of the Czech Ministry for Agriculture for support of this contribution. The input data used for the analysis were provided by the Czech Hydrometeorological Institute. References: Bobbink, R., Hicks, K., Galloway, J., Spranger, T., Alkemade, R. et al. (2010): Global Assessment of Nitrogen Deposition Effects on Terrestrial Plant Diversity: a Synthesis. Ecological Applications 20 (1), 30-59. Fowler D., O'Donoghue M., Muller J.B.A, et al. (2005): A chronology of nitrogen deposition in the UK between 1900 and 2000. Watter, Air & Soil Pollution: Focus

  16. ECONOMIC GROWTH ANALYSIS SYSTEM: USER'S GUIDE VERSION 2.0

    EPA Science Inventory

    The two-volume report describes the development of and provides information needed to operate, the Economic Growth Analysis System (E-GAS) Version 2.0 model. The model will be used to project emissions inventories of volatile organic compounds (VOCs), oxides of nitrogen (NOx), a...

  17. ECONOMIC GROWTH ANALYSIS SYSTEM: REFERENCE MANUAL VERSION 2.0

    EPA Science Inventory

    The two-volume report describes the development of and provides information needed to operate, the Economic Growth Analysis System (E-GAS) Version 2.0 model. The model will be used to project emissions inventories of volatile organic compounds (VOCs), oxides of nitrogen (NOx), a...

  18. ECONOMIC GROWTH ANALYSIS SYSTEM: USER'S GUIDE VERSION 2.0

    EPA Science Inventory

    The two-volume report describes the development of and provides information needed to operate, the Economic Growth Analysis System (E-GAS) Version 2.0 model. The model will be used to project emissions inventories of volatile organic compounds (VOCs), oxides of nitrogen (NOx), a...

  19. ECONOMIC GROWTH ANALYSIS SYSTEM: REFERENCE MANUAL VERSION 2.0

    EPA Science Inventory

    The two-volume report describes the development of and provides information needed to operate, the Economic Growth Analysis System (E-GAS) Version 2.0 model. The model will be used to project emissions inventories of volatile organic compounds (VOCs), oxides of nitrogen (NOx), a...

  20. Enhanced concentrations of reactive nitrogen species in wildfire smoke

    NASA Astrophysics Data System (ADS)

    Benedict, Katherine B.; Prenni, Anthony J.; Carrico, Christian M.; Sullivan, Amy P.; Schichtel, Bret A.; Collett, Jeffrey L.

    2017-01-01

    During the summer of 2012 the Hewlett Gulch and High Park wildfires burned an area of 400 km2 northwest of Fort Collins, Colorado. These fires both came within 20 km of the Department of Atmospheric Science at Colorado State University, allowing for extensive measurements of smoke-impacted air masses over the course of several weeks. In total, smoke plumes were observed at the measurement site for approximately 125 h. During this time, measurements were made of multiple reactive nitrogen compounds, including gas phase species NH3, NOx, and HNO3, and particle phase species NO3- and NH4+, plus an additional, unspeciated reactive nitrogen component that is measured by high temperature conversion over a catalyst to NO. Concurrent measurements of CO, levoglucosan and PM2.5 served to confirm the presence of smoke at the monitoring site. Significant enhancements were observed for all of the reactive nitrogen species measured in the plumes, except for NH4+ which did not show enhancements, likely due to the fresh nature of the plume, the presence of sufficient regional ammonia to have already neutralized upwind sulfate, and the warm conditions of the summer measurement period which tend to limit ammonium nitrate formation. Excess mixing ratios for NH3 and NOx relative to excess mixing ratios of CO in the smoke plumes, ΔNH3/ΔCO (ppb/ppb) and ΔNOx/ΔCO (ppb/ppb), were determined to be 0.027 ± 0.002 and 0.0057 ± 0.0007, respectively. These ratios suggest that smoldering combustion was the dominant source of smoke during our plume interceptions. Observations from prior relevant laboratory and field measurements of reactive nitrogen species are also briefly summarized to help create a more comprehensive picture of reactive nitrogen and fire.

  1. Properties of nitrogen-doped amorphous hydrogenated carbon films

    SciTech Connect

    Amir, O.; Kalish, R. )

    1991-11-01

    Nitrogen-containing hydrogenated amorphous carbon (a-C:H(N)) films are grown from a dc plasma of a N{sub 2}+C{sub 6}H{sub 6} gas mixture. By varying the N{sub 2} fraction in this mixture films with different amounts of N are produced. The actual amount of nitrogen in the {ital a}-C:H(N) films is determined by nuclear reaction analysis and by Auger electron spectroscopy profiling. The nitrogen concentration in the films grows exponentially with nitrogen content in the gas mixture reaching concentrations as high as 10 at.% for the films grown from a N{sub 2}-rich gas mixture (N{sub 2}/(N{sub 2}+C{sub 6}H{sub 6})=0.75). The electrical and structural properties of the N{sub 2}-doped films are studied by performing electrical conductivity, thermopower (TP), optical absorption, and electron-paramagnetic resonance measurements. Films with low ({lt}1 at.%) nitrogen content exhibit fairly high resistivities, have an optical gap of 1 eV, are rich with dangling bonds (5{times}10{sup 20} cm{sup {minus}3}) and their thermopower is positive and in the mV/K regime, indicating conductivity in the valence band tail. However, with increased N doping, the resistivity decreases and the optical band gap shrinks and reached zero for the highest doped film. The TPs for films containing more than 1 at.% are in the {mu}V/K range, indicating hopping conductivity around the Fermi level. The results of all measurements are consistent with the model of Robertson for the electrical structure of amorphous hydrogenated carbon and for the proposed doping mechanism in this material.

  2. The 20-20-20 Airships NASA Centennial Challenge

    NASA Astrophysics Data System (ADS)

    Kiessling, Alina; Diaz, Ernesto; Miller, Sarah; Rhodes, Jason; Ortega, Sam; Hall, Jeffrey L.; Friedl, Randy; Booth, Jeff

    2015-01-01

    A NASA Centennial Challenge; (www.nasa.gov/challenges) is in development to spur innovation in stratospheric airships as a science platform. We anticipate a multi-million dollar class prize for the first organization to fly a powered airship that remains stationary at 20km (65,000 ft) altitude for over 20 hours with a 20kg payload. The design must be scalable to longer flights with more massive payloads.In NASA's constrained budget environment, there are few opportunities for space missions in astronomy and Earth science, and these have very long lead times. We believe that airships (powered, maneuverable, lighter-than-air vehicles) could offer significant gains in observing time, sky and ground coverage, data downlink capability, and continuity of observations over existing suborbital options at competitive prices. This technology would also have broad commercial applications including communications and asset tracking. We seek to spur private industry (or non-profit institutions, including Universities) to demonstrate the capability for sustained airship flights as astronomy and Earth science platforms. This poster will introduce the challenge in development and provide details of who to contact for more information.

  3. Seasonal Nitrogen Cycles on Pluto

    NASA Technical Reports Server (NTRS)

    Hansen, Candice J.; Paige, David A.

    1996-01-01

    A thermal model, developed to predict seasonal nitrogen cycles on Triton, has been modified and applied to Pluto. The model was used to calculate the partitioning of nitrogen between surface frost deposits and the atmosphere, as a function of time for various sets of input parameters. Volatile transport was confirmed to have a significant effect on Pluto's climate as nitrogen moved around on a seasonal time scale between hemispheres, and sublimed into and condensed out of the atmosphere. Pluto's high obliquity was found to have a significant effect on the distribution of frost on its surface. Conditions that would lead to permanent polar caps on Triton were found to lead to permanent zonal frost bands on Pluto. In some instances, frost sublimed from the middle of a seasonal cap outward, resulting in a "polar bald spot". Frost which was darker than the substrate did not satisfy observables on Pluto, in contrast to our findings for Triton. Bright frost (brighter than the substrate) came closer to matching observables. Atmospheric pressure varied seasonally. The amplitudes, and to a lesser extent the phase, of the variation depended significantly on frost and substrate properties. Atmospheric pressure was found to be determined both by Pluto's distance from the sun and by the subsolar latitude. In most cases two peaks in atmospheric pressure were observed annually: a greater one associated with the sublimation of the north polar cap just as Pluto receded from perihelion, and a lesser one associated with the sublimation of the south polar cap as Pluto approached perihelion. Our model predicted frost-free dark substrate surface temperatures in the 50 to 60 K range, while frost temperatures typically ranged between 30 to 40 K. Temporal changes in frost coverage illustrated by our results, and changes in the viewing geometry of Pluto from the Earth, may be important for interpretation of ground-based measurements of Pluto's thermal emission.

  4. Seasonal Nitrogen Cycles on Pluto

    NASA Technical Reports Server (NTRS)

    Hansen, Candice J.; Paige, David A.

    1996-01-01

    A thermal model, developed to predict seasonal nitrogen cycles on Triton, has been modified and applied to Pluto. The model was used to calculate the partitioning of nitrogen between surface frost deposits and the atmosphere, as a function of time for various sets of input parameters. Volatile transport was confirmed to have a significant effect on Pluto's climate as nitrogen moved around on a seasonal time scale between hemispheres, and sublimed into and condensed out of the atmosphere. Pluto's high obliquity was found to have a significant effect on the distribution of frost on its surface. Conditions that would lead to permanent polar caps on Triton were found to lead to permanent zonal frost bands on Pluto. In some instances, frost sublimed from the middle of a seasonal cap outward, resulting in a "polar bald spot". Frost which was darker than the substrate did not satisfy observables on Pluto, in contrast to our findings for Triton. Bright frost (brighter than the substrate) came closer to matching observables. Atmospheric pressure varied seasonally. The amplitudes, and to a lesser extent the phase, of the variation depended significantly on frost and substrate properties. Atmospheric pressure was found to be determined both by Pluto's distance from the sun and by the subsolar latitude. In most cases two peaks in atmospheric pressure were observed annually: a greater one associated with the sublimation of the north polar cap just as Pluto receded from perihelion, and a lesser one associated with the sublimation of the south polar cap as Pluto approached perihelion. Our model predicted frost-free dark substrate surface temperatures in the 50 to 60 K range, while frost temperatures typically ranged between 30 to 40 K. Temporal changes in frost coverage illustrated by our results, and changes in the viewing geometry of Pluto from the Earth, may be important for interpretation of ground-based measurements of Pluto's thermal emission.

  5. Nitrogen oxides under pressure: stability, ionization, polymerization, and superconductivity.

    PubMed

    Li, Dongxu; Oganov, Artem R; Dong, Xiao; Zhou, Xiang-Feng; Zhu, Qiang; Qian, Guangrui; Dong, Huafeng

    2015-11-17

    Nitrogen oxides are textbook class of molecular compounds, with extensive industrial applications. Nitrogen and oxygen are also among the most abundant elements in the universe. We explore the N-O system at 0 K and up to 500 GPa though ab initio evolutionary simulations. Results show that two phase transformations of stable molecular NO2 occur at 7 and 64 GPa, and followed by decomposition of NO2 at 91 GPa. All of the NO(+)NO3(-) structures are found to be metastable at T = 0 K, so experimentally reported ionic NO(+)NO3(-) is either metastable or stabilized by temperature. N2O5 becomes stable at 9 GPa, and transforms from P-1 to C2/c structure at 51 GPa. NO becomes thermodynamically stable at 198 GPa. This polymeric phase is superconducting (Tc = 2.0 K) and contains a -N-N- backbone.

  6. Nitrogen fertilizer influence on aflatoxin contamination of corn in Louisiana.

    PubMed

    Tubajika, K M; Mascagni, H J; Damann, K E; Russin, J S

    1999-12-01

    Studies were conducted in 1997 and 1998 on a Gigger silt loam at the Macon Ridge Research Station at Winnsboro, LA, to determine the influence of nitrogen (N) rate, timing, and starter nitrogen fertilizer on aflatoxin contamination in corn. Fertilizer N (0, 50, 100, 150, 200, and 250 lb of N/acre), two timings (at planting and six-leaf stage), and starter N fertilizer (a control and 10 lb of N/acre applied in furrow) were evaluated. Application of starter, N rates, and the interaction of starter with N timing and N rates significantly affected aflatoxin levels. Rates of 50-250 lb of N/acre were 34-43% lower in aflatoxin contamination than plots receiving no N. The application of 10 lb of N/acre starter reduced the aflatoxin levels by 20% compared to the no-starter control.

  7. Gamma ray irradiation for sludge solubilization and biological nitrogen removal

    NASA Astrophysics Data System (ADS)

    Kim, Tak-Hyun; Lee, Myunjoo; Park, Chulhwan

    2011-12-01

    This study was conducted to investigate the effects of gamma ray irradiation on the solubilization of waste sewage sludge. The recovery of an organic carbon source from sewage sludge by gamma ray irradiation was also studied. The gamma ray irradiation showed effective sludge solubilization efficiencies. Both soluble chemical oxygen demand (SCOD) and biochemical oxygen demand (BOD 5) increased by gamma ray irradiation. The feasibility of the solubilized sludge carbon source for a biological nitrogen removal was also investigated. A modified continuous bioreactor (MLE process) for a denitrification was operated for 20 days by using synthetic wastewater. It can be concluded that the gamma ray irradiation was useful for the solubilization of sludge and the recovery of carbon source from the waste sewage sludge for biological nitrogen removal.

  8. Mitigating ammonia nitrogen deficiency in dairy wastewaters for algae cultivation.

    PubMed

    Lu, Qian; Zhou, Wenguang; Min, Min; Ma, Xiaochen; Ma, Yiwei; Chen, Paul; Zheng, Hongli; Doan, Yen T T; Liu, Hui; Chen, Chi; Urriola, Pedro E; Shurson, Gerald C; Ruan, Roger

    2016-02-01

    This study demonstrated that the limiting factor to algae growth on dairy wastewater was the ammonia nitrogen deficiency. Dairy wastewaters were mixed with a slaughterhouse wastewater that has much higher ammonia nitrogen content. The results showed the mixing wastewaters improved the nutrient profiles and biomass yield at low cost. Algae grown on mixed wastewaters contained high protein (55.98-66.91%) and oil content (19.10-20.81%) and can be exploited to produce animal feed and biofuel. Furthermore, algae grown on mixed wastewater significantly reduced nutrient contents remained in the wastewater after treatment. By mitigating limiting factor to algae growth on dairy wastewaters, the key issue of low biomass yield of algae grown on dairy wastewaters was resolved and the wastewater nutrient removal efficiency was significantly improved by this study.

  9. Reaction between nitric oxide and ozone in solid nitrogen

    NASA Technical Reports Server (NTRS)

    Lucas, D.; Pimentel, G. C.

    1979-01-01

    Nitrogen dioxide, NO2, is produced when nitric oxide, NO, and ozone, O3, are suspended in a nitrogen matrix at 11-20 K. The NO2 is formed with first-order kinetics, a 12 K rate constant of (1.4 + or - 0.2) x 0.00001/sec, and an apparent activation energy of 106 + or - 10 cal/mol. Isotopic labeling, variation of concentrations, and cold shield experiments show that the growth of NO2 is due to reaction between ozone molecules and NO monomers, and that the reaction is neither infrared-induced nor does it seem to be a heavy atom tunneling process. Reaction is attributed to nearest-neighbor NO.O3 pairs probably held in a specific orientational relationship that affects the kinetic behavior. When the temperature is raised, more such reactive pairs are generated, presumably by local diffusion. Possible mechanisms are discussed.

  10. Charcoal/Nitrogen Adsorption Cryocooler

    NASA Technical Reports Server (NTRS)

    Bard, Steven

    1987-01-01

    Refrigerator with no wear-related moving parts produces 0.5 W of cooling at 118 K. When fully developed, refrigerator needs no electrical power, and life expectancy of more than 10 yr, operates unattended to cool sensitive infrared detectors for long periods. Only moving parts in adsorption cryocooler are check valves. As charcoal is cooled in canister, gas pressure drops, allowing inlet check valve to open and admit more nitrogen. When canister is heated, pressure rises, closing inlet valve and eventually opening outlet valve.

  11. Nitrogen fixation method and apparatus

    DOEpatents

    Chen, H.L.

    1983-08-16

    A method and apparatus for achieving nitrogen fixation includes a volumetric electric discharge chamber. The volumetric discharge chamber provides an even distribution of an electron beam, and enables the chamber to be maintained at a controlled energy to pressure (E/p) ratio. An E/p ratio of from 5 to 15 kV/atm of O[sub 2]/cm promotes the formation of vibrationally excited N[sub 2]. Atomic oxygen interacts with vibrationally excited N[sub 2] at a much quicker rate than unexcited N[sub 2], greatly improving the rate at which NO is formed. 1 fig.

  12. Nitrogen fixation method and apparatus

    DOEpatents

    Chen, Hao-Lin

    1983-01-01

    A method and apparatus for achieving nitrogen fixation includes a volumetric electric discharge chamber. The volumetric discharge chamber provides an even distribution of an electron beam, and enables the chamber to be maintained at a controlled energy to pressure (E/p) ratio. An E/p ratio of from 5 to 15 kV/atm of O.sub.2 /cm promotes the formation of vibrationally excited N.sub.2. Atomic oxygen interacts with vibrationally excited N.sub.2 at a much quicker rate than unexcited N.sub.2, greatly improving the rate at which NO is formed.

  13. Total nitrogen content of deep sea basalts

    NASA Technical Reports Server (NTRS)

    Norris, T. L.; Schaeffer, O. A.

    1982-01-01

    An estimate of the total nitrogen content of the earth's mantle, aimed at furnishing a further constraint for earth atmosphere origin and evolution models, was attempted through thermal neutron activation analysis via N-14(n,p)C-14 for the case of deep sea basalt glasses from the East Pacific Rise, the Mid-Atlantic Rift, and the Juan de Fuca Ridge. The increased nitrogen abundance of matrix material from the same samples as the glasses may be due to the incorporation of chemically-bound nitrogen from sea water, rather than dissolved molecular nitrogen. A discussion is presented of factors affecting observed basalt nitrogen content and its interpretation in terms of mantle nitrogen abundance. A 2 ppm N lower limit is estimated for the mantle.

  14. Nitrogen uptake and utilization by intact plants

    NASA Technical Reports Server (NTRS)

    Raper, C. D., Jr.; Tolley-Henry, L. C.

    1986-01-01

    The results of experiments support the proposed conceptual model that relates nitrogen uptake activity by plants as a balanced interdependence between the carbon-supplying function of the shoot and the nitrogen-supplying function of the roots. The data are being used to modify a dynamic simulation of plant growth, which presently describes carbon flows through the plant, to describe nitrogen uptake and assimilation within the plant system. Although several models have been proposed to predict nitrogen uptake and partitioning, they emphasize root characteristics affecting nutrient uptake and relay on empirical methods to describe the relationship between nitrogen and carbon flows within the plant. Researchers, on the other hand, propose to continue to attempt a mechanistic solution in which the effects of environment on nitrogen (as well as carbon) assimilation are incorporated through their direct effects on photosynthesis, respiration, and aging processes.

  15. Klf15 orchestrates circadian nitrogen homeostasis

    PubMed Central

    Jeyaraj, Darwin; Scheer, Frank A.J.L.; Ripperger, Jürgen A.; Haldar, Saptarsi M.; Lu, Yuan; Prosdocimo, Domenick A.; Eapen, Sam J.; Eapen, Betty L.; Cui, Yingjie; Mahabeleshwar, Ganapathi H.; Lee, Hyoung-gon; Smith, Mark A.; Casadesus, Gemma; Mintz, Eric M.; Sun, Haipeng; Wang, Yibin; Ramsey, Kathryn M.; Bass, Joseph; Shea, Steven A.; Albrecht, Urs; Jain, Mukesh K.

    2012-01-01

    SUMMARY Diurnal variation in nitrogen homeostasis is observed across phylogeny. But whether these are endogenous rhythms, and if so, molecular mechanisms that link nitrogen homeostasis to the circadian clock remain unknown. Here, we provide evidence that a clock-dependent peripheral oscillator, Krüppel-like factor15 transcriptionally coordinates rhythmic expression of multiple enzymes involved in mammalian nitrogen homeostasis. In particular, Krüppel-like factor15-deficient mice exhibit no discernable amino acid rhythm, and the rhythmicity of ammonia to urea detoxification is impaired. Of the external cues, feeding plays a dominant role in modulating Krüppel-like factor15 rhythm and nitrogen homeostasis. Further, when all behavioral, environmental and dietary cues were controlled in humans, nitrogen homeostasis still expressed endogenous circadian rhythmicity. Thus, in mammals, nitrogen homeostasis exhibits circadian rhythmicity, and is orchestrated by Krüppel-like factor15. PMID:22405069

  16. Total nitrogen content of deep sea basalts

    NASA Technical Reports Server (NTRS)

    Norris, T. L.; Schaeffer, O. A.

    1982-01-01

    An estimate of the total nitrogen content of the earth's mantle, aimed at furnishing a further constraint for earth atmosphere origin and evolution models, was attempted through thermal neutron activation analysis via N-14(n,p)C-14 for the case of deep sea basalt glasses from the East Pacific Rise, the Mid-Atlantic Rift, and the Juan de Fuca Ridge. The increased nitrogen abundance of matrix material from the same samples as the glasses may be due to the incorporation of chemically-bound nitrogen from sea water, rather than dissolved molecular nitrogen. A discussion is presented of factors affecting observed basalt nitrogen content and its interpretation in terms of mantle nitrogen abundance. A 2 ppm N lower limit is estimated for the mantle.

  17. Description of Liquid Nitrogen Experimental Test Facility

    NASA Technical Reports Server (NTRS)

    Jurns, John M.; Jacobs, Richard E.; Saiyed, Naseem H.

    1991-01-01

    The Liquid Nitrogen Test Facility is a unique test facility for ground-based liquid nitrogen experimentation. The test rig consists of an insulated tank of approximately 12.5 cubic ft in volume, which is supplied with liquid nitrogen from a 300 gal dewar via a vacuum jacketed piping system. The test tank is fitted with pressure and temperature measuring instrumentation, and with two view ports which allow visual observation of test conditions. To demonstrate the capabilities of the facility, the initial test program is briefly described. The objective of the test program is to measure the condensation rate by injecting liquid nitrogen as a subcooled spray into the ullage of a tank 50 percent full of liquid nitrogen at saturated conditions. The condensation rate of the nitrogen vapor on the subcooled spray can be analytically modeled, and results validated and corrected by experimentally measuring the vapor condensation on liquid sprays.

  18. Nitrogen loss during solar drying of biosolids.

    PubMed

    O'Shaughnessy, S A; Song, I; Artiola, J F; Choi, C Y

    2008-01-01

    Solar drying has been used extensively to dewater biosolids for ease of transportation and to a lesser degree to reduce pathogens prior to land application. The nitrogen in biosolids makes them a relatively inexpensive but valuable source of fertilizer. In this study, nitrogen loss from tilled and untilled biosolids was investigated during the solar drying process. Samples of aerobically and anaerobically digested biosolids during three solar drying experiments were analyzed for their nitrate (NO3-) and ammonium (NH4+) ions concentrations. Nitrogen losses varied depending on the solar drying season and tillage. Although not directly measured, the majority of nitrogen loss occurred through ammonia volatilization; organic nitrogen content (organic N) remained relatively stable for each sample, nitrate concentrations for the majority of samples remained below detectable levels and the decline of ammonium-nitrogen (NH4(+)-N) generally followed the trend of moisture loss in the biosolids.

  19. The Sensitivity of Moss-Associated Nitrogen Fixation towards Repeated Nitrogen Input

    PubMed Central

    Rousk, Kathrin; Michelsen, Anders

    2016-01-01

    Nitrogen (N2) fixation is a major source of available N in ecosystems that receive low amounts of atmospheric N deposition. In boreal forest and subarctic tundra, the feather moss Hylocomium splendens is colonized by N2 fixing cyanobacteria that could contribute fundamentally to increase the N pool in these ecosystems. However, N2 fixation in mosses is inhibited by N input. Although this has been shown previously, the ability of N2 fixation to grow less sensitive towards repeated, increased N inputs remains unknown. Here, we tested if N2 fixation in H. splendens can recover from increased N input depending on the N load (0, 5, 20, 80, 320 kg N ha-1 yr-1) after a period of N deprivation, and if sensitivity towards increased N input can decrease after repeated N additions. Nitrogen fixation in the moss was inhibited by the highest N addition, but was promoted by adding 5 kg N ha-1 yr-1, and increased in all treatments during a short period of N deprivation. The sensitivity of N2 fixation towards repeated N additions seem to decrease in the 20 and 80 kg N additions, but increased in the highest N addition (320 kg N ha-1 yr-1). Recovery of N in leachate samples increased with increasing N loads, suggesting low retention capabilities of mosses if N input is above 5 kg N ha-1 yr-1. Our results demonstrate that the sensitivity towards repeated N additions is likely to decrease if N input does not exceed a certain threshold. PMID:26731691

  20. The Sensitivity of Moss-Associated Nitrogen Fixation towards Repeated Nitrogen Input.

    PubMed

    Rousk, Kathrin; Michelsen, Anders

    2016-01-01

    Nitrogen (N2) fixation is a major source of available N in ecosystems that receive low amounts of atmospheric N deposition. In boreal forest and subarctic tundra, the feather moss Hylocomium splendens is colonized by N2 fixing cyanobacteria that could contribute fundamentally to increase the N pool in these ecosystems. However, N2 fixation in mosses is inhibited by N input. Although this has been shown previously, the ability of N2 fixation to grow less sensitive towards repeated, increased N inputs remains unknown. Here, we tested if N2 fixation in H. splendens can recover from increased N input depending on the N load (0, 5, 20, 80, 320 kg N ha(-1) yr(-1)) after a period of N deprivation, and if sensitivity towards increased N input can decrease after repeated N additions. Nitrogen fixation in the moss was inhibited by the highest N addition, but was promoted by adding 5 kg N ha(-1) yr(-1), and increased in all treatments during a short period of N deprivation. The sensitivity of N2 fixation towards repeated N additions seem to decrease in the 20 and 80 kg N additions, but increased in the highest N addition (320 kg N ha(-1) yr(-1)). Recovery of N in leachate samples increased with increasing N loads, suggesting low retention capabilities of mosses if N input is above 5 kg N ha(-1) yr(-1). Our results demonstrate that the sensitivity towards repeated N additions is likely to decrease if N input does not exceed a certain threshold.

  1. Cereal area and nitrogen use efficiency are drivers of future nitrogen fertilizer consumption.

    PubMed

    Dobermann, Achim; Cassman, Kenneth G

    2005-12-01

    At a global scale, cereal yields and fertilizer N consumption have increased in a near-linear fashion during the past 40 years and are highly correlated with one another. However, large differences exist in historical trends of N fertilizer usage and nitrogen use efficiency (NUE) among regions, countries, and crops. The reasons for these differences must be understood to estimate future N fertilizer requirements. Global nitrogen needs will depend on: (i) changes in cropped cereal area and the associated yield increases required to meet increasing cereal demand from population and income growth, and (ii) changes in NUE at the farm level. Our analysis indicates that the anticipated 38% increase in global cereal demand by 2025 can be met by a 30% increase in N use on cereals, provided that the steady decline in cereal harvest area is halted and the yield response to applied N can be increased by 20%. If losses of cereal cropping area continue at the rate of the past 20 years (-0.33% per year) and NUE cannot be increased substantially, a 60% increase in global N use on cereals would be required to meet cereal demand. Interventions to increase NUE and reduce N losses to the environment must be accomplished at the farm- or field-scale through a combination of improved technologies and carefully crafted local policies that contribute to the adoption of improved N management; uniform regional or national directives are unlikey to be effective at both sustaining yield increases and improving NUE. Examples from several countries show that increases in NUE at rates of 1% per year or more can be achieved if adequate investments are made in research and extension. Failure to arrest the decrease in cereal crop area and to improve NUE in the world's most important agricultural systems will likely cause severe damage to environmental services at local, regional, and global scales due to a large increase in reactive N load in the environment.

  2. Cereal area and nitrogen use efficiency are drivers of future nitrogen fertilizer consumption.

    PubMed

    Dobermann, Achim; Cassman, Kenneth G

    2005-09-01

    At a global scale, cereal yields and fertilizer N consumption have increased in a near-linear fashion during the past 40 years and are highly correlated with one another. However, large differences exist in historical trends of N fertilizer usage and nitrogen use efficiency (NUE) among regions, countries, and crops. The reasons for these differences must be understood to estimate future N fertilizer requirements. Global nitrogen needs will depend on: (i) changes in cropped cereal area and the associated yield increases required to meet increasing cereal demand from population and income growth, and (ii) changes in NUE at the farm level. Our analysis indicates that the anticipated 38% increase in global cereal demand by 2025 can be met by a 30% increase in N use on cereals, provided that the steady decline in cereal harvest area is halted and the yield response to applied N can be increased by 20%. If losses of cereal cropping area continue at the rate of the past 20 years (-0.33% per year) and NUE cannot be increased substantially, a 60% increase in global N use on cereals would be required to meet cereal demand. Interventions to increase NUE and reduce N losses to the environment must be accomplished at the farm-or field-scale through a combination of improved technologies and carefully crafted local policies that contribute to the adoption of improved N management; uniform regional or national directives are unlikely to be effective at both sustaining yield increases and improving NUE. Examples from several countries show that increases in NUE at rates of 1% per year or more can be achieved if adequate investments are made in research and extension. Failure to arrest the decrease in cereal crop area and to improve NUE in the world's most important agricultural systems will likely cause severe damage to environmental services at local, regional, and global scales due to a large increase in reactive N load in the environment.

  3. Landau level splitting in nitrogen-seeded epitaxial graphene

    SciTech Connect

    Rothwell, S. L.; Wang, F.; Liu, G.; Xu, C.; Feldman, L. C.; Conrad, E. H.; Guisinger, N. P.; Cohen, P. I.

    2016-07-01

    We present a new form of semiconducting graphene grown on C-face silicon carbide, SiC(0001), seeded with a sub-monolayer of nitrogen. This graphene exhibits a gap of 0.3-0.7 eV from the Fermi level to the valence band dependent on lm thickness as measured via angle resolved photo-emission spectroscopy (ARPES). Scanning tunneling microscopy (STM) images imply that the bandgap may be the result of strain-induced confinement. STM indicates that much of the graphene consists of wide at hexagonal plateaus, 8-20 nm2 on average, surrounded by both smooth and disordered folds of length scales from 0.5-2 nm tall, 1-4 nm thick, and 1-20 nm long. The remainder of the surface is covered in smooth or disordered ripples and folds intermixed. Scanning tunneling spectroscopy (STS) measurements on all features show peaks suggestive of Landau levels, and have been analyzed to give pseudo-magnetic field magnitudes. The magnetic lengths associated with these fields are less than the average plateau diameter but comparable to typical fold widths. We consider a growth process whereby the graphene grows pinned to the substrate by the interface nitrogen. The graphene experiences compressive strain as a result of both this pinning as well as competing thermal expansion forces between the substrate and lm. As a result, graphene on nitrogen-seeded SiC has a more concentrated network of strained ripples and folds than seen on C-face SiC graphene without nitrogen.

  4. Landau level splitting in nitrogen-seeded epitaxial graphene

    DOE PAGES

    Rothwell, S. L.; Wang, F.; Liu, G.; ...

    2016-07-01

    We present a new form of semiconducting graphene grown on C-face silicon carbide, SiC(0001), seeded with a sub-monolayer of nitrogen. This graphene exhibits a gap of 0.3-0.7 eV from the Fermi level to the valence band dependent on lm thickness as measured via angle resolved photo-emission spectroscopy (ARPES). Scanning tunneling microscopy (STM) images imply that the bandgap may be the result of strain-induced confinement. STM indicates that much of the graphene consists of wide at hexagonal plateaus, 8-20 nm2 on average, surrounded by both smooth and disordered folds of length scales from 0.5-2 nm tall, 1-4 nm thick, and 1-20more » nm long. The remainder of the surface is covered in smooth or disordered ripples and folds intermixed. Scanning tunneling spectroscopy (STS) measurements on all features show peaks suggestive of Landau levels, and have been analyzed to give pseudo-magnetic field magnitudes. The magnetic lengths associated with these fields are less than the average plateau diameter but comparable to typical fold widths. We consider a growth process whereby the graphene grows pinned to the substrate by the interface nitrogen. The graphene experiences compressive strain as a result of both this pinning as well as competing thermal expansion forces between the substrate and lm. As a result, graphene on nitrogen-seeded SiC has a more concentrated network of strained ripples and folds than seen on C-face SiC graphene without nitrogen.« less

  5. Landau level splitting in nitrogen-seeded epitaxial graphene

    SciTech Connect

    Rothwell, S. L.; Wang, F.; Liu, G.; Xu, C.; Feldman, L. C.; Conrad, E. H.; Guisinger, N. P.; Cohen, P. I.

    2016-07-01

    We present a new form of semiconducting graphene grown on C-face silicon carbide, SiC(0001), seeded with a sub-monolayer of nitrogen. This graphene exhibits a gap of 0.3-0.7 eV from the Fermi level to the valence band dependent on lm thickness as measured via angle resolved photo-emission spectroscopy (ARPES). Scanning tunneling microscopy (STM) images imply that the bandgap may be the result of strain-induced confinement. STM indicates that much of the graphene consists of wide at hexagonal plateaus, 8-20 nm2 on average, surrounded by both smooth and disordered folds of length scales from 0.5-2 nm tall, 1-4 nm thick, and 1-20 nm long. The remainder of the surface is covered in smooth or disordered ripples and folds intermixed. Scanning tunneling spectroscopy (STS) measurements on all features show peaks suggestive of Landau levels, and have been analyzed to give pseudo-magnetic field magnitudes. The magnetic lengths associated with these fields are less than the average plateau diameter but comparable to typical fold widths. We consider a growth process whereby the graphene grows pinned to the substrate by the interface nitrogen. The graphene experiences compressive strain as a result of both this pinning as well as competing thermal expansion forces between the substrate and lm. As a result, graphene on nitrogen-seeded SiC has a more concentrated network of strained ripples and folds than seen on C-face SiC graphene without nitrogen.

  6. Soil biochemical properties of grassland ecosystems under anthropogenic emission of nitrogen compounds

    NASA Astrophysics Data System (ADS)

    Kudrevatykh, Irina; Ivashchenko, Kristina; Ananyeva, Nadezhda

    2016-04-01

    Inflow of pollutants in terrestrial ecosystems nowadays increases dramatically, that might be led to disturbance of natural biogeochemical cycles and landscapes structure. Production of nitrogen fertilizers is one of the air pollution sources, namely by nitrogen compounds (NH4+, NO3-, NO2-). Air pollution by nitrogen compounds of terrestrial ecosystems might be affected on soil biochemical properties, which results increasing mineral nitrogen content in soil, changing soil P/N and Al/Ca ratios, and, finally, the deterioration of soil microbial community functioning. The research is focused on the assessment of anthropogenic emission of nitrogen compounds on soil properties of grassland ecosystems in European Russia. Soil samples (Voronic Chernozem Pachic, upper 10 cm mineral layer, totally 10) were taken from grassland ecosystem: near (5-10 m) nitrogen fertilizer factory (NFF), and far from it (20-30 km, served as a control) in Tula region. In soil samples the NH4+ and NO3- (Kudeyarov's photocolorimetric method), P, Ca, Al (X-ray fluorescence method) contents were measured. Soil microbial biomass carbon (Cmic) was analyzed by substrate-induced respiration method. Soil microbial respiration (MR) was assessed by CO2 rate production. Soil microbial metabolic quotient (qCO2) was calculated as MR/Cmic ratio. Near NFF the soil ammonium and nitrate nitrogen contents were a strongly varied, variation coefficient (CV) was 42 and 86This study was supported by Russian Foundation of Basic Research Grant No. 14-04-00098, 15-44-03220, 15-04-00915.

  7. Effects of Soil Warming and Nitrogen Addition on Soil Respiration in a New Zealand Tussock Grassland

    PubMed Central

    Graham, Scott L.; Hunt, John E.; Millard, Peter; McSeveny, Tony; Tylianakis, Jason M.; Whitehead, David

    2014-01-01

    Soil respiration (RS) represents a large terrestrial source of CO2 to the atmosphere. Global change drivers such as climate warming and nitrogen deposition are expected to alter the terrestrial carbon cycle with likely consequences for RS and its components, autotrophic (RA) and heterotrophic respiration (RH). Here we investigate the impacts of a 3°C soil warming treatment and a 50 kg ha−1 y−1 nitrogen addition treatment on RS, RH and their respective seasonal temperature responses in an experimental tussock grassland. Average respiration in untreated soils was 0.96±0.09 μmol m−2 s−1 over the course of the experiment. Soil warming and nitrogen addition increased RS by 41% and 12% respectively. These treatment effects were additive under combined warming and nitrogen addition. Warming increased RH by 37% while nitrogen addition had no effect. Warming and nitrogen addition affected the seasonal temperature response of RS by increasing the basal rate of respiration (R10) by 14% and 20% respectively. There was no significant interaction between treatments for R10. The treatments had no impact on activation energy (E0). The seasonal temperature response of RH was not affected by either warming or nitrogen addition. These results suggest that the additional CO2 emissions from New Zealand tussock grassland soils as a result of warming-enhanced RS constitute a potential positive feedback to rising atmospheric CO2 concentration. PMID:24621790

  8. Effects of soil warming and nitrogen addition on soil respiration in a New Zealand tussock grassland.

    PubMed

    Graham, Scott L; Hunt, John E; Millard, Peter; McSeveny, Tony; Tylianakis, Jason M; Whitehead, David

    2014-01-01

    Soil respiration (RS) represents a large terrestrial source of CO2 to the atmosphere. Global change drivers such as climate warming and nitrogen deposition are expected to alter the terrestrial carbon cycle with likely consequences for RS and its components, autotrophic (RA) and heterotrophic respiration (RH). Here we investigate the impacts of a 3°C soil warming treatment and a 50 kg ha(-1) y(-1) nitrogen addition treatment on RS, RH and their respective seasonal temperature responses in an experimental tussock grassland. Average respiration in untreated soils was 0.96±0.09 μmol m(-2) s(-1) over the course of the experiment. Soil warming and nitrogen addition increased RS by 41% and 12% respectively. These treatment effects were additive under combined warming and nitrogen addition. Warming increased RH by 37% while nitrogen addition had no effect. Warming and nitrogen addition affected the seasonal temperature response of RS by increasing the basal rate of respiration (R10) by 14% and 20% respectively. There was no significant interaction between treatments for R10. The treatments had no impact on activation energy (E0). The seasonal temperature response of RH was not affected by either warming or nitrogen addition. These results suggest that the additional CO2 emissions from New Zealand tussock grassland soils as a result of warming-enhanced RS constitute a potential positive feedback to rising atmospheric CO2 concentration.

  9. Characterization of La/Fe/TiO₂ and Its Photocatalytic Performance in Ammonia Nitrogen Wastewater.

    PubMed

    Luo, Xianping; Chen, Chunfei; Yang, Jing; Wang, Junyu; Yan, Qun; Shi, Huquan; Wang, Chunying

    2015-11-17

    La/Fe/TiO₂ composite photocatalysts were synthesized by Sol-Gel method and well characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen-physical adsorption, and UV-Vis diffuse reflectance spectra (UV-Vis DRS). It is interesting that the doped catalysts were in anatase phase while the pure TiO₂ was in rutile phase. In addition, the composites possessed better physical chemical properties in photocatalytic activity than pure TiO₂: stronger visible-light-response ability, larger specific surface area, and more regular shape in morphology. The photodegradation results of ammonia nitrogen indicate that: the La/Fe/TiO₂ had higher catalytic activity to ammonia nitrogen waste water compared pure TiO₂ and the other single metal-doped TiO₂. pH 10 and 2 mmol/L H₂O₂ were all beneficial to the removal of ammonia nitrogen by La/Fe/TiO₂. However, the common inorganic ions of Cl(-), NO₃(-), SO₄(2-), HCO₃(-)/CO₃²(-), Na⁺, K⁺, Ca(2+) and Mg(2+) in water all inhibited the degradation of ammonia nitrogen. By balance calculation, at least 20% of ammonia nitrogen was converted to N₂ during the 64.6% removal efficiency of ammonia nitrogen.

  10. Anaerobic ammonium oxidation and its contribution to nitrogen removal in China’s coastal wetlands

    PubMed Central

    Hou, Lijun; Zheng, Yanling; Liu, Min; Li, Xiaofei; Lin, Xianbiao; Yin, Guoyu; Gao, Juan; Deng, Fengyu; Chen, Fei; Jiang, Xiaofen

    2015-01-01

    Over the past several decades, human activities have caused substantial enrichment of reactive nitrogen in China’s coastal wetlands. Although anaerobic ammonium oxidation (anammox), the process of oxidizing ammonium into dinitrogen gas through the reduction of nitrite, is identified as an important process for removing reactive nitrogen, little is known about the dynamics of anammox and its contribution to nitrogen removal in nitrogen-enriched environments. Here, we examine potential rates of anammox and associate them with bacterial diversity and abundance across the coastal wetlands of China using molecular and isotope tracing techniques. High anammox bacterial diversity was detected in China’s coastal wetlands and included Candidatus Scalindua, Kuenenia, Brocadia, and Jettenia. Potential anammox rates were more closely associated with the abundance of anammox bacteria than to their diversity. Among all measured environmental variables, temperature was a key environmental factor, causing a latitudinal distribution of the anammox bacterial community composition, biodiversity and activity along the coastal wetlands of China. Based on nitrogen isotope tracing experiments, anammox was estimated to account for approximately 3.8–10.7% of the total reactive nitrogen removal in the study area. Combined with denitrification, anammox can remove 20.7% of the total external terrigenous inorganic nitrogen annually transported into China’s coastal wetland ecosystems. PMID:26494435

  11. Nitrogen removal in maturation ponds: tracer experiments with 15N-labelled ammonia.

    PubMed

    Camargo Valero, M A; Mara, D D

    2007-01-01

    A primary maturation pond (M1) was spiked with labelled ammonium chloride (15NH4Cl) to track ammonium transformations associated with algal uptake and subsequent sedimentation. Conventional sampling based on grab samples collected from M1 influent, water column and effluent, and processed for unfiltered and filtered TKN, ammonium, nitrite and nitrate, found low total nitrogen removal (8%) and high ammonium nitrogen removal (90%). Stable isotope analysis of 15N from suspended organic and ammonium nitrogen fractions in M1 effluent revealed that labelled ammonium was mainly found in the organic fraction (69% of the 15N recovered), rather than the inorganic fraction (5%). Algal uptake was the predominant pathway for ammonia removal, even though conditions were favourable for ammonia volatilization (8.9 < pH <10.1 units, 15.2 < temperature <18.8 degrees C). Total nitrogen was removed by ammonia volatilization at 15 g N/ha d (3%), organic nitrogen sedimentation at 105 g N/ha d (20%), and in-pond accumulation due to algal uptake at 377 g N/ha d (71%). Algal uptake of ammonium and subsequent sedimentation and retention in the benthic sludge, after partial ammonification of the algal organic nitrogen, is thus likely to be the dominant mechanism for permanent nitrogen removal in maturation ponds during warm summer months in England.

  12. Anaerobic ammonium oxidation and its contribution to nitrogen removal in China’s coastal wetlands

    NASA Astrophysics Data System (ADS)

    Hou, Lijun; Zheng, Yanling; Liu, Min; Li, Xiaofei; Lin, Xianbiao; Yin, Guoyu; Gao, Juan; Deng, Fengyu; Chen, Fei; Jiang, Xiaofen

    2015-10-01

    Over the past several decades, human activities have caused substantial enrichment of reactive nitrogen in China’s coastal wetlands. Although anaerobic ammonium oxidation (anammox), the process of oxidizing ammonium into dinitrogen gas through the reduction of nitrite, is identified as an important process for removing reactive nitrogen, little is known about the dynamics of anammox and its contribution to nitrogen removal in nitrogen-enriched environments. Here, we examine potential rates of anammox and associate them with bacterial diversity and abundance across the coastal wetlands of China using molecular and isotope tracing techniques. High anammox bacterial diversity was detected in China’s coastal wetlands and included Candidatus Scalindua, Kuenenia, Brocadia, and Jettenia. Potential anammox rates were more closely associated with the abundance of anammox bacteria than to their diversity. Among all measured environmental variables, temperature was a key environmental factor, causing a latitudinal distribution of the anammox bacterial community composition, biodiversity and activity along the coastal wetlands of China. Based on nitrogen isotope tracing experiments, anammox was estimated to account for approximately 3.8-10.7% of the total reactive nitrogen removal in the study area. Combined with denitrification, anammox can remove 20.7% of the total external terrigenous inorganic nitrogen annually transported into China’s coastal wetland ecosystems.

  13. Characterization of La/Fe/TiO2 and Its Photocatalytic Performance in Ammonia Nitrogen Wastewater

    PubMed Central

    Luo, Xianping; Chen, Chunfei; Yang, Jing; Wang, Junyu; Yan, Qun; Shi, Huquan; Wang, Chunying

    2015-01-01

    La/Fe/TiO2 composite photocatalysts were synthesized by Sol-Gel method and well characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen-physical adsorption, and UV-Vis diffuse reflectance spectra (UV-Vis DRS). It is interesting that the doped catalysts were in anatase phase while the pure TiO2 was in rutile phase. In addition, the composites possessed better physical chemical properties in photocatalytic activity than pure TiO2: stronger visible-light-response ability, larger specific surface area, and more regular shape in morphology. The photodegradation results of ammonia nitrogen indicate that: the La/Fe/TiO2 had higher catalytic activity to ammonia nitrogen waste water compared pure TiO2 and the other single metal-doped TiO2. pH 10 and 2 mmol/L H2O2 were all beneficial to the removal of ammonia nitrogen by La/Fe/TiO2. However, the common inorganic ions of Cl−, NO3−, SO42−, HCO3−/CO32−, Na+, K+, Ca2+ and Mg2+ in water all inhibited the degradation of ammonia nitrogen. By balance calculation, at least 20% of ammonia nitrogen was converted to N2 during the 64.6% removal efficiency of ammonia nitrogen. PMID:26593929

  14. Anaerobic ammonium oxidation and its contribution to nitrogen removal in China's coastal wetlands.

    PubMed

    Hou, Lijun; Zheng, Yanling; Liu, Min; Li, Xiaofei; Lin, Xianbiao; Yin, Guoyu; Gao, Juan; Deng, Fengyu; Chen, Fei; Jiang, Xiaofen

    2015-10-23

    Over the past several decades, human activities have caused substantial enrichment of reactive nitrogen in China's coastal wetlands. Although anaerobic ammonium oxidation (anammox), the process of oxidizing ammonium into dinitrogen gas through the reduction of nitrite, is identified as an important process for removing reactive nitrogen, little is known about the dynamics of anammox and its contribution to nitrogen removal in nitrogen-enriched environments. Here, we examine potential rates of anammox and associate them with bacterial diversity and abundance across the coastal wetlands of China using molecular and isotope tracing techniques. High anammox bacterial diversity was detected in China's coastal wetlands and included Candidatus Scalindua, Kuenenia, Brocadia, and Jettenia. Potential anammox rates were more closely associated with the abundance of anammox bacteria than to their diversity. Among all measured environmental variables, temperature was a key environmental factor, causing a latitudinal distribution of the anammox bacterial community composition, biodiversity and activity along the coastal wetlands of China. Based on nitrogen isotope tracing experiments, anammox was estimated to account for approximately 3.8-10.7% of the total reactive nitrogen removal in the study area. Combined with denitrification, anammox can remove 20.7% of the total external terrigenous inorganic nitrogen annually transported into China's coastal wetland ecosystems.

  15. Elimination of nitrogen present in swine manure using a high-efficiency biotrickling filter.

    PubMed

    Raby, Karine; Ramirez, Antonio Avalos; Heitz, Michèle

    2013-01-01

    Experiments were performed to remove nitrogen as ammonium in biotrickling filters (BTFs) treating synthetic swine manure. Two BTFs packed with polypropylene spheres and ceramic beads were used. BTFs were continuously fed, and leachate obtained was recirculated at different flow rates in the range from 0 to 1.5 L min(-1). When increasing the recirculation flow rate, the carbon dioxide (CO2) production rate increased from 16.5 to 25.6 g CO2 m(-3) h(-1) and nitrogen elimination decreased from 99% to 86% for the polypropylene spheres, whereas for the ceramic beads the CO2 production rate decreased from 20.3 to 15.0 g CO2 m(-3) h(-1) and nitrogen removal from 99% to 90%. The increase of recirculation flow rates also promoted the production of nitrite (NO2(-)) in the leachate. For both packing types, when increasing nitrogen loads from 60 to 240 g N m(-3) day(-1) without recirculation of leachate, the BTFs achieved nitrogen removals of more than 99%. For the same nitrogen loads, nitrogen removal increased from 90% to 99% for the BTF packed with ceramic beads at a recirculation flow rate of 0.6 L min(-1). Operating the BTFs with continuous purge was optimal for biomass production with a maximum level of 71.0 g m(-3) day(-1).

  16. Proteomic analysis for low and high nitrogen-responsive proteins in the leaves of rice genotypes grown at three nitrogen levels.

    PubMed

    Hakeem, Khalid Rehman; Chandna, Ruby; Ahmad, Altaf; Qureshi, Mohd Irfan; Iqbal, Muhammad

    2012-10-01

    Nitrogen (N) is an essential nutrient for plants. Increase in crop production is associated with increase in N fertilizers. Excessive use of N fertilizers and the low nitrogen utilization efficiency by crop plants is a major cause for environmental damage. Therefore, to reduce the N-fertilizer pollution, there is an urgent need to improve nitrogen use efficiency. Identification and/or development of genotypes which can grow and yield well at low nitrogen levels may provide a solution. Understanding the molecular mechanism of differential nitrogen use efficiency of the genotypes may provide some clues. Keeping the above facts in mind, in this study we have identified the high N-responsive and low N-responsive contrasting rice genotypes, out of 20 genotypes that were grown at low (1 mM), moderate (10 mM), and high (25 mM) levels of N (KNO(3)). Proteome analysis of leaves revealed that the proteins involved in the energy production/regulation and metabolism in plant leaf tissues are differentially expressed under N treatments. Moreover, some disease-resistant and stress-induced proteins were found to be overexpressed at high levels of N. The present study could be useful in identifying proteins responding to different levels of nitrogen fertilization, which may open new avenues for a better understanding of N use efficiency, and for developing new strategies to enhance N efficiency in cereal crops.

  17. Proteins as nitrogen source for plants

    PubMed Central

    Smolander, Aino; Kitunen, Veikko; Godlewski, Mirosław

    2010-01-01

    Interest in the problem of plant nitrogen nutrition is increasing. Certain plants can use not only inorganic nitrogen but also intact amino acids and short peptides. According to our studies, the roots of several agricultural and wild-living plants are able to exude proteases and use them to create a pool of accessible N. This mini-review offers an overview of the problem of protease exudation by plant roots and its potential role in plant nitrogen nutrition. PMID:20505350

  18. Evaluation of a spacecraft nitrogen generator

    NASA Technical Reports Server (NTRS)

    Marshall, R. D.; Knebel, W. J.

    1977-01-01

    An experiment was completed to demonstrate that low ammonia concentrations in the product nitrogen stream are possible using the staging concept. Mixtures of nitrogen, hydrogen and ammonia were fed into a temperature controlled packed bed ammonia dissociator. An ammonia concentration of 1.03% in the feed stream was reduced to less than 50 ppm at temperatures greater than or equal to 777K. The actual inlet ammonia concentration to the final nitrogen generation module ammonia dissociation stage was only 0.09%.

  19. Temperature, plant species and residence time effects on nitrogen removal in model treatment wetlands.

    PubMed

    Allen, C R; Stein, O R; Hook, P B; Burr, M D; Parker, A E; Hafla, E C

    2013-01-01

    Total nitrogen (TN) removal in treatment wetlands (TWs) is challenging due to nitrogen cycle complexity and the variation of influent nitrogen species. Plant species, season, temperature and hydraulic loading most likely influence root zone oxygenation and appurtenant nitrogen removal, especially for ammonium-rich wastewater. Nitrogen data were collected from two experiments utilizing batch-loaded (3-, 6-, 9- and 20-day residence times), sub-surface TWs monitored for at least one year during which temperature was varied between 4 and 24 °C. Synthetic wastewater containing 17 mg/l N as NH4 and 27 mg/l amino-N, 450 mg/l chemical oxygen demand (COD), and 13 mg/l SO4-S was applied to four replicates of Carex utriculata, Schoenoplectus acutus and Typha latifolia and unplanted controls. Plant presence and species had a greater effect on TN removal than temperature or residence time. Planted columns achieved approximately twice the nitrogen removal of unplanted controls (40-95% versus 20-50% removal) regardless of season and temperature. TWs planted with Carex outperformed both Typha and Schoenoplectus and demonstrated less temperature dependency. TN removal with Carex was excellent at all temperatures and residence times; Schoenoplectus and Typha TN removal improved at longer residence times. Reductions in TN were not accompanied by increases in NO3, which was consistently below 1 mg/l N.

  20. Indirect and direct determination of the casein content of milk by Kjeldahl nitrogen analysis: collaborative study.

    PubMed

    Lynch, J M; Barbano, D M; Fleming, J R

    1998-01-01

    The classic method for determination of milk casein is based on precipitation of casein at pH 4.6. Precipitated milk casein is removed by filtration and the nitrogen content of either the precipitate (direct casein method) or filtrate (noncasein nitrogen; NCN) is determined by Kjeldahl analysis. For the indirect casein method, milk total nitrogen (TN; Method 991.20) is also determined and casein is calculated as TN minus NCN. Ten laboratories tested 9 pairs of blind duplicate raw milk materials with a casein range of 2.42-3.05% by both the direct and indirect casein methods. Statistical performance expressed in protein equivalents (nitrogen x 6.38) with invalid and outlier data removed was as follows: NCN method (wt%), mean = 0.762, sr = 0.010, sR = 0.016, repeatability relative standard deviation (RSDr) = 1.287%, reproducibility relative standard deviation (RSDr) = 2.146%; indirect casein method (wt%), mean = 2.585, repeatability = 0.015, reproducibility = 0.022, RSDr = 0.560%, RSDR = 0.841; direct casein method (wt%), mean = 2.575, sr = 0.015, sR = 0.025, RSDr = 0.597%, RSDR = 0.988%. Method performance was acceptable and comparable to similar Kjeldahl methods for determining nitrogen content of milk (Methods 991.20, 991.21, 991.22, 991.23). The direct casein, indirect casein, and noncasein nitrogen methods have been adopted by AOAC INTERNATIONAL.

  1. Application of nitrogen-alloyed martensitic stainless steels in the aviation industry

    SciTech Connect

    Stein, G.; Kirschner, W.; Lueg, J.

    1997-12-31

    Nitrogen in stainless martensitic steels has a beneficial influence on the mechanical as well as on the chemical properties. However the effect of nitrogen is limited due to the rather low solubility of this element. A special alloy development in combination with a pressurized melting technique lead to distinctly higher nitrogen contents. Stainless martensitic steels containing high nitrogen contents are manufactured by VSG today on an industrial scale using the PESR-process (Pressurized Electroslag Remelting). Depending on special applications these steels are available with different chemical analysis under the trademark CRONIDUR. The basic composition of all CRONIDUR-alloys consists of about 15% Chromium, 1% Molybdenum, 0.15 to 0.35% Carbon and 0.20 to 0.40% Nitrogen. The combination of Cr + Mo + N leads to a superior corrosion resistance of these HNS-steels (HNS: High Nitrogen Steels) in comparison to similar carbon based alloys. Focused on applications with a required minimum hardness of 58 HRC, like stainless bearings or screw shafts, the C+N-content is tuned between 0.60 and 0.80% (Brand: CRONIDUR 30). Additions of max. 0.3% Vanadium and 0.1% Niobium qualifies the brand CRONIDUR 20 for enhanced temperature applications like turbine disks or blades.

  2. Occurrence and transport of nitrogen in the Big Sunflower River, northwestern Mississippi, October 2009-June 2011

    USGS Publications Warehouse

    Barlow, Jeannie R.B.; Coupe, Richard H.

    2014-01-01

    ammonia and nitrate plus nitrite; conversely, at sites farther downstream (that is, at Sunflower and Anguilla), nitrate plus nitrite concentrations were generally higher than concentrations of organic nitrogen and ammonia. In addition to the routinely collected samples, water samples from the Big Sunflower River Basin were collected using a Lagrangian sampling scheme, which attempts to follow a single mass of water through time in order to determine how it changes through processing or other pathways as the water moves downstream. Lagrangian sampling was conducted five times during the study period: (1) April 8–21, 2010, (2) May 12–June 3, 2010, (3) June 15–July 1, 2010, (4) August 23–30, 2010, and (5) May 16–20, 2011. Streamflow conditions were variable for each sampling event because of input from local precipitation and irrigation return flow, and streamflow losses through the streambed. Streamflow and total nitrogen flux increased with drainage area, and the dominant form of nitrogen varied with drainage area size and temporally across sampling events. Results from each method indicate relatively conservative transport of nitrogen within the 160 miles between Clarksdale and Anguilla, providing further validation of the SPARROW models. Furthermore, these results suggest relatively conservative transport of nitrogen from the Big Sunflower River to the Gulf of Mexico and, therefore, imply a fairly close association of nutrient application and export from the Big Sunflower River Basin to the Mississippi River. However, within the Big Sunflower River Basin, two potential nitrogen sinks were identified and include the transport and potential transformation of nitrogen through the streambed and the sequestration and potential transformation of nitrogen above the drainage control structures downstream of Anguilla. By coupling these potential loss mechanisms with nitrogen transport dynamics, it may be possible to further reduce the amount of nitrogen leaving the Big

  3. Nitrogen on Mars: Insights from Curiosity

    NASA Technical Reports Server (NTRS)

    Stern, J. C.; Sutter, B.; Jackson, W. A.; Navarro-Gonzalez, Rafael; McKay, Chrisopher P.; Ming, W.; Archer, P. Douglas; Glavin, D. P.; Fairen, A. G.; Mahaffy, Paul R.

    2017-01-01

    Recent detection of nitrate on Mars indicates that nitrogen fixation processes occurred in early martian history. Data collected by the Sample Analysis at Mars (SAM) instrument on the Curiosity Rover can be integrated with Mars analog work in order to better understand the fixation and mobility of nitrogen on Mars, and thus its availability to putative biology. In particular, the relationship between nitrate and other soluble salts may help reveal the timing of nitrogen fixation and post-depositional behavior of nitrate on Mars. In addition, in situ measurements of nitrogen abundance and isotopic composition may be used to model atmospheric conditions on early Mars.

  4. Nitrogen related shallow thermal donors in silicon

    NASA Astrophysics Data System (ADS)

    Fujita, N.; Jones, R.; Öberg, S.; Briddon, P. R.

    2007-07-01

    In this letter, the authors investigate the electrical properties of nitrogen related shallow thermal donor (STD) candidates and their concentrations under different doping conditions by means of density functional theory. Experimentally, the existence of STDs containing one nitrogen atom and both even and odd numbers of oxygen atoms has been proposed. However, so far first principles studies have not presented a candidate for the latter. Here, they show that the NO defect possesses a shallow donor level. Adding one or two more oxygen atoms results in the donor level to become shallower. The fraction of shallow nitrogen related donors to N dimers increases in material with low concentration of nitrogen.

  5. Characterization of organic nitrogen in IBCSP coals

    SciTech Connect

    Kruge, M.A.

    1991-01-01

    The overall objective of this study was to determine the content and distribution of organic nitrogen in a series of IBCSP coals and their isolated macerals. The specific objectives were: to determine the bulk nitrogen contents for coals, isolated macerals, oxidation products and residues, solvent extracts and their liquid chromatographic fractions, and pyrolyzates; to determine the distribution of organic nitrogen in all coal derivatives enumerated in Objective 1 which are Gas Chromatography (GC)-amenable. This will be accomplished by GC-Thermionic Specific Detectors; to determine the molecular structure of the major nitrogen compounds detected in Objective 2, using mass spectrometry.

  6. Modeling reactive nitrogen in North America: recent ...

    EPA Pesticide Factsheets

    Nitrogen is an essential building block of all proteins and thus an essential nutrient for all life. The bulk of nitrogen in the environment is tightly bound as non-reactive N2. Reactive nitrogen, which is naturally produced via enzymatic reactions, forest fires and lightning, is continually recycled and cascades through air, water, and soil media (Galloway et al., 2003). Human activity has perturbed this cycle through the combustion of fossil fuels and synthesis of fertilizers. The anthropogenic contribution to this cycle is now larger than natural sources in the United States and globally (Galloway et al., 2004). Reactive nitrogen enters the biosphere primarily from emissions of oxidized nitrogen to the atmosphere from combustion sources, as inorganic fertilizer applied to crops as reduced nitrogen fixed from atmospheric N2 through the Haber-Bosch process, as organic fertilizers such as manure, and through the cultivation of nitrogen fixing crops (Canfield et al., 2010). Both the United States (US) Clean Air Act and the Canadian Environmental Protection Act (CEPA) have substantially reduced the emissions of oxidized nitrogen in North America through NOx controls on smokestacks and exhaust pipes (Sickles and Shadwick, 2015; AQA, 2015). However, reduced nitrogen emissions have remained constant during the last few decades of emission reductions. The National Exposure Research Laboratory’s Atmospheric Modeling Division (AMAD) c

  7. Nitrogen ion clusters in Triton's atmosphere

    NASA Technical Reports Server (NTRS)

    Delitsky, Mona L.; Turco, Richard P.; Jacobson, Mark Z.

    1990-01-01

    The nitrogen ion chemistry that controls Triton's ionospheric composition and may be responsible for the hazes detected by the Voyager spacecraft are discussed. In particular, it is shown that nitrogen cluster ion formation should readily occur in Triton's thin cold atmosphere. The very low temperatures of Triton's atmosphere imply that these clustered ions can nucleate into solid nitrogen particles, creating the extended visible hazes. A model based on the chemical kinetics of nitrogen ions predicts a dense ionosphere at 200-400 km, as detected by Voyager radio occultation measurements.

  8. Substantial nitrogen pollution embedded in international trade

    NASA Astrophysics Data System (ADS)

    Oita, Azusa; Malik, Arunima; Kanemoto, Keiichiro; Geschke, Arne; Nishijima, Shota; Lenzen, Manfred

    2016-02-01

    Anthropogenic emissions of reactive nitrogen to the atmosphere and water bodies can damage human health and ecosystems. As a measure of a nation’s contribution to this potential damage, a country’s nitrogen footprint has been defined as the quantity of reactive nitrogen emitted during the production, consumption and transportation of commodities consumed within that country, whether those commodities are produced domestically or internationally. Here we use global emissions databases, a global nitrogen cycle model, and a global input-output database of domestic and international trade to calculate the nitrogen footprints for 188 countries as the sum of emissions of ammonia, nitrogen oxides and nitrous oxide to the atmosphere, and of nitrogen potentially exportable to water bodies. Per-capita footprints range from under 7 kg N yr-1 in some developing countries to over 100 kg N yr-1 in some wealthy nations. Consumption in China, India, the United States and Brazil is responsible for 46% of global emissions. Roughly a quarter of the global nitrogen footprint is from commodities that were traded across country borders. The main net exporters have significant agricultural, food and textile exports, and are often developing countries, whereas important net importers are almost exclusively developed economies. We conclude that substantial local nitrogen pollution is driven by demand from consumers in other countries.

  9. The Asian nitrogen cycle case study.

    PubMed

    Zheng, Xunhua; Fu, Congbin; Xu, Xingkai; Yan, Xiaodong; Huang, Yao; Han, Shenghui; Hu, Fei; Chen, Guanxiong

    2002-03-01

    We analyzed nitrogen budgets at national and regional levels on a timeline from 1961-2030 using a model, IAP-N 1.0. The model was designed based upon the Inter-governmental Panel on Climate Change (IPCC) methods using Asia-specific parameters and a Food and Agriculture Organization of the United Nations (FAO) database. In this paper we discuss new reactive-nitrogen and its various fates, and environmental nitrogen enrichment and its driving forces. The anthropogenic reactive nitrogen of Asia dramatically increased from approximately 14.4 Tg N yr-1 in 1961 to approximately 67.7 Tg N yr-1 in 2000 and is likely to be 105.3 Tg N yr-1 by 2030. Most of the anthropogenic reactive-nitrogen has accumulated in the environment. We found that an increasing demand for food and energy supplies and the lack of effective measures to improve the efficiency of fertilizer nitrogen use, as well as effective measures for the prevention of NOx emissions from fossil-fuel combustion, are the principal drivers behind the environmental nitrogen-enrichment problem. This problem may be finally solved by substituting synthetic nitrogen fertilizers with new high-efficiency nitrogen sources, but solutions are dependent on advances in biological technology.

  10. Nitrogen availability in tropical forests of Brazil

    NASA Astrophysics Data System (ADS)

    Martinelli, L. A.

    2015-12-01

    Nitrogen availability is considered to be high in tropical forest, especially in relation to temperate forests. However, there is among tropical forest a significant variability in nutrient concentrations and stocks either in soils as well as in the vegetation. Here we review the nitrogen distribution and availability in more than 60 forest sites encompassing different soil types and precipitation regimes of the two main tropical forests biomes of Brazil: the Amazon and the Atlantic Forest. We aimed to determine factors that control nitrogen availability in these forests, using as a proxy of such availability parameters like: foliar and soil nitrogen concentrations, nitrogen stable isotopic composition, and foliar nitrogen:phosphorus ratio. Our main hypothesis is that nitrogen availability will be higher in forest where dry-season precipitation is low and/or weathered old soils prevailed. On the contrary, tropical forests over young soils and/or precipitation is high over the year will have a lower nitrogen availability and will be more phosphorus than nitrogen limited.

  11. The social costs of nitrogen

    PubMed Central

    Keeler, Bonnie L.; Gourevitch, Jesse D.; Polasky, Stephen; Isbell, Forest; Tessum, Chris W.; Hill, Jason D.; Marshall, Julian D.

    2016-01-01

    Despite growing recognition of the negative externalities associated with reactive nitrogen (N), the damage costs of N to air, water, and climate remain largely unquantified. We propose a comprehensive approach for estimating the social cost of nitrogen (SCN), defined as the present value of the monetary damages caused by an incremental increase in N. This framework advances N accounting by considering how each form of N causes damages at specific locations as it cascades through the environment. We apply the approach to an empirical example that estimates the SCN for N applied as fertilizer. We track impacts of N through its transformation into atmospheric and aquatic pools and estimate the distribution of associated costs to affected populations. Our results confirm that there is no uniform SCN. Instead, changes in N management will result in different N-related costs depending on where N moves and the location, vulnerability, and preferences of populations affected by N. For example, we found that the SCN per kilogram of N fertilizer applied in Minnesota ranges over several orders of magnitude, from less than $0.001/kg N to greater than $10/kg N, illustrating the importance of considering the site, the form of N, and end points of interest rather than assuming a uniform cost for damages. Our approach for estimating the SCN demonstrates the potential of integrated biophysical and economic models to illuminate the costs and benefits of N and inform more strategic and efficient N management. PMID:27713926

  12. BELOWGROUND NITROGEN UPTAKE AND ALLOCATION ...

    EPA Pesticide Factsheets

    Anthropogenic nitrogen inputs coupled with rising sea level complicate predictions of marsh stability. As marsh stability is a function of its vegetation, it is important to understand the mechanisms that drive community dynamics. Many studies have examined aboveground dynamics and nutrient cycling, but few have studied the belowground uptake and allocation of nitrogen. Literature suggests that D. spicata may dominate the marsh platform in nutrient-rich conditions, though the mechanism driving the vegetation shift is unclear. Our study examines belowground nutrient uptake and allocation underlying these patterns. To determine whether D. spicata is a more efficient scavenger of nutrients than S. alterniflora we performed a 15N pulse-chase experiment. Tracer was added to mesocosms growing D. spicata and S. alterniflora in monoculture. After the initial pulse, a subset of pots were sacrificed weekly and partitioned into detailed depth intervals for 15N analysis of several belowground pools: live coarse and fine roots, live rhizomes, dead organic matter, and bulk sediment. Comparisons between D. spicata and S. alterniflora uptake and allocation can explain mechanisms of competitive advantage and predictions of D. spicata dominance. Additionally, we used denitrification enzyme assays (DEA) and greenhouse gas slurries to quantify denitrification rates and potentials. Initial results suggest that the vegetation types support similar N-relevant microbial communities. Th

  13. Nitrogen management in bioreactor landfills

    SciTech Connect

    Price, G. Alexander; Barlaz, Morton A.; Hater, Gary R

    2003-07-01

    One scenario for long-term nitrogen management in landfills is ex situ nitrification followed by denitrification in the landfill. The objective of this research was to measure the denitrification potential of actively decomposing and well decomposed refuse. A series of 10-l reactors that were actively producing methane were fed 400 mg NO{sub 3}-N /l every 48 h for periods of 19-59 days. Up to 29 nitrate additions were either completely or largely depleted within 48 h of addition and the denitrification reactions did not adversely affect the leachate pH. Nitrate did inhibit methane production, but the reactors recovered their methane-producing activity with the termination of nitrate addition. In well decomposed refuse, the nitrate consumption rate was reduced but was easily stimulated by the addition of either acetate or an overlayer of fresh refuse. Addition of acetate at five times the amount required to reduce nitrate did not lead to the production of NH{sub 4}{sup +} by dissimilatory nitrate reduction. The most probable number of denitrifying bacteria decreased by about five orders of magnitude during refuse decomposition in a reactor that did not receive nitrate. However, rapid denitrification commenced immediately with nitrate addition. This study shows that the use of a landfill as a bioreactor for the conversion of nitrate to a harmless byproduct, nitrogen gas, is technically viable.

  14. The social costs of nitrogen.

    PubMed

    Keeler, Bonnie L; Gourevitch, Jesse D; Polasky, Stephen; Isbell, Forest; Tessum, Chris W; Hill, Jason D; Marshall, Julian D

    2016-10-01

    Despite growing recognition of the negative externalities associated with reactive nitrogen (N), the damage costs of N to air, water, and climate remain largely unquantified. We propose a comprehensive approach for estimating the social cost of nitrogen (SCN), defined as the present value of the monetary damages caused by an incremental increase in N. This framework advances N accounting by considering how each form of N causes damages at specific locations as it cascades through the environment. We apply the approach to an empirical example that estimates the SCN for N applied as fertilizer. We track impacts of N through its transformation into atmospheric and aquatic pools and estimate the distribution of associated costs to affected populations. Our results confirm that there is no uniform SCN. Instead, changes in N management will result in different N-related costs depending on where N moves and the location, vulnerability, and preferences of populations affected by N. For example, we found that the SCN per kilogram of N fertilizer applied in Minnesota ranges over several orders of magnitude, from less than $0.001/kg N to greater than $10/kg N, illustrating the importance of considering the site, the form of N, and end points of interest rather than assuming a uniform cost for damages. Our approach for estimating the SCN demonstrates the potential of integrated biophysical and economic models to illuminate the costs and benefits of N and inform more strategic and efficient N management.

  15. 20 CFR 225.20 - General.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DETERMINATIONS PIA's Used in Computing Survivor Annuities and the Amount of the Residual Lump-Sum Payable § 225.20 General. The Survivor Tier I PIA and the Employee RIB PIA are used in computing the tier I component of a survivor annuity. The Combined Earnings PIA, Social Security Earnings PIA and Railroad...

  16. 20 CFR 401.20 - Scope.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... § 401.20 Scope. (a) Access. Sections 401.30 through 401.95, which set out SSA's rules for implementing... contained in SSA's program records are set out in §§ 401.100 through 401.200 of this part. These regulations also apply to the disclosure of other Federal program information which SSA maintains. That information...

  17. 20 CFR 401.20 - Scope.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... § 401.20 Scope. (a) Access. Sections 401.30 through 401.95, which set out SSA's rules for implementing... contained in SSA's program records are set out in §§ 401.100 through 401.200 of this part. These regulations also apply to the disclosure of other Federal program information which SSA maintains. That information...

  18. 20 CFR 401.20 - Scope.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... § 401.20 Scope. (a) Access. Sections 401.30 through 401.95, which set out SSA's rules for implementing... contained in SSA's program records are set out in §§ 401.100 through 401.200 of this part. These regulations also apply to the disclosure of other Federal program information which SSA maintains. That information...

  19. 20 CFR 401.20 - Scope.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... § 401.20 Scope. (a) Access. Sections 401.30 through 401.95, which set out SSA's rules for implementing... contained in SSA's program records are set out in §§ 401.100 through 401.200 of this part. These regulations also apply to the disclosure of other Federal program information which SSA maintains. That information...

  20. Characterization of sputtered zirconium nitride films deposited at various argon:nitrogen ratio

    NASA Astrophysics Data System (ADS)

    Patel, Nicky P.; Chauhan, Kamlesh V.; Kapopara, Jaydeep M.; Jariwala, Nayan N.; Rawal, Sushant K.

    2016-09-01

    Zirconium nitride films were deposited by reactive magnetron sputtering using argon as inert gas and nitrogen as reactive gas. The nitrogen flow rate in argon:nitrogen ratio was increased from 4sccm to 20sccm by an increment of 4sccm. The effect of increment in nitrogen flow rate on various properties of deposited zirconium nitride films are reported in this paper. The structural characterization was done by X-Ray diffraction which confirms (011) peak of Zr3N4 and a very low intensity (111) peak of Zr3N4. Optical properties was investigated by Uv-Vis-NIR spectrophotometer which showed that the films were transparent and maximum transmittance observed was around 82%. The wettability properties was investigated by contact angle goniometer which showed the films were hydrophobic and maximum contact angle achieved was 99.50.

  1. Experimental thermal conductivity, thermal diffusivity, and specific heat values for mixtures of nitrogen, oxygen, and argon

    NASA Technical Reports Server (NTRS)

    Perkins, R. A.; Cieszkiewicz, M. T.

    1991-01-01

    Experimental measurements of thermal conductivity and thermal diffusivity obtained with a transient hot-wire apparatus are reported for three mixtures of nitrogen, oxygen, and argon. Values of the specific heat, Cp, are calculated from these measured values and the density calculated with an equation of state. The measurements were made at temperatures between 65 and 303 K with pressures between 0.1 and 70 MPa. The data cover the vapor, liquid, and supercritical gas phases for the three mixtures. The total reported points are 1066 for the air mixture (78.11 percent nitrogen, 20.97 percent oxygen, and 0.92 percent argon), 1058 for the 50 percent nitrogen, 50 percent oxygen mixture, and 864 for the 25 percent nitrogen, 75 oxygen mixture. Empirical thermal conductivity correlations are provided for the three mixtures.

  2. Effects of sublethal ammonia on nitrogen metabolism of rainbow trout in relation to temperature

    SciTech Connect

    Linton, T.K.; Reid, S.D.; Wood, C.M.

    1994-12-31

    This 90 day study was designed to assess the effects of sublethal ammonia at ambient water temperature and at ambient + 2C on juvenile rainbow trout. A challenge experiment was then conducted to test whether prior sublethal exposure induced increased ammonia tolerance. Routine ``in-tank`` oxygen consumption and nitrogenous waste excretion rates were measured monthly as well as plasma ammonia, muscle and liver ammonia and urea, and liver protein turnover rates to quantify the physiological effects of this treatment on nitrogen metabolism. The results indicate that +20C had little effect on nitrogen metabolism until the summer maximum of 21 C was reached, and that chronic exposure to 70 {mu}mol/L total ammonia led to alterations in nitrogen metabolism which contributed to the reduction of the increased internal ammonia load. However, the alterations associated with exposure to sublethal ammonia did not lead to a greater tolerance of fish exposed to 5,700 {mu}mol/L total ammonia.

  3. Modifications of Superconducting Properties of Niobium Caused by Nitrogen Doping Recipes for High Q Cavities

    SciTech Connect

    Vostrikov, Alexander; Checchin, Mattia; Grassellino, Anna; Kim, Young-Kee; Romanenko, Alexander

    2015-06-01

    A study is presented on the superconducting properties of niobium used for the fabrication of the SRF cavities after treating by recently discovered nitrogen doping methods. Cylindrical niobium samples have been subjected to the standard surface treatments applied to the cavities (electro-polishing, l 20°C bake) and compared with samples treated by additional nitrogen doping recipes routinely used to reach ultra-high quality factor values (>3· 1010 at 2 K, 16 MV/m). The DC magnetization curves and the complex magnetic AC susceptibility have been measured. Evidence for the lowered field of first flux penetration after nitrogen doping is found suggesting a correlation with the lowered quench fields. Superconducting critical temperatures Tc = 9.25 K are found to be in agreement with previous measurements, and no strong effect on the critical surface field (Bd) from nitrogen doping was found.

  4. The Influence of Nitrogen on the Biological Properties of Soil Contaminated with Zinc.

    PubMed

    Strachel, Rafał; Wyszkowska, Jadwiga; Baćmaga, Małgorzata

    2017-03-01

    This study analyzed the relationship between nitrogen fertilization and the biological properties of soil contaminated with zinc. The influence of various concentrations of zinc and nitrogen on the microbiological and biochemical activity of soil was investigated. In a laboratory experiment, loamy sand with pHKCl 5.6 was contaminated with zinc (ZnCl2) and fertilized with urea as a source of nitrogen. The activity of acid phosphatase, alkaline phosphatase, urease and β-glucosidase, and microbial counts were determined in soil samples after 2 and 20 weeks of incubation. Zinc generally stimulated hydrolase activity, but the highest zinc dose (1250 mg kg(-1)) led to the inhibition of hydrolases. Nitrogen was not highly effective in neutralizing zinc's negative effect on enzyme activity, but it stimulated the growth of soil-dwelling microorganisms. The changes in soil acidity observed after the addition of urea modified the structure of microbial communities.

  5. Removal of nitrate-nitrogen from drinking water using bamboo powder charcoal.

    PubMed

    Mizuta, Kei; Matsumoto, Toshitatsu; Hatate, Yasuo; Nishihara, Keiichi; Nakanishi, Tomoki

    2004-12-01

    The adsorption effectiveness of bamboo powder charcoal (BPC); made from the residual of Moso bamboo manufacturing; in removing nitrate-nitrogen from water has been investigated. Commercial activated carbon (CAC) was also used to compare the effectiveness of adsorption in removal of nitrate-nitrogen. The adsorption effectiveness of BPC was higher than that of CAC; regardless of the concentration of nitrate-nitrogen; in the range of 0-10 mg/l. The effect of temperature on adsorption by BPC and CAC in the range of 10-20 degrees C was also investigated. From the results, it was found that the temperature dependency of the adsorption effectiveness of BPC was weaker than that of CAC. This fact indicates that BPC can be an attractive option for the in situ treatment by adsorption of nitrate-nitrogen-contaminated underground and surface water.

  6. Wet and dry atmospheric depositions of inorganic nitrogen during plant growing season in the coastal zone of Yellow River Delta.

    PubMed

    Yu, Junbao; Ning, Kai; Li, Yunzhao; Du, Siyao; Han, Guangxuan; Xing, Qinghui; Wu, Huifeng; Wang, Guangmei; Gao, Yongjun

    2014-01-01

    The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing season in the coastal zone of the Yellow River Delta (YRD) using automatic sampling equipment. The results showed that SO4 (2-) and Na(+) were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m(-2), in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3 (-)-N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4 (+)-N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3 (-)-N and NH4 (+)-N was ~31.38% and ~20.50% for the contents of NO3 (-)-N and NH4 (+)-N in 0-10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal zone of the YRD.

  7. Wet and Dry Atmospheric Depositions of Inorganic Nitrogen during Plant Growing Season in the Coastal Zone of Yellow River Delta

    PubMed Central

    Li, Yunzhao; Du, Siyao; Han, Guangxuan; Xing, Qinghui; Wu, Huifeng; Wang, Guangmei

    2014-01-01

    The ecological problems caused by dry and wet deposition of atmospheric nitrogen have been widespread concern in the world. In this study, wet and dry atmospheric depositions were monitored in plant growing season in the coastal zone of the Yellow River Delta (YRD) using automatic sampling equipment. The results showed that SO42− and Na+ were the predominant anion and cation, respectively, in both wet and dry atmospheric depositions. The total atmospheric nitrogen deposition was ~2264.24 mg m−2, in which dry atmospheric nitrogen deposition was about 32.02%. The highest values of dry and wet atmospheric nitrogen deposition appeared in May and August, respectively. In the studied area, NO3−–N was the main nitrogen form in dry deposition, while the predominant nitrogen in wet atmospheric deposition was NH4+–N with ~56.51% of total wet atmospheric nitrogen deposition. The average monthly attribution rate of atmospheric deposition of NO3−–N and NH4+–N was ~31.38% and ~20.50% for the contents of NO3−–N and NH4+–N in 0–10 cm soil layer, respectively, suggested that the atmospheric nitrogen was one of main sources for soil nitrogen in coastal zone of the YRD. PMID:24977238

  8. Effect of nitrogen addition on the structural, electrical, and optical properties of In-Sn-Zn oxide thin films

    NASA Astrophysics Data System (ADS)

    Jia, Junjun; Torigoshi, Yoshifumi; Suko, Ayaka; Nakamura, Shin-ichi; Kawashima, Emi; Utsuno, Futoshi; Shigesato, Yuzo

    2017-02-01

    Indium-tin-zinc oxide (ITZO) films were deposited at various nitrogen flow ratios using magnetron sputtering. At a nitrogen flow ratio of 40%, the structure of ITZO film changed from amorphous, with a short-range-ordered In2O3 phase, to a c-axis oriented InN polycrystalline phase, where InN starts to nucleate from an amorphous In2O3 matrix. Whereas, nitrogen addition had no obvious effect on the structure of indium-gallium-zinc oxide (IGZO) films even at a nitrogen flow ratio of 100%. Nitrogen addition also suppressed the formation of oxygen-related vacancies in ITZO films when the nitrogen flow ratio was less than 20%, and higher nitrogen addition led to an increase in carrier density. Moreover, a red-shift in the optical band edge was observed as the nitrogen flow ratio increased, which could be attributed to the generation of InN crystallites. We anticipate that the present findings demonstrating nitrogen-addition induced structural changes can help to understand the environment-dependent instability in amorphous IGZO or ITZO based thin-film transistors (TFTs).

  9. Optical Detection of Anomalous Nitrogen in Comets

    NASA Astrophysics Data System (ADS)

    2003-12-01

    . Introducing instead the terrestrial ratio for nitrogen-15 (1/272) significantly degrades the fit and thus that ratio can clearly be ruled out in Comet LINEAR. At the time of the VLT observations, the comet was of 9th magnitude, i.e. about 15 times fainter than what can be perceived with the unaided eye. The distance from the Sun was about 180 million km; the distance from the Earth was 186 million km. The observations included calibration spectra of sunlight reflected from the lunar surface; they were used to "subtract" the solar signatures in the comet's spectrum, caused by reflection of sunlight from the dust particles around the comet. As expected, in addition to emission from "normal" CN-molecules ( 12 C 14 N), the UVES data also show emission lines of the 13 C 14 N-molecule that contains the rare isotope carbon-13. The derived 12 C/ 13 C isotopic ratio is 115 ± 20, quite similar to the "standard" solar system value of 89. However, there is also a series of weak features that are positioned exactly at the theoretical wavelengths of emission lines from 12 C 15 N-molecules, cf. PR Photo 28c/03 . The excellent fit that is evident in this diagram proves beyond any doubt the presence of nitrogen-15 in Comet LINEAR and allows a quite accurate determination of the isotopic ratio. The "anomalous" nitrogen isotope ratio in comets In 1997, the same group of astronomers obtained spectra of the (at that time) much brighter Comet Hale-Bopp with the 2.6-m NOT telescope (Roque de los Muchachos Observatory, La Palma, Canary Islands, Spain) in order to investigate the isotopic ratio of carbon-12 to carbon-13. Claude Arpigny remembers: " Interestingly, our spectra of Hale-Bopp showed a number of weak and unidentified emission lines. We later realised that they were positioned close to the theoretical wavelengths of some lines from the 12 C 15 N-molecule. This was a pleasant surprise, as lines from that molecular species were previously believed to be so faint that they would not be

  10. Farmer driven national monitoring of nitrogen concentrations in drainage water in Denmark

    NASA Astrophysics Data System (ADS)

    Piil, Kristoffer; Lemming, Camilla; Kolind Hvid, Søren; Knudsen, Leif

    2014-05-01

    Field drains are often considered to short circuit the hydrological cycle in agricultural catchments and lead to an increased risk of nitrogen loss to the environment. Because of increased regulation of agricultural practices due to catchment management plans, resulting from the implementation of the water frame directive, Danish farmers pushed for a large scale monitoring of nitrogen loss from field drains. Therefore, the knowledge centre for agriculture, Denmark, organized a three year campaign where farmers and local agricultural advisory centres collected water samples from field drains three to five times during the winter season. Samples were analysed for nitrate and total nitrogen. Combined, more than 600 drains were monitored over the three years. During the first two years of monitoring, average winter concentrations of total nitrogen ranged from 0.1 mg N L-1 to 31.1 mg N L-1, and the fraction of total nitrogen present as nitrate ranged from 0% to 100%. This variation is much larger than what is observed in the Danish national monitoring and assessment programme, which monitors only a few drains in selected catchments. Statistical analysis revealed that drainage water nitrogen concentrations were significantly correlated to the cropping system and the landscape type (high ground/lowlands/raised seabed) in which the monitored fields were situated. The average total nitrogen concentration was more than 2 mg N L-1 lower on raised seabed than on high ground, and the average fraction of total nitrogen present as nitrate was more than 20% lower. This indicates that substantial nitrate reduction occurs at or above the drain depth on raised sea flats, in particular in the north of Denmark. This inherent nitrogen retention on raised seabed is not taken into account in the current environmental regulation, nor in the first generation catchment management plans. The monitoring program demonstrated large variation in nitrogen concentrations in drainage water, in

  11. Contributions of secondary forest and nitrogen dynamics to terrestrial carbon uptake

    NASA Astrophysics Data System (ADS)

    Yang, X.; Richardson, T. K.; Jain, A. K.

    2010-04-01

    We use a terrestrial carbon-nitrogen cycle component of the Integrated Science Assessment Model (ISAM) to investigate the impacts of nitrogen dynamics on regrowing secondary forests over the 20th century. We further examine what the impacts of nitrogen deposition and land use change history are on terrestrial carbon uptake since preindustrial time. Our results suggest that global total net land use emissions for the 1990s associated with changes in cropland, pastureland, and wood harvest are 1.22 GtC/yr. Without considering the secondary forest regrowth, the estimated net global total land use emissions are 1.58 GtC/yr or about 0.36 GtC/yr higher than if secondary forest regrowth is considered. Results also show that without considering the nitrogen dynamics and deposition, the estimated global total secondary forest sink for the 1990s is 0.90 GtC/yr or about 0.54 GtC/yr higher than estimates that include the impacts of nitrogen dynamics and deposition. Nitrogen deposition alone is responsible for about 0.13 GtC/yr of the total secondary forest sink. While nitrogen is not a limiting nutrient in the intact primary forests in tropical regions, our study suggests that nitrogen becomes a limiting nutrient for regrowing secondary forests of the tropical regions, in particular Latin America and Tropical Africa. This is because land use change activities, especially wood harvest, removes large amounts of nitrogen from the system when slash is burnt or wood is removed for harvest. However, our model results show that carbon uptake is enhanced in the tropical secondary forests of the Indian region. We argue that this may be due to enhanced nitrogen mineralization and increased nitrogen availability following land use change in the Indian tropical forest ecosystems. Results also demonstrate that there is a significant amount of carbon accumulating in the Northern Hemisphere where most land use changes and forest regrowth has occurred in recent decades. This study indicates

  12. Contributions of secondary forest and nitrogen dynamics to terrestrial carbon uptake

    NASA Astrophysics Data System (ADS)

    Yang, X.; Richardson, T. K.; Jain, A. K.

    2010-10-01

    We use a terrestrial carbon-nitrogen cycle component of the Integrated Science Assessment Model (ISAM) to investigate the impacts of nitrogen dynamics on regrowing secondary forests over the 20th century. We further examine what the impacts of nitrogen deposition and land use change history are on terrestrial carbon uptake since preindustrial time. Our results suggest that global total net land use emissions for the 1990s associated with changes in cropland, pastureland, and wood harvest are 1.22 GtC/yr. Without considering the secondary forest regrowth, the estimated net global total land use emissions are 1.58 GtC/yr or about 0.36 GtC/yr higher than if secondary forest regrowth is considered. Results also show that without considering the nitrogen dynamics and deposition, the estimated global total secondary forest sink for the 1990s is 0.90 GtC/yr or about 0.54 GtC/yr higher than estimates that include the impacts of nitrogen dynamics and deposition. Nitrogen deposition alone is responsible for about 0.13 GtC/yr of the total secondary forest sink. While nitrogen is not a limiting nutrient in the intact primary forests in tropical regions, our study suggests that nitrogen becomes a limiting nutrient for regrowing secondary forests of the tropical regions, in particular Latin America and Tropical Africa. This is because land use change activities, especially wood harvest, removes large amounts of nitrogen from the system when slash is burnt or wood is removed for harvest. However, our model results show that carbon uptake is enhanced in the tropical secondary forests of the Indian region. We argue that this may be due to enhanced nitrogen mineralization and increased nitrogen availability following land use change in the Indian tropical forest ecosystems. Results also demonstrate that there is a significant amount of carbon accumulating in the Northern Hemisphere where most land use changes and forest regrowth has occurred in recent decades. This study indicates

  13. RELATIONSHIPS BETWEEEN NITROGEN LOADING AND CONCENTRATIONS OF NITROGEN AND CHLOROPHYLL IN COASTAL EMBAYMENTS

    EPA Science Inventory

    We describe results obtained with a simple model that uses loading rates of total nitrogen (TN), defined as dissolved inorganic nitrogen plus dissolved and particulate organic nitrogen, to calculate annually and spatially averaged concentrations of TN in coastal embayments. We al...

  14. NITROGEN OUTPUTS FROM FECAL AND URINE DEPOSITION OF SMALL MAMMALS: IMPLICATIONS FOR NITROGEN CYCLING

    EPA Science Inventory

    The contribution of small mammals to nitrogen cycling is poorly understood, but it could have reverberations back to the producer community by maintaining or perhaps magnifying nitrogen availability. Our objective was to model nitrogen outputs (deposition of feces and urine) of ...

  15. The nitrogen footprint tool network: a multi-institution program to reduce nitrogen pollution

    EPA Science Inventory

    Anthropogenic sources of reactive nitrogen have local and global impacts on air and water quality and detrimental effects on human and ecosystem health. This paper uses the nitrogen footprint tool (NFT) to determine the amount of nitrogen (N) released as a result of institutional...

  16. NITROGEN OUTPUTS FROM FECAL AND URINE DEPOSITION OF SMALL MAMMALS: IMPLICATIONS FOR NITROGEN CYCLING

    EPA Science Inventory

    The contribution of small mammals to nitrogen cycling is poorly understood, but it could have reverberations back to the producer community by maintaining or perhaps magnifying nitrogen availability. Our objective was to model nitrogen outputs (deposition of feces and urine) of ...

  17. Biological soil crusts accelerate the nitrogen cycle through large NO and HONO emissions in drylands

    PubMed Central

    Wu, Dianming; Tamm, Alexandra; Ruckteschler, Nina; Rodríguez-Caballero, Emilio; Meusel, Hannah; Elbert, Wolfgang; Behrendt, Thomas; Sörgel, Matthias; Cheng, Yafang; Crutzen, Paul J.; Su, Hang; Pöschl, Ulrich

    2015-01-01

    Reactive nitrogen species have a strong influence on atmospheric chemistry and climate, tightly coupling the Earth’s nitrogen cycle with microbial activity in the biosphere. Their sources, however, are not well constrained, especially in dryland regions accounting for a major fraction of the global land surface. Here, we show that biological soil crusts (biocrusts) are emitters of nitric oxide (NO) and nitrous acid (HONO). Largest fluxes are obtained by dark cyanobacteria-dominated biocrusts, being ∼20 times higher than those of neighboring uncrusted soils. Based on laboratory, field, and satellite measurement data, we obtain a best estimate of ∼1.7 Tg per year for the global emission of reactive nitrogen from biocrusts (1.1 Tg a−1 of NO-N and 0.6 Tg a−1 of HONO-N), corresponding to ∼20% of global nitrogen oxide emissions from soils under natural vegetation. On continental scales, emissions are highest in Africa and South America and lowest in Europe. Our results suggest that dryland emissions of reactive nitrogen are largely driven by biocrusts rather than the underlying soil. They help to explain enigmatic discrepancies between measurement and modeling approaches of global reactive nitrogen emissions. As the emissions of biocrusts strongly depend on precipitation events, climate change affecting the distribution and frequency of precipitation may have a strong impact on terrestrial emissions of reactive nitrogen and related climate feedback effects. Because biocrusts also account for a large fraction of global terrestrial biological nitrogen fixation, their impacts should be further quantified and included in regional and global models of air chemistry, biogeochemistry, and climate. PMID:26621714

  18. Biological soil crusts accelerate the nitrogen cycle through large NO and HONO emissions in drylands.

    PubMed

    Weber, Bettina; Wu, Dianming; Tamm, Alexandra; Ruckteschler, Nina; Rodríguez-Caballero, Emilio; Steinkamp, Jörg; Meusel, Hannah; Elbert, Wolfgang; Behrendt, Thomas; Sörgel, Matthias; Cheng, Yafang; Crutzen, Paul J; Su, Hang; Pöschl, Ulrich

    2015-12-15

    Reactive nitrogen species have a strong influence on atmospheric chemistry and climate, tightly coupling the Earth's nitrogen cycle with microbial activity in the biosphere. Their sources, however, are not well constrained, especially in dryland regions accounting for a major fraction of the global land surface. Here, we show that biological soil crusts (biocrusts) are emitters of nitric oxide (NO) and nitrous acid (HONO). Largest fluxes are obtained by dark cyanobacteria-dominated biocrusts, being ∼20 times higher than those of neighboring uncrusted soils. Based on laboratory, field, and satellite measurement data, we obtain a best estimate of ∼1.7 Tg per year for the global emission of reactive nitrogen from biocrusts (1.1 Tg a(-1) of NO-N and 0.6 Tg a(-1) of HONO-N), corresponding to ∼20% of global nitrogen oxide emissions from soils under natural vegetation. On continental scales, emissions are highest in Africa and South America and lowest in Europe. Our results suggest that dryland emissions of reactive nitrogen are largely driven by biocrusts rather than the underlying soil. They help to explain enigmatic discrepancies between measurement and modeling approaches of global reactive nitrogen emissions. As the emissions of biocrusts strongly depend on precipitation events, climate change affecting the distribution and frequency of precipitation may have a strong impact on terrestrial emissions of reactive nitrogen and related climate feedback effects. Because biocrusts also account for a large fraction of global terrestrial biological nitrogen fixation, their impacts should be further quantified and included in regional and global models of air chemistry, biogeochemistry, and climate.

  19. Tunneling ionization of vibrationally excited nitrogen molecules

    NASA Astrophysics Data System (ADS)

    Kornev, Aleksei S.; Zon, Boris A.

    2015-09-01

    Ionization of molecular nitrogen plays an important role in the process of light-filament formation in air. In the present paper we theoretically investigated tunneling ionization of the valence 3 σg and 1 πu shells in a N2 molecule using a strong near-infrared laser field. This research is based on our previously proposed theory of anti-Stokes-enhanced tunneling ionization with quantum accounting for the vibrationally excited states of the molecules [A. S. Kornev and B. A. Zon, Phys. Rev. A 86, 043401 (2012), 10.1103/PhysRevA.86.043401]. We demonstrated that if the N2 molecule is ionized from the ground vibrational state, then the contribution of the 1 πu orbital is 0.5%. In contrast, for vibrationally excited states with a certain angle between the light polarization vector and the molecule axis, both shells can compete and even reverse their contributions due to the anti-Stokes mechanism. The structure constants of molecular orbitals are extracted from numerical solutions to the Hartree-Fock equations. This approach correctly takes into account the exchange interaction. Quantum consideration of vibrational motion results in the occurrence of the critical vibrational state, the tunneling ionization from which has the maximum rate. The numbers of the critical vibrational states are different for different valence shells. In addition, quantum description of vibrations changes the rate of ionization from the ground vibrational state by 20%-40% in comparison with the quasiclassical results.

  20. Nitrogen supply system based on hydrazine dissociation

    NASA Technical Reports Server (NTRS)

    Heppner, D. B.; Quattrone, P. D.

    1981-01-01

    Future long-duration manned space missions will require a method of generating N2 for cabin leakage makeup and repressurization. Life Systems, working with NASA, is developing a Nitrogen Supply Subsystem (NSS) based on the dissociation of N2H4 into a mixture of H2 and N2. The latter is separated to provide the makeup N2. Recent advances in specific hardware developments have resulted in the design and fabrication of a nominal 3.6 kg/day N2 generation module. The design integrates a N2H4 catalytic dissociator, three ammonia (NH3) dissociation stages and four H2 separation stages into a 33 kg, 14 cu dm module. A technique has been devised to alternate the NH3 dissociation and H2 separation stages to give high N2 purity in the product stream. Tests have shown the product stream to contain less than 0.5 percent H2 and 20 ppm NH3. This paper discusses the development and test activities of the NSS program. It reviews the design, configuration, operation and projected performance characteristics of a 4.4 kg/day NSS suitable for NASA's planned Space Operations Center.

  1. Nitrogen speciation in mantle and crustal fluids

    NASA Astrophysics Data System (ADS)

    Li, Yuan; Keppler, Hans

    2014-03-01

    Seventy-nine experiments have been carried out at 600-1400 °C, 2-35 kbar, and oxygen fugacities ranging from the Fe-FeO to the Re-ReO2 buffer to investigate the nitrogen speciation in mantle and crustal N-H-O fluids. Laser Raman analyses of fluid inclusions trapped in situ in quartz and olivine crystals show that N2 and/or NH3 are the only detectable nitrogen species in the fluids at the conditions of the present study. The results further show that in the fluids of the oxidized shallow upper mantle, nitrogen is mostly present as N2, while in the deep reduced upper mantle, NH3 is the dominant nitrogen species. Nitrogen speciation in subduction zone fluids is also calculated from the experimental data to constrain the efficiency of nitrogen recycling. The data show that a hot, oxidized slab is an efficient barrier for deep nitrogen subduction, while a cold, reduced slab would favor recycling nitrogen into the deep mantle. The nitrogen species in magmatic fluids of mid-ocean ridge basalt and arc magmas are predominantly N2, but a significant fraction of nitrogen can be NH3 at certain conditions. The nitrogen species in fluids released from the solidifying magma ocean and the reduced young mantle may have been mostly NH3. The release of such fluids may have created a reduced atmosphere on the every early Earth, with an elevated concentration of NH3. This may not only resolve the faint young Sun paradox but may also have created favorable conditions for the formation of biomolecules through Miller-Urey type reactions.

  2. Mechanisms of nitrogen retention in forest ecosystems - A field experiment

    NASA Technical Reports Server (NTRS)

    Vitousek, P. M.; Matson, P. A.

    1984-01-01

    Intensive forest management led to elevated losses of nitrogen from a recently harvested loblolly pine plantation in North Carolina. Measurements of nitrogen-15 retention in the field demonstrated that microbial uptake of nitrogen during the decomposition of residual organic material was the most important process retaining nitrogen. Management practices that remove this material cause increased losses of nitrogen to aquatic ecosystems and the atmosphere.

  3. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Urea nitrogen test system. 862.1770 Section 862....1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to measure urea nitrogen (an end-product of nitrogen metabolism) in whole blood, serum, plasma, and...

  4. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Urea nitrogen test system. 862.1770 Section 862....1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to measure urea nitrogen (an end-product of nitrogen metabolism) in whole blood, serum, plasma, and...

  5. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Urea nitrogen test system. 862.1770 Section 862....1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to measure urea nitrogen (an end-product of nitrogen metabolism) in whole blood, serum, plasma, and...

  6. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Urea nitrogen test system. 862.1770 Section 862....1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to measure urea nitrogen (an end-product of nitrogen metabolism) in whole blood, serum, plasma, and...

  7. 21 CFR 862.1770 - Urea nitrogen test system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Urea nitrogen test system. 862.1770 Section 862....1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to measure urea nitrogen (an end-product of nitrogen metabolism) in whole blood, serum, plasma, and...

  8. Mechanisms of nitrogen retention in forest ecosystems - A field experiment

    NASA Technical Reports Server (NTRS)

    Vitousek, P. M.; Matson, P. A.

    1984-01-01

    Intensive forest management led to elevated losses of nitrogen from a recently harvested loblolly pine plantation in North Carolina. Measurements of nitrogen-15 retention in the field demonstrated that microbial uptake of nitrogen during the decomposition of residual organic material was the most important process retaining nitrogen. Management practices that remove this material cause increased losses of nitrogen to aquatic ecosystems and the atmosphere.

  9. Dark Stomatal Movement in Sunflowers in Response to Illumination under Nitrogen.

    PubMed

    Couchat, P; Lasceve, G; Audouin, P

    1982-04-01

    Experiments were performed on intact sunflowers (Helianthus annuus) placed in a specially designed experimental chamber which allows instantaneous modifications of the atmospheric composition without changing any other conditions. After one night in normal conditions, the plant was illuminated under pure nitrogen atmosphere; the opening stomatal movement, measured as a transpiration rate variation, was inhibited. After an anoxia time period not exceeding one hour, the light was turned off and normal air restored. The stomatal movement was no longer inhibited, and a transient increase in the transpiration rate, referred to here as the postillumination transpiration peak (PITP), was observed.The quantity of transpired water during the PITP can be related to the total incident light energy supplied during the light-nitrogen period. Furthermore, the addition of a dark-nitrogen period between the light-nitrogen and dark-air periods caused the PITP to decrease. The PITP is almost suppressed after a 20-minute dark-nitrogen period.It is shown that the PITP does not result from a hydropassive mechanism but is metabolically controlled. Moreover, it seems that the PITP is not due to a CO(2)-suppression effect during the light-nitrogen period.The results are interpreted in terms of stomatal mechanism. The metabolites leading to PITP originate from the reducing equivalents created during the light-nitrogen period. They could be synthesized at the beginning of the PITP period (darkness under normal air) or during the dark-nitrogen plus CO(2) period between the light-nitrogen and PITP periods. The results obtained are related to the first steps of classical photoactive stomatal opening.

  10. Removal efficiency and balance of nitrogen in a recirculating aquaculture system integrated with constructed wetlands.

    PubMed

    Zhong, Fei; Liang, Wei; Yu, Tao; Cheng, Shui P; He, Feng; Wu, Zhen B

    2011-01-01

    The nitrogen (N) balance for aquaculture is an important aspect, especially in China, and it is attributed to the eutrophication in many freshwater bodies. In recent years, constructed wetlands (CWs) have been widely used in wastewater treatment and ecosystem restoration. A recirculating aquaculture system (RAS) consisting of CWs and 4 fish ponds was set up in Wuhan, China. Channel catfish (Ictalurus punctatus) fingerlings were fed for satiation daily for 168 days with 2 diets containing 5.49 % and 6.53 % nitrogen, respectively. The objectives of this study were to investigate the N budget in the RAS, and try to find out the feasibility of controlling N accumulation in the fish pond. It is expected that the study can provide a mass balance for the fate of N in the eco-friendly treatment system to avoid eutrophication. The results showed that the removal rates of ammonia (NH(+)(4)-N), sum of nitrate & nitrite (NO(-)(X)-N), and total nitrogen (TN) by the CWs were 20-55%, 38-84 % and 39-57 %, respectively. Denitrification in the CWs was the main pathway of nitrogen loss (41.67 %). Nitrogen accumulation in pond water and sediment accounted for 3.39 % and 12.65 % of total nitrogen loss, respectively. The nitrogen removal efficiency and budget showed that the CW could be used to control excessive nitrogen accumulation in fish ponds. From the viewpoint of the nitrogen pollution control, the RAS combined with the constructed wetland can be applied to ensure the sustainable development for aquaculture.

  11. Nitrogen Out of the Bottle: The Challenge of Managing the Genie

    NASA Astrophysics Data System (ADS)

    Galloway, J. N.

    2012-12-01

    Human activity converts more N2 to reactive nitrogen (Nr; all nitrogen species other than N2) than do natural terrestrial processes (mostly biological nitrogen fixation (BNF) in unmanaged ecosystems). Most of the Nr is created as a consequence of food production, fossil fuel combustion and industry. The Haber-Bosch process, invented in the early 20th century, now provides a virtually inexhaustible supply of nitrogen fertilizer. This one invention is responsible for the existence of about half of the world's population. That's the good news. The other news is that most of this nitrogen (and additional amounts from fossil fuel combustion and industry) is lost to the environment where it has exceeded the ability of the environment to convert it back to unreactive N2. The accumulating Nr contributes to smog, greenhouse effect, ecosystem eutrophication, acid rain and loss of stratospheric ozone in a sequential manner—the nitrogen cascade. Collectively these changes alter climate, decrease air quality, and diminish ecosystem sustainability. The challenge is how do we manage the genie—make sure we get the benefits of nitrogen, while minimizing the problems it causes. The paper will layout the possible, the probable and the improbable (but if it occurred, would be transformative) options for nitrogen management. Included will be the role that a nation vs. a person should play. The paper will also give examples of success stories, where nitrogen losses to the environment have been decreased, without impacting the service being provided—food and energy production. The paper will conclude with a forecast to the future, based upon the RCP scenarios for 2100.

  12. From roots to globe: How the terrestrial nitrogen cycle alters the global carbon cycle?

    NASA Astrophysics Data System (ADS)

    Shi, M.; Fisher, J. B.; Brzostek, E. R.; Phillips, R.

    2014-12-01

    Plants typically expend a significant portion of their available carbon for nitrogen (N) acquisition, especially through root exudation in N-limited soils; this is the amount of carbon that would otherwise go to growth in the presence of ample N. Most global terrestrial biogeochemistry models (TBMs) do not consider the carbon cost for N acquisition. In order to evaluate the carbon-nitrogen trade process and improve the carbon­-nitrogen dynamics in TBMs, this study integrates a cutting-edge global plant nitrogen model—Fixation and Uptake of Nitrogen (FUN) version 2.0 (FUN2.0) into the Community Land Model 4.0. The coupled model (i.e., CLM4CN-FUN2.0) is tested at local and global scales. Generally, plant N acquisition is dynamically simulated, and the carbon cost for N acquisition is estimated by the coupled model. Sensitivity tests indicate that the low soil N uptakes of the coupled model are associated with the low soil mineral N amount represented by CLM4CN. According to the observational evidence, the retranslocated N pool in CLM4CN needs to be combined with other non-structural N pools. These deficiencies in the model open new possibilities for improving TBMs, which is widely used in global climate change studies.

  13. Optical properties of hydroxyethyl cellulose film treated with nitrogen plasma

    NASA Astrophysics Data System (ADS)

    Mahmoud, K. H.

    2016-03-01

    Hydroxyethyl cellulose (HEC) film has been prepared by casting technique. The prepared sample has been treated with nitrogen plasma at different exposure times. The optical absorption was recorded at room temperature in the wavelength range of 200-800 nm. Absorbance fitting procedure curves revealed a direct allowed transition with optical band gap, Eopt, of 4.9 eV for pristine film, and this value decreases to 4.30 eV for 20 min plasma treatment time. The band tail values (Ee) were found to be increased under plasma time treatment from 1.74 eV in case of the pristine film to 2.20 eV for 20 min. The dispersion of refractive index and complex dielectric constants under plasma treatment was also studied. Variation of color parameters under effect of the plasma treatment is analyzed in the framework of CIE L*U*V* color space.

  14. Biodegradation of the High Explosive Hexanitrohexaazaiso-wurtzitane (CL-20)

    PubMed Central

    Karakaya, Pelin; Christodoulatos, Christos; Koutsospyros, Agamemnon; Balas, Wendy; Nicolich, Steve; Sidhoum, Mohammed

    2009-01-01

    The aerobic biodegradability of the high explosive CL-20 by activated sludge and the white rot fungus Phanerochaete chrysosporium has been investigated. Although activated sludge is not effective in degrading CL-20 directly, it can mineralize the alkaline hydrolysis products. Phanerochaete chrysosporium degrades CL-20 in the presence of supplementary carbon and nitrogen sources. Biodegradation studies were conducted using various nutrient media under diverse conditions. Variables included the CL-20 concentration; levels of carbon (as glycerol) and ammonium sulfate and yeast extract as sources of nitrogen. Cultures that received CL-20 at the time of inoculation transformed CL-20 completely under all nutrient conditions studied. When CL-20 was added to pre-grown cultures, degradation was limited. The extent of mineralization was monitored by the 14CO2 time evolution; up to 51% mineralization was achieved when the fungus was incubated with [14C]-CL-20. The kinetics of CL-20 biodegradation by Phanerochaete chrysosporium follows the logistic kinetic growth model. PMID:19440524

  15. Intercropping enhances soil carbon and nitrogen.

    PubMed

    Cong, Wen-Feng; Hoffland, Ellis; Li, Long; Six, Johan; Sun, Jian-Hao; Bao, Xing-Guo; Zhang, Fu-Suo; Van Der Werf, Wopke

    2015-04-01

    Intercropping, the simultaneous cultivation of multiple crop species in a single field, increases aboveground productivity due to species complementarity. We hypothesized that intercrops may have greater belowground productivity than sole crops, and sequester more soil carbon over time due to greater input of root litter. Here, we demonstrate a divergence in soil organic carbon (C) and nitrogen (N) content over 7 years in a field experiment that compared rotational strip intercrop systems and ordinary crop rotations. Soil organic C content in the top 20 cm was 4% ± 1% greater in intercrops than in sole crops, indicating a difference in C sequestration rate between intercrop and sole crop systems of 184 ± 86 kg C ha(-1) yr(-1). Soil organic N content in the top 20 cm was 11% ± 1% greater in intercrops than in sole crops, indicating a difference in N sequestration rate between intercrop and sole crop systems of 45 ± 10 kg N ha(-1) yr(-1). Total root biomass in intercrops was on average 23% greater than the average root biomass in sole crops, providing a possible mechanism for the observed divergence in soil C sequestration between sole crop and intercrop systems. A lowering of the soil δ(15) N signature suggested that increased biological N fixation and/or reduced gaseous N losses contributed to the increases in soil N in intercrop rotations with faba bean. Increases in soil N in wheat/maize intercrop pointed to contributions from a broader suite of mechanisms for N retention, e.g., complementary N uptake strategies of the intercropped plant species. Our results indicate that soil C sequestration potential of strip intercropping is similar in magnitude to that of currently recommended management practises to conserve organic matter in soil. Intercropping can contribute to multiple agroecosystem services by increased yield, better soil quality and soil C sequestration. © 2014 John Wiley & Sons Ltd.

  16. Cascading costs: an economic nitrogen cycle.

    PubMed

    Moomaw, William R; Birch, Melissa B L

    2005-09-01

    The chemical nitrogen cycle is becoming better characterized in terms of fluxes and reservoirs on a variety of scales. Galloway has demonstrated that reactive nitrogen can cascade through multiple ecosystems causing environmental damage at each stage before being denitrified to N(2). We propose to construct a parallel economic nitrogen cascade (ENC) in which economic impacts of nitrogen fluxes can be estimated by the costs associated with each stage of the chemical cascade. Using economic data for the benefits of damage avoided and costs of mitigation in the Chesapeake Bay basin, we have constructed an economic nitrogen cascade for the region. Since a single ton of nitrogen can cascade through the system, the costs also cascade. Therefore evaluating the benefits of mitigating a ton of reactive nitrogen released needs to consider the damage avoided in all of the ecosystems through which that ton would cascade. The analysis reveals that it is most cost effective to remove a ton of nitrogen coming from combustion since it has the greatest impact on human health and creates cascading damage through the atmospheric, terrestrial, aquatic and coastal ecosystems. We will discuss the implications of this analysis for determining the most cost effective policy option for achieving environmental quality goals.

  17. Cascading costs: an economic nitrogen cycle.

    PubMed

    Moomaw, William R; Birch, Melissa B L

    2005-12-01

    The chemical nitrogen cycle is becoming better characterized in terms of fluxes and reservoirs on a variety of scales. Galloway has demonstrated that reactive nitrogen can cascade through multiple ecosystems causing environmental damage at each stage before being denitrified to N2. We propose to construct a parallel economic nitrogen cascade (ENC) in which economic impacts of nitrogen fluxes can be estimated by the costs associated with each stage of the chemical cascade. Using economic data for the benefits of damage avoided and costs of mitigation in the Chesapeake Bay basin, we have constructed an economic nitrogen cascade for the region. Since a single tonne of nitrogen can cascade through the system, the costs also cascade. Therefore evaluating the benefits of mitigating a tonne of reactive nitrogen released needs to consider the damage avoided in all of the ecosystems through which that tonne would cascade. The analysis reveals that it is most cost effective to remove a tonne of nitrogen coming from combustion since it has the greatest impact on human health and creates cascading damage through the atmospheric, terrestrial, aquatic and coastal ecosystems. We will discuss the implications of this analysis for determining the most cost effective policy option for achieving environmental quality goals.

  18. A reactive nitrogen budget for Lake Michigan

    EPA Science Inventory

    The reactive nitrogen budget for Lake Michigan was reviewed and updated, making use of recent estimates of watershed and atmospheric nitrogen loads. The updated total N load to Lake Michigan was approximately double the previous estimate from the Lake Michigan Mass Balance study ...

  19. Reactive nitrogen emissions from agricultural operations

    USDA-ARS?s Scientific Manuscript database

    Reactive nitrogen is essential to the growth of plants and animals and is typically the most limiting nutrient in agricultural production. While reactive nitrogen in fertilizer has enabled the growing global population to maintain food production, the inefficient and sometimes excessive use of nitro...

  20. Modeling Nitrogen Cycling in Delaware Estuary

    NASA Astrophysics Data System (ADS)

    Tabatabai, A.; Wilkin, J.

    2016-02-01

    Estuaries play a critical role in transforming the biogeochemical properties of water that originates from fluvial sources before it is ultimately discharged to the coastal ocean. Nutrient cycling and export within the Delaware Estuary affect the ecosystem functions both within Delaware Bay and on the adjacent continental shelf. A realistic coupled hydrodynamical-biogeochemical modeling framework was developed for the Delaware Bay using ROMS (Regional Ocean Modeling System; myroms.org) to quantify nitrogen fluxes and budgets. The modeling system includes inert and age tracers to identify water transport pathways. Model skill assessment used a host of in-situ physical and biogeochemical data, and satellite products. The nitrogen budget was estimated for a five-year period of 2007-2011. A large portion of the incoming nitrogen from terrestrial sources is denitrified or buried in the Bay. Positive net ecosystem production contributes to organic nitrogen export to the shelf. There is strong interannual variability in riverine nitrogen inflows, but in years with greater riverine nitrogen input most of the excess nitrogen is buried, denitrified or exported to the shelf; the net ecosystem production shows less variability. By taking advantage of a process-based biogeochemical model and an ensemble of available observed and empirical evidence, this study provides more detailed information about nitrogen fluxes in Delaware Estuary than previously established.

  1. Ambient Ammonium Contribution to total Nitrogen Deposition

    EPA Science Inventory

    There has been a wealth of evidence over the last decade illustrating the rising importance of reduced inorganic nitrogen (NHx = ammonia gas, NH3, plus particulate ammonium, p-NH4) in the overall atmospheric mass balance and deposition of nitrogen as emissions of oxidized nitrog...

  2. EMERGY ANALYSIS OF THE PREHISTORIC NITROGEN CYCLE

    EPA Science Inventory

    Several relationships between the specific emergy or the emergy per unit mass and the mass concentration of nitrogen were shown to exist through an analysis of the global nitrogen cycle. These observed relationships were interpreted by examining the nature of the underlying ener...

  3. AEROBIC DENITRIFICATION: IMPLICATIONS FOR NITROGEN FATE MODELING

    EPA Science Inventory

    In the Mississippi, as well as most nitrogen-degraded rivers and streams, NO3- is the dominant N species and therefore understanding its biogeochemical behavior is critical for accurate nitrogen fate modeling. To our knowledge this is the first work to report aerobic denitrificat...

  4. How to Calculate Your Institution's Nitrogen Footprint

    EPA Science Inventory

    The Nitrogen Footprint Tool (NFT) allows institutions to estimate and manage their nitrogen footprint, and EPA’s Sustainable and Healthy Communities program is supporting an effort to test and expand this approach at multiple colleges, universities and institutions across t...

  5. How to Calculate Your Institution's Nitrogen Footprint

    EPA Science Inventory

    The Nitrogen Footprint Tool (NFT) allows institutions to estimate and manage their nitrogen footprint, and EPA’s Sustainable and Healthy Communities program is supporting an effort to test and expand this approach at multiple colleges, universities and institutions across t...

  6. EMERGY ANALYSIS OF THE PREHISTORIC NITROGEN CYCLE

    EPA Science Inventory

    Several relationships between the specific emergy or the emergy per unit mass and the mass concentration of nitrogen were shown to exist through an analysis of the global nitrogen cycle. These observed relationships were interpreted by examining the nature of the underlying ener...

  7. AEROBIC DENITRIFICATION: IMPLICATIONS FOR NITROGEN FATE MODELING

    EPA Science Inventory

    In the Mississippi, as well as most nitrogen-degraded rivers and streams, NO3- is the dominant N species and therefore understanding its biogeochemical behavior is critical for accurate nitrogen fate modeling. To our knowledge this is the first work to report aerobic denitrificat...

  8. Nitrogen fixation in a coral reef community.

    PubMed

    Wiebe, W J; Johannes, R E; Webb, K L

    1975-04-18

    Algal reef flats at Enewetak Atoll, Marshall Islands, fix atmospheric nitrogen at rates comparable to those in managed agriculture. The dominant nitrogen fixer appears to be the blue-green alga Calothrix crustacea. Since this nutrient enrichment contributes to the high productivity of adjacent coral reefs and undoubtedly to atoll lagoons, it is recommended that the algal reef flats receive increased conservation priority.

  9. Nitrogen Saturation in Temperate Forest Ecosystems

    Treesearch

    John Aber; William McDowell; Knute Nadelhoffer; Alison Magill; Glenn Berntson; Mark Kamakea; Steven McNulty; William Currie; Lindsey Rustad; Ivan Fernandez

    1998-01-01

    Nitrogen emissions to the atmosphere due to human activity remain elevated in industrialized regions of the world and are accelerating in many developing regions (Galloway 1995). Although the deposition of sulfur has been reduced over much of the United States and Europe by aggressive environmental protection policies, current nitrogen deposition reduction targets in...

  10. The Oxides of Nitrogen in Air Pollution.

    ERIC Educational Resources Information Center

    California State Air Resources Board, Sacramento.

    Research on the health effects of oxides of nitrogen and on the role of oxides of nitrogen in producing photochemical smog effects is presented in this report. Prepared by the California State Department of Public Health at the request of the State Legislature, it gives a comprehensive review of available information, as well as the need for air…

  11. Nitrogen loss during solar drying of biosolids

    USDA-ARS?s Scientific Manuscript database

    Solar drying has been used extensively to dewater biosolids for ease of transportation and to a lesser degree to reduce pathogens prior to land application. The nitrogen in biosolids makes it a relatively inexpensive but valuable source of fertilizer. In this study, nitrogen loss from tilled and unt...

  12. A reactive nitrogen budget for Lake Michigan

    EPA Science Inventory

    The reactive nitrogen budget for Lake Michigan was reviewed and updated, making use of recent estimates of watershed and atmospheric nitrogen loads. The updated total N load to Lake Michigan was approximately double the previous estimate from the Lake Michigan Mass Balance study ...

  13. The Nitrogen-Nitride Anode.

    SciTech Connect

    Delnick, Frank M.

    2014-10-01

    Nitrogen gas N 2 can be reduced to nitride N -3 in molten LiCl-KCl eutectic salt electrolyte. However, the direct oxidation of N -3 back to N 2 is kinetically slow and only occurs at high overvoltage. The overvoltage for N -3 oxidation can be eliminated by coordinating the N -3 with BN to form the dinitridoborate (BN 2 -3 ) anion which forms a 1-D conjugated linear inorganic polymer with -Li-N-B-N- repeating units. This polymer precipitates out of solution as Li 3 BN 2 which becomes a metallic conductor upon delithiation. Li 3 BN 2 is oxidized to Li + + N 2 + BN at about the N 2 /N -3 redox potential with very little overvoltage. In this report we evaluate the N 2 /N -3 redox couple as a battery anode for energy storage.

  14. Combuster. [low nitrogen oxide formation

    NASA Technical Reports Server (NTRS)

    Mckay, R. A. (Inventor)

    1978-01-01

    A combuster is provided for utilizing a combustible mixture containing fuel and air, to heat a load fluid such as water or air, in a manner that minimizes the formation of nitrogen oxide. The combustible mixture passes through a small diameter tube where the mixture is heated to its combustion temperature, while the load fluid flows past the outside of the tube to receive heat. The tube is of a diameter small enough that the combustible mixture cannot form a flame, and yet is not subject to wall quench, so that combustion occurs, but at a temperature less than under free flame conditions. Most of the heat required for heating the combustible mixture to its combustion temperature, is obtained from heat flow through the walls of the pipe to the mixture.

  15. Nitrogen tetroxide scrubber data analysis

    NASA Technical Reports Server (NTRS)

    Simon, E. D.

    1978-01-01

    A major difficulty in the analysis of scrubber data is that of separating the physical effects, such as mass transfer, from the physico-chemical effects, such as reaction rates. This is especially true for the absorbtion of nitrogen tetroxide in the various liquids that were tested in the NASA-Kennedy Space Center Hypergolic Toxic Scrubber Program. A fruitful approach to correlating the data for outlet concentrations was to treat the overall absorbtion as a pseudo first-order absorbtion equation. This approach provided a method for normalizing the data to constant inlet concentration, constant sump liquor condition, and constant scrubbing time, and permitted evaluation of the test and fluid parameters that affected both absorbtion rate and scrubbing time. The analysis indicated that scrubber performance may be improved by optimizing liquor concentrations and liquor flowrate distributions.

  16. Nitrogen fixation by marine cyanobacteria.

    PubMed

    Zehr, Jonathan P

    2011-04-01

    Discrepancies between estimates of oceanic N(2) fixation and nitrogen (N) losses through denitrification have focused research on identifying N(2)-fixing cyanobacteria and quantifying cyanobacterial N(2) fixation. Previously unrecognized cultivated and uncultivated unicellular cyanobacteria have been discovered that are widely distributed, and some have very unusual properties. Uncultivated unicellular N(2)-fixing cyanobacteria (UCYN-A) lack major metabolic pathways including the tricarboxylic acid cycle and oxygen-evolving photosystem II. Genomes of the oceanic N(2)-fixing cyanobacteria are highly conserved at the DNA level, and genetic diversity is maintained by genome rearrangements. The major cyanobacterial groups have different physiological and ecological constraints that result in highly variable geographic distributions, with implications for the marine N-cycle budget.

  17. INSENSITIVE HIGH-NITROGEN COMPOUNDS

    SciTech Connect

    D. CHAVEZ; ET AL

    2001-03-01

    The conventional approach to developing energetic molecules is to chemically place one or more nitro groups onto a carbon skeleton, which is why the term ''nitration'' is synonymous to explosives preparation. The nitro group carries the oxygen that reacts with the skeletal carbon and hydrogen fuels, which in turn produces the heat and gaseous reaction products necessary for driving an explosive shock. These nitro-containing energetic molecules typically have heats of formation near zero and therefore most of the released energy is derived from the combustion process. Our investigation of the tetrazine, furazan and tetrazole ring systems has offered a different approach to explosives development, where a significant amount of the chemical potential energy is derived from their large positive heats of formation. Because these compounds often contain a large percentage of nitrogen atoms, they are usually regarded as high-nitrogen fuels or explosives. A general artifact of these high-nitrogen compounds is that they are less sensitive to initiation (e.g. by impact) when compared to traditional nitro-containing explosives of similar performances. Using the precursor, 3,6-bis-(3,5-dimethylpyrazol-1-yl)-s-tetrazine, several useful energetic compounds based on the s-tetrazine system have been synthesized and studied. Some of the first compounds are 3,6-diamino-s-tetrazine-1,4-dioxide (LAX-112) and 3,6-dihydrazino-s-tetrazine (DHT). LAX-112 was once extensively studied as an insensitive explosive by Los Alamos; DHT is an example of a high-nitrogen explosive that relies entirely on its heat of formation for sustaining a detonation. Recent synthesis efforts have yielded an azo-s-tetrazine, 3,3'-azobis(6-amino-s-tetrazine) or DAAT, which has a very high positive heat of formation. The compounds, 4,4'-diamino-3,3'-azoxyfurazan (DAAF) and 4,4'-diamino-3,3'-azofurazan (DAAzF), may have important future roles in insensitive explosive applications. Neither DAAF nor DAAzF can be

  18. Impacts of reactive nitrogen on climate change in China

    PubMed Central

    Shi, Yalan; Cui, Shenghui; Ju, Xiaotang; Cai, Zucong; Zhu, Yong-Guan

    2015-01-01

    China is mobilizing the largest anthropogenic reactive nitrogen (Nr) in the world due to agricultural, industrial and urban development. However, the climate effects related to Nr in China remain largely unclear. Here we comprehensively estimate that the net climate effects of Nr are −100 ± 414 and 322 ± 163 Tg CO2e on a GTP20 and a GTP100 basis, respectively. Agriculture contributes to warming at 187 ± 108 and 186 ± 56 Tg CO2e on a 20-y and 100-y basis, respectively, dominated by long-lived nitrous oxide (N2O) from fertilized soils. On a 20-y basis, industry contributes to cooling at −287 ± 306 Tg CO2e, largely owing to emissions of nitrogen oxides (NOx) altering tropospheric ozone, methane and aerosol concentrations. However, these effects are short-lived. The effect of industry converts to warming at 136 ± 107 Tg CO2e on a 100-y basis, mainly as a result of the reduced carbon (C) sink from the NOx-induced ozone effect on plant damage. On balance, the warming effects of gaseous Nr are partly offset by the cooling effects of N-induced carbon sequestration in terrestrial ecosystems. The large mitigation potentials through reductions in agricultural N2O and industrial NOx will accompany by a certain mitigation pressure from limited N-induced C sequestration in the future. PMID:25631557

  19. Methanotrophs Contribute to Peatland Nitrogen

    NASA Astrophysics Data System (ADS)

    Larmola, Tuula; Leppänen, Sanna M.; Tuittila, Eeva-Stiina; Aarva, Maija; Merilä, Päivi; Fritze, Hannu; Tiirola, Marja

    2016-04-01

    Atmospheric nitrogen (N2) fixation is potentially an important N input mechanism to peatland ecosystems, but the extent of this process may have been underestimated because of the methods traditionally used inhibit the activity of methanothrophs. We examined the linkage of methane (CH4) oxidation and N2 fixation using 15N2 technique. Dominant flark and hummock Sphagnum species were collected from twelve pristine peatlands in Siikajoki, Finland, which varied in age from 200 to 2,500 y due to the postglacial rebound. The mosses were incubated in a two-day field 15N2 and 13CH4 pulse labelling experiment and the incorporation of 15N2 and 13CH4 in biomass was measured with Isotope Ratio Mass Spectrometer. The rates of Sphagnum-associated N2 fixation (0.1-2.9 g N m-2 y-1) were up to 10 times the current N deposition rates. Methane-induced N2 fixation contributed to over 1/3 of moss-associated N2 fixation in younger stages, but was switched off in old successional stages, despite active CH4 oxidation in these stages. Both the N2 fixation rates and the methanotrophic contribution to N2 fixation during peatland succession were primarily constrained by phosphorus availability. Previously overlooked methanotrophic N contribution may explain rapid peat and N accumulation during fen stages of peatland development. Reference. Larmola T., Leppänen S.M., Tuittila E.-S, Aarva M., Merilä P., Fritze H., Tiirola M. (2014) Methanotrophy induces nitrogen fixation during peatland development. Proceedings of the National Academy of Sciences USA 111 (2): 734-739.

  20. Visualizing Individual Nitrogen Dopants in Monolayer Graphene

    SciTech Connect

    Hybertsen, M.S.; Zhao, L.; He, R.; Rim, K.T.; Kim, K.S.; Zhou, H.; Gutierrez, C.; Chockalingam, S.; Arguello, C.; Palova, L.; Reichman, D.R.; Heinz, T.F.; Kim, P.; Pinczuk, A.; Flynn, G.W.; Pasupathy, A.N.

    2011-08-19

    In monolayer graphene, substitutional doping during growth can be used to alter its electronic properties. We used scanning tunneling microscopy, Raman spectroscopy, x-ray spectroscopy, and first principles calculations to characterize individual nitrogen dopants in monolayer graphene grown on a copper substrate. Individual nitrogen atoms were incorporated as graphitic dopants, and a fraction of the extra electron on each nitrogen atom was delocalized into the graphene lattice. The electronic structure of nitrogen-doped graphene was strongly modified only within a few lattice spacings of the site of the nitrogen dopant. These findings show that chemical doping is a promising route to achieving high-quality graphene films with a large carrier concentration.

  1. Atmospheric organic nitrogen deposition explored at workshop

    NASA Astrophysics Data System (ADS)

    Church, Thomas M.

    Atmospheric organic nitrogen (AON) is an important nitrogen component with significant deposition in many natural waters. The range and quality of the data are varied, but deposited organic nitrogen (DON) is ubiquitous globally, both in extent and magnitude.The Environmental Protection Agency's Chesapeake Bay Program (CBP) sponsored a workshop last year to determine what is known about organic nitrogen in atmospheric deposition and to establish research priorities needed to obtain an adequate database for coastal waters such as Chesapeake Bay Working groups at the meeting concluded that AON represents a poorly quantified array of broadly reactive natural and pollutant species; that because of compromises in collection, preservation, and analysis, wet deposition of total organic nitrogen is inadequately quantified and dry deposition is not quantified at all; and that because of a lack of data on bioactive species, the effect of AON and DON on ecosystems is largely unknown.

  2. Visualizing Individual Nitrogen Dopants in Monolayer Graphene

    SciTech Connect

    L Zhao; R He; K Rim; T Schiros; K Kim; H Zhou; C Gutierrez; S Chockalingam; C Arguello; et al.

    2011-12-31

    In monolayer graphene, substitutional doping during growth can be used to alter its electronic properties. We used scanning tunneling microscopy, Raman spectroscopy, x-ray spectroscopy, and first principles calculations to characterize individual nitrogen dopants in monolayer graphene grown on a copper substrate. Individual nitrogen atoms were incorporated as graphitic dopants, and a fraction of the extra electron on each nitrogen atom was delocalized into the graphene lattice. The electronic structure of nitrogen-doped graphene was strongly modified only within a few lattice spacings of the site of the nitrogen dopant. These findings show that chemical doping is a promising route to achieving high-quality graphene films with a large carrier concentration.

  3. Atomic nitrogen measurements in the upper thermosphere

    NASA Technical Reports Server (NTRS)

    Mauersberger, K.; Engebretson, M. J.; Potter, W. E.; Kayser, D. C.; Nier, A. O.

    1977-01-01

    The open source neutral mass spectrometer on board the Atmosphere Explorer satellites measures, besides other neutral constituents, atomic nitrogen densities in the upper thermosphere. Atomic nitrogen combines with atomic oxygen on the walls of the mass spectrometer ion source to form NO. From the measured NO concentration atomic nitrogen is deduced. Studies of the diurnal variation show that the maximum atomic nitrogen densities occur near 1600 local solar time (LST) and minimum densities near 0400 LST. The diurnal amplitude at 300 km is about a factor of 8, which is lower than predicted in present models. Atomic nitrogen also exhibits a pronounced seasonal variation with an amplitude similar to that of the diurnal variation; summer values are considerably higher than winter ones.

  4. Excitation of atomic nitrogen by electron impact

    NASA Technical Reports Server (NTRS)

    Stone, E. J.; Zipf, E. C.

    1972-01-01

    Absolute cross sections were measured for the excitation of the N I(1134, 1164, 1168, 1200, 1243, and 1743 A) multiplets by electron impact on atomic nitrogen. The presence of vibrationally excited molecular nitrogen in the discharged gas was confirmed, and its effect on the measurements is discussed. The ratio of the oscillator strengths of the 1200 and 1134 A resonance transitions is presented, as well as the branching ratio for the N I(1311/1164 A) multiplets. Striking differences in the distribution of intensity between the spectra of atomic nitrogen and molecular nitrogen excited by energetic electrons suggest an optical method for measuring the density of atomic nitrogen in the upper atmosphere.

  5. Development of a nitrogen generation system

    NASA Technical Reports Server (NTRS)

    Heppner, D. B.; Marshall, R. D.; Powell, J. D., III; Schubert, F. H.

    1980-01-01

    An eight-stage nitrogen generation module was developed. The design integrated a hydrazine catalytic dissociator, three ammonia dissociation stages and four palladium/silver hydrogen separator stages. Alternating ammonia dissociation and hydrogen separation stages are used to remove hydrogen and ammonia formed in the dissociation of hydrazine which results in negligible ammonia and hydrogen concentrations in the product nitrogen stream. An engineering breadboard nitrogen supply subsystem was also developed. It was developed as an integratable subsystem for a central spacecraft air revitalization system. The subsystem consists of the hydrazine storage and feed mechanism, the nitrogen generation module, the peripheral mechanical and electrical components required to control and monitor subsystem performance, and the instrumentation required to interface with other subsystems of an air revitalization system. The breadboard nitrogen supply subsystem was integrated and tested with a one-person capacity experimental air revitalization system. The integration, checkout and testing was successfully accomplished.

  6. Reactive nitrogen species in cellular signaling

    PubMed Central

    Adams, Levi; Franco, Maria C

    2015-01-01

    The transduction of cellular signals occurs through the modification of target molecules. Most of these modifications are transitory, thus the signal transduction pathways can be tightly regulated. Reactive nitrogen species are a group of compounds with different properties and reactivity. Some reactive nitrogen species are highly reactive and their interaction with macromolecules can lead to permanent modifications, which suggested they were lacking the specificity needed to participate in cell signaling events. However, the perception of reactive nitrogen species as oxidizers of macromolecules leading to general oxidative damage has recently evolved. The concept of redox signaling is now well established for a number of reactive oxygen and nitrogen species. In this context, the post-translational modifications introduced by reactive nitrogen species can be very specific and are active participants in signal transduction pathways. This review addresses the role of these oxidative modifications in the regulation of cell signaling events. PMID:25888647

  7. Thermal degradation of cereal straws in air and nitrogen

    SciTech Connect

    Ghaly, A.E.; Ergundenler, A.

    1991-12-31

    The termogravimetric behavior of four cereal straws (wheat, barley, oats, and rye) was examined at three heating rates (10, 20, and 50{degrees}C/min) in air and nitrogen atmospheres. The thermal degradation rate in active and passive pyrolysis zones, the initial degradation temperature, and the residual weight at 600{degrees}C were determined for these straws in both atmospheres. Increasing the heating rate increased the thermal degradation rate, and decreased both the initial degradation temperature and the residual weight at 600{degrees}C. The higher the cellulosic content of the straw, the higher the thermal degradation rate and the initial degradation temperature. Also, higher ash content in the straw resulted in higher residual weight at 600{degrees}C. The thermal degradation rate in active pyrolysis zone was lower in air atmosphere than in nitrogen atmosphere, whereas the thermal degradation rate in passive pyrolysis zone and the residual weight at 600{degrees}C were higher in nitrogen atmosphere than in air atmosphere.

  8. Controlled release of alendronate from nitrogen-doped mesoporous carbon

    DOE PAGES

    Saha, Dipendu; Spurri, Amanda; Chen, Jihua; ...

    2016-04-13

    With this study, we have synthesized a nitrogen doped mesoporous carbon with the BET surface area of 1066 m2/g, total pore volume 0.6 cm3/g and nitrogen content of 0.5%. Total alendronate adsorption in this carbon was ~5%. The release experiments were designed in four different media with sequential pH values of 1.2, 4.5, 6.8 and 7.4 for 3, 1, 3 and 5 h, respectively and at 37 °C to imitate the physiological conditions of stomach, duodenum, small intestine and colon, respectively. Release of the drug demonstrated a controlled fashion; only 20% of the drug was released in the media withmore » pH = 1.2, whereas 64% of the drug was released in pH = 7.4. This is in contrary to pure alendronate that was completely dissolved within 30 min in the first release media (pH = 1.2) only. The relatively larger uptake of alendronate in this carbon and its sustained fashion of release can be attributed to the hydrogen bonding between the drug and the nitrogen functionalities on carbon surface. Based on this result, it can be inferred that this formulation may lower the side effects of oral delivery of alendronate.« less

  9. Nitrogen incorporation into lignite humic acids during microbial degradation

    SciTech Connect

    Dong, L.H.; Yuan, H.L.

    2009-07-01

    Previous study showed that nitrogen content in lignite humic acids (HA) increased significantly during lignite biodegradation. In this paper we evaluated the factors responsible for the increased level of N in HA and the formation of new nitrogen compound following microbial degradation. When the ammonium sulfate concentration in lignite medium was 0.5%, the N-content in HA was higher than that in the crude lignite humic acid (cHA); when the ammonium sulfate concentration was epsilon 0.5%, both the biodegraded humic acid (bHA) N-content and the content of bHA in lignite increased significantly, but at 2.0% no increase was observed. This indicated that HA incorporated N existing in the lignite medium, and more HA can incorporate more N with the increase of bHA amount in lignite during microbial degradation. CP/MAS {sup 15}N NMR analysis showed that the N incorporated into HA during biotransformation was in the form of free or ionized NH{sub 2}-groups in amino acids and sugars, as well as NH{sub 4}{sup +}. We propose nitrogen can be incorporated into HA biotically and abiotically. The high N content bHA has a potential application in agriculture since N is essential for plant growth.

  10. Controlled release of alendronate from nitrogen-doped mesoporous carbon

    SciTech Connect

    Saha, Dipendu; Spurri, Amanda; Chen, Jihua; Hensley, Dale K.

    2016-04-13

    With this study, we have synthesized a nitrogen doped mesoporous carbon with the BET surface area of 1066 m2/g, total pore volume 0.6 cm3/g and nitrogen content of 0.5%. Total alendronate adsorption in this carbon was ~5%. The release experiments were designed in four different media with sequential pH values of 1.2, 4.5, 6.8 and 7.4 for 3, 1, 3 and 5 h, respectively and at 37 °C to imitate the physiological conditions of stomach, duodenum, small intestine and colon, respectively. Release of the drug demonstrated a controlled fashion; only 20% of the drug was released in the media with pH = 1.2, whereas 64% of the drug was released in pH = 7.4. This is in contrary to pure alendronate that was completely dissolved within 30 min in the first release media (pH = 1.2) only. The relatively larger uptake of alendronate in this carbon and its sustained fashion of release can be attributed to the hydrogen bonding between the drug and the nitrogen functionalities on carbon surface. Based on this result, it can be inferred that this formulation may lower the side effects of oral delivery of alendronate.

  11. Nitrogen attenuation of terrestrial carbon cycle response to global environmental factors

    USGS Publications Warehouse

    Jain, A.A.; Yang, Xiaojuan; Kheshgi, H.; McGuire, Anthony; Post, W.; Kicklighter, David W.

    2009-01-01

    Nitrogen cycle dynamics have the capacity to attenuate the magnitude of global terrestrial carbon sinks and sources driven by CO2 fertilization and changes in climate. In this study, two versions of the terrestrial carbon and nitrogen cycle components of the Integrated Science Assessment Model (ISAM) are used to evaluate how variation in nitrogen availability influences terrestrial carbon sinks and sources in response to changes over the 20th century in global environmental factors including atmospheric CO2 concentration, nitrogen inputs, temperature, precipitation and land use. The two versions of ISAM vary in their treatment of nitrogen availability: ISAM-NC has a terrestrial carbon cycle model coupled to a fully dynamic nitrogen cycle while ISAM-C has an identical carbon cycle model but nitrogen availability is always in sufficient supply. Overall, the two versions of the model estimate approximately the same amount of global mean carbon uptake over the 20th century. However, comparisons of results of ISAM-NC relative to ISAM-C reveal that nitrogen dynamics: (1) reduced the 1990s carbon sink associated with increasing atmospheric CO2 by 0.53 PgC yr−1 (1 Pg = 1015g), (2) reduced the 1990s carbon source associated with changes in temperature and precipitation of 0.34 PgC yr−1 in the 1990s, (3) an enhanced sink associated with nitrogen inputs by 0.26 PgC yr−1, and (4) enhanced the 1990s carbon source associated with changes in land use by 0.08 PgC yr−1 in the 1990s. These effects of nitrogen limitation influenced the spatial distribution of the estimated exchange of CO2 with greater sink activity in high latitudes associated with climate effects and a smaller sink of CO2 in the southeastern United States caused by N limitation associated with both CO2 fertilization and forest regrowth. These results indicate that the dynamics of nitrogen availability are important to consider in assessing the spatial distribution and temporal dynamics of terrestrial carbon

  12. Nitrogen attenuation of terrestrial carbon cycle response to global environmental factors

    SciTech Connect

    Jain, Atul; Yang, Xiaojuan; Kheshgi, Haroon; Mcguire, David; Post, Wilfred M

    2009-01-01

    Nitrogen cycle dynamics have the capacity to attenuate the magnitude of global terrestrial carbon sinks and sources driven by CO2 fertilization and changes in climate. In this study, two versions of the terrestrial carbon and nitrogen cycle components of the Integrated Science Assessment Model (ISAM) are used to evaluate how variation in nitrogen availability influences terrestrial carbon sinks and sources in response to changes over the 20th century in global environmental factors including atmospheric CO2 concentration, nitrogen inputs, temperature, precipitation and land use. The two versions of ISAM vary in their treatment of nitrogen availability: ISAM-NC has a terrestrial carbon cycle model coupled to a fully dynamic nitrogen cycle while ISAM-C has an identical carbon cycle model but nitrogen availability is always in sufficient supply. Overall, the two versions of the model estimate approximately the same amount of global mean carbon uptake over the 20th century. However, comparisons of results of ISAM-NC relative to ISAM-C reveal that nitrogen dynamics: (1) reduced the 1990s carbon sink associated with increasing atmospheric CO2 by 0.53 PgC yr1 (1 Pg = 1015g), (2) reduced the 1990s carbon source associated with changes in temperature and precipitation of 0.34 PgC yr1 in the 1990s, (3) an enhanced sink associated with nitrogen inputs by 0.26 PgC yr1, and (4) enhanced the 1990s carbon source associated with changes in land use by 0.08 PgC yr1 in the 1990s. These effects of nitrogen limitation influenced the spatial distribution of the estimated exchange of CO2 with greater sink activity in high latitudes associated with climate effects and a smaller sink of CO2 in the southeastern United States caused by N limitation associated with both CO2 fertilization and forest regrowth. These results indicate that the dynamics of nitrogen availability are important to consider in assessing the spatial distribution and temporal dynamics of terrestrial carbon sources and

  13. Atmospheric nitrogen deposition to the northwestern Pacific: seasonal variation and source attribution

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Zhang, L.; Pan, Y.; Wang, Y.; Paulot, F.; Henze, D. K.

    2015-09-01

    Rapid Asian industrialization has led to increased downwind atmospheric nitrogen deposition threatening the marine environment. We present an analysis of the sources and processes controlling atmospheric nitrogen deposition to the northwestern Pacific, using the GEOS-Chem global chemistry model and its adjoint model at 1/2° × 2/3° horizontal resolution over East Asia and its adjacent oceans. We focus our analyses on the marginal seas: the Yellow Sea and the South China Sea. Asian nitrogen emissions in the model are 28.6 Tg N a-1 as NH3 and 15.7 Tg N a-1 as NOx. China has the largest sources with 12.8 Tg N a-1 as NH3 and 7.9 Tg N a-1 as NOx; the high-NH3 emissions reflect its intensive agricultural activities. We find Asian NH3 emissions are a factor of 3 higher in summer than winter. The model simulation for 2008-2010 is evaluated with NH3 and NO2 column observations from satellite instruments, and wet deposition flux measurements from surface monitoring sites. Simulated atmospheric nitrogen deposition to the northwestern Pacific ranges 0.8-20 kg N ha-1 a-1, decreasing rapidly downwind of the Asian continent. Deposition fluxes average 11.9 kg N ha-1 a-1 (5.0 as reduced nitrogen NHx and 6.9 as oxidized nitrogen NOy) to the Yellow Sea, and 5.6 kg N ha-1 a-1 (2.5 as NHx and 3.1 as NOy) to the South China Sea. Nitrogen sources over the ocean (ship NOx and oceanic NH3) have little contribution to deposition over the Yellow Sea, about 7 % over the South China Sea, and become important (greater than 30 %) further downwind. We find that the seasonality of nitrogen deposition to the northwestern Pacific is determined by variations in meteorology largely controlled by the East Asian monsoon and in nitrogen emissions. The model adjoint further estimates that nitrogen deposition to the Yellow Sea originates from sources over China (92 % contribution) and the Korean peninsula (7 %), and by sectors from fertilizer use (24 %), power plants (22 %), and transportation (18

  14. Friction wear and auger analysis of iron implanted with 1.5-MeV nitrogen ions

    NASA Technical Reports Server (NTRS)

    Ferrante, J.; Jones, W. R., Jr.

    1982-01-01

    The effect of implantation of 1.5-MeV nitrogen ions on the friction and wear characteristics of pure iron sliding against steel was studied in a pin-on disk apparatus. An implantation dose of 5 x 10 to the 17th power ions/sq cm was used. Small reductions in initial and steady-state wear rates were observed for nitrogen-implanted iron riders as compared with unimplanted controls. Auger electron spectroscopy revealed a subsurface Gaussian nitrogen distribution with a maximum concentration of 15 at. % at a depth of 8 x 10 to the -7th m. A similar analysis within the wear scar of an implanted rider after 20 microns of wear yielded only background nitrogen concentration, thus giving no evidence for diffusion of nitrogen beyond the implanted range.

  15. Evaluation of the Impact of Alveolar Nitrogen Excretion on Indices Derived from Multiple Breath Nitrogen Washout

    PubMed Central

    Nielsen, Niklas; Nielsen, Jorgen G.; Horsley, Alex R.

    2013-01-01

    Background A large body of evidence has now accumulated describing the advantages of multiple breath washout tests over conventional spirometry in cystic fibrosis (CF). Although the majority of studies have used exogenous sulphur hexafluoride (SF6) as the tracer gas this has also led to an increased interest in nitrogen washout tests, despite the differences between these methods. The impact of body nitrogen excreted across the alveoli has previously been ignored. Methods A two-compartment lung model was developed that included ventilation heterogeneity and dead space (DS) effects, but also incorporated experimental data on nitrogen excretion. The model was used to assess the impact of nitrogen excretion on washout progress and accuracy of functional residual capacity (FRC) and lung clearance index (LCI) measurements. Results Excreted nitrogen had a small effect on accuracy of FRC (1.8%) in the healthy adult model. The error in LCI calculated with true FRC was greater (6.3%), and excreted nitrogen contributed 21% of the total nitrogen concentration at the end of the washout. Increasing DS and ventilation heterogeneity both caused further increase in measurement error. LCI was increased by 6–13% in a CF child model, and excreted nitrogen increased the end of washout nitrogen concentration by 24–49%. Conclusions Excreted nitrogen appears to have complex but clinically significant effects on washout progress, particularly in the presence of abnormal gas mixing. This may explain much of the previously described differences in washout outcomes between SF6 and nitrogen. PMID:24039916

  16. Evaluation of the impact of alveolar nitrogen excretion on indices derived from multiple breath nitrogen washout.

    PubMed

    Nielsen, Niklas; Nielsen, Jorgen G; Horsley, Alex R

    2013-01-01

    A large body of evidence has now accumulated describing the advantages of multiple breath washout tests over conventional spirometry in cystic fibrosis (CF). Although the majority of studies have used exogenous sulphur hexafluoride (SF6) as the tracer gas this has also led to an increased interest in nitrogen washout tests, despite the differences between these methods. The impact of body nitrogen excreted across the alveoli has previously been ignored. A two-compartment lung model was developed that included ventilation heterogeneity and dead space (DS) effects, but also incorporated experimental data on nitrogen excretion. The model was used to assess the impact of nitrogen excretion on washout progress and accuracy of functional residual capacity (FRC) and lung clearance index (LCI) measurements. Excreted nitrogen had a small effect on accuracy of FRC (1.8%) in the healthy adult model. The error in LCI calculated with true FRC was greater (6.3%), and excreted nitrogen contributed 21% of the total nitrogen concentration at the end of the washout. Increasing DS and ventilation heterogeneity both caused further increase in measurement error. LCI was increased by 6-13% in a CF child model, and excreted nitrogen increased the end of washout nitrogen concentration by 24-49%. Excreted nitrogen appears to have complex but clinically significant effects on washout progress, particularly in the presence of abnormal gas mixing. This may explain much of the previously described differences in washout outcomes between SF6 and nitrogen.

  17. [Effects of water deficit and nitrogen fertilization on winter wheat growth and nitrogen uptake].

    PubMed

    Qi, You-Ling; Zhang, Fu-Cang; Li, Kai-Feng

    2009-10-01

    Winter wheat plants were cultured in vitro tubes to study their growth and nitrogen uptake under effects of water deficit at different growth stages and nitrogen fertilization. Water deficit at any growth stages could obviously affect the plant height, leaf area, dry matter accumulation, and nitrogen uptake. Jointing stage was the most sensitive stage of winter wheat growth to water deficit, followed by flowering stage, grain-filling stage, and seedling stages. Rewatering after the water deficit at seedling stage had a significant compensation effect on winter wheat growth, and definite compensation effect was observed on the biomass accumulation and nitrogen absorption when rewatering was made after the water deficit at flowering stage. Under the same nitrogen fertilization levels, the nitrogen accumulation in root with water deficit at seedling, jointing, flowering, and grain-filling stages was reduced by 25.82%, 55.68%, 46.14%, and 16.34%, and the nitrogen accumulation in aboveground part was reduced by 33.37%, 51.71%, 27.01%, and 2.60%, respectively, compared with no water deficit. Under the same water deficit stages, the nitrogen content and accumulation of winter wheat decreased with decreasing nitrogen fertilization level, i. e., 0.3 g N x kg(-1) FM > 0.2 g N x kg(-1) FM > 0.1 g N x kg(-1) FM. Nitrogen fertilization had obvious regulation effect on winter wheat plant growth, dry matter accumulation, and nitrogen uptake under water stress.

  18. Toward a nitrogen footprint calculator for Tanzania

    NASA Astrophysics Data System (ADS)

    Hutton, Mary Olivia; Leach, Allison M.; Leip, Adrian; Galloway, James N.; Bekunda, Mateete; Sullivan, Clare; Lesschen, Jan Peter

    2017-03-01

    We present the first nitrogen footprint model for a developing country: Tanzania. Nitrogen (N) is a crucial element for agriculture and human nutrition, but in excess it can cause serious environmental damage. The Sub-Saharan African nation of Tanzania faces a two-sided nitrogen problem: while there is not enough soil nitrogen to produce adequate food, excess nitrogen that escapes into the environment causes a cascade of ecological and human health problems. To identify, quantify, and contribute to solving these problems, this paper presents a nitrogen footprint tool for Tanzania. This nitrogen footprint tool is a concept originally designed for the United States of America (USA) and other developed countries. It uses personal resource consumption data to calculate a per-capita nitrogen footprint. The Tanzania N footprint tool is a version adapted to reflect the low-input, integrated agricultural system of Tanzania. This is reflected by calculating two sets of virtual N factors to describe N losses during food production: one for fertilized farms and one for unfertilized farms. Soil mining factors are also calculated for the first time to address the amount of N removed from the soil to produce food. The average per-capita nitrogen footprint of Tanzania is 10 kg N yr-1. 88% of this footprint is due to food consumption and production, while only 12% of the footprint is due to energy use. Although 91% of farms in Tanzania are unfertilized, the large contribution of fertilized farms to N losses causes unfertilized farms to make up just 83% of the food production N footprint. In a developing country like Tanzania, the main audiences for the N footprint tool are community leaders, planners, and developers who can impact decision-making and use the calculator to plan positive changes for nitrogen sustainability in the developing world.

  19. Urea fertilizer increases growth of 20-year-old, thinned Douglas-fir on poor quality site

    Treesearch

    Richard E. Miller; Donald L. Reukema

    1977-01-01

    In 20-year-old, site V Douglas-fir in southwest Washington, fertilizing with nitrogen increased average 5-year diameter and height growth of concurrently released dominant trees by about 85 percent. There was no additional response when phosphorus, potassium, and sulfur were added with the nitrogen fertilizer. Thinning with no other treatment in this moderately stocked...

  20. High Energy Cutting and Stripping Utilizing Liquid Nitrogen

    NASA Technical Reports Server (NTRS)

    Hume, Howard; Noah, Donald E.; Hayes, Paul W.

    2005-01-01

    The Aerospace Industry has endeavored for decades to develop hybrid materials that withstand the rigors of mechanized flight both within our atmosphere and beyond. The development of these high performance materials has led to the need for environmentally friendly technologies for material re-work and removal. The NitroJet(TM) is a fluid jet technology that represents an evolution of the widely used, large-scale water jet fluid jet technology. It involves the amalgamation of fluid jet technology and cryogenics technology to create a new capability that is applicable where water jet or abrasive jet (water jet plus entrained abrasive) are not suitable or acceptable because of technical constraints such as process or materials compatibility, environmental concerns and aesthetic or legal requirements. The NitroJet(TM) uses ultra high-pressure nitrogen to cut materials, strip numerous types of coatings such as paint or powder coating, clean surfaces and profile metals. Liquid nitrogen (LN2) is used as the feed stream and is pressurized in two stages. The first stage pressurizes sub cooled LN2 to an intermediate pressure of between 15,000 and 20,000 psi at which point the temperature of the LN2 is about -250 F. The discharge from this stage is then introduced as feed to a dual intensifier system, which boosts the pressure from 15,000 - 20,000 psi up to the maximum operating pressure of 55,000 psi. A temperature of about -220 F is achieved at which point the nitrogen is supercritical. In this condition the nitrogen cuts, strips and abrades much like ultra high-pressure water would but without any residual liquid to collect, remove or be contaminated. Once the nitrogen has performed its function it harmlessly flashes back into the atmosphere as pure nitrogen gas. The system uses heat exchangers to control and modify the temperature of the various intake and discharge nitrogen streams. Since the system is hydraulically operated, discharge pressures can be easily varied over