WorldWideScience

Sample records for atmospheric nitrogen fluorescence

  1. The nitrogen cycle: Atmosphere interactions

    Science.gov (United States)

    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.

  2. Nitrogen fluorescence in air for observing extensive air showers

    CERN Document Server

    Keilhauer, B; Fraga, M; Matthews, J; Sakaki, N; Tameda, Y; Tsunesada, Y; Ulrich, A

    2012-01-01

    Extensive air showers initiate the fluorescence emissions from nitrogen molecules in air. The UV-light is emitted isotropically and can be used for observing the longitudinal development of extensive air showers in the atmosphere over tenth of kilometers. This measurement technique is well-established since it is exploited for many decades by several cosmic ray experiments. However, a fundamental aspect of the air shower analyses is the description of the fluorescence emission in dependence on varying atmospheric conditions. Different fluorescence yields affect directly the energy scaling of air shower reconstruction. In order to explore the various details of the nitrogen fluorescence emission in air, a few experimental groups have been performing dedicated measurements over the last decade. Most of the measurements are now finished. These experimental groups have been discussing their techniques and results in a series of \\emph{Air Fluorescence Workshops} commenced in 2002. At the 8$^{\\rm{th}}$ Air Fluoresc...

  3. Atmospheric Nitrogen input to the Kattegat

    DEFF Research Database (Denmark)

    Asman, W.A.H.; Hertel, O.; Berkowicz, R.

    1995-01-01

    An overview is given of the processes involved in the atmospheric deposition of nitrogen compounds. These processes are incorporated in an atmospheric transport model that is used to calculate the nitrogen input to the Kattegat, the sea area between Denmark and Sweden. The model results show...... that the total atmospheric nitrogen input to the Kattegat is approximately 960 kg N km(-2) yr(-1). The nitrogen input to the Kattegat is dominated by the wet depositions of NHx (42%) and NOy (30%). The contribution from the dry deposition of NHx is 17% and that of the dry deposition of NOy is 11......%. The contribution of the atmospheric input of nitrogen to the Kattegat is about 30% of the total input including the net transport from other sea areas, runoff etc....

  4. Can mushrooms fix atmospheric nitrogen?

    Indian Academy of Sciences (India)

    At maximum mycelial colonization by the bradyrhizobial strain and biofilm formation, the cultures were subjected to acetylene reduction assay (ARA). Another set of the cultures was evaluated for growth and nitrogen accumulation. Nitrogenase activity was present in the biofilm, but not when the fungus or the bradyrhizobial ...

  5. The Atmospheric Fate of Organic Nitrogen Compounds

    Science.gov (United States)

    Borduas, Nadine

    Organic nitrogen compounds are present in our atmosphere from biogenic and anthropogenic sources and have impacts on air quality and climate. Due to recent advances in instrumentation, these compounds are being detected in the gas and particle phases, raising questions as to their source, processing and sinks in the environment. With their recently identified role as contributors to aerosol formation and growth, their novel large scale use as solvents in carbon capture and storage (CCS) technology and their emissions from cigarette smoke, it is now important to address the gaps in our understanding of the fate of organic nitrogen. Experimentally and theoretically, I studied the chemical atmospheric fate of specific organic nitrogen compounds in the amine, amide and isocyanate families, yielding information that can be used in chemical transport models to assess the fate of this emerging class of atmospheric molecules. I performed kinetic laboratory studies in a smog chamber to measure the room temperature rate coefficient for reaction with the hydroxyl radical of monoethanolamine, nicotine, and five different amides. I employed online-mass spectrometry techniques to quantify the oxidation products. I found that amines react quickly with OH radicals with lifetimes of a few hours under sunlit conditions, producing amides as oxidation products. My studies on amides revealed that they have much longer lifetimes in the atmosphere, ranging from a few hours to a week. Photo-oxidation of amides produces isocyanates and I investigated these mechanisms in detail using ab initio calculations. Furthermore, I experimentally measured isocyanic acid's Henry's Law constant as well as its hydrolysis rate constants to better understand its sinks in the atmosphere. Finally, I re-examined the structure-activity relationship (SAR) of organic nitrogen molecules for improved model parameterizations.

  6. Mesoscale, Sources and Models: Sources for Nitrogen in the Atmosphere

    DEFF Research Database (Denmark)

    Hertel, O.

    1994-01-01

    Projektet Mesoscales, Sources and Models: Sources for Nitrogen in the Atmosphere er opdelt i 3 delprojekter: Sources - farmland, Sources - sea og Sources - biogenic nitrogen.......Projektet Mesoscales, Sources and Models: Sources for Nitrogen in the Atmosphere er opdelt i 3 delprojekter: Sources - farmland, Sources - sea og Sources - biogenic nitrogen....

  7. Fluorescent hydroxyl emissions from Saturn's ring atmosphere.

    Science.gov (United States)

    Hall, D T; Feldman, P D; Holberg, J B; McGrath, M A

    1996-04-26

    Just before earth passed through Saturn's ring plane on 10 August 1995, the Hubble Space Telescope Faint Object Spectrograph detected ultraviolet fluorescent emissions from a tenuous atmosphere of OH molecules enveloping the rings. Brightnesses decrease with increasing distance above the rings, implying a scale height of about 0.45 Saturn radii (Rs). A spatial scan 0.28Rs above the A and B rings indicates OH column densities of about 10(13) cm(-2) and number densities of up to 700 cm(-3). Saturn's rings must produce roughly 10(25) to 10(29) OH molecules per second to maintain the observed OH distribution.

  8. [Characteristics of atmospheric nitrogen wet deposition in Beijing urban area].

    Science.gov (United States)

    He, Cheng-Wu; Ren, Yu-Fen; Wang, Xiao-Ke; Mao, Yu-Xiang

    2014-02-01

    With the ion-exchange resin method, the atmospheric nitrogen wet deposition in Beijing urban area within the Fifth Ring Road was investigated from June to October, 2012. The relationship between atmospheric nitrogen wet deposition and rainfall precipitation was investigated, the differences of nitrogen wet deposition in different months, different ring roads (the Fifth Ring Road, the Fourth Ring Road, the Third Ring Road and the Second Ring Road) and different functional areas (institutes and colleges district, ring-road, residential areas, railway station and public garden) were also investigated. The results showed that the average value and standard deviation of ammonia-nitrogen, nitrate-nitrogen and nitrite-nitrogen were significantly different during different months in 2012. The atmospheric nitrite nitrogen deposition first decreased and then increased, the maximum value appeared in September. The positive relationships between ammonia nitrogen (nitrate nitrogen) and mean monthly precipitation and negative relationships between nitrite nitrogen and mean monthly precipitation were both significant (P functional areas, but only the nitrite nitrogen deposition had obvious regional difference. The differences of the three nitrogen depositions among different ring roads were all not significant and it meant that the nitrogen wet deposition was equally distributed in Beijing urban area.

  9. Atmospheric nitrogen budget in Sahelian dry savannas

    Directory of Open Access Journals (Sweden)

    C. Delon

    2010-03-01

    Full Text Available The atmospheric nitrogen budget depends on emission and deposition fluxes both as reduced and oxidized nitrogen compounds. In this study, a first attempt at estimating the Sahel nitrogen budget for the year 2006 is made, through measurements and simulations at three stations from the IDAF network situated in dry savanna ecosystems. Dry deposition fluxes are estimated from measurements of NO2, HNO3 and NH3 gaseous concentrations and from simulated dry deposition velocities, and wet deposition fluxes are calculated from NH4+ and NO3 concentrations in samples of rain. Emission fluxes are estimated including biogenic emission of NO from soils (an Artificial Neural Network module has been inserted into the ISBA-SURFEX surface model, emission of NOx and NH3 from domestic fires and biomass burning, and volatilization of NH3 from animal excreta. Uncertainties are calculated for each contribution of the budget.

    This study uses original and unique data from remote and hardly-ever-explored regions.The monthly evolution of oxidized N compounds shows that emission and deposition increase at the beginning of the rainy season because of large emissions of biogenic NO (pulse events. Emission of oxidized compounds is dominated by biogenic emission from soils (domestic fires and biomass burning of oxidized compounds account for 0 to 13% at the most at the annual scale, depending on the station, whereas emission of NH3 is dominated by the process of volatilization from soils. At the annual scale, the average gaseous dry deposition accounts for 47% of the total estimated deposition flux, for both oxidized and reduced compounds. The average estimated wet plus dry deposition flux in dry savanna ecosystems is 7.5±1.8 kgN ha−1 yr−1, with approximately 30% attributed to oxidized compounds, and the rest attributed

  10. Global Maps of Atmospheric Nitrogen Deposition, 1860, 1993, and 2050

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set provides global gridded estimates of atmospheric deposition of total inorganic nitrogen (N), NHx (NH3 and NH4+), and NOy (all oxidized forms of...

  11. Global Maps of Atmospheric Nitrogen Deposition, 1860, 1993, and 2050

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set provides global gridded estimates of atmospheric deposition of total inorganic nitrogen (N), NHx (NH3 and NH4+), and NOy (all oxidized forms...

  12. Formation of nitrogenated organic aerosols in the Titan upper atmosphere

    Science.gov (United States)

    Imanaka, Hiroshi; Smith, Mark A.

    2010-01-01

    Many aspects of the nitrogen fixation process by photochemistry in the Titan atmosphere are not fully understood. The recent Cassini mission revealed organic aerosol formation in the upper atmosphere of Titan. It is not clear, however, how much and by what mechanism nitrogen is incorporated in Titan’s organic aerosols. Using tunable synchrotron radiation at the Advanced Light Source, we demonstrate the first evidence of nitrogenated organic aerosol production by extreme ultraviolet–vacuum ultraviolet irradiation of a N2/CH4 gas mixture. The ultrahigh-mass-resolution study with laser desorption ionization-Fourier transform-ion cyclotron resonance mass spectrometry of N2/CH4 photolytic solid products at 60 and 82.5 nm indicates the predominance of highly nitrogenated compounds. The distinct nitrogen incorporations at the elemental abundances of H2C2N and HCN, respectively, are suggestive of important roles of H2C2N/HCCN and HCN/CN in their formation. The efficient formation of unsaturated hydrocarbons is observed in the gas phase without abundant nitrogenated neutrals at 60 nm, and this is confirmed by separately using 13C and 15N isotopically labeled initial gas mixtures. These observations strongly suggest a heterogeneous incorporation mechanism via short lived nitrogenated reactive species, such as HCCN radical, for nitrogenated organic aerosol formation, and imply that substantial amounts of nitrogen is fixed as organic macromolecular aerosols in Titan’s atmosphere. PMID:20616074

  13. Reactive Nitrogen in Atmospheric Emission Inventories

    Science.gov (United States)

    Excess reactive Nitrogen (NT) has become one of the most pressing environmental problems leading to air pollution, acidification and eutrophication of ecosystems, biodiversity impacts, leaching of nitrates into groundwater and global warming. This paper investigates how current i...

  14. Heat transport of nitrogen in helium atmospheric pressure microplasma

    CERN Document Server

    Xu, Shaofeng

    2013-01-01

    Stable DC atmospheric pressure normal glow discharges in ambient air were produced between the water surface and the metallic capillary coupled with influx of helium gas. Multiple independent repeated trials indicated that vibrational temperature of nitrogen rises from 3200 to 4622 K, and rotational temperature of nitrogen decreases from 1270 to 570 K as gas flux increasing from 20 to 80 sccm and discharge current decreasing from 11 to 3 mA. Furthermore, it was found that the vibrational degree of the nitrogen molecule has priority to gain energy than the rotational degree of nitrogen molecule in nonequilibrium helium microplasma.

  15. Atmospheric nitrogen compounds: Occurrence, composition and deposition

    DEFF Research Database (Denmark)

    Nielsen, T.; Pilegaard, K.; Egeløv, A.H.

    1996-01-01

    Traffic in cities and on highways is an important contributor to NOy atmospheric pollution in open areas. In this situation both the concentration and composition of NOy compounds show a wide variation and are dependent on meteorological and atmospheric chemical conditions. The proportion of NOz...... compounds (HNO3+nitrate+PAN+ PPN+N2O5+organic nitrates) increases while that of NOx decreases with increasing ozone concentrations. The dry deposition velocity of NO2 was determined to be 0.2 cm s(-1) above vegetation. The dry deposition contribution of the different NOy compounds was evaluated....... The possibility that a significant contribution is caused by a group of unidentified NOy compounds cannot be excluded. Therefore, future investigations of atmospheric pollution of sensitive ecosystems, at conditions with a relatively high atmospheric content of NOy compared to that of NH3, ought to take...

  16. Graphitic Nitrogen Triggers Red Fluorescence in Carbon Dots.

    Science.gov (United States)

    Holá, Kateřina; Sudolská, Mária; Kalytchuk, Sergii; Nachtigallová, Dana; Rogach, Andrey L; Otyepka, Michal; Zbořil, Radek

    2017-11-20

    Carbon dots (CDs) are a stable and highly biocompatible fluorescent material offering great application potential in cell labeling, optical imaging, LED diodes, and optoelectronic technologies. Because their emission wavelengths provide the best tissue penetration, red-emitting CDs are of particular interest for applications in biomedical technologies. Current synthetic strategies enabling red-shifted emission include increasing the CD particle size (sp2 domain) by a proper synthetic strategy and tuning the surface chemistry of CDs with suitable functional groups (e.g., carboxyl). Here we present an elegant route for preparing full-color CDs with well-controllable fluorescence at blue, green, yellow, or red wavelengths. The two-step procedure involves the synthesis of a full-color-emitting mixture of CDs from citric acid and urea in formamide followed by separation of the individual fluorescent fractions by column chromatography based on differences in CD charge. Red-emitting CDs, which had the most negative charge, were separated as the last fraction. The trend in the separation, surface charge, and red-shift of photoluminescence was caused by increasing amount of graphitic nitrogen in the CD structure, as was clearly proved by XPS, FT-IR, Raman spectroscopy, and DFT calculations. Importantly, graphitic nitrogen generates midgap states within the HOMO-LUMO gap of the undoped systems, resulting in significantly red-shifted light absorption that in turn gives rise to fluorescence at the low-energy end of the visible spectrum. The presented findings identify graphitic nitrogen as another crucial factor that can red-shift the CD photoluminescence.

  17. Nitrogen concentrations in mosses indicate the spatial distribution of atmospheric nitrogen deposition in Europe

    Energy Technology Data Exchange (ETDEWEB)

    Harmens, H., E-mail: hh@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Norris, D.A., E-mail: danor@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Cooper, D.M., E-mail: cooper@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Mills, G., E-mail: gmi@ceh.ac.uk [Centre for Ecology and Hydrology, Environment Centre Wales, Deiniol Road, Bangor, Gwynedd LL57 2UW (United Kingdom); Steinnes, E., E-mail: Eiliv.Steinnes@chem.ntnu.no [Department of Chemistry, Norwegian University of Science and Technology, 7491 Trondheim (Norway); Kubin, E., E-mail: Eero.Kubin@metla.fi [Finnish Forest Research Institute, Kirkkosaarentie 7, 91500 Muhos (Finland); Thoeni, L., E-mail: lotti.thoeni@fub-ag.ch [FUB-Research Group for Environmental Monitoring, Alte Jonastrasse 83, 8640 Rapperswil (Switzerland); Aboal, J.R., E-mail: jesusramon.aboal@usc.es [University of Santiago de Compostela, Faculty of Biology, Department of Ecology, 15782 Santiago de Compostela (Spain); Alber, R., E-mail: Renate.Alber@provinz.bz.it [Environmental Agency of Bolzano, 39055 Laives (Italy); Carballeira, A., E-mail: alejo.carballeira@usc.es [University of Santiago de Compostela, Faculty of Biology, Department of Ecology, 15782 Santiago de Compostela (Spain); Coskun, M., E-mail: coskunafm@yahoo.com [Canakkale Onsekiz Mart University, Faculty of Medicine, Department of Medical Biology, 17100 Canakkale (Turkey); De Temmerman, L., E-mail: ludet@var.fgov.be [Veterinary and Agrochemical Research Centre, Tervuren (Belgium); Frolova, M., E-mail: marina.frolova@lvgma.gov.lv [Latvian Environment, Geology and Meteorology Agency, Riga (Latvia); Gonzalez-Miqueo, L., E-mail: lgonzale2@alumni.unav.es [Univ. of Navarra, Irunlarrea No 1, 31008 Pamplona (Spain)

    2011-10-15

    In 2005/6, nearly 3000 moss samples from (semi-)natural location across 16 European countries were collected for nitrogen analysis. The lowest total nitrogen concentrations in mosses (<0.8%) were observed in northern Finland and northern UK. The highest concentrations ({>=}1.6%) were found in parts of Belgium, France, Germany, Slovakia, Slovenia and Bulgaria. The asymptotic relationship between the nitrogen concentrations in mosses and EMEP modelled nitrogen deposition (averaged per 50 km x 50 km grid) across Europe showed less scatter when there were at least five moss sampling sites per grid. Factors potentially contributing to the scatter are discussed. In Switzerland, a strong (r{sup 2} = 0.91) linear relationship was found between the total nitrogen concentration in mosses and measured site-specific bulk nitrogen deposition rates. The total nitrogen concentrations in mosses complement deposition measurements, helping to identify areas in Europe at risk from high nitrogen deposition at a high spatial resolution. - Highlights: > Nitrogen concentrations in mosses were determined at ca. 3000 sites across Europe. > Moss concentrations were compared with EMEP modelled nitrogen deposition. > The asymptotic relationship for Europe showed saturation at ca. 15 kg N ha{sup -1} y{sup -1}. > Linear relationships were found with measured nitrogen deposition in some countries. > Moss concentrations complement deposition measurements at high spatial resolution. - Mosses as biomonitors of atmospheric nitrogen deposition in Europe.

  18. Biological fixation of atmospheric nitrogen in the Mediterranean Sea

    Energy Technology Data Exchange (ETDEWEB)

    Bethoux, J.P.; Copin-Montegut, G.

    1986-11-01

    Nutrient concentration in the Mediterranean Sea is controlled by water exchanges through the Strait of Gibraltar and by atmospheric and terrestrial inputs. Various peculiarities in the nitrogen and phosphorus geochemical cycles are pointed out, namely a low N:P atomic ratio (6.4) in terrestrial discharges, and a budget well balanced for phosphorus (where terrestrial discharges amount to about 80% of the outflow) but apparently very deficient in nitrogen, despite a high N:P atomic ratio (22), in Mediterranean deep waters. This suggests the possibility of a surprisingly high rate of direct atmospheric N uptake by the Mediterranean ecosystem (possibly seagrasses Posidonia oceanica and pelagic bacterioplankton species).

  19. Challenges in quantifying biosphere-atmosphere exchange of nitrogen species.

    NARCIS (Netherlands)

    Sutton, M.A.; Nemitz, E.; Erisman, J.W.; Beier, C.; Butterbach-Bahl, K.; Cellier, P.; Vries, de W.; Cotrufo, F.; Skiba, U.; Marco, Di C.; Jones, S.; Laville, P.; Soussana, J.F.; Loubet, B.; Twigg, M.; Famulari, D.; Whitehead, J.; Gallagher, M.W.; Neftel, A.; Flechard, C.R.; Herrmann, B.; Calanca, P.L.; Schjoerring, J.K.; Daemmgen, U.; Horvath, L.; Tang, Y.S.; Emmet, B.A.; Tietema, A.; Penuelas, J.; Kesik, M.; Brueggemann, N.; Pilegaard, K.; Vesala, T.; Campbell, C.L.; Olesen, J.E.; Dragosits, U.; Theobald, M.R.; Levy, P.; Mobbs, D.C.; Milne, R.; Viovy, N.; Vuichard, N.; Smith, J.U.; Smith, P.; Bergamaschi, P.; Fowler, D.; Reis, Dos S.

    2007-01-01

    Recent research in nitrogen exchange with the atmosphere has separated research communities according to N form. The integrated perspective needed to quantify the net effect of N on greenhouse-gas balance is being addressed by the NitroEurope Integrated Project (NEU). Recent advances have depended

  20. Challenges in quantifying biosphere-atmosphere exchange of nitrogen species

    DEFF Research Database (Denmark)

    Sutton, M.A.; Nemitz, E.; Erisman, J.W.

    2007-01-01

    Recent research in nitrogen exchange with the atmosphere has separated research communities according to N form. The integrated perspective needed to quantify the net effect of N on greenhouse-gas balance is being addressed by the NitroEurope Integrated Project (NEU). Recent advances have depended...... on improved methodologies, while ongoing challenges include gas-aerosol interactions, organic nitrogen and N2 fluxes. The NEU strategy applies a 3-tier Flux Network together with a Manipulation Network of global-change experiments, linked by common protocols to facilitate model application. Substantial...

  1. Governing processes for reactive nitrogen compounds in the European atmosphere

    Science.gov (United States)

    Hertel, O.; Skjøth, C. A.; Reis, S.; Bleeker, A.; Harrison, R. M.; Cape, J. N.; Fowler, D.; Skiba, U.; Simpson, D.; Jickells, T.; Kulmala, M.; Gyldenkærne, S.; Sørensen, L. L.; Erisman, J. W.; Sutton, M. A.

    2012-12-01

    Reactive nitrogen (Nr) compounds have different fates in the atmosphere due to differences in the governing processes of physical transport, deposition and chemical transformation. Nr compounds addressed here include reduced nitrogen (NHx: ammonia (NH3) and its reaction product ammonium (NH4+)), oxidized nitrogen (NOy: nitrogen monoxide (NO) + nitrogen dioxide (NO2) and their reaction products) as well as organic nitrogen compounds (organic N). Pollution abatement strategies need to take into account the differences in the governing processes of these compounds when assessing their impact on ecosystem services, biodiversity, human health and climate. NOx (NO + NO2) emitted from traffic affects human health in urban areas where the presence of buildings increases the residence time in streets. In urban areas this leads to enhanced exposure of the population to NOx concentrations. NOx emissions generally have little impact on nearby ecosystems because of the small dry deposition rates of NOx. These compounds need to be converted into nitric acid (HNO3) before removal through deposition is efficient. HNO3 sticks quickly to any surface and is thereby either dry deposited or incorporated into aerosols as nitrate (NO3-). In contrast to NOx compounds, NH3 has potentially high impacts on ecosystems near the main agricultural sources of NH3 because of its large ground-level concentrations along with large dry deposition rates. Aerosol phase NH4+ and NO3- contribute significantly to background PM2.5 and PM10 (mass of aerosols with an aerodynamic diameter of less than 2.5 and 10 μm, respectively) with an impact on radiation balance as well as potentially on human health. Little is known quantitatively and qualitatively about organic N in the atmosphere, other than that it contributes a significant fraction of wet-deposited N, and is present in both gaseous and particulate forms. Further studies are needed to characterise the sources, air chemistry and

  2. An Overview of Modeling Middle Atmospheric Odd Nitrogen

    Science.gov (United States)

    Jackman, Charles H.; Kawa, S. Randolph; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Odd nitrogen (N, NO, NO2, NO3, N2O5, HNO3, HO2NO2, ClONO2, and BrONO2) constituents are important components in the control of middle atmospheric ozone. Several processes lead to the production of odd nitrogen (NO(sub y)) in the middle atmosphere (stratosphere and mesosphere) including the oxidation of nitrous oxide (N2O), lightning, downflux from the thermosphere, and energetic charged particles (e.g., galactic cosmic rays, solar proton events, and energetic electron precipitation). The dominant production mechanism of NO(sub y) in the stratosphere is N2O oxidation, although other processes contribute. Mesospheric NO(sub y) is influenced by N2O oxidation, downflux from the thermosphere, and energetic charged particles. NO(sub y) is destroyed in the middle atmosphere primarily via two processes: 1) dissociation of NO to form N and O followed by N + NO yielding N2 + O to reform even nitrogen; and 2) transport to the troposphere where HNO3 can be rapidly scavenged in water droplets and rained out of the atmosphere. There are fairly significant differences among global models that predict NO(sub y). NO(sub y) has a fairly long lifetime in the stratosphere (months to years), thus disparate transport in the models probably contributes to many of these differences. Satellite and aircraft measurement provide modeling tests of the various components of NO(sub y). Although some recent reaction rate measurements have led to improvements in model/measurement agreement, significant differences do remain. This presentation will provide an overview of several proposed sources and sinks of NO(sub y) and their regions of importance. Multi-dimensional modeling results for NO(sub y) and its components with comparisons to observations will also be presented.

  3. Integrated method for the measurement of trace nitrogenous atmospheric bases

    Directory of Open Access Journals (Sweden)

    D. Key

    2011-12-01

    Full Text Available Nitrogenous atmospheric bases are thought to play a key role in the global nitrogen cycle, but their sources, transport, and sinks remain poorly understood. Of the many methods available to measure such compounds in ambient air, few meet the current need of being applicable to the complete range of potential analytes and fewer still are convenient to implement using instrumentation that is standard to most laboratories. In this work, an integrated approach to measuring trace, atmospheric, gaseous nitrogenous bases has been developed and validated. The method uses a simple acid scrubbing step to capture and concentrate the bases as their phosphite salts, which then are derivatized and analyzed using GC/MS and/or LC/MS. The advantages of both techniques in the context of the present measurements are discussed. The approach is sensitive, selective, reproducible, as well as convenient to implement and has been validated for different sampling strategies. The limits of detection for the families of tested compounds are suitable for ambient measurement applications (e.g., methylamine, 1 pptv; ethylamine, 2 pptv; morpholine, 1 pptv; aniline, 1 pptv; hydrazine, 0.1 pptv; methylhydrazine, 2 pptv, as supported by field measurements in an urban park and in the exhaust of on-road vehicles.

  4. Effects of elevated atmospheric carbon dioxide on soil nitrogen cycling

    Science.gov (United States)

    Hofmockel, Kirsten S.

    elevated atmospheric CO2 on soil nitrogen cycling at the ecosystem scale, despite an increase in N demand of 0.86 g m-2 y -1 under elevated CO2. My results suggest that elevated CO2 does not alter soil nitrogen cycling at the decadal time scale. Retranslocation within trees and slowly cycling soil organic pools are likely supporting the increased N demand under elevated CO2. Longer-term studies may reveal differences in soil organic matter and carbon sequestration dynamics under ambient and elevated CO2.

  5. Governing processes for reactive nitrogen compounds in the European atmosphere

    Directory of Open Access Journals (Sweden)

    O. Hertel

    2012-12-01

    Full Text Available Reactive nitrogen (Nr compounds have different fates in the atmosphere due to differences in the governing processes of physical transport, deposition and chemical transformation. Nr compounds addressed here include reduced nitrogen (NHx: ammonia (NH3 and its reaction product ammonium (NH4+, oxidized nitrogen (NOy: nitrogen monoxide (NO + nitrogen dioxide (NO2 and their reaction products as well as organic nitrogen compounds (organic N. Pollution abatement strategies need to take into account the differences in the governing processes of these compounds when assessing their impact on ecosystem services, biodiversity, human health and climate. NOx (NO + NO2 emitted from traffic affects human health in urban areas where the presence of buildings increases the residence time in streets. In urban areas this leads to enhanced exposure of the population to NOx concentrations. NOx emissions generally have little impact on nearby ecosystems because of the small dry deposition rates of NOx. These compounds need to be converted into nitric acid (HNO3 before removal through deposition is efficient. HNO3 sticks quickly to any surface and is thereby either dry deposited or incorporated into aerosols as nitrate (NO3. In contrast to NOx compounds, NH3 has potentially high impacts on ecosystems near the main agricultural sources of NH3 because of its large ground-level concentrations along with large dry deposition rates. Aerosol phase NH4+ and NO3 contribute significantly to background PM2.5 and PM10 (mass of aerosols with an aerodynamic diameter of less than 2.5 and 10 μm, respectively with an impact on radiation balance as well as potentially on human

  6. Response of global soil consumption of atmospheric methane to changes in atmospheric climate and nitrogen deposition

    Science.gov (United States)

    Zhuang, Qianlai; Chen, Min; Xu, Kai; Tang, Jinyun; Saikawa, Eri; Lu, Yanyu; Melillo, Jerry M.; Prinn, Ronald G.; McGuire, A. David

    2013-01-01

    Soil consumption of atmospheric methane plays an important secondary role in regulating the atmospheric CH4 budget, next to the dominant loss mechanism involving reaction with the hydroxyl radical (OH). Here we used a process-based biogeochemistry model to quantify soil consumption during the 20th and 21st centuries. We estimated that global soils consumed 32–36 Tg CH4 yr−1 during the 1990s. Natural ecosystems accounted for 84% of the total consumption, and agricultural ecosystems only consumed 5 Tg CH4 yr−1 in our estimations. During the twentieth century, the consumption rates increased at 0.03–0.20 Tg CH4 yr−2 with seasonal amplitudes increasing from 1.44 to 3.13 Tg CH4 month−1. Deserts, shrublands, and xeric woodlands were the largest sinks. Atmospheric CH4 concentrations and soil moisture exerted significant effects on the soil consumption while nitrogen deposition had a moderate effect. During the 21st century, the consumption is predicted to increase at 0.05-1.0 Tg CH4 yr−2, and total consumption will reach 45–140 Tg CH4 yr−1 at the end of the 2090s, varying under different future climate scenarios. Dry areas will persist as sinks, boreal ecosystems will become stronger sinks, mainly due to increasing soil temperatures. Nitrogen deposition will modestly reduce the future sink strength at the global scale. When we incorporated the estimated global soil consumption into our chemical transport model simulations, we found that nitrogen deposition suppressed the total methane sink by 26 Tg during the period 1998–2004, resulting in 6.6 ppb higher atmospheric CH4 mixing ratios compared to without considering nitrogen deposition effects. On average, a cumulative increase of every 1 Tg soil CH4 consumption decreased atmospheric CH4 mixing ratios by 0.26 ppb during the period 1998–2004.

  7. Ultrafast laser-collision-induced fluorescence in atmospheric pressure plasma

    Science.gov (United States)

    Barnat, E. V.; Fierro, A.

    2017-04-01

    The implementation and demonstration of laser-collision-induced fluorescence (LCIF) generated in atmospheric pressure helium environments is presented in this communication. As collision times are observed to be fast (~10 ns), ultrashort pulse laser excitation (discharge conditions presented in this study (640 Torr He), the lower limit of electron density detection is ~1012 e cm-3. The spatial profiles of the 23S helium metastable and electrons are presented as functions of E/N to demonstrate the spatial resolving capabilities of the LCIF method.

  8. Autofluorescence of atmospheric bioaerosols – fluorescent biomolecules and potential interferences

    Directory of Open Access Journals (Sweden)

    C. Pöhlker

    2012-01-01

    Full Text Available Primary biological aerosol particles (PBAP are an important subset of air particulate matter with a substantial contribution to the organic aerosol fraction and potentially strong effects on public health and climate. Recent progress has been made in PBAP quantification by utilizing real-time bioaerosol detectors based on the principle that specific organic molecules of biological origin such as proteins, coenzymes, cell wall compounds and pigments exhibit intrinsic fluorescence. The properties of many fluorophores have been well documented, but it is unclear which are most relevant for detection of atmospheric PBAP. The present study provides a systematic synthesis of literature data on potentially relevant biological fluorophores. We analyze and discuss their relative importance for the detection of fluorescent biological aerosol particles (FBAP by online instrumentation for atmospheric measurements such as the ultraviolet aerodynamic particle sizer (UV-APS or the wide issue bioaerosol sensor (WIBS.

    In addition, we provide new laboratory measurement data for selected compounds using bench-top fluorescence spectroscopy. Relevant biological materials were chosen for comparison with existing literature data and to fill in gaps of understanding. The excitation-emission matrices (EEM exhibit pronounced peaks at excitation wavelengths of ~280 nm and ~360 nm, confirming the suitability of light sources used for online detection of FBAP. They also show, however, that valuable information is missed by instruments that do not record full emission spectra at multiple wavelengths of excitation, and co-occurrence of multiple fluorophores within a detected sample will likely confound detailed molecular analysis. Selected non-biological materials were also analyzed to assess their possible influence on FBAP detection and generally exhibit only low levels of background-corrected fluorescent emission. This study strengthens the hypothesis that ambient

  9. Talif quantification of nitrogen atoms applied to experimental simulation of Titan's atmosphere

    Science.gov (United States)

    Sebbar, Touhami Es; Yves, Benilan; Arzoumanian, Emmanuel; Gazeau, Marie-Claire

    Titan, Saturn's largest moon, has an atmosphere mainly composed of nitrogen ( 98 % N2 ) and methane ( 2 % CH4 ). In Titan's upper atmosphere, these compounds are dissociated by energetic electrons coming from the magnetosphere of Saturn and solar photons: nitrogen atoms and CH3 , CH2 and CH radicals are produced. The recombination of these fragments and the following complex chemistry leads finally to the formation of complex hydrocarbons and nitriles. Within the SETUP program (see presentation session F32), simulation experiments will be carried out with the aim to explicit the mechanisms involved in the chemical evolution of Titan's atmosphere. Indeed, the initial gas mixture (N2 /CH4 ) will be submitted in a dedicated reactor to an energy deposition, in situ time resolved analysis of the resulting sample (qualification and quantification of intermediates species, as well as stable compounds) will be performed by a laser technique (C.R.D.S.: Cavity Ring Down Spectroscopy). Representativeness of our simulations in term of energy deposition is ensured by the use of both UV photons (dissociation of CH4 by a continuous lamp or a pulsed laser) and electrons (dissociation of N2 by a cold plasma). One of our actual concern is to make sure that the cold plasma induces a ratio of nitrogen atoms versus dinitrogen molecules equivalent to the one existing in Titan's high atmosphere. Consequently, we are studying the N production in the reactor as the function of different parameters of the discharge: initial flow of N2 , discharge power, gas pressure and residence time. Quantification of N in its ground state is performed, by the Two photons Absorption Laser Induced Fluorescence technique (TALIF): a UV laser beam excitation at 206.6 nm [N (2p3 4 S 3/2 ) → N (3p 4 S3/2 ) transition] is used, the fluorescence is detected between 742 and 746 nm [N (3p 4 S3/2 ) → N (3s 4 P1/2,3/2,5/2 ) transition]. The TALIF measurements which give the relative nitrogen atom density are

  10. Challenges in quantifying biosphere-atmosphere exchange of nitrogen species

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, M.A. [Centre for Ecology and Hydrology (CEH), Edinburgh Research Station, Bush Estate, Penicuik, EH26 0QB (United Kingdom)], E-mail: ms@ceh.ac.uk; Nemitz, E. [Centre for Ecology and Hydrology (CEH), Edinburgh Research Station, Bush Estate, Penicuik, EH26 0QB (United Kingdom); Erisman, J.W. [ECN, Clean Fossil Fuels, PO Box 1, 1755 ZG Petten (Netherlands); Beier, C. [Riso National Laboratory, PO Box 49, DK-4000 Roskilde (Denmark); Bahl, K. Butterbach [Institute of Meteorology and Climate Research, Atmos. Environ. Research (IMK-IFU), Research Centre Karlsruhe GmbH, Kreuzeckbahnstr. 19, 82467 Garmisch-Partenkirchen (Germany); Cellier, P. [INRA Unite Mixte de Recherche, 78850 Thiverval-Grignon (France); Vries, W. de [Alterra, Green World Research, PO Box 47, 6700 AA Wageningen (Netherlands); Cotrufo, F. [Dip. Scienze Ambientali, Seconda Universita degli Studi di Napoli, via Vivaldi 43, 81100 Caserta (Italy); Skiba, U.; Di Marco, C.; Jones, S. [Centre for Ecology and Hydrology (CEH), Edinburgh Research Station, Bush Estate, Penicuik, EH26 0QB (United Kingdom); Laville, P.; Soussana, J.F.; Loubet, B. [INRA Unite Mixte de Recherche, 78850 Thiverval-Grignon (France); Twigg, M.; Famulari, D. [Centre for Ecology and Hydrology (CEH), Edinburgh Research Station, Bush Estate, Penicuik, EH26 0QB (United Kingdom); Whitehead, J.; Gallagher, M.W. [School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Williamson Building, Oxford Road, Manchester, M13 9PL (United Kingdom); Neftel, A.; Flechard, C.R. [Agroscope FAL Reckenholz, Federal Research Station for Agroecology and Agriculture, PO Box, CH 8046 Zurich (Switzerland)] (and others)

    2007-11-15

    Recent research in nitrogen exchange with the atmosphere has separated research communities according to N form. The integrated perspective needed to quantify the net effect of N on greenhouse-gas balance is being addressed by the NitroEurope Integrated Project (NEU). Recent advances have depended on improved methodologies, while ongoing challenges include gas-aerosol interactions, organic nitrogen and N{sub 2} fluxes. The NEU strategy applies a 3-tier Flux Network together with a Manipulation Network of global-change experiments, linked by common protocols to facilitate model application. Substantial progress has been made in modelling N fluxes, especially for N{sub 2}O, NO and bi-directional NH{sub 3} exchange. Landscape analysis represents an emerging challenge to address the spatial interactions between farms, fields, ecosystems, catchments and air dispersion/deposition. European up-scaling of N fluxes is highly uncertain and a key priority is for better data on agricultural practices. Finally, attention is needed to develop N flux verification procedures to assess compliance with international protocols. - Current N research is separated by form; the challenge is to link N components, scales and issues.

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

    Directory of Open Access Journals (Sweden)

    Hao Wang

    2015-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hao; Wang, Yun; Dai, Xiao; Zou, Guifu, E-mail: kqzhang@suda.edu.cn, E-mail: zouguifu@suda.edu.cn [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Gao, Peng; Zhang, Ke-Qin, E-mail: kqzhang@suda.edu.cn, E-mail: zouguifu@suda.edu.cn; Du, Dezhuang [National Engineering Laboratory for Modern Silk, College of Textile and Clothing Engineering, Soochow University, Suzhou 215123 (China); Guo, Jun [Testing and Analysis Center, Soochow University, Suzhou 215123 (China)

    2015-08-01

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

  13. Measuring reactive oxygen and nitrogen species with fluorescent probes: challenges and limitations

    Science.gov (United States)

    Kalyanaraman, Balaraman; Darley-Usmar, Victor; Davies, Kelvin J.A.; Dennery, Phyllis A.; Forman, Henry Jay; Grisham, Matthew B.; Mann, Giovanni E.; Moore, Kevin; Roberts, L. Jackson; Ischiropoulos, Harry

    2013-01-01

    The purpose of this position paper is to present a critical analysis of the challenges and limitations of the most widely used fluorescent probes for detecting and measuring reactive oxygen and nitrogen species. Where feasible, we have made recommendations for the use of alternate probes and appropriate analytical techniques that measure the specific products formed from the reactions between fluorescent probes and reactive oxygen and nitrogen species. We have proposed guidelines that will help present and future researchers with regard to the optimal use of selected fluorescent probes and interpretation of results. PMID:22027063

  14. Box-modeling of the impacts of atmospheric nitrogen deposition and benthic remineralization on the nitrogen cycle of the eastern tropical South Pacific

    OpenAIRE

    Su, B; M. Pahlow; Oschlies, A.

    2015-01-01

    Both atmospheric deposition and benthic remineralization influence the marine nitrogen cycle, and hence ultimately also marine primary production. The biological and biogeochemical relations of the eastern tropical South Pacific (ETSP) to nitrogen deposition, benthic denitrification and phosphate regeneration are analysed in a prognostic box model of the oxygen, nitrogen and phosphorus cycles in the ETSP. In the model, atmospheric nitrogen...

  15. Mechanisms controlling soil carbon sequestration under atmospheric nitrogen deposition

    Energy Technology Data Exchange (ETDEWEB)

    R.L. Sinsabaugh; D.R. Zak; D.L. Moorhead

    2008-02-19

    Increased atmospheric nitrogen (N) deposition can alter the processing and storage of organic carbon in soils. In 2000, we began studying the effects of simulated atmospheric N deposition on soil carbon dynamics in three types of northern temperate forest that occur across a wide geographic range in the Upper Great Lakes region. These ecosystems range from 100% oak in the overstory (black oak-white oak ecosystem; BOWO) to 0% overstory oak (sugar maple-basswood; SMBW) and include the sugar maple-red oak ecosystem (SMRO) that has intermediate oak abundance. The leaf litter biochemistry of these ecosystems range from highly lignified litter (BOWO) to litter of low lignin content (SMBW). We selected three replicate stands of each ecosystem type and established three plots in each stand. Each plot was randomly assigned one of three levels of N deposition (0, 30 & 80 kg N ha-1 y-1) imposed by adding NaNO3 in six equal increments applied over the growing season. Through experiments ranging from the molecular to the ecosystem scales, we produced a conceptual framework that describes the biogeochemistry of soil carbon storage in N-saturated ecosystems as the product of interactions between the composition of plant litter, the composition of the soil microbial community and the expression of extracellular enzyme activities. A key finding is that atmospheric N deposition can increase or decrease the soil C storage by modifying the expression of extracellular enzymes by soil microbial communities. The critical interactions within this conceptual framework have been incorporated into a new class of simulations called guild decomposition models.

  16. Effect of reaction temperature on structure and fluorescence properties of nitrogen-doped carbon dots

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yi [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Chemistry and Chemical Engineering, Lyuliang University, Lyuliang 033001 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Wang, Yaling [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Feng, Xiaoting [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zhang, Feng [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Yang, Yongzhen, E-mail: yyztyut@126.com [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Xuguang, E-mail: liuxuguang@tyut.edu.cn [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2016-11-30

    Highlights: • Nitrogen-doped carbon dots (NCDs) from ammonia solution and citric acid were synthesized at different temperatures. • Quantum yield (QY) of NCDs depends largely on the amount of fluorescent polymer chains (FPC), more FPC gives higher QY. • The law of QY of NCDs first increase and then decrease with the reaction temperature increased is found and explained. • Nitrogen doping plays significant role in getting increased UV–vis absorption and QY. - Abstract: To investigate the effect of reaction temperature and nitrogen doping on the structure and fluorescence properties of carbon dots (CDs), six kinds of nitrogen-doped CDs (NCDs) were synthesized at reaction temperatures of 120, 140, 160, 180, 200 and 220 °C, separately, by using citric acid as carbon source and ammonia solution as nitrogen source. Nitrogen-free CDs (N-free CDs-180) was also prepared at 180 °C by using citric acid as the only carbon source for comparison. Results show that reaction temperature has obvious effect on carbonization degree, quantum yield (QY), ultraviolet-visible (UV–vis) absorption and photoluminescence (PL) spectra but less effect on functional groups, nitrogen doping degree and fluorescence lifetime of NCDs. Compared with N-free CDs-180, NCDs-180 possesses enchanced QY and longer fluorescence lifetime. Doping nitrogen has obvious effect on UV–vis absorption and PL spectra but less effect on particles sizes and carbonization degree. The formation mechanism of NCDs is explored: QY of NCDs depends largely on the number of fluorescent polymer chains (FPC), the competition between FPC formation on the surface of NCDs and carbon core growth leads to the change in number of FPC, and consequently to the NCDs with highest QY at appropriate hydrothermal temperature.

  17. Origin and Evolution of Titan's Nitrogen Atmosphere - A Cassini-Huygens Perspective

    Science.gov (United States)

    Atreya, Sushil K.

    2014-05-01

    Prior to Cassini-Huygens, it was debated how Titan acquired its earth-like atmosphere of nitrogen [1]. This talk will review the history of Titan's atmosphere, models, and the unique role of Cassini-Huygens in understanding the origin and evolution of an atmosphere of nitrogen on Titan. After hydrogen and helium, nitrogen is the fourth most abundant element in the solar system. In the colder outer solar system beyond 5 AU, nitrogen is bound to hydrogen in the giant planets. Thus ammonia (NH3), not N2, is the dominant reservoir of nitrogen in these objects. The satellites that form in the relatively warm and dense subnebula of the gas giant planets, Jupiter and Saturn, may acquire nitrogen as NH3 during their accretion [2], although some models had proposed N2, not NH3, as the stable form of nitrogen in the subnebulae. The latter is reflected in the atmosphere of Triton, which almost certainly accreted nitrogen directly as N2, since N2 can be the stable form of nitrogen in the very cold environment of Neptune. Before Cassini-Huygens, it was debated whether Titan, the largest moon of Saturn, also acquired its nitrogen directly as N2, putting it in the same class as Neptune's moon Triton half its size, or the nitrogen on Titan was secondary atmosphere, produced from a nitrogen bearing molecule, putting Titan in the class with terrestrial planets. The evidence from Cassini-Huygens to be discussed in this talk leaves no doubt that Titan's nitrogen atmosphere is secondary [3]. Probable scenarios of the sustenance, evolution and reduction or demise of this atmosphere will also be explored. References: [1]Owen T. (2000), Planet. Space Sci. 48, 747-752. [2]Prinn R.G., Fegley B. (1981), Astrophys J. 249, 308-317. [3]Atreya S.K., Lorenz R.D., Waite J.H. (2009), pp 177-199, in Titan (R.H. Brown et al., eds.) Springer.

  18. Nitrogen fractionation in the atmospheres of Pluto and Titan - implications for the origin of nitrogen in KBOs and comets

    Science.gov (United States)

    Mandt, Kathleen; Luspay-Kuti, Adrienn; Jessup, Kandis Lea; Hue, Vincent; Kammer, Josh; Filwett, Rachael

    2017-04-01

    Recent observations of the composition of Pluto's atmosphere made by the Alice Ultraviolet Spectrometer on New Horizons and by the Atacama Large Millimeter Array (ALMA) have shown that Pluto's nitrogen chemistry differs significantly from that observed in Titan's upper atmosphere. The isotope ratios, 14N/15N, in N2 and HCN in Titan's atmosphere are 167.6 and 68, respectively. They differ by more than a factor of two because photodissociation of molecular nitrogen in Titan's atmosphere leads to a significant enrichment of the heavy nitrogen isotope, 15N, in HCN. However, ALMA observations were not able to detect HC15N in Pluto's atmosphere, setting a lower limit of 125 for 14N/15N in HCN. We have applied our model for simulating nitrogen isotope chemistry in Titan's atmosphere to Pluto, constrained by New Horizons observations, and explore possible explanations of the lower limit provided by ALMA. These results have implications for the origin of nitrogen on Pluto, other Kuiper Belt Objects (KBOs), and for comets like the Rosetta mission target 67P/Churyumov-Gerasimenko, which is thought to originate in the Kuiper Belt.

  19. Atmospheric ammonia and particulate inorganic nitrogen over the United States

    Directory of Open Access Journals (Sweden)

    C. L. Heald

    2012-11-01

    Full Text Available We use in situ observations from the Interagency Monitoring of PROtected Visual Environments (IMPROVE network, the Midwest Ammonia Monitoring Project, 11 surface site campaigns as well as Infrared Atmospheric Sounding Interferometer (IASI satellite measurements with the GEOS-Chem model to investigate inorganic aerosol loading and atmospheric ammonia concentrations over the United States. IASI observations suggest that current ammonia emissions are underestimated in California and in the springtime in the Midwest. In California this underestimate likely drives the underestimate in nitrate formation in the GEOS-Chem model. However in the remaining continental United States we find that the nitrate simulation is biased high (normalized mean bias > = 1.0 year-round, except in Spring (due to the underestimate in ammonia in this season. None of the uncertainties in precursor emissions, the uptake efficiency of N2O5 on aerosols, OH concentrations, the reaction rate for the formation of nitric acid, or the dry deposition velocity of nitric acid are able to explain this bias. We find that reducing nitric acid concentrations to 75% of their simulated values corrects the bias in nitrate (as well as ammonium in the US. However the mechanism for this potential reduction is unclear and may be a combination of errors in chemistry, deposition and sub-grid near-surface gradients. This "updated" simulation reproduces PM and ammonia loading and captures the strong seasonal and spatial gradients in gas-particle partitioning across the United States. We estimate that nitrogen makes up 15−35% of inorganic fine PM mass over the US, and that this fraction is likely to increase in the coming decade, both with decreases in sulfur emissions and increases in ammonia emissions.

  20. Laser-excited fluorescence for measuring atmospheric pollution

    Science.gov (United States)

    Menzies, R. T.

    1975-01-01

    System measures amount of given pollutant at specific location. Infrared laser aimed at location has wavelength that will cause molecules of pollutant to fluoresce. Detector separates fluorescence from other radiation and measures its intensity to indicate concentration of pollutant.

  1. [Effects of nitrogen application and elevated atmospheric CO2 on electron transport and energy partitioning in flag leaf photosynthesis of wheat].

    Science.gov (United States)

    Zhang, Xu-cheng; Yu, Xian-feng; Ma, Yi-fan

    2011-03-01

    Wheat (Triticum aestivum) plants were pot-cultured in open top chambers at the nitrogen application rate of 0 and 200 mg x kg(-1) soil and the atmospheric CO2 concentration of 400 and 760 micromol x mol(-1). Through the determination of flag leaf nitrogen and chlorophyll contents, photosynthetic rate (Pn)-intercellar CO2 concentration (Ci) response curve, and chlorophyll fluorescence parameters at heading stage, the photosynthetic electron transport rate and others were calculated, aimed to investigate the effects of nitrogen application and elevated atmospheric CO2 concentration on the photosynthetic energy partitioning in wheat flag leaves. Elevated atmospheric CO2 concentration decreased the leaf nitrogen and chlorophyll contents, compared with the ambient one, and the chlorophyll a/b ratio increased at the nitrogen application rate of 200 mg x kg(-1). With the application of nitrogen, no evident variations were observed in the maximal photochemical efficiency (Fv/Fm), maximal quantum yield under irradiance (Fv'/Fm') of PS II reaction center, photochemical fluorescence quenching coefficient (q(p)), and actual PS II efficiency under irradiance (phi(PS II) at elevated atmospheric CO2 concentration, and the total photosynthetic electron transport rate (J(F)) of PS II reaction center had no evident increase, though the non-photochemical fluorescence quenching coefficient (NPQ) decreased significantly. With no nitrogen application, the Fv'/Fm', psi(PS II), and NPQ at elevated atmospheric CO2 concentration decreased significantly, and the J(F) had a significant decrease though the Fv/Fm and q(p) did not vary remarkably. Nitrogen application increased the J(F) and photochemical electron transport rate (Jc); while elevated atmospheric CO2 concentration decreased the photorespiration electron transport rate (J0), Rubisco oxidation rate (V0), ratio of photorespiration to photochemical electron transport rate (J0/Jc) , and Rubisco oxidation/carboxylation rate (Vo/Vc), but

  2. A reevaluation of the magnitude and impacts of anthropogenic atmospheric nitrogen inputs on the ocean

    Science.gov (United States)

    Jickells, T. D.; Buitenhuis, E.; Altieri, K.; Baker, A. R.; Capone, D.; Duce, R. A.; Dentener, F.; Fennel, K.; Kanakidou, M.; LaRoche, J.; Lee, K.; Liss, P.; Middelburg, J. J.; Moore, J. K.; Okin, G.; Oschlies, A.; Sarin, M.; Seitzinger, S.; Sharples, J.; Singh, A.; Suntharalingam, P.; Uematsu, M.; Zamora, L. M.

    2017-02-01

    We report a new synthesis of best estimates of the inputs of fixed nitrogen to the world ocean via atmospheric deposition and compare this to fluvial inputs and dinitrogen fixation. We evaluate the scale of human perturbation of these fluxes. Fluvial inputs dominate inputs to the continental shelf, and we estimate that about 75% of this fluvial nitrogen escapes from the shelf to the open ocean. Biological dinitrogen fixation is the main external source of nitrogen to the open ocean, i.e., beyond the continental shelf. Atmospheric deposition is the primary mechanism by which land-based nitrogen inputs, and hence human perturbations of the nitrogen cycle, reach the open ocean. We estimate that anthropogenic inputs are currently leading to an increase in overall ocean carbon sequestration of 0.4% (equivalent to an uptake of 0.15 Pg C yr-1 and less than the Duce et al. (2008) estimate). The resulting reduction in climate change forcing from this ocean CO2 uptake is offset to a small extent by an increase in ocean N2O emissions. We identify four important feedbacks in the ocean atmosphere nitrogen system that need to be better quantified to improve our understanding of the perturbation of ocean biogeochemistry by atmospheric nitrogen inputs. These feedbacks are recycling of (1) ammonia and (2) organic nitrogen from the ocean to the atmosphere and back, (3) the suppression of nitrogen fixation by increased nitrogen concentrations in surface waters from atmospheric deposition, and (4) increased loss of nitrogen from the ocean by denitrification due to increased productivity stimulated by atmospheric inputs.

  3. Governing processes for reactive nitrogen compounds in the European atmosphere

    DEFF Research Database (Denmark)

    Hertel, Ole; Skjøth, Carsten Ambelas; Reis, S.

    2012-01-01

    +)), oxidized nitrogen (NOy: nitrogen monoxide (NO) + nitrogen dioxide (NO2) and their reaction products) as well as organic nitrogen compounds (organic N). Pollution abatement strategies need to take into account the differences in the governing processes of these compounds when assessing their impact...... into aerosols as nitrate (NO3-). In contrast to NOx compounds, NH3 has potentially high impacts on ecosystems near the main agricultural sources of NH3 because of its large ground-level concentrations along with large dry deposition rates. Aerosol phase NH4+ and NO3- contribute significantly to background PM2...

  4. Fluorescence action spectra of algae and bean leaves at room and at liquid nitrogen temperatures

    NARCIS (Netherlands)

    Goedheer, J.C.

    1965-01-01

    Fluorescence action spectra were determined, both at room temperature and at liquid nitrogen temperature, with various blue-green, red and green algae, and greening bean leaves. The action spectra of algae were established with samples of low light absorption as well as dense

  5. Assessing atmospheric nitrogen deposition to natural and semi-natural ecosystems

    DEFF Research Database (Denmark)

    Hertel, Ole; Geels, Camilla; Frohn, Lise Marie

    2013-01-01

    phase ammonia derived from local livestock production. Long-range transport, however, often constitutes the largest contribution to the overall atmospheric terrestrial reactive nitrogen loadings in Denmark. This is often in the range 10-15 kg N ha(-1) yr(-1) and consists mainly of aerosol phase nitrate...... and ammonium (reaction products of nitrogen oxides and ammonia), but also dry deposition of other reactive nitrogen compounds (mainly nitrogen oxides in the form of gas phase nitric acid and nitrogen dioxide). In Denmark's environmental management of the sensitive terrestrial ecosystems modelling tools...... are required that account for both the local and the long-range transported contributions. This motivated development of the Danish Ammonia MOdelling System (DAMOS) that has been successfully applied to the assessment of atmospheric nitrogen loadings to sensitive Danish ecosystems. We present here three...

  6. Modeling Historical and Projected Future Atmospheric Nitrogen Loading to the Chesapeake Bay Watershed

    Science.gov (United States)

    Land use and climate change are expected to alter key processes in the Chesapeake Bay watershed and can potentially exacerbate the impact of excess nitrogen. Atmospheric sources are one of the largest loadings of nitrogen to the Chesapeake Bay watershed. In this study, we explore...

  7. In Situ Denitrification and Biological Nitrogen Fixation Under Enhanced Atmospheric Reactive Nitrogen Deposition in UK Peatlands

    Science.gov (United States)

    Ullah, Sami; Saiz Val, Ernesto; Sgouridis, Fotis; Peichl, Matthias; Nilsson, Mats

    2017-04-01

    Dinitrogen (N2) and nitrous oxide (N2O) losses due to denitrification and biological N2 fixation (BNF) are the most uncertain components of the nitrogen (N) cycle in peatlands under enhanced atmospheric reactive nitrogen (Nr) deposition. This uncertainty hampers our ability to assess the contribution of denitrification to the removal of biologically fixed and/or atmospherically deposited Nr in peatlands. This uncertainty emanates from the difficulty in measuring in situ soil N2 and N2O production and consumption in peatlands. In situ denitrification and its contribution to total N2O flux was measured monthly between April 2013 and October 2014 in peatlands in two UK catchments. An adapted 15N-Gas Flux method1 with low level addition of 15N tracer (0.03 ± 0.005 kg 15N ha-1) was used to measure denitrification and its contribution to net N2O production (DN2O/TN2O). BNF was measured in situ through incubation of selected sphagnum species under 15N2 gas tracer. Denitrification2 varied temporally and averaged 8 kg N-N2 ha-1 y-1. The contribution of denitrification was about 48% to total N2O flux3 of 0.05 kg N ha-1 y-1. Soil moisture, temperature, ecosystem respiration, pH and mineral N content mainly regulated the flux of N2 and N2O. Preliminary results showed suppression of BNF, which was 1.8 to 7 times lower in peatland mosses exposed to ˜15 to 20 kg N ha-1 y-1 Nr deposition in the UK than in peatland mosses in northern Sweden with background Nr deposition. Overall, the contribution of denitrification to Nr removal in the selected peatlands was ˜50% of the annual Nr deposition rates, making these ecosystems vulnerable to chronic N saturation. These results point to a need for a more comprehensive annual BNF measurement to more accurately account for total Nr input into peatlands and its atmospheric loss due to denitrification. References Sgouridis F, Stott A & Ullah S, 2016. Application of the 15N-Gas Flux method for measuring in situ N2 and N2O fluxes due to

  8. Polarized Fluorescence from Nitrogen Molecules Excited by Polarized Electron Impact

    Science.gov (United States)

    Maseberg, J. W.; Furst, J. E.; Gay, T. J.

    2005-05-01

    We have measured the optical excitation function and relative Stokes parameters for 388±5 nm fluorescence from spin-polarized electron impact excitation of molecular N2. Specifically, the circular polarization fraction normalized to the incident electron spin, P3/Pe, was found to be +1(5)% at an electron energy of 30eV. This result, even though it contains contributions from 6 different triplet spectral lines, is consistent with the data of the Münster group [1] who measured the N2 337 nm C3πu - B3πg (ν'=0, ν=0) transition and found P3 Mette et al., Verhandl. DPG (VI) 29, 462 (1994). [2] A.S. Green et al., Phys. Rev. Lett. 92, 093201 (2004).

  9. Total Nitrogen Deposition (wet+dry) from the Atmosphere

    Data.gov (United States)

    U.S. Environmental Protection Agency — Oxides of Nitrogen are emitted primarily as by-products of combustion. Sources include power plants, industrial boilers, and automobiles. In addition, agricultural...

  10. Effects of N2O and O2 addition to nitrogen Townsend dielectric barrier discharges at atmospheric pressure on the absolute ground-state atomic nitrogen density

    KAUST Repository

    Es-sebbar, Et-touhami

    2012-11-27

    Absolute ground-state density of nitrogen atoms N (2p3 4S3/2) in non-equilibrium Townsend dielectric barrier discharges (TDBDs) at atmospheric pressure sustained in N2/N2O and N2/O2 gas mixtures has been measured using Two-photon absorption laser-induced fluorescence (TALIF) spectroscopy. The quantitative measurements have been obtained by TALIF calibration using krypton as a reference gas. We previously reported that the maximum of N (2p3 4S3/2) atom density is around 3 × 1014 cm-3 in pure nitrogen TDBD, and that this maximum depends strongly on the mean energy dissipated in the gas. In the two gas mixtures studied here, results show that the absolute N (2p3 4S3/2) density is strongly affected by the N2O and O2 addition. Indeed, the density still increases exponentially with the energy dissipated in the gas but an increase in N2O and O2 amounts (a few hundreds of ppm) leads to a decrease in nitrogen atom density. No discrepancy in the order of magnitude of N (2p3 4S3/2) density is observed when comparing results obtained in N2/N2O and N2/O2 mixtures. Compared with pure nitrogen, for an energy of ∼90 mJ cm-3, the maximum of N (2p3 4S3/2) density drops by a factor of 3 when 100 ppm of N2O and O2 are added and it reduces by a factor of 5 for 200 ppm, to reach values close to our TALIF detection sensitivity for 400 ppm (1 × 1013 cm -3 at atmospheric pressure). © 2013 IOP Publishing Ltd.

  11. Oh where OH where is Oh? Measuring the Elusive Hydroxyl Radical in the Atmosphere Using Laser-Induced Fluorescence

    Science.gov (United States)

    Stevens, Philip S.

    2016-06-01

    The hydroxyl radical (OH) plays a central role in the chemistry of the atmosphere. In addition to controlling the lifetimes of many trace gases important to issues of global climate change and stratospheric ozone depletion, the OH radical initiates the oxidation of carbon monoxide and volatile organic compounds which in the presence of nitrogen oxides can lead to the production of ground-level ozone and secondary organic aerosols, the primary components of photochemical smog. Accurate measurements of OH radical concentrations in the atmosphere can provide critical tests of our understanding of atmospheric chemistry and ground-level ozone production in urban and rural areas. Because of its high reactivity, mixing ratios of OH in the atmosphere are extremely low (typically less than 0.1 parts per trillion) and its chemical lifetime very short (less than 1 second). As a result, measurements of OH present a serious analytical challenge, especially on the timescale necessary to test our understanding of the fast photochemistry of the atmosphere. This presentation will describe the Indiana University laser-induced fluorescence instrument for the sensitive detection of OH radicals in the atmosphere, including recent results from several measurement campaigns in both urban and rural environments.

  12. Atmospheric nitrogen in the Mississippi River Basin - Amissions, deposition and transport

    Science.gov (United States)

    Lawrence, G.B.; Goolsby, D.A.; Battaglin, W.A.; Stensland, G.J.

    2000-01-01

    Atmospheric deposition of nitrogen has been cited as a major factor in the nitrogen saturation of forests in the north-eastern United States and as a contributor to the eutrophication of coastal waters, including the Gulf of Mexico near the mouth of the Mississippi River. Sources of nitrogen emissions and the resulting spatial patterns of nitrogen deposition within the Mississippi River Basin, however, have not been fully documented. An assessment of atmospheric nitrogen in the Mississippi River Basin was therefore conducted in 1998-1999 to: (1) evaluate the forms in which nitrogen is deposited from the atmosphere; (2) quantify the spatial distribution of atmospheric nitrogen deposition throughout the basin; and (3) relate locations of emission sources to spatial deposition patterns to evaluate atmospheric transport. Deposition data collected through the NADP/NTN (National Atmospheric Deposition Program/National Trends Network) and CASTNet (Clean Air Status and Trends Network) were used for this analysis. NO(x) Tier 1 emission data by county was obtained for 1992 from the US Environmental Protection Agency (Emissions Trends Viewer CD, 1985-1995, version 1.0, September 1996) and NH3 emissions data was derived from the 1992 Census of Agriculture (US Department of Commerce. Census of Agriculture, US Summary and County Level Data, US Department of Commerce, Bureau of the Census. Geographic Area series, 1995:1b) or the National Agricultural Statistics Service (US Department of Agriculture. National Agricultural Statistics Service Historical Data. Accessed 7/98 at URL, 1998. http://www.usda.gov/nass/pubs/hisdata.htm). The highest rates of wet deposition of NO3- were in the north-eastern part of the basin, downwind of electric utility plants and urban areas, whereas the highest rates of wet deposition of NH4+ were in Iowa, near the center of intensive agricultural activities in the Midwest. The lowest rates of atmospheric nitrogen deposition were on the western (windward

  13. Biogeochemical context impacts seawater pH changes resulting from atmospheric sulfur and nitrogen deposition

    NARCIS (Netherlands)

    Hagens, M.; Hunter, K.A.; Liss, P.S.; Middelburg, J.J.

    2014-01-01

    Seawater acidification can be induced both by absorption of atmospheric carbon dioxide (CO2) and by atmospheric deposition of sulfur and nitrogen oxides and ammonia. Their relative significance, interplay, and dependency on water column biogeochemistry are not well understood. Using a simple

  14. Nutritional constraints in ombrotrophic Sphagnum plants under increasing atmospheric nitrogen deposition in Europe

    NARCIS (Netherlands)

    Bragazza, L.; Tahvanainen, T.; Kutnar, L.; Rydin, H.; Limpens, J.; Hajek, M.; Grosvernier, P.; Hansen, I.; Lacumin, P.; Gerdol, R.

    2004-01-01

    We studied the effects of increasing levels of atmospheric nitrogen (N) deposition on nutrient limitation of ombrotrophic Sphagnum plants. • Fifteen mires in 11 European countries were selected across a natural gradient of bulk atmospheric N deposition from 0.1 to 2 g/m2 year-1. Nutritional

  15. Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington forests, USA

    Science.gov (United States)

    Linda H. Geiser; Sarah E. Jovan; Doug A. Glavich; Matthew K. Porter

    2010-01-01

    Critical loads (CLs) define maximum atmospheric deposition levels apparently preventative of ecosystem harm. We present first nitrogen CLs for northwestern North America's maritime forests. Using multiple linear regression, we related epiphytic-macrolichen community composition to: 1) wet deposition from the National Atmospheric Deposition Program, 2) wet, dry,...

  16. Investigation of Atmospheric Effects on Retrieval of Sun-Induced Fluorescence Using Hyperspectral Imagery.

    Science.gov (United States)

    Ni, Zhuoya; Liu, Zhigang; Li, Zhao-Liang; Nerry, Françoise; Huo, Hongyuan; Sun, Rui; Yang, Peiqi; Zhang, Weiwei

    2016-04-06

    Significant research progress has recently been made in estimating fluorescence in the oxygen absorption bands, however, quantitative retrieval of fluorescence data is still affected by factors such as atmospheric effects. In this paper, top-of-atmosphere (TOA) radiance is generated by the MODTRAN 4 and SCOPE models. Based on simulated data, sensitivity analysis is conducted to assess the sensitivities of four indicators-depth_absorption_band, depth_nofs-depth_withfs, radiance and Fs/radiance-to atmospheric parameters (sun zenith angle (SZA), sensor height, elevation, visibility (VIS) and water content) in the oxygen absorption bands. The results indicate that the SZA and sensor height are the most sensitive parameters and that variations in these two parameters result in large variations calculated as the variation value/the base value in the oxygen absorption depth in the O₂-A and O₂-B bands (111.4% and 77.1% in the O₂-A band; and 27.5% and 32.6% in the O₂-B band, respectively). A comparison of fluorescence retrieval using three methods (Damm method, Braun method and DOAS) and SCOPE Fs indicates that the Damm method yields good results and that atmospheric correction can improve the accuracy of fluorescence retrieval. Damm method is the improved 3FLD method but considering atmospheric effects. Finally, hyperspectral airborne images combined with other parameters (SZA, VIS and water content) are exploited to estimate fluorescence using the Damm method and 3FLD method. The retrieval fluorescence is compared with the field measured fluorescence, yielding good results (R² = 0.91 for Damm vs. SCOPE SIF; R² = 0.65 for 3FLD vs. SCOPE SIF). Five types of vegetation, including ailanthus, elm, mountain peach, willow and Chinese ash, exhibit consistent associations between the retrieved fluorescence and field measured fluorescence.

  17. The contribution of manure and fertilizer nitrogen to atmospheric nitrous oxide since 1860

    Science.gov (United States)

    Davidson, Eric A.

    2009-09-01

    Atmospheric nitrous oxide concentrations have been increasing since the industrial revolution and currently account for 6% of total anthropogenic radiative forcing. Microbial production in soils is the dominant nitrous oxide source; this has increased with increasing use of nitrogen fertilizers. However, fertilizer use alone cannot account for the historical trends of atmospheric concentrations of nitrous oxide. Here, I analyse atmospheric concentrations, industrial sources of nitrous oxide, and fertilizer and manure production since 1860. Before 1960, agricultural expansion, including livestock production, may have caused globally significant mining of soil nitrogen, fuelling a steady increase in atmospheric nitrous oxide. After 1960, the rate of the increase rose, due to accelerating use of synthetic nitrogen fertilizers. Using a regression model, I show that 2.0% of manure nitrogen and 2.5% of fertilizer nitrogen was converted to nitrous oxide between 1860 and 2005; these percentage contributions explain the entire pattern of increasing nitrous oxide concentrations over this period. Consideration of processes that re-concentrate soil nitrogen, such as manure production by livestock, improved `hind-casting' of nitrous oxide emissions. As animal protein consumption in human diets increases globally, management of manure will be an important component of future efforts to reduce anthropogenic nitrous oxide sources.

  18. Atmospheric Nitrogen Deposition: An increasingly Important Source of "new" Nitrogen Supporting Coastal Eutrophication

    Science.gov (United States)

    Paerl, H. W.; Whitall, D. R.; Dennis, R. L.

    2004-12-01

    Atmospheric deposition of nitrogen (AD-N) to the North Atlantic Ocean (NAO) basin arises from diverse pollution sources in North America and Western Europe; these sources have increased by 5 to10 fold since the Industrial Revolution, agricultural expansion and urbanization in the NAO airshed and continue to increase in both geographic and depositional magnitudes. Based on recent estimates, AD-N flux (11.2 Tg N per year) accounts for 46-57 per cent of the total new or externally-supplied anthropogenic N flux to the NAO. In US estuarine and coastal waters, from 10 to over 40 per cent of new N loading is attributed to AD-N; estimates for North Carolina's Albemarle-Pamlico Sound system range from 20 to over 30 per cent. In developing regions of the world, AD-N is one of the most rapidly expanding sources of new N. AD-N has been linked to eutrophication in N-sensitive coastal waters. In North Carolina, N deposition has increased since the 1960's as a result of urbanization (chiefly NOx) and more recently agricultural growth (NH4+ and organic N). In particular, rapidly-expanding livestock operations have led to increases in the generation of N-enriched wastes and manures; a substantial proportion (30- >70 per cent) of which may be emitted as NH3 gas. Recent growth and intensification of animal operations in the midwest and coastal regions (e.g., Mid-Atlantic coastal plain) have been linked to increasing amounts of NH4+ deposition, according to a 2 decadal analysis of the National Acid Deposition Program (NADP) network. The impacts of both increasing amounts and altered chemical composition of AD-N are being examined in the N-limited, eutrophying (i.e., expanding algal blooms, hypoxia and anoxia) Neuse River Estuary, Pamlico Sound and coastal waters of North Carolina. Because of its relatively large contribution to total new N loading and potential biogeochemical and ecological importance in N sensitive waters, AD-N requires attention from air/watershed nutrient budgeting

  19. Responses of two summer annuals to interactions of atmospheric carbon dioxide and soil nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, R.B.

    1987-01-01

    The competitive relationship between Chenopodium album L. (C{sub 3}) and Amaranthus hybridus L. (C{sub 4}) was investigated in two atmospheric CO{sub 2} levels and tow soil nitrogen levels. Biomass and leaf surface area of Amaranthus plants did not respond to CO{sub 2} enrichment. Only in high nitrogen did Chenopodium plants respond to increased CO{sub 2} with greater biomass and leaf surface area. Nitrogen use efficiency (NUE) was higher in Amaranthus than in Chenopodium in all treatments except for the high-nitrogen high-CO{sub 2} treatment. Under conditions of high nitrogen and low CO{sub 2}, Chenopodium was a poor competitor, but competition favored Chenopodium in high nitrogen and high CO{sub 2}. In low nitrogen and high CO{sub 2}, competition favored Chenopodium on a dry weight basis, but favored Amaranthus on a seed weight basis, reflecting early senescence of Chenopodium. In low nitrogen and high CO{sub 2}, competition favored Amaranthus on a dry weight basis, but favored Chenopodium on a seed weight basis. Physiological aspects of the growth of Chenopodium and Amaranthus were studied. Acclimation to elevated CO{sub 2} occurred at the enzyme level in Chenopodium. Under conditions of high nitrogen and no competition, individual Chenopodium plants responded to elevated CO{sub 2} with greater biomass, leaf surface area, and maximum net photosynthetic rates. In high nitrogen, leaf nitrogen, soluble protein, and RuBP carboxylase activity of Chenopodium decreased and NUE increased when grown in elevated CO{sub 2}. In low nitrogen without competition, Chenopodium showed no significant response to CO{sub 2} enrichment. Amarantus grown in high and low nitrogen without competition showed no significant changes in leaf nitrogen, soluble protein, carboxylase activity, chlorophyll, or NUE of in response to CO{sub 2} enrichment.

  20. Wet and Dry Atmospheric Depositions of Inorganic Nitrogen during Plant Growing Season in the Coastal Zone of Yellow River Delta

    Directory of Open Access Journals (Sweden)

    Junbao Yu

    2014-01-01

    Full Text Available 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.

  1. Vertical profiles of atmospheric fluorescent aerosols observed by a mutil-channel lidar spectrometer system

    Science.gov (United States)

    Huang, Z.; Huang, J.; Zhou, T.; Sugimoto, N.; Bi, J.

    2015-12-01

    Zhongwei Huang1*, Jianping Huang1, Tian Zhou1, Nobuo Sugimoto2, Jianrong Bi1 and Jinsen Shi11Key Laboratory for Semi-Arid Climate Change of the Ministry of Education, College of Atmospheric Sciences, Lanzhou University, Lanzhou, China. 2Atmospheric Environment Division, National Institutes for Environmental Studies, Tsukuba, Japan Email: huangzhongwei@lzu.edu.cn Abstract Atmospheric aerosols have a significant impact on regional and globe climate. The challenge in quantifying aerosol direct radiative forcing and aerosol-cloud interactions arises from large spatial and temporal heterogeneity of aerosol concentrations, compositions, sizes, shape and optical properties (IPCC, 2007). Lidar offers some remarkable advantages for determining the vertical structure of atmospheric aerosols and their related optical properties. To investigate the characterization of atmospheric aerosols (especially bioaerosols) with high spatial and temporal resolution, we developed a Raman/fluorescence/polarization lidar system employed a multi-channel spectrometer, with capabilities of providing measurements of Raman scattering and laser-induced fluorescence excitation at 355 nm from atmospheric aerosols. Meanwhile, the lidar system operated polarization measurements both at 355nm and 532nm wavelengths, aiming to obtain more information of aerosols. It employs a high power pulsed laser and a received telescope with 350mm diameter. The receiver could simultaneously detect a wide fluorescent spectrum about 178 nm with spectral resolution 5.7 nm, mainly including an F/3.7 Crossed Czerny-Turner spectrograph, a grating (1200 gr/mm) and a PMT array with 32 photocathode elements. Vertical structure of fluorescent aerosols in the atmosphere was observed by the developed lidar system at four sites across northwest China, during 2014 spring field observation that conducted by Lanzhou University. It has been proved that the developed lidar could detect the fluorescent aerosols with high temporal and

  2. Fluorescent probes to investigate nitric oxide and other reactive nitrogen species in biology (truncated form: fluorescent probes of reactive nitrogen species).

    Science.gov (United States)

    McQuade, Lindsey E; Lippard, Stephen J

    2010-02-01

    Reactive nitrogen species (RNS), such as nitric oxide and its higher oxides, play important roles in cell signaling during many physiological and pathological events. Elucidation of the exact functions of these important biomolecules has been hampered by the inability to detect RNS reliably under biological conditions. A surge of research into RNS chemistry has resulted in the design of a new generation of fluorescent probes that are specific and sensitive for their respective RNS analytes. Progress in the field of nitric oxide, peroxynitrite, and nitroxyl sensing promises to advance our knowledge of important signaling events involving these species and lead to a better understanding of oxidative biochemistry crucial to health and disease. 2009 Elsevier Ltd. All rights reserved.

  3. Relationship between atmospheric ammonia concentration and nitrogen content in terricolous lichen (Cladonia portentosa)

    DEFF Research Database (Denmark)

    Nielsen, Knud Erik; Andersen, Helle Vibeke; Strandberg, Morten Tune

    2014-01-01

    From April 2006 to April 2007, the geographical and seasonal variation in nitrogen content in terricolous lichen (Cladonia portentosa) and atmospheric ammonia concentrations were measured at five heathland sites. The seasonal variation in the nitrogen content of the lichen was small, even though...... there was a large seasonal variation in the air concentration of ammonia. A sizable local variation in the nitrogen content of the lichen was found even at the scale of a few kilometres. The nitrogen content in the lichen showed a high correlation to the yearly mean value of the measured ammonia concentration...... in air at the different locations. This investigation is part of a larger attempt to incorporate effects of nitrogen in the conservation status of terrestrial habitat types....

  4. An assessment of the atmospheric nitrogen budget on the South African Highveld

    Directory of Open Access Journals (Sweden)

    Kristy E. Ross

    2010-05-01

    Full Text Available Atmospheric reactive nitrogen concentrations on the South African Highveld have become a growing concern, with satellite images indicating very high nitrogen dioxide (NO2 concentrations in the region. This study investigated the nitrogen budget on the Highveld through the analysis of the concentration of the atmospheric nitrogen species on a temporal scale as well as the atmospheric conversion, transport and removal of these species. Data were collected at Eskom’s Elandsfontein ambient air quality monitoring site, which is centrally located on the industrialised Highveld. A year’s dataset from 2005 and 2006 was analysed and it was found that nitrogen oxide (NOx concentrations were higher in winter as a result of stable atmospheric conditions, as well as prevalent westerly and north-westerly airflow, which transported emissions directly from the nearby power station sources to the monitoring site. Nitrate (NO3 concentrations also peaked during winter, with a distinct biomass burning peak during August 2005. Diurnally, NOx concentrations indicated a tall-stack industrial source, where concentrations peaked at midday. The NO3 concentrations were higher at night than during the day; during the day the NO3 radical is rapidly photolysed and nitrates cannot be produced. Case studies indicated that the conversion rate of nitric oxide (NO to NO2 was highly variable as a result of varying atmospheric factors, which include time of day, dispersion, stability and regional atmospheric chemistry. These rates ranged from 11% to 59% per hour. Rates of dry deposition of NO, NO2 and NO3 were generally higher during winter as a result of higher atmospheric concentrations and increased atmospheric stability. Nitrogen was predominantly deposited as NO2 throughout the year, except during spring when NO3 deposition dominated. The total annual

  5. Effect of carbon and nitrogen assimilation on chlorophyll fluorescence emission by the cyanobacterium Anacystis nidulans

    Energy Technology Data Exchange (ETDEWEB)

    Romero, J.M.; Lara, C. (Instituto de Bioquimica Vegetal y Fotosintesis, Univ. de Sevilla y CSIC, Sevilla (ES)); Sivak, M.N. (Dept. of Biochemistry, Michigan State Univ., East Lansing (US))

    1992-01-01

    O{sub 2} evolution and chlorophyll A fluorescence emission have been monitored in intact cells of the cyanobacterium Anacystis nidulans 1402-1 to study the influence of carbon and nitrogen assimilation on the operation of the photosynthetic apparatus. The pattern of fluorescence induction in dark-adapted cyanobacterial cells was different from that of higher plants. Cyanobacteria undergo large, rapid state transitions upon illumination, which lead to marked changes in the fluorescence yield, complicating the estimation of quenching coefficients. The Kautsky effect was not evident, although it could be masked by a state II-state I transition, upon illumination with actinic light. The use of inhibitors of carbon assimilation such as D,L-glyceraldehyde or iodoacetamide allowed us to relate changes in variable fluorescence to active CO{sub 2} fixation. Ammonium, but not nitrate, induced non-photochemical fluorescence quenching, in agreement with a previous report on green algae, indicative of an ammonium-induced state i transition. (au).

  6. Box-modeling of the impacts of atmospheric nitrogen deposition and benthic remineralization on the nitrogen cycle of the eastern tropical South Pacific

    Science.gov (United States)

    Su, B.; Pahlow, M.; Oschlies, A.

    2015-09-01

    Both atmospheric deposition and benthic remineralization influence the marine nitrogen cycle, and hence ultimately also marine primary production. The biological and biogeochemical relations of the eastern tropical South Pacific (ETSP) to nitrogen deposition, benthic denitrification and phosphate regeneration are analysed in a prognostic box model of the oxygen, nitrogen and phosphorus cycles in the ETSP. In the model, atmospheric nitrogen deposition based on estimates for the years 2000-2009 is offset by half by reduced N2 fixation, with the other half transported out of the model domain. Both model- and data-based benthic denitrification are found to trigger nitrogen fixation, partly compensating for the NO3- loss. Since phosphate is the ultimate limiting nutrient in the model, enhanced sedimentary phosphate regeneration under suboxic conditions stimulates primary production and subsequent export production and NO3- loss in the oxygen minimum zone (OMZ). A sensitivity analysis of the local response to both atmospheric deposition and benthic remineralization indicates dominant stabilizing feedbacks in the ETSP, which tend to keep a balanced nitrogen inventory, i.e., nitrogen input by atmospheric deposition is counteracted by decreasing nitrogen fixation; NO3- loss via benthic denitrification is partly compensated by increased nitrogen fixation; enhanced nitrogen fixation stimulated by phosphate regeneration is partly removed by the stronger water-column denitrification. Even though the water column in our model domain acts as a NO3- source, the ETSP including benthic denitrification might become a NO3- sink.

  7. Nitrogen mineralization across an atmospheric nitrogen deposition gradient in Southern California deserts

    Science.gov (United States)

    L.E. Rao; D.R. Parker; Andrzej Bytnerowicz; E.B. Allen

    2009-01-01

    Dry nitrogen deposition is common in arid ecosystems near urban and agricultural centers, yet its impacts on natural environments are relatively understudied. We examined the effects of N deposition on soil N mineralization across a depositional gradient at Joshua Tree National Park. We hypothesized that N deposition affects N mineralization by promoting...

  8. Effect of feed-gas humidity on nitrogen atmospheric-pressure plasma jet for biological applications.

    Science.gov (United States)

    Stephan, Karl D; McLean, Robert J C; DeLeon, Gian; Melnikov, Vadim

    2016-11-14

    We investigate the effect of feed-gas humidity on the oxidative properties of an atmospheric-pressure plasma jet using nitrogen gas. Plasma jets operating at atmospheric pressure are finding uses in medical and biological settings for sterilization and other applications involving oxidative stress applied to organisms. Most jets use noble gases, but some researchers use less expensive nitrogen gas. The feed-gas water content (humidity) has been found to influence the performance of noble-gas plasma jets, but has not yet been systematically investigated for jets using nitrogen gas. Low-humidity and high-humidity feed gases were used in a nitrogen plasma jet, and the oxidation effect of the jet was measured quantitatively using a chemical dosimeter known as FBX (ferrous sulfate-benzoic acid-xylenol orange). The plasma jet using high humidity was found to have about ten times the oxidation effect of the low-humidity jet, as measured by comparison with the addition of measured amounts of hydrogen peroxide to the FBX dosimeter. Atmospheric-pressure plasma jets using nitrogen as a feed gas have a greater oxidizing effect with a high level of humidity added to the feed gas.

  9. Atmospheric deposition of nitrogen to the Baltic Sea in the period 1995–2006

    Directory of Open Access Journals (Sweden)

    J. Bartnicki

    2011-10-01

    Full Text Available The EMEP/MSC-W model has been used to compute atmospheric nitrogen deposition into the Baltic Sea basin for the period of 12 yr: 1995–2006. The level of annual total nitrogen deposition into the Baltic Sea basin has changed from 230 Gg N in 1995 to 199 Gg N in 2006, decreasing 13 %. This value corresponds well with the total nitrogen emission reduction (11 % in the HELCOM Contracting Parties. However, inter-annual variability of nitrogen deposition to the Baltic Sea basin is relatively large, ranging from −13 % to +17 % of the averaged value. It is mainly caused by the changing meteorological conditions and especially precipitation in the considered period. The calculated monthly deposition pattern is similar for most of the years showing maxima in the autumn months October and November. The source allocation budget for atmospheric nitrogen deposition to the Baltic Sea basin was calculated for each year of the period 1997–2006. The main emission sources contributing to total nitrogen deposition are: Germany 18–22 %, Poland 11–13 % and Denmark 8–11 %. There is also a significant contribution from distant sources like the United Kingdom 6–9 %, as well as from the international ship traffic on the Baltic Sea 4–5 %.

  10. Source receptor relations for the calculation of atmospheric deposition to the North Sea: Nitrogen and Cadmium

    NARCIS (Netherlands)

    van Jaarsveld JA; de Leeuw FAAM

    1993-01-01

    In this report a simplified atmospheric transport model for estimating the deposition of nitrogen (both NOx and NHx) and cadmium to the North Sea is presented. In this so-called meta-model a linear relationship between the emissions from a source area and the resulting deposition at receptor points

  11. The impact of atmospheric ammonia and temperature on growth and nitrogen metabolism of winter wheat

    NARCIS (Netherlands)

    Clement, J.M A M; Loorbach, J; Meijer, J; van Hasselt, P.R; Stulen, G

    The effect of atmospheric ammonia in combination with low and moderate growth temperature on growth and nitrogen metabolism of winter wheat plants (Triticum aestivum L. cv. Urban) was investigated. Plants were exposed to 0, 1000 and 2000 nl l(-1) NH3 for 1 week at moderate day/night temperatures

  12. Conditional vulnerability of plant diversity to atmospheric nitrogen deposition across the United States

    Science.gov (United States)

    Samuel M. Simkin; Edith B. Allen; William D. Bowman; Christopher M. Clark; Jayne Belnap; Matthew L. Brooks; Brian S. Cade; Scott L. Collins; Linda H. Geiser; Frank S. Gilliam; Sarah E. Jovan; Linda H. Pardo; Bethany K. Schulz; Carly J. Stevens; Katharine N. Suding; Heather L. Throop; Donald M. Waller

    2016-01-01

    Atmospheric nitrogen (N) deposition has been shown to decrease plant species richness along regional deposition gradients in Europe and in experimental manipulations. However, the general response of species richness to N deposition across different vegetation types, soil conditions, and climates remains largely unknown even though responses may be contingent on these...

  13. A reevaluation of the magnitude and impacts of anthropogenic atmospheric nitrogen inputs on the ocean

    NARCIS (Netherlands)

    Jickells, T.D.; Buitenhuis, E.; Altieri, K.; Baker, A.R.; Capone, D.; Duce, R.A.; Dentener, Frank; Fennel, F.; Kanakidou, M.; LaRoche, J.; Lee, K.; Liss, P.; Middelburg, Jack J.; Moore, J.K.; Okin, G.; Oschlies, A.; Sarin, M.; Seitzinger, S.; Sharples, J.; Singh, A.; Suntharalingam, P.; Uematsu, M.; Zamora, L.M.

    We report a new synthesis of best estimates of the inputs of fixed nitrogen to the world ocean via atmospheric deposition and compare this to fluvial inputs and dinitrogen fixation. We evaluate the scale of human perturbation of these fluxes. Fluvial inputs dominate inputs to the continental shelf,

  14. Accounting for the effect of temperature in clarifying the response of foliar nitrogen isotope ratios to atmospheric nitrogen deposition.

    Science.gov (United States)

    Chen, Chongjuan; Li, Jiazhu; Wang, Guoan; Shi, Minrui

    2017-12-31

    Atmospheric nitrogen deposition affects nitrogen isotope composition (δ 15 N) in plants. However, both negative effect and positive effect have been reported. The effects of climate on plant δ 15 N have not been corrected for in previous studies, this has impeded discovery of a true effect of atmospheric N deposition on plant δ 15 N. To obtain a more reliable result, it is necessary to correct for the effects of climatic factors. Here, we measured δ 15 N and N contents of plants and soils in Baiwangshan and Mount Dongling, north China. Atmospheric N deposition in Baiwangshan was much higher than Mount Dongling. Generally, however, foliar N contents showed no difference between the two regions and foliar δ 15 N was significantly lower in Baiwangshan than Mount Dongling. The corrected foliar δ 15 N after accounting for a predicted value assumed to vary with temperature was obviously more negative in Baiwangshan than Mount Dongling. Thus, this suggested the necessity of temperature correction in revealing the effect of N deposition on foliar δ 15 N. Temperature, soil N sources and mycorrhizal fungi could not explain the difference in foliar δ 15 N between the two regions, this indicated that atmospheric N deposition had a negative effect on plant δ 15 N. Additionally, this study also showed that the corrected foliar δ 15 N of bulk data set increased with altitude above 1300m in Mount Dongling, this provided an another evidence for the conclusion that atmospheric N deposition could cause 15 N-depletion in plants. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Nitrogen-Doped Carbon Quantum Dots as Fluorescent Probes for Sensitive and Selective Detection of Nitrite

    Directory of Open Access Journals (Sweden)

    Zhibiao Feng

    2017-11-01

    Full Text Available Nitrites are the upstream precursors of the carcinogenic nitrosamines, which are widely found in the natural environment and many food products. It is important to develop a simple and sensitive sensor for detecting nitrites. In this work, a fluorescence probe based on nitrogen-doped carbon quantum dots (N-CQDs was developed for the sensitive and selective determination of nitrites. At pH 2, the fluorescence of N-CQDs can be selectively quenched by nitrite due to the fact N-nitroso compounds can be formed in the reaction of amide groups with nitrous acid, which results in fluorescence static quenching. Under optimal conditions, fluorescence intensity quenching upon addition of nitrite gives a satisfactory linear relationship covering the linear range of 0.2–20 μM, and the limit of detection (LOD is 40 nM. Moreover, this method has been successfully applied to the determination of nitrites in tap water, which indicates its great potential for monitoring of nitrites in environmental samples.

  16. Atmospheric and sub-atmospheric dielectric barrier discharges in helium and nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Sublet, A [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, CH-1015 Lausanne (Switzerland); Ding, C [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, CH-1015 Lausanne (Switzerland); Dorier, J-L [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, CH-1015 Lausanne (Switzerland); Hollenstein, Ch [Ecole Polytechnique Federale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association Euratom-Confederation Suisse, CH-1015 Lausanne (Switzerland); Fayet, P [Tetra Pak (Suisse) SA, Tetra Pak R and D Plasma Technology, CH-1680 Romont (Switzerland); Coursimault, F [Tetra Pak (Suisse) SA, Tetra Pak R and D Plasma Technology, CH-1680 Romont (Switzerland)

    2006-11-01

    Dielectric barrier discharges (DBDs) are investigated in helium and nitrogen as a function of pressure from 5 to 1000 mbar. Different regimes are observed: glow, Townsend, multi-peak and filamentary, depending on pressure, power and electrode gap. In helium, DBD is a glow-like discharge with a transition to multi-peak or Townsend discharge at high power. In nitrogen, the discharge is Townsend-like and shows a transition to multi-peak mode below 300 mbar. Transition to filamentary mode is observed for large gaps. Fast exposure imaging is used to investigate multi-peak mode in nitrogen. Electrical measurements and time-resolved optical emission spectroscopy are used to characterize the discharge, to study the evolution of metastable species as a function of the pressure and to analyse the discharge startup. These results offer new perspectives for the operation of DBDs in low vacuum.

  17. On extreme atmospheric and marine nitrogen fluxes and chlorophyll-a levels in the Kattegat Strait

    DEFF Research Database (Denmark)

    Hasager, C.B.; Carstensen, J.; Ellermann, T.

    2003-01-01

    A retrospective analysis is carried out to investigate the importance of the vertical fluxes of nitrogen to the marine sea surface layer in which high chlorophyll a levels may cause blooms of harmful algae and subsequent turn over and oxygen depletion at the bottom of the sea. Typically nitrogen......-water entrainment forced by high winds greatly exceeds the atmospheric pool of nitrogen washed out by precipitation. At the frontal zone of the Kattegat Strait and Skagerrak, the nitrogen deep-water entrainment is very high and this explains the high 10-year return chlorophyll level at 8 mg m(-3) in the Kattegat...... Strait. In the southern part, the extreme chlorophyll level is only 4 mg m(-3) according to the statistics of a multi-year time-series of water samples. The chlorophyll level varies greatly in time and space as documented by a series of SeaWiFS satellite maps (OC4v4 algorithm) of chlorophyll Scan...

  18. Optical Reflectance and Fluorescence for Detecting Nitrogen Needs in Zea mays L.

    Science.gov (United States)

    McMurtrey, J. E.; Middleton, E. M.; Corp. L. A.; Campbell, P. K. Entcheva; Butcher, L. M.; Daughtry, C. S. T.

    2003-01-01

    Nitrogen (N) status in field grown corn (Zea mays L.) was assessed using spectral techniques. Passive reflectance remote sensing and, both passive and active fluorescence sensing methods were investigated. Reflectance and fluorescence methods are reported to detect changes in the primary plant pigments (chlorophylls a and b; carotenoids) in higher plant species. As a general rule, foliar chlorophyll a (Chl a) and chlorophyll b (Chl b) usually exist in approx.3:l ratio. In plants under stress, Chl b content is affected before Chl a reductions occur. For reflectance, a version of the chlorophyll absorption in reflectance index (CARI) method was tested with narrow bands from the Airborne Imaging Spectroradiometer for Applications (ASIA). CARI minimizes the effects of soil background on the signal from green canopies. A modified CARI (MCARI) was used to track total Chl a levels in the red dip of the spectrum from the corn canopy. A second MCARI was used to track the auxiliary plant pigments (Chl b and the carotenoids) in the yellow/orange/red edge part of the reflectance spectrum. The difference between these two MCARI indices detected variations in N levels across the field plot canopies using ASIA data. At the leaf level, ratios of fluorescence emissions in the blue, green, red and far-red wavelengths sensed responses that were associated with the plant pigments, and were indicative of energy transfer in the photosynthetic process. N stressed corn stands could be distinguish from those with optimally applied N with fluorescence emission spectra obtained from individual corn leaves. Both reflectance and fluorescence methods are sensitive in detecting corn N needs and may be especially powerful in monitoring crop conditions if both types of information can be combined.

  19. Reaction of Unalloyed and Cr-Mo Alloyed Steels with Nitrogen from the Sintering Atmosphere

    Science.gov (United States)

    Dlapka, Magdalena; Gierl-Mayer, Christian; Calderon, Raquel de Oro; Danninger, Herbert; Bengtsson, Sven; Dudrova, Eva

    2016-12-01

    Nitrogen is usually regarded as an inert sintering atmosphere for PM steels; however, this cannot be taken for granted in particular for steels alloyed with nitride forming elements. Among those elements, chromium has become more and more important as an alloying element in sintered low alloy structural steels in the last decade due to the moderate alloying cost and the excellent mechanical properties obtainable, in particular when sinter hardening is applied. The high affinity of Cr to oxygen and the possible ways to overcome related problems have been the subject of numerous studies, while the fact that chromium is also a fairly strong nitride forming element has largely been neglected at least for low alloy steel grades, although frequently used materials like steels from Cr and Cr-Mo prealloyed powders are commonly sintered in atmospheres consisting mainly of nitrogen. In the present study, nitrogen pickup during sintering at different temperatures and for varying times has been studied for Cr-Mo prealloyed steel grades as well as for unalloyed carbon steel. Also the effect of the cooling rate and its influence on the properties, of the microstructure and the composition have been investigated. It showed that the main nitrogen uptake occurs not during isothermal sintering but rather during cooling. It could be demonstrated that a critical temperature range exists within which the investigated CrM-based steel is particularly sensitive to nitrogen pickup.

  20. How intensive agriculture affects surface-atmosphere exchange of nitrogen and carbon compounds over peatland

    Science.gov (United States)

    Bruemmer, C.; Richter, U.; Schrader, F.; Hurkuck, M.; Kutsch, W. L.

    2016-12-01

    Mid-latitude peatlands are often exposed to high atmospheric nitrogen deposition when located in close vicinity to agricultural land. As the impacts of altered deposition rates on nitrogen-limited ecosystems are poorly understood, we investigated the surface-atmosphere exchange of several nitrogen and carbon compounds using multiple high-resolution measurement techniques and modeling. Our study site was a protected semi-natural bog ecosystem. Local wind regime and land use in the adjacent area clearly regulated whether total reactive nitrogen (∑Nr) concentrations were ammonia (NH3) or NOx-dominated. Eddy-covariance measurements of NH3 and ∑Nr revealed concentration, temperature and surface wetness-dependent deposition rates. Intermittent periods of NH3 and ∑Nr emission likely attributed to surface water re-emission and soil efflux, respectively, were found, thereby indicating nitrogen oversaturation in this originally N-limited ecosystem. Annual dry plus wet deposition resulted in 20 to 25 kg N ha-1 depending on method and model used, which translated into a four- to fivefold exceedance of the ecosystem-specific critical load. As the bog site had likely been exposed to the observed atmospheric nitrogen burden over several decades, a shift in grass species' composition towards a higher number of nitrophilous plants was already visible. Three years of CO2 eddy flux measurements showed that the site was a small net sink in the range of 33 to 268 g CO2 m-2 yr-1. Methane emissions of 32 g CO2-eq were found to partly offset the sequestered carbon through CO2. Our study demonstrates the applicability of novel micrometeorological measurement techniques in biogeochemical sciences and stresses the importance of monitoring long-term changes in vulnerable ecosystems under anthropogenic pressure and climate change.

  1. Does high reactive nitrogen input from the atmosphere decrease the carbon sink strength of a peatland?

    Science.gov (United States)

    Brümmer, Christian; Zöll, Undine; Hurkuck, Miriam; Schrader, Frederik; Kutsch, Werner

    2017-04-01

    Mid-latitude peatlands are often exposed to high atmospheric nitrogen deposition when located in close vicinity to agricultural land. As the impacts of altered deposition rates on nitrogen-limited ecosystems are poorly understood, we investigated the surface-atmosphere exchange of several nitrogen and carbon compounds using multiple high-resolution measurement techniques and modeling. Our study site was a protected semi-natural bog ecosystem. Local wind regime and land use in the adjacent area clearly regulated whether total reactive nitrogen (ΣNr) concentrations were ammonia (NH3) or NOx-dominated. Eddy-covariance measurements of NH3 and ΣNr revealed concentration, temperature and surface wetness-dependent deposition rates. Intermittent periods of NH3 and ΣNr emission likely attributed to surface water re-emission and soil efflux, respectively, were found, thereby indicating nitrogen oversaturation in this originally N-limited ecosystem. Annual dry plus wet deposition resulted in 20 to 25 kg N ha-1 depending on method and model used, which translated into a four- to fivefold exceedance of the ecosystem-specific critical load. As the bog site had likely been exposed to the observed atmospheric nitrogen burden over several decades, a shift in grass species' composition towards a higher number of nitrophilous plants was already visible. Three years of CO2 eddy flux measurements showed that the site was a small net sink in the range of 33 to 268 g CO2 m-2 yr-1. Methane emissions of 32 g CO2-eq were found to partly offset the sequestered carbon through CO2. Our study indicates that the sink strength of the peatland has likely been decreased through elevated N deposition over the past decades. It also demonstrates the applicability of novel micrometeorological measurement techniques in biogeochemical sciences and stresses the importance of monitoring long-term changes in vulnerable ecosystems under anthropogenic pressure and climate change.

  2. [Effects of nitrogen fertilization on wheat leaf photosynthesis under elevated atmospheric CO2 concentration].

    Science.gov (United States)

    Yu, Xian-feng; Zhang, Xu-cheng; Guo, Tian-wen; Yu, Jia

    2010-09-01

    In this paper, the effects of nitrogen (N) fertilization on the wheat leaf photosynthesis under long-term elevated atmospheric CO2 concentration (760 micromol x mol(-1)) was studied, based on the measurements of photosynthetic gas exchange parameters and light intensity-photosynthetic rate response curves at jointing stage. Under the long-term elevated atmospheric CO2 concentration, applying sufficient N could increase the wheat leaf photosynthetic rate (Pn), transpiration rate (Tr), and instantaneous water use efficiency (WUEi). Comparing with those under ambient atmospheric CO2 concentration, the Po and WUEi under the elevated atmospheric CO2 concentration increased, while the stomatal conductance (Gs) and intercellular CO2 concentration (Ci) decreased. With the increase of light flux intensity, the Pn and WUEi under the elevated atmospheric CO2 concentration were higher those under ambient atmospheric CO2 concentration, Gs was in adverse, while Ci and Tr had less change. At high fertilization rate of N, the Gs was linearly positively correlated with Pn, Tr, and WUEi, and the Gs and Ci had no correlation with each other under the elevated atmospheric CO2 concentration but negatively correlated under ambient atmospheric CO2 concentration. At low fertilization rate of N, the Gs had no correlations with Pn and WUEi but linearly positively correlated with Ci and Tr. It was suggested that under the elevated atmospheric CO2 concentration, the wheat leaf Pn at low N fertilization rate was limited by non-stomatal factor.

  3. A lower limit of atmospheric pressure on early Mars inferred from nitrogen and argon isotopic compositions

    Science.gov (United States)

    Kurokawa, Hiroyuki; Kurosawa, Kosuke; Usui, Tomohiro

    2018-01-01

    We examine the history of the loss and replenishment of the Martian atmosphere using elemental and isotopic compositions of nitrogen and noble gases. The evolution of the atmosphere is calculated by taking into consideration various processes: impact erosion and replenishment by asteroids and comets, atmospheric escape induced by solar radiation and wind, volcanic degassing, and gas deposition by interplanetary dust particles. Our model reproduces the elemental and isotopic compositions of N and noble gases (except for Xe) in the Martian atmosphere, as inferred from exploration missions and analyses of Martian meteorites. Other processes such as ionization-induced fractionation, which are not included in our model, are likely to make a large contribution in producing the current Xe isotope composition. Since intense impacts during the heavy bombardment period greatly affect the atmospheric mass, the atmospheric pressure evolves stochastically. Whereas a dense atmosphere preserves primitive isotopic compositions, a thin atmosphere on early Mars is severely influenced by stochastic impact events and following escape-induced fractionation. The onset of fractionation following the decrease in atmospheric pressure is explained by shorter timescales of isotopic fractionation under a lower atmospheric pressure. The comparison of our numerical results with the less fractionated N (15N/14N) and Ar (38Ar/36Ar) isotope compositions of the ancient atmosphere recorded in the Martian meteorite Allan Hills 84001 provides a lower limit of the atmospheric pressure in 4 Ga to preserve the primitive isotopic compositions. We conclude that the atmospheric pressure was higher than approximately 0.5 bar at 4 Ga.

  4. Measurement and modeling of ozone and nitrogen oxides produced by laser breakdown in oxygen-nitrogen atmospheres.

    Science.gov (United States)

    Gornushkin, Igor B; Stevenson, Chris L; Galbács, Gábor; Smith, Ben W; Winefordner, James D

    2003-11-01

    The production of ozone nad nitrogen oxides was studied during multiple laser breakdown in oxygen-nitrogen mixtures at atmospheric pressure. About 2000 laser shots at 10(10) W cm-2 were delivered into a sealed reaction chamber. The chamber with a long capillary was designed to measure absorption of O3, NO, and NO2 as a function of the number of laser shots. The light source for absorption measurements was the continuum radiation emitted by the plasma during the first 0.2 microsecond of its evolution. A kinetic model was developed that encompassed the principal chemical reactions between the major atmospheric components and the products of laser breakdown. In the model, the laser plasma was treated as a source of nitric oxide and atomic oxygen, whose rates of production were calculated using measured absorption by NO, NO2, and O3. The calculated concentration profiles for NO, NO2, and O3 were in good agreement with measured profiles over a time scale of 0-200 s. The steady-state concentration of ozone was measured in a flow cell in air. For a single breakdown in air, the estimated steady-state yield of ozone was 2 x 10(12) molecules, which agreed with the model prediction. This study can be of importance for general understanding of laser plasma chemistry and for elucidating the nature of spectral interferences and matrix effects that may take place in applied spectrochemical analysis.

  5. Organic carbon input from atmospheric deposition: a potential driver of nitrogen export from barren alpine ecosystems (Invited)

    Science.gov (United States)

    Mladenov, N.; Williams, M. W.; Schmidt, S. K.

    2010-12-01

    There is urgency to improve our understanding of how biogeochemical cycling and surface water quality in high-elevation catchments will respond to a combination of changes in climate, atmospheric deposition of pollutants, and potential increases in dust deposition. Previous work has shown that atmospheric wet and dry deposition is an important source of dissolved organic matter for alpine lakes, with important consequences for aquatic ecosystem functioning. Here we investigate new linkages between atmospheric deposition of organic matter and terrestrial biogeochemical processes, namely nitrification. Our goal is to better understand the substantial increase in mean annual nitrogen (N) export that has been observed in Rocky Mountain and other alpine watersheds, while N deposition rates have remained constant. The combination of increasing temperatures and dust emissions, melting glaciers, and surprisingly high amounts of microbial activity in recently deglaciated soils, suggest that carbon (C) cycling in these barren alpine catchments may have an important and, thus far, unexplored role in nitrification and N export. Our results show that the quantity of atmospheric organic carbon inputs approaches that of biological C fixation in magnitude. We hypothesize that heterotrophic processing of atmospheric and autotrophic C inputs and the resulting increased availability of amine compounds may enhance nitrification and intensify N export from alpine catchments. Results from optical spectroscopy further demonstrate that water soluble organic carbon from atmospheric deposition has low aromaticity, is high in amino acid-like moieties (Figure 1), and may represent a labile carbon source for terrestrial and aquatic alpine microorganisms. Fig 1. TOP: Fluorescence excitation emission matrix (EEM) of a representative wet deposition sample (collected 24-30 June, 2009 at Niwot Ridge, Colorado). FI = fluorescence index; SUVA = specific UV absorbance (L mg-1 m-1); AA = amino acid

  6. Atmosphere-Surface Exchange of Reactive Nitrogen and its Implications for PM2.5

    Science.gov (United States)

    Wentworth, G.; Murphy, J. G.; Gregoire, P.; Tevlin, A.; Hems, R.; Cheyne, C.

    2012-12-01

    Recently it has been suggested that the surface-atmosphere exchange of both ammonia (NH3) and nitrous acid (HONO) can occur in a bidirectional fashion governed by a compensation point (i.e. the atmospheric mixing ratio where the flux changes direction). The compensation point corresponds to the gas phase mixing ratio that is in equilibrium with the dissolved constituents at the surface (soil water, plant tissue), governed by solubility and acid dissociation constants. Direct calculation of compensation point values is not trivial, because of the dependence on soil temperature, moisture, pH and the nitrogen distribution in the system. The presence of atmospheric particulate matter can further influence surface flux by providing a reactive sink for trace gases in the atmosphere. An accurate understanding of the factors governing bidirectional flux is required in order for air quality models to accurately predict trace gas mixing ratios, aerosol composition and spatial patterns of nitrogen deposition. A field study was conducted in southwestern Ontario during the summer of 2012 to measure the atmospheric and surface components of the system to provide observational constraints to test our understanding of the bi-directional exchange of reactive nitrogen. An Ambient Ion Monitor Ion Chromatograph (AIM-IC) was used to quantify the water-soluble trace gases (NH3, SO2, HNO3, HCl, and HONO) as well as water-soluble ions in PM2.5 with hourly time resolution. The same IC methods were used in an offline fashion to monitor soil ammonium, nitrite and nitrate composition. Challenges in selecting sampling and extraction protocols that can provide representative soil pH and nitrogen content are discussed.

  7. Fluorescence excited in a thunderstorm atmosphere by relativistic runaway electron avalanches

    Science.gov (United States)

    Babich, L. P.; Bochkov, E. I.

    2017-05-01

    The spectrum and spatiotemporal evolution of the fluorescence of an atmospheric discharge developing in the regime of relativistic runaway electron avalanche (RREA) generation have been calculated without involving the relativistic feedback. The discharges generating narrow bipolar pulses, along with the discharges responsible for terrestrial gamma-ray flashes, are shown to be relatively dark. Nevertheless, the fluorescence excited by a discharge involving RREAs can be recorded with cameras used to record high-altitude optical phenomena. A possible connection between a certain class of optical phenomena observed at the tops of thunderclouds and RREA emission is pointed out.

  8. Fluxes of total reactive atmospheric nitrogen (ΣNr using eddy covariance above arable land

    Directory of Open Access Journals (Sweden)

    Christophe R. Flechard

    2013-02-01

    Full Text Available The amount and timing of reactive nitrogen exchange between agricultural land and the atmosphere play a key role in evaluating ecosystem productivity and in addressing atmospheric nitrogen budgets and transport. With the recent development of the Total Reactive Atmospheric Nitrogen Converter (TRANC apparatus, a methodology has been provided for continuous measurement of the sum of all airborne nitrogen containing species (ΣNr allowing for diurnal and seasonal investigations. We present ΣNr concentration and net flux data from an 11-month field campaign conducted at an arable field using the TRANC system within an eddy-covariance setup. Clear diurnal patterns of both ΣNr concentrations and fluxes with significant dependencies on atmospheric stability and stomatal regulation were observed in the growing season. TRANC data were compared with monthly-averaged concentrations and dry deposition rates of selected Nr compounds using DELTA denuders and ensemble-averages of four inferential models, respectively. Similar seasonal trends were found for Nr concentrations from DELTA and TRANC measurements with values from the latter being considerably higher than those of DELTA denuders. The variability of the difference between these two systems could be explained by seasonally changing source locations of NOx contributions to the TRANC signal. As soil and vegetation Nr emissions to the atmosphere are generally not treated by inferential (dry deposition models, TRANC data showed lower monthly deposition rates than those obtained from inferential modelling. Net ΣNr exchange was almost neutral (~0.072 kg N ha−1 at the end of the observation period. However, during most parts of the year, slight but permanent net ΣNr deposition was found. Our measurements demonstrate that fertilizer addition followed by substantial ΣNr emissions plays a crucial role in a site's annual atmospheric nitrogen budget. As long-term Nr measurements with high temporal

  9. Nitrogen and Triple Oxygen Isotopic Analyses of Atmospheric Particulate Nitrate over the Pacific Ocean

    Science.gov (United States)

    Kamezaki, Kazuki; Hattori, Shohei; Iwamoto, Yoko; Ishino, Sakiko; Furutani, Hiroshi; Miki, Yusuke; Miura, Kazuhiko; Uematsu, Mitsuo; Yoshida, Naohiro

    2017-04-01

    Nitrate plays a significant role in the biogeochemical cycle. Atmospheric nitrate (NO3- and HNO3) are produced by reaction precursor as NOx (NO and NO2) emitted by combustion, biomass burning, lightning, and soil emission, with atmospheric oxidants like ozone (O3), hydroxyl radical (OH), peroxy radical and halogen oxides. Recently, industrial activity lead to increases in the concentrations of nitrogen species (NOx and NHy) throughout the environment. Because of the increase of the amount of atmospheric nitrogen deposition, the oceanic biogeochemical cycle are changed (Galloway et al., 2004; Kim et al., 2011). However, the sources and formation pathways of atmospheric nitrate are still uncertain over the Pacific Ocean because the long-term observation is limited. Stable isotope analysis is useful tool to gain information of sources, sinks and formation pathways. The nitrogen stable isotopic composition (δ15N) of atmospheric particulate NO3- can be used to posses information of its nitrogen sources (Elliott et al., 2007). Triple oxygen isotopic compositions (Δ17O = δ17O - 0.52 ×δ18O) of atmospheric particulate NO3- can be used as tracer of the relative importance of mass-independent oxygen bearing species (e.g. O3, BrO; Δ17O ≠ 0 ‰) and mass-dependent oxygen bearing species (e.g. OH radical; Δ17O ≈ 0 ‰) through the formation processes from NOx to NO3- in the atmosphere (Michalski et al., 2003; Thiemens, 2006). Here, we present the isotopic compositions of atmospheric particulate NO3- samples collected over the Pacific Ocean from 40˚ S to 68˚ N. We observed significantly low δ15N values for atmospheric particulate NO3- on equatorial Pacific Ocean during both cruises. Although the data is limited, combination analysis of δ15N and Δ17O values for atmospheric particulate NO3- showed the possibility of the main nitrogen source of atmospheric particulate NO3- on equatorial Pacific Ocean is ammonia oxidation in troposphere. Furthermore, the Δ17O values

  10. The neutral atmosphere temperature experiment. [for thermospheric nitrogen measurement on AEROS satellite

    Science.gov (United States)

    Spencer, N. W.; Pelz, D. T.; Niemann, H. B.; Carignan, G. R.; Caldwell, J. R.

    1974-01-01

    The AEROS Neutral Atmosphere Temperature Experiment (NATE) is designed to measure the kinetic temperature of molecular nitrogen in the thermosphere. A quadrupole mass spectrometer tuned to N2 measures the N2 density variation in a small spherical antechamber having a knife-edged orifice which is exposed to the atmosphere at the outer surface of the spacecraft. The changing density of N2 due to the spinning motion of the spacecraft permits determination of the velocity distribution of the N2 from which the temperature is calculated. An alternate mode of operation of the instrument allows measurement of the other gases in the atmosphere as well as N2 permitting determination of the neutral particle composition of the atmosphere.

  11. A New Fluorescence Method for Determination of Ammonium Nitrogen in Aquatic Environment Using Derivatization with Benzyl Chloride

    OpenAIRE

    Cao,Guiping; Su, Yang; Zhuang,Yafeng; Lu,Jilai

    2016-01-01

    We introduce a novel approach in simple and highly sensitive fluorometric determination of ammonium nitrogen. The proposed method is based on a fluorescence derivatization with benzyl chloride. The benzyl chloride was converted to a new fluorescent derivative by reaction with ammonium ion (NH4+) in the presence of sodium bicarbonate. The excitation and emission wavelengths were 258 and 284 nm, respectively. The effects of benzyl chloride concentration, sodium bicarbonate concentration, reacti...

  12. Isotopic composition of nitrogen - Implications for the past history of Mars' atmosphere

    Science.gov (United States)

    Mcelroy, M. B.; Yung, Y. L.; Nier, A. O.

    1976-01-01

    Models are presented for the past history of nitrogen on Mars, based on Viking measurements showing that the atmosphere is enriched in N-15. The enrichment is attributed to selective escape, with fast atoms formed in the exosphere by electron impact dissociation of N2 and by dissociative recombination of N2(+). The initial partial pressure of N2 should have been at least as large as several millibars and could have been as large as 30 millibars if surface processes were to represent an important sink for atmospheric HNO2 and HNO3.

  13. Apollo experience report: Processing of lunar samples in a sterile nitrogen atmosphere

    Science.gov (United States)

    Mcpherson, T. M.

    1972-01-01

    A sterile nitrogen atmosphere processing cabinet line was installed in the Lunar Receiving Laboratory to process returned lunar samples with minimum organic contamination. Design and operation of the cabinet line were complicated by the requirement for biological sterilization and isolation, which necessitated extensive filtration, leak-checking, and system sterilization before use. Industrial techniques were applied to lunar sample processing to meet requirements for time-critical experiments while handling a large flow of samples.

  14. Kinetic and photochemical data for atmospheric chemistry reactions of the nitrogen oxides

    Science.gov (United States)

    Hampson, R. F., Jr.

    1980-01-01

    Data sheets for thermal and photochemical reactions of importance in the atmospheric chemistry of the nitrogen oxides are presented. For each reaction the available experimental data are summarized and critically evaluated, and a preferred value of the rate coefficient is given. The selection of the preferred value is discussed and an estimate of its accuracy is given. For the photochemical process, the data are summarized, and preferred for the photoabsorption cross section and primary quantum yields are given.

  15. A two-photon laser-induced fluorescence field instrument for ground-based and airborne measurements of atmospheric NO

    Science.gov (United States)

    Bradshaw, J. D.; Rodgers, M. O.; Sandholm, S. T.; Kesheng, S.; Davis, D. D.

    1985-01-01

    This paper reports on a new two-photon laser-induced fluorescence (TP-LIF) sensor capable of making routine measurements at the few parts per trillion volume level. This direct spectroscopic detection method has been demonstrated to be a reliable instrument while performing both on the ground and in the air. As currently designed it is unique in being 'signal' rather than 'signal-to-noise' limited. The latter characteristic enables the TP-LIF sensor to make atmospheric measurements of NO under environmental conditions that might normally be considered unsuitable for a laser technique. These include clouds, rain, and, in general, high-atmospheric-aerosol loading conditions. Of special interest is the insensitivity of the TP-LIF NO instrument to changes in pressure while operating in the troposphere. This characteristic has enabled this sensor to be used to record real-time altitude profiles of NO. Future improvements should make possible two measurement opportunities: (1) NO flux measurements via the airborne eddy-correlation method and (2) nitrogen isotopic distribution measurements (e.g., (N-15)(0-16) versus (N-14)(0-16) as a means of identifying specific NO(x) sources.

  16. Carbon dioxide level and form of soil nitrogen regulate assimilation of atmospheric ammonia in young trees.

    Science.gov (United States)

    Silva, Lucas C R; Salamanca-Jimenez, Alveiro; Doane, Timothy A; Horwath, William R

    2015-08-21

    The influence of carbon dioxide (CO2) and soil fertility on the physiological performance of plants has been extensively studied, but their combined effect is notoriously difficult to predict. Using Coffea arabica as a model tree species, we observed an additive effect on growth, by which aboveground productivity was highest under elevated CO2 and ammonium fertilization, while nitrate fertilization favored greater belowground biomass allocation regardless of CO2 concentration. A pulse of labelled gases ((13)CO2 and (15)NH3) was administered to these trees as a means to determine the legacy effect of CO2 level and soil nitrogen form on foliar gas uptake and translocation. Surprisingly, trees with the largest aboveground biomass assimilated significantly less NH3 than the smaller trees. This was partly explained by declines in stomatal conductance in plants grown under elevated CO2. However, unlike the (13)CO2 pulse, assimilation and transport of the (15)NH3 pulse to shoots and roots varied as a function of interactions between stomatal conductance and direct plant response to the form of soil nitrogen, observed as differences in tissue nitrogen content and biomass allocation. Nitrogen form is therefore an intrinsic component of physiological responses to atmospheric change, including assimilation of gaseous nitrogen as influenced by plant growth history.

  17. Thresholds for protecting Pacific Northwest ecosystems from atmospheric deposition of nitrogen: state of knowledge report

    Science.gov (United States)

    Cummings, Tonnie; Blett, Tamara; Porter, Ellen; Geiser, Linda; Graw, Rick; McMurray, Jill; Perakis, Steven S.; Rochefort, Regina

    2014-01-01

    The National Park Service and U.S. Forest Service manage areas in the states of Idaho, Oregon, and Washington – collectively referred to in this report as the Pacific Northwest - that contain significant natural resources and provide many recreational opportunities. The agencies are mandated to protect the air quality and air pollution-sensitive resources on these federal lands. Human activity has greatly increased the amount of nitrogen emitted to the atmosphere, resulting in elevated amounts of nitrogen being deposited in park and forest ecosystems. There is limited information in the Pacific Northwest about the levels of nitrogen that negatively affect natural systems, i.e., the critical loads. The National Park Service and U.S. Forest Service, with scientific input from the U.S. Geological Survey, have developed an approach for accumulating additional nitrogen critical loads information in the Pacific Northwest and using the data in planning and regulatory arenas. As a first step in that process, this report summarizes the current state of knowledge about nitrogen deposition, effects, and critical loads in the region. It also describes ongoing research efforts and identifies and prioritizes additional data needs.

  18. TRANC – a novel fast-response converter to measure total reactive atmospheric nitrogen

    Directory of Open Access Journals (Sweden)

    V. Wolff

    2012-05-01

    Full Text Available The input and loss of plant available nitrogen (reactive nitrogen: Nr from/to the atmosphere can be an important factor for the productivity of ecosystems and thus for its carbon and greenhouse gas exchange. We present a novel converter for reactive nitrogen (TRANC: Total Reactive Atmospheric Nitrogen Converter, which offers the opportunity to quantify the sum of all airborne reactive nitrogen compounds (∑Nr in high time resolution. The basic concept of the TRANC is the full conversion of all Nr to nitrogen monoxide (NO within two reaction steps. Initially, reduced Nr compounds are being oxidised, and oxidised Nr compounds are thermally converted to lower oxidation states. Particulate Nr is being sublimated and oxidised or reduced afterwards. In a second step, remaining higher nitrogen oxides or those generated in the first step are catalytically converted to NO with carbon monoxide used as reduction gas. The converter is combined with a fast response chemiluminescence detector (CLD for NO analysis and its performance was tested for the most relevant gaseous and particulate Nr species under both laboratory and field conditions. Recovery rates during laboratory tests for NH3 and NO2 were found to be 95 and 99%, respectively, and 97% when the two gases were combined. In-field longterm stability over an 11-month period was approved by a value of 91% for NO2. Effective conversion was also found for ammonium and nitrate containing particles. The recovery rate of total ambient Nr was tested against the sum of individual measurements of NH3, HNO3, HONO, NH4+, NO3−, and NOx using a combination of different well-established devices. The results show that the TRANC-CLD system precisely captures fluctuations in ∑Nr concentrations and also matches the sum of all individual Nr compounds measured by the different single techniques. The TRANC features a specific design with very short distance between the sample air inlet and the place where the thermal

  19. Sulfur and nitrogen co-doped carbon dots sensors for nitric oxide fluorescence quantification

    Energy Technology Data Exchange (ETDEWEB)

    Simões, Eliana F.C. [Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Faculdade de Farmácia da Universidade de Coimbra, Pólo das Ciências da Saúde, 3000-548 Coimbra (Portugal); Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Departamento de Geociências, Ambiente e Ordenamento do Território, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre 687, 4169-007 Porto (Portugal); Leitão, João M.M., E-mail: jleitao@ff.uc.pt [Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Faculdade de Farmácia da Universidade de Coimbra, Pólo das Ciências da Saúde, 3000-548 Coimbra (Portugal); Esteves da Silva, Joaquim C.G. [Centro de Investigação em Química da Universidade do Porto (CIQ-UP), Departamento de Geociências, Ambiente e Ordenamento do Território, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre 687, 4169-007 Porto (Portugal)

    2017-04-01

    Microwave synthetized sulfur and nitrogen co-doped carbon dots responded selectively to nitric oxide (NO) at pH 7. Citric acid, urea and sodium thiosulfate in the proportion of 1:1:3 were used respectively as carbon, nitrogen and sulfur sources in the carbon dots microwave synthesis. For this synthesis, the three compounds were diluted in 15 mL of water and exposed for 5 min to a microwave radiation of 700 W. It is observed that the main factor contributing to the increased sensitivity and selectivity response to NO at pH 7 is the sodium thiosulfate used as sulfur source. A linear response range from 1 to 25 μM with a sensitivity of 16 μM{sup −1} and a detection limit of 0.3 μM were obtained. The NO quantification capability was assessed in standard and in fortified serum solutions. - Highlights: • S,N co-doped CDs were microwave synthetized from citric acid, urea and sodium thiosulfate. • The NO fluorescence sensing was evaluated at pH 7. • The selective and sensitive detection of NO at pH 7 was achieved. • Good NO quantification results in serum samples were obtained.

  20. The influence of leaf-atmosphere NH3(g ) exchange on the isotopic composition of nitrogen in plants and the atmosphere.

    Science.gov (United States)

    Johnson, Jennifer E; Berry, Joseph A

    2013-10-01

    The distribution of nitrogen isotopes in the biosphere has the potential to offer insights into the past, present and future of the nitrogen cycle, but it is challenging to unravel the processes controlling patterns of mixing and fractionation. We present a mathematical model describing a previously overlooked process: nitrogen isotope fractionation during leaf-atmosphere NH3(g ) exchange. The model predicts that when leaf-atmosphere exchange of NH3(g ) occurs in a closed system, the atmospheric reservoir of NH3(g ) equilibrates at a concentration equal to the ammonia compensation point and an isotopic composition 8.1‰ lighter than nitrogen in protein. In an open system, when atmospheric concentrations of NH3(g ) fall below or rise above the compensation point, protein can be isotopically enriched by net efflux of NH3(g ) or depleted by net uptake. Comparison of model output with existing measurements in the literature suggests that this process contributes to variation in the isotopic composition of nitrogen in plants as well as NH3(g ) in the atmosphere, and should be considered in future analyses of nitrogen isotope circulation. The matrix-based modelling approach that is introduced may be useful for quantifying isotope dynamics in other complex systems that can be described by first-order kinetics. © 2013 John Wiley & Sons Ltd.

  1. Recent changes in the oxidized to reduced nitrogen ratio in atmospheric precipitation

    Science.gov (United States)

    Kurzyca, Iwona; Frankowski, Marcin

    2017-10-01

    In this study, the characteristics of precipitation in terms of various nitrogen forms (NO3-, NO2-, NH4+, Norganic, Ntotal) is presented. The samples were collected in the areas of different anthropogenic pressure (urban area vs. ecologically protected woodland area, ∼30 km distant from each other; Wielkopolska region, Poland). Based on the Nox and Nred emission profiles (Nox/Nred ratio), temporal and spatial comparison was carried out. For both sites, during a decade of observation, more than 60% of samples had higher contribution of N-NH4+ than N-NO3-, the amount of N-NO2- was negligible, and organic nitrogen amounted to 30% of total nitrogen content which varied up to 16 mg/l. The precipitation events w ith high concentration of nitrogen species were investigated in terms of possible local and remote sources of nitrogen (synoptic meteorology), to indicate the areas which can act as potential sources of N-compounds. Based on the chemometric analysis, it was found that Nred implies Nox and vice versa, due to interactions between them in the atmosphere. Taking into account the analysis of precipitation occurring simultaneously in both locations (about 50% of all rainfall episodes), it was observed that such factor as anthropogenic pressure differentiates but does not determine the chemical composition of precipitation in the investigated areas (urban vs. woodland area; distance of ∼30 km). Thermodynamics of the atmosphere had a significant impact on concentrations of N-NO3- and N-NH4+ in precipitation, as well as the circulation of air masses and remote N sources responsible for transboundary inflow of pollutants.

  2. Atmospheric Ammonia and Particulate Inorganic Nitrogen Monitoring in the United States - A Comparison Study

    Science.gov (United States)

    Kariyawasam, T.

    2016-12-01

    Due to emission by disproportionately high livestock numbers and increased nitrogen fertilization, Ammonia (NH3) has come to play an increasingly important role in the global biogeochemical cycle of reactive nitrogen as well as in secondary aerosol formation and climate. Because of the public health problems it causes and the effects on the atmosphere, monitoring the global distribution of NH3 sources becomes crucial. Accurate measurements of atmospheric NH3 via ground level sensors and satellites are fundamentally essential for meteorological forecasting, hazard warning and various other applications. Since the NH3 retrieval quality is affected by meteorological properties, such as the vertical temperature, water vapor profiles, surface temperatures, and emissivity, which are used to model the atmosphere, even though satellite systems has the capability of monitoring environmental variables with high temporal and spatial coverages, they lack precision at or near ground level. Due to cost of implementation and technical maintenance constraints, daily global coverage of accurate NH3 in situ measurements from ground based sensors is also often limited in spatial representation. In research related to climate and atmospheric physics, the advances in sensor technology have led to the use of automated sensors in a variety of climate and atmospheric data analysis applications. The extant research is expanding further but lacks a framework to consider the current and future trends, gaps, challenges and opportunities. This research will attempt to provide insight into key capabilities of the current and potential future approaches and will present a framework to better understand NH3 research with the use of in - situ as well as remote sensors in detecting NH3 in the ambient atmosphere.

  3. Autofluorescence of atmospheric bioaerosols - fluorescent biomolecules, biological standard particles and potential interferences

    Science.gov (United States)

    Pöhlker, C.; Huffmann, J. A.; Pöschl, U.

    2012-04-01

    Primary biological aerosol particles (PBAP) such as pollen, fungal spores, bacteria, biogenic polymers and debris from larger organisms are known to influence atmospheric chemistry and physics, the biosphere and public health. PBAP account for up to ~30% of fine and up to ~70% of coarse particulate matter in urban, rural and pristine environment and are released with estimated emission rates of up to ~1000 Tg/a [1]. Continuous measurements of the abundance, variability and diversity of PBAP have been difficult until recently, however. The application of on-line instruments able to detect autofluorescence from biological particles in real-time has been a promising development for the measurement of PBAP concentrations and fluxes in different environments [2,3]. The detected fluorescent biological aerosol particles (FBAP) can be regarded as a subset of PBAP, although the exact relationship between PBAP and FBAP is still being investigated. Autofluorescence of FBAP is usually a superposition of fluorescence from a mixture of individual fluorescent molecules (fluorophores). Numerous biogenic fluorophores such as amino acids (e.g., tryptophan, tyrosine), coenzymes (e.g., NAD(P)H, riboflavin) and biopolymers (e.g., cellulose) emit fluorescent light due to heterocyclic aromatic rings or conjugated double bonds within their molecular structures. The tryptophan emission peak is a common feature of most bioparticles because the amino acid is a constituent of many proteins and peptides. The influence of the coenzymes NAD(P)H and riboflavin on the autofluorescence of bacteria can be regarded as an indicator for bacterial metabolism and has been utilized to discriminate between viable and non-viable organisms [4]. However, very little information is available about other essential biofluorophores in fungal spores and pollen. In order to better understand the autofluorescence behavior of FBAP, we have used fluorescence spectroscopy and fluorescence microscopy to analyze standard

  4. The effect of nitrogen additions on bracken fern and its insect herbivores at sites with high and low atmospheric pollution

    Science.gov (United States)

    M.E. Jones; M.E. Fenn; T.D. Paine

    2011-01-01

    The impact of atmospheric pollution, including nitrogen deposition, on bracken fern herbivores has never been studied. Bracken fern is globally distributed and has a high potential to accumulate nitrogen in plant tissue. We examined the response of bracken fern and its herbivores to N fertilization at a high and low pollution site in forests downwind of Los Angeles,...

  5. Governing processes for reactive nitrogen compounds in the atmosphere in relation to ecosystem climatic and human health impacts

    NARCIS (Netherlands)

    Hertel, O.; Skjøth, C.A.; Reis, S.; Bleeker, A.; Harrison, R.; Cape, J.N.; Fowler, D.; Skiba, U.; Simpson, D.; Jickells, T.; Kulmala, M.; Gyldenærne, S.; Sørensen, L.L.; Erisman, J.W.; Sutton, M.A.

    2012-01-01

    Reactive nitrogen (Nr) compounds have different fates in the atmosphere due to differences in governing processes of physical transport, deposition and chemical transformation. Nr compounds addressed here include reduced nitrogen (NHx: ammonia (NH3) and its reaction product ammonium (NH4+)),

  6. Light stress effect and by nitrogen deficiency in plants of Petiveria alliacea measured with two-chlorophyll-fluorescence technique

    Science.gov (United States)

    Zuluaga, H.; Oviedo, A.; Solarte, Efrain; Pena, E. J.

    2004-10-01

    The chlorophyll fluorescence was studied in Petiveria alliacea plants exposed to different nitrogen concentrations and light radiation, the response was measured by two different forms; (1) measuring the photosynthetic efficiency with a pulse amplitude modulated fluorometro (PAM) emitted by a 650 nm diode and (2) measuring the fluorescence spectra caused by high power 452 nm diode with a SD2000 spectrometer. It was found out that the photosynthetic efficiency decreased in the plants exposed to high radiance and low nitrogen. Two chlorophyll fluorescence peaks were observed on 684 nm and 739 nm, the intensities in this wavelengths are inversely related with the light radiance. The correlation between the FIR and photosynthetic efficiency was very strong (r2 = -0.809, p Alliacea plants.

  7. ADVANTAGE OF VACUUM VERSUS NITROGEN TO ACHIEVE INERT ATMOSPHERE DURING SOFTWOOD THERMAL MODIFICATION

    Directory of Open Access Journals (Sweden)

    Kévin CANDELIER

    2014-12-01

    Full Text Available Wood heat treatment is an attractive alternative to improve decay resistance of wood species with low natural durability. Durability and mechanical properties are strongly correlated to thermal degradation of wood cells wall components. Mass loss resulting from this degradation is a good indicator of treatment intensity and final treated wood properties. Several types of convective heating processes exist currently differing mainly by the nature of the inert atmosphere used during treatment: nitrogen, steam or oil. Conductive heat treatment using vacuum as inert atmosphere is an attractive new alternative to previous classical methods. Heat transfer by conduction has been reported to provide better treatment homogeneity than heat transfer using convection. The aim of this study is to investigate the effect of vacuum comparatively to nitrogen on the thermal degradation pathways and on the conferred properties to the material. It appears that utilization of vacuum permit a better control of thermal degradation reactions limiting the mass loss resulting from degradation of wood cell wall polymers. Chemical analysis indicates that wood heat treated under nitrogen present higher Klason lignin and carbon contents, lower hemicelluloses and neutral monosaccharides contents comparatively to wood heat treated under vacuum. At the same time, mechanical properties are less affected under vacuum, which constitute another advantage of this technology.

  8. Nitrogen-doped twisted graphene grown on copper by atmospheric pressure CVD from a decane precursor

    Directory of Open Access Journals (Sweden)

    Ivan V. Komissarov

    2017-01-01

    Full Text Available We present Raman studies of graphene films grown on copper foil by atmospheric pressure CVD with n-decane as a precursor, a mixture of nitrogen and hydrogen as the carrier gas, under different hydrogen flow rates. A novel approach for the processing of the Raman spectroscopy data was employed. It was found that in particular cases, the various parameters of the Raman spectra can be assigned to fractions of the films with different thicknesses. In particular, such quantities as the full width at half maximum of the 2D peak and the position of the 2D graphene band were successfully applied for the elaborated approach. Both the G- and 2D-band positions of single layer fractions were blue-shifted, which could be associated with the nitrogen doping of studied films. The XPS study revealed the characteristics of incorporated nitrogen, which was found to have a binding energy around 402 eV. Moreover, based on the statistical analysis of spectral parameters and the observation of a G-resonance, the twisted nature of the double-layer fraction of graphene grown with a lower hydrogen feeding rate was demonstrated. The impact of the varied hydrogen flow rate on the structural properties of graphene and the nitrogen concentration is also discussed.

  9. Nitrogen-doped twisted graphene grown on copper by atmospheric pressure CVD from a decane precursor.

    Science.gov (United States)

    Komissarov, Ivan V; Kovalchuk, Nikolai G; Labunov, Vladimir A; Girel, Ksenia V; Korolik, Olga V; Tivanov, Mikhail S; Lazauskas, Algirdas; Andrulevičius, Mindaugas; Tamulevičius, Tomas; Grigaliūnas, Viktoras; Meškinis, Šarunas; Tamulevičius, Sigitas; Prischepa, Serghej L

    2017-01-01

    We present Raman studies of graphene films grown on copper foil by atmospheric pressure CVD with n-decane as a precursor, a mixture of nitrogen and hydrogen as the carrier gas, under different hydrogen flow rates. A novel approach for the processing of the Raman spectroscopy data was employed. It was found that in particular cases, the various parameters of the Raman spectra can be assigned to fractions of the films with different thicknesses. In particular, such quantities as the full width at half maximum of the 2D peak and the position of the 2D graphene band were successfully applied for the elaborated approach. Both the G- and 2D-band positions of single layer fractions were blue-shifted, which could be associated with the nitrogen doping of studied films. The XPS study revealed the characteristics of incorporated nitrogen, which was found to have a binding energy around 402 eV. Moreover, based on the statistical analysis of spectral parameters and the observation of a G-resonance, the twisted nature of the double-layer fraction of graphene grown with a lower hydrogen feeding rate was demonstrated. The impact of the varied hydrogen flow rate on the structural properties of graphene and the nitrogen concentration is also discussed.

  10. Dominant Overall Chemical Reaction in a Chlorine Trifluoride Silicon Nitrogen System at Atmospheric Pressure

    Science.gov (United States)

    Habuka, Hitoshi; Otsuka, Toru; Qu, Wei-Feng

    1999-11-01

    This study evaluates the overall chemical reaction in a chlorine trifluoride silicon nitrogen system at atmospheric pressure, based on the observation of the dominant chemical species in the gas phase using a quadrupole mass spectra analyzer coupled with a horizontal cold-wall single-wafer epitaxial reactor. Chlorine trifluoride gas etches the silicon surface, producing two major products, silicon tetrafluoride gas and chlorine gas, at room temperature and 530 K. The production of chlorosilanes was not observed in this study. The results obtained in this study indicate that the dominant overall chemical reaction in a chlorine trifluoride silicon nitrogen system is 3Si + 4ClF3 →3SiF4 ↑+ 2Cl2 ↑.

  11. Effect of fluorescence characteristics and different algorithms on the estimation of leaf nitrogen content based on laser-induced fluorescence lidar in paddy rice.

    Science.gov (United States)

    Yang, Jian; Sun, Jia; Du, Lin; Chen, Biwu; Zhang, Zhenbing; Shi, Shuo; Gong, Wei

    2017-02-20

    Paddy rice is one of the most significant food sources and an important part of the ecosystem. Thus, accurate monitoring of paddy rice growth is highly necessary. Leaf nitrogen content (LNC) serves as a crucial indicator of growth status of paddy rice and determines the dose of nitrogen (N) fertilizer to be used. This study aims to compare the predictive ability of the fluorescence spectra excited by different excitation wavelengths (EWs) combined with traditional multivariate analysis algorithms, such as principal component analysis (PCA), back-propagation neural network (BPNN), and support vector machine (SVM), for estimating paddy rice LNC from the leaf level with three different fluorescence characteristics as input variables. Then, six estimation models were proposed. Compared with the five other models, PCA-BPNN was the most suitable model for the estimation of LNC by improving R2 and reducing RMSE and RE. For 355, 460 and 556 nm EWs, R2 was 0.89, 0.80 and 0.88, respectively. Experimental results demonstrated that the fluorescence spectra excited by 355 and 556 nm EWs were superior to those excited by 460 nm for the estimation of LNC with different models. BPNN algorithm combined with PCA may provide a helpful exploratory and predictive tool for fluorescence spectra excited by appropriate EW based on practical application requirements for monitoring the N status of crops.

  12. Soil HONO Emissions and Its Potential Impact on the Atmospheric Chemistry and Nitrogen Cycle

    Science.gov (United States)

    Su, H.; Chen, C.; Zhang, Q.; Poeschl, U.; Cheng, Y.

    2014-12-01

    Hydroxyl radicals (OH) are a key species in atmospheric photochemistry. In the lower atmosphere, up to ~30% of the primary OH radical production is attributed to the photolysis of nitrous acid (HONO), and field observations suggest a large missing source of HONO. The dominant sources of N(III) in soil, however, are biological nitrification and denitrification processes, which produce nitrite ions from ammonium (by nitrifying microbes) as well as from nitrate (by denitrifying microbes). We show that soil nitrite can release HONO and explain the reported strength and diurnal variation of the missing source. The HONO emissions rates are estimated to be comparable to that of nitric oxide (NO) and could be an important source of atmospheric reactive nitrogen. Fertilized soils appear to be particularly strong sources of HONO. Thus, agricultural activities and land-use changes may strongly influence the oxidizing capacity of the atmosphere. A new HONO-DNDC model was developed to simulate the evolution of HONO emissions in agriculture ecosystems. Because of the widespread occurrence of nitrite-producing microbes and increasing N and acid deposition, the release of HONO from soil may also be important in natural environments, including forests and boreal regions. Reference: Su, H. et al., Soil Nitrite as a Source of Atmospheric HONO and OH Radicals, Science, 333, 1616-1618, 10.1126/science.1207687, 2011.

  13. Quantifying atmospheric nitrogen deposition through a nationwide monitoring network across China

    Science.gov (United States)

    Xu, W.; Luo, X. S.; Pan, Y. P.; Zhang, L.; Tang, A. H.; Shen, J. L.; Zhang, Y.; Li, K. H.; Wu, Q. H.; Yang, D. W.; Zhang, Y. Y.; Xue, J.; Li, W. Q.; Li, Q. Q.; Tang, L.; Lu, S. H.; Liang, T.; Tong, Y. A.; Liu, P.; Zhang, Q.; Xiong, Z. Q.; Shi, X. J.; Wu, L. H.; Shi, W. Q.; Tian, K.; Zhong, X. H.; Shi, K.; Tang, Q. Y.; Zhang, L. J.; Huang, J. L.; He, C. E.; Kuang, F. H.; Zhu, B.; Liu, H.; Jin, X.; Xin, Y. J.; Shi, X. K.; Du, E. Z.; Dore, A. J.; Tang, S.; Collett, J. L., Jr.; Goulding, K.; Zhang, F. S.; Liu, X. J.

    2015-07-01

    Global reactive nitrogen (Nr) deposition to terrestrial ecosystems has increased dramatically since the industrial revolution. This is especially true in recent decades in China due to continuous economic growth. However, there are no comprehensive reports of both measured dry and wet Nr deposition across China. We therefore conducted a multiple-year study during the period mainly from 2010 to 2014 to monitor atmospheric concentrations of five major Nr species of gaseous NH3, NO2 and HNO3, and inorganic nitrogen (NH4+ and NO3-) in both particles and precipitation, based on a Nationwide Nitrogen Deposition Monitoring Network (NNDMN, covering 43 sites) in China. Wet deposition fluxes of Nr species were measured directly; dry deposition fluxes were estimated using airborne concentration measurements and inferential models. Our observations reveal large spatial variations of atmospheric Nr concentrations and dry and wet Nr deposition. The annual average concentrations (1.3-47.0 μg N m-3) and dry plus wet deposition fluxes (2.9-75.2 kg N ha-1 yr-1) of inorganic Nr species ranked by region as North China > Southeast China > Southwest China > Northeast China > Northwest China > the Tibetan Plateau or by land use as urban > rural > background sites, reflecting the impact of anthropogenic Nr emission. Average dry and wet N deposition fluxes were 18.5 and 19.3 kg N ha-1 yr-1, respectively, across China, with reduced N deposition dominating both dry and wet deposition. Our results suggest atmospheric dry N deposition is equally important to wet N deposition at the national scale and both deposition forms should be included when considering the impacts of N deposition on environment and ecosystem health.

  14. Atmospheric deposition of inorganic nitrogen in Spanish forests of Quercus ilex measured with ion-exchange resins and conventional collectors

    Science.gov (United States)

    Héctor García-Gomez; Sheila Izquieta-Rojano; Laura Aguillaume; Ignacio González-Fernández; Fernando Valiño; David Elustondo; Jesús M. Santamaría; Anna Àvila; Mark E. Fenn; Rocío Alonso

    2016-01-01

    Atmospheric nitrogen deposition is one of the main threats for biodiversity and ecosystem functioning. Measurement techniques like ion-exchange resin collectors (IECs), which are less expensive and time-consuming than conventional methods, are gaining relevance in the study of atmospheric deposition and are recommended to expand monitoring networks. In the present work...

  15. DNA damage in oral cancer cells induced by nitrogen atmospheric pressure plasma jets

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xu; Ptasinska, Sylwia [Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Klas, Matej [Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Liu, Yueying [Harper Cancer Research Institute, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Sharon Stack, M. [Harper Cancer Research Institute, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

    2013-06-10

    The nitrogen atmospheric pressure plasma jet (APPJ) was applied to induce DNA damage of SCC-25 oral cancer cells. Optical emission spectra were taken to characterize the reactive species produced in APPJ. In order to explore the spatial distribution of plasma effects, cells were placed onto photo-etched grid slides and the antibody H2A.X was used to locate double strand breaks of DNA inside nuclei using an immunofluorescence assay. The number of cells with double strand breaks in DNA was observed to be varied due to the distance from the irradiation center and duration of plasma treatment.

  16. Characterization of atmospheric pressure plasma treated wool/cashmere textiles: Treatment in nitrogen

    Science.gov (United States)

    Zanini, Stefano; Citterio, Attilio; Leonardi, Gabriella; Riccardi, Claudia

    2018-01-01

    We performed atmospheric pressure plasma treatments of wool/cashmere (15/85%) textiles with a dielectric barrier discharge (DBD) in nitrogen. The chemical properties of the plasma treated samples were investigated with attenuated total reflectance Fourier transform infrared (FTIR/ATR) spectroscopy, X-ray photoelectron microscopy (XPS), and fatty acid gas chromatographic analysis. Changes in mechanical properties and tactile performance of textiles after the plasma treatment were determined using the KES-F system. The analyses reveal significant surface modification of the treated fabrics, which enhances their surface wettability.

  17. Historical changes in atmospheric nitrogen deposition to Cape Cod, Massachusetts, USA

    Energy Technology Data Exchange (ETDEWEB)

    Bowen, J.L.; Valiela, I. [Boston University Marine Program, Marine Biological Lab., Woods Hole, MA (United States)

    2001-02-01

    We reconstructed the historical trends in atmospheric deposition of nitrogen to Cape Cod, Massachusetts, from 1910 to 1995 by compiling data from literature sources, and adjusting the data for geographical and methodological differences. The reconstructed data suggest that NO{sub 3}-N wet deposition to this region increased from a low of 0.9kgNha{sup -1}yr{sup -1} in 1925 to a high of approximately 4kgNha{sup -1}yr{sup -1} around 1980. The trend in NO{sub 3}-N deposition has remained since the early 1980s at around 3.6kgNha{sup -1}yr{sup -1}. In contrast, NH{sub 4}-N wet deposition decreased from more than 4kgNha{sup -1}yr{sup -1} in the mid 1920s to about 1.5kgNha{sup -1}yr{sup -1} from the late-1940s until today. Emissions of NO{sub x}-N in the Cape Cod airshed increased at a rate of 2.1kgNha{sup -1} per decade since 1910, a rate that is an order of magnitude higher than NO{sub 3}-N deposition. Estimates of NH{sub 3} emissions to the northeast United States and Canada have decreased slightly throughout the century, but the decrease in reconstructed N-NH{sub 4}{sup +} deposition rates does not parallel emissions estimates. The trend in reconstructed total nitrogen deposition suggests an overall increase through the century at a rate of 0.26kgNha{sup -1} per decade. This overall increase in deposition may expose coastal forests to rates of nitrogen addition that, if exceeded, could induce nitrogen saturation and increase nitrogen loads to adjoining estuaries. (Author)

  18. Shifts in lake N: P stoichiometry and nutrient limitation driven by atmospheric nitrogen deposition

    Science.gov (United States)

    Elser, J.J.; Andersen, T.; Baron, J.S.; Bergstrom, A.-K.; Jansson, M.; Kyle, M.; Nydick, K.R.; Steger, L.; Hessen, D.O.

    2009-01-01

    Human activities have more than doubled the amount of nitrogen (N) circulating in the biosphere. One major pathway of this anthropogenic N input into ecosystems has been increased regional deposition from the atmosphere. Here we show that atmospheric N deposition increased the stoichiometric ratio of N and phosphorus (P) in lakes in Norway, Sweden, and Colorado, United States, and, as a result, patterns of ecological nutrient limitation were shifted. Under low N deposition, phytoplankton growth is generally N-limited; however, in high-N deposition lakes, phytoplankton growth is consistently P-limited. Continued anthropogenic amplification of the global N cycle will further alter ecological processes, such as biogeochemical cycling, trophic dynamics, and biological diversity, in the world's lakes, even in lakes far from direct human disturbance.

  19. The application of artificial neural networks for discrete wavelength retrievals of atmospheric nitrogen dioxide from space

    Science.gov (United States)

    Lawrence, J.; Singh Anand, J.; Leigh, R.; Chang, M.; Monks, P. S.

    2012-12-01

    Despite emission reductions in Europe, air quality continues to be a major health and policy issue. Significant areas of uncertainty persist in relating emissions, atmospheric composition and human exposure within the urban atmosphere. Furthermore, air quality continues to worsen in some highly populated parts of the world. The current air quality monitoring framework is based upon bottom-up emission estimates coupled with sparse in situ monitoring. Research at the University of Leicester in the UK is being conducted to investigate the feasibility of using a technique of discrete wavelength sunlight spectroscopy to derive concentrations of the pollutant nitrogen dioxide from a satellite platform. This technique has the potential to enable very light and compact instrumentation and may subsequently provide abundant air quality data of significant value to users and policy makers. A back propagation multi-layered perceptron artificial neural network (ANN) has been developed to retrieve atmospheric slant columns of nitrogen dioxide from simulated measurements. The ANN approach enables retrievals to be performed much faster than other retrieval methods once the network has been appropriately trained, which is a particularly useful feature in instances where a large quantity of retrievals is required in near real time. To generate the required training data for the ANN to understand the necessary relationships a radiative transfer model SCIATRAN was run to provide millions of spectral intensities and slant column concentrations. To enable the radiative transfer simulations to realistically portray urban air quality the SCIATRAN model was fed atmospheric profile and aerosol data from modelled air quality forecasts over London to enable assimilation of the atmospheric composition of a typical urban environment. The training data produced by SCIATRAN was configured to span a range of solar azimuth and zenith angles to provide results which are applicable to all low earth

  20. A novel fluorescence biosensor for sensitivity detection of tyrosinase and acid phosphatase based on nitrogen-doped graphene quantum dots.

    Science.gov (United States)

    Qu, Zhengyi; Na, Weidan; Liu, Xiaotong; Liu, Hua; Su, Xingguang

    2018-01-02

    In this paper, we developed a sensitive fluorescence biosensor for tyrosinase (TYR) and acid phosphatase (ACP) activity detection based on nitrogen-doped graphene quantum dots (N-GQDs). Tyrosine could be catalyzed by TYR to generate dopaquinone, which could efficiently quench the fluorescence of N-GQDs, and the degree of fluorescence quenching of N-GQDs was proportional to the concentration of TYR. In the presence of ACP, l-Ascorbic acid-2-phosphate (AAP) was hydrolyzed to generate ascorbic acid (AA), and dopaquinone was reduced to l-dopa, resulting in the fluorescence recovery of the quenched fluorescence by dopaquinone. Thus, a novel fluorescence biosensor for the detection of TYR and ACP activity based on N-GQDs was constructed. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of TYR and ACP in the range of 0.43-3.85 U mL-1 and 0.04-0.7 mU mL-1 with a detection limit of 0.15 U mL-1 and 0.014 mU mL-1, respectively. The feasibility of the proposed biosensor in real samples assay was also studied and satisfactory results were obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Highly fluorescent nitrogen-doped carbon dots derived from Phyllanthus acidus utilized as a fluorescent probe for label-free selective detection of Fe3+ions, live cell imaging and fluorescent ink.

    Science.gov (United States)

    Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel; Aseer, Kanikkai Raja; Perumal, Suguna; Karthik, Namachivayam; Lee, Yong Rok

    2018-01-15

    A facile, economical and one-step hydrothermal method is used to synthesize highly durable fluorescent nitrogen-doped carbon dots (FNCDs) by utilizing Phyllanthus acidus (P. acidus) and aqueous ammonia as the carbon and nitrogen sources, respectively. The synthesized FNCDs have an average size of 4.5±1nm and showed bright blue fluorescence under the irradiation of UV-light at an excitation wavelength of 365nm. It exhibits a quantum yield (QY) of 14% at an excitation wavelength of 350nm with maximum emission at 420nm. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy characterizations clearly showed the formation of FNCDs that predominantly consists of nitrogen and hydroxyl groups which can provide more adsorption sites. In addition, the above study reveals the successful bonding of nitrogen with carbon (C-N) in the FNCDs. The synthesized FNCDs with high QY can be used as efficient fluorescent probes for the detection of Fe 3+ . Based on the linear relationship between normalized fluorescence intensity and concentration of Fe 3+ ions, the prepared FNCDs can be used for label-free sensitive and selective detection of Fe 3+ ions in a wide concentration range of 2-25μM with a detection limit of 0.9μM. The present study proves that synthesized FNCDs has durable fluorescence, soluble in water very well and thus act as a promising candidate for the diverse applications such as label-free sensitive and selective detection of Fe 3+ , fluorescent ink and cellular imaging with good biocompatibility and low cytotoxicity. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Atmospheric deposition and critical loads for nitrogen and metals in Arctic Alaska: Review and current status

    Science.gov (United States)

    Linder, Greg L.; Brumbaugh, William G.; Neitlich, Peter; Little, Edward

    2013-01-01

    To protect important resources under their bureau’s purview, the United States National Park Service’s (NPS) Arctic Network (ARCN) has developed a series of “vital signs” that are to be periodically monitored. One of these vital signs focuses on wet and dry deposition of atmospheric chemicals and further, the establishment of critical load (CL) values (thresholds for ecological effects based on cumulative depositional loadings) for nitrogen (N), sulfur, and metals. As part of the ARCN terrestrial monitoring programs, samples of the feather moss Hylocomium splendens are being col- lected and analyzed as a cost-effective means to monitor atmospheric pollutant deposition in this region. Ultimately, moss data combined with refined CL values might be used to help guide future regulation of atmospheric contaminant sources potentially impacting Arctic Alaska. But first, additional long-term studies are needed to determine patterns of contaminant deposition as measured by moss biomonitors and to quantify ecosystem responses at particular loadings/ ranges of contaminants within Arctic Alaska. Herein we briefly summarize 1) current regulatory guidance related to CL values 2) derivation of CL models for N and metals, 3) use of mosses as biomonitors of atmospheric deposition and loadings, 4) preliminary analysis of vulnerabilities and risks associated with CL estimates for N, 5) preliminary analysis of existing data for characterization of CL values for N for interior Alaska and 6) implications for managers and future research needs.

  3. NATO Advanced Research Workshop on The Biogeochemical Cycling of Sulfur and Nitrogen in the Remote Atmosphere

    CERN Document Server

    Charlson, Robert; Andreae, Meinrat; Rodhe, Henning

    1985-01-01

    Viewed from space, the Earth appears as a globe without a beginning or an end. Encompassing the globe is the atmosphere with its three phases-­ gaseous, liquid, and solid--moving in directions influenced by sunlight, gravity, and rotation. The chemical compositions of these phases are determined by biogeochemical cycles. Over the past hundred years, the processes governing the rates and reactions in the atmospheric biogeochemical cycles have typically been studied in regions where scientists lived. Hence, as time has gone by, the advances in our knowledge of atmospheric chemical cycles in remote areas have lagged substantially behind those for more populated areas. Not only are the data less abundant, they are also scattered. Therefore, we felt a workshop would be an excellent mechanism to assess the state­ of-knowledge of the atmospheric cycles of sulfur and nitrogen in remote areas and to make recommendations for future research. Thus, a NATO Advanced Research Workshop '~he Biogeochemical Cycling of Sulfu...

  4. A case study of the relative effects of power plant nitrogen oxides and sulfur dioxide emission reductions on atmospheric nitrogen deposition.

    Science.gov (United States)

    Vijayaraghavan, Krish; Seigneur, Christian; Bronson, Rochelle; Chen, Shu-Yun; Karamchandani, Prakash; Walters, Justin T; Jansen, John J; Brandmeyer, Jo Ellen; Knipping, Eladio M

    2010-03-01

    The contrasting effects of point source nitrogen oxides (NOx) and sulfur dioxide (SO2) air emission reductions on regional atmospheric nitrogen deposition are analyzed for the case study of a coal-fired power plant in the southeastern United States. The effect of potential emission reductions at the plant on nitrogen deposition to Escambia Bay and its watershed on the Florida-Alabama border is simulated using the three-dimensional Eulerian Community Multiscale Air Quality (CMAQ) model. A method to quantify the relative and individual effects of NOx versus SO2 controls on nitrogen deposition using air quality modeling results obtained from the simultaneous application of NOx and SO2 emission controls is presented and discussed using the results from CMAQ simulations conducted with NOx-only and SO2-only emission reductions; the method applies only to cases in which ambient inorganic nitrate is present mostly in the gas phase; that is, in the form of gaseous nitric acid (HNO3). In such instances, the individual effects of NOx and SO2 controls on nitrogen deposition can be approximated by the effects of combined NOx + SO2 controls on the deposition of NOy, (the sum of oxidized nitrogen species) and reduced nitrogen species (NHx), respectively. The benefit of controls at the plant in terms of the decrease in nitrogen deposition to Escambia Bay and watershed is less than 6% of the overall benefit due to regional Clean Air Interstate Rule (CAIR) controls.

  5. Historical mining of soil nitrogen was a likely source of atmospheric nitrous oxide

    Science.gov (United States)

    Davidson, E. A.

    2009-12-01

    Prior to the advent of use of synthetic nitrogen (N) fertilizers, agricultural expansion was often followed by depletion of soil carbon and N stocks. While the mining of soil N permits a period of productive agriculture, it may also result in transfers of soil N to groundwater, surface water, and the atmosphere. Atmospheric nitrous oxide (N2O) concentrations have been increasing since the industrial revolution and currently account for 6% of total anthropogenic radiative forcing. Microbial production in soils is the dominant N2O source. The use of synthetic N fertilizers alone cannot account for the historical trends of atmospheric concentrations of N2O, because the increase in atmospheric N2O began well before N fertilizers were widely used. Here, I analyze atmospheric concentrations, industrial sources of N2O, and fertilizer and manure production since 1860. Prior to 1960, agricultural expansion, including livestock production, appears to have caused globally significant mining of soil N, fuelling a steady increase in atmospheric N2O. Post 1960, the rate of the increase rose, due to accelerating use of synthetic N fertilizers. Using a regression model, I show that 2% of manure N and 2.5% of fertilizer N were converted to N2O between 1860 and 2005; these percentage contributions explain the entire pattern of increasing N2O concentrations over this period. Consideration of processes that re-concentrate soil N, such as manure production by livestock, improved hind-casting of N2O emissions. Any process in the past, present, or future that causes either accumulation or depletion of N reservoirs in soils or sediments could affect N2O emissions. As animal protein consumption in human diets increases globally, management of manure will be an important component of future mitigation efforts to reduce anthropogenic N2O sources.

  6. Atmospheric cycles of nitrogen oxides and ammonia. [source strengths and destruction rates

    Science.gov (United States)

    Bottger, A.; Ehhalt, D. H.; Gravenhorst, G.

    1981-01-01

    The atmospheric cycles of nitrogenous trace compounds for the Northern and Southern Hemispheres are discussed. Source strengths and destruction rates for the nitrogen oxides: NO, NO2 and HNO3 -(NOX) and ammonia (NH3) are given as a function of latitude over continents and oceans. The global amounts of NOX-N and NH3-N produced annually in the period 1950 to 1975 (34 + 5 x one trillion g NOx-N/yr and 29 + or - 6 x one trillion g NH3-N/yr) are much less than previously assumed. Globally, natural and anthropogenic emissions are of similar magnitude. The NOx emission from anthropogenic sources is 1.5 times that from natural processes in the Northern Hemisphere, whereas in the Southern Hemisphere, it is a factor of 3 or 4 less. More than 80% of atmospheric ammonia seems to be derived from excrements of domestic animals, mostly by bulk deposition: 24 + or - 9 x one trillion g NO3 -N/yr and 21 + or - 9 x one trillion g NH4+-N/yr. Another fraction may be removed by absorption on vegetation and soils.

  7. Pyrolysis and combustion of tobacco in a cigarette smoking simulator under air and nitrogen atmosphere.

    Science.gov (United States)

    Busch, Christian; Streibel, Thorsten; Liu, Chuan; McAdam, Kevin G; Zimmermann, Ralf

    2012-04-01

    A coupling between a cigarette smoking simulator and a time-of-flight mass spectrometer was constructed to allow investigation of tobacco smoke formation under simulated burning conditions. The cigarette smoking simulator is designed to burn a sample in close approximation to the conditions experienced by a lit cigarette. The apparatus also permits conditions outside those of normal cigarette burning to be investigated for mechanistic understanding purposes. It allows control of parameters such as smouldering and puff temperatures, as well as combustion rate and puffing volume. In this study, the system enabled examination of the effects of "smoking" a cigarette under a nitrogen atmosphere. Time-of-flight mass spectrometry combined with a soft ionisation technique is expedient to analyse complex mixtures such as tobacco smoke with a high time resolution. The objective of the study was to separate pyrolysis from combustion processes to reveal the formation mechanism of several selected toxicants. A purposely designed adapter, with no measurable dead volume or memory effects, enables the analysis of pyrolysis and combustion gases from tobacco and tobacco products (e.g. 3R4F reference cigarette) with minimum aging. The combined system demonstrates clear distinctions between smoke composition found under air and nitrogen smoking atmospheres based on the corresponding mass spectra and visualisations using principal component analysis.

  8. DNA damage in oral cancer and normal cells induced by nitrogen atmospheric pressure plasma jets

    Science.gov (United States)

    Han, Xu; Kapaldo, James; Liu, Yueying; Stack, M. Sharon; Ptasinska, Sylwia

    2015-09-01

    Nitrogen atmospheric pressure plasma jets (APPJs) have been shown to effectively induce DNA double strand breaks in SCC25 oral cancer cells. The APPJ source constructed in our laboratory operates based on dielectric barrier discharge. It consists of two copper electrodes alternatively wrapping around a fused silica tube with nitrogen as a feed gas. It is generally more challenging to ignite plasma in N2 atmosphere than in noble gases. However, N2 provides additional advantages such as lower costs compared to noble gases, thus this design can be beneficial for the future long-term clinical use. To compare the effects of plasma on cancer cells (SCC25) and normal cells (OKF), the cells from both types were treated at the same experimental condition for various treatment times. The effective area with different damage levels after the treatment was visualized as 3D maps. The delayed damage effects were also explored by varying the incubation times after the treatment. All of these studies are critical for a better understanding of the damage responses of cellular systems exposed to the plasma radiation, thus are useful for the development of the advanced plasma cancer therapy. The research described herein was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Basic Energy Sciences, Office of Science, United States Department of Energy through Grant No. DE-FC02-04ER15533.

  9. Nitrogen dioxide (NO2) uptake by vegetation controlled by atmospheric concentrations and plant stomatal aperture

    Science.gov (United States)

    Chaparro-Suarez, I. G.; Meixner, F. X.; Kesselmeier, J.

    2011-10-01

    Nitrogen dioxide (NO2) exchange between the atmosphere and five European tree species was investigated in the laboratory using a dynamic branch enclosure system (consisting of two cuvettes) and a highly specific NO2 analyzer. NO2 measurements were performed with a sensitive gas phase chemiluminescence NO detector combined with a NO2 specific (photolytic) converter, both from Eco-Physics (Switzerland). This highly specific detection system excluded bias from other nitrogen compounds. Investigations were performed at two light intensities (Photosynthetic Active Radiation, PAR, 450 and 900 μmol m-2 s-1) and NO2 concentrations between 0 and 5 ppb. Ambient parameters (air temperature and relative humidity) were held constant. The data showed dominant NO2 uptake by the respective tree species under all conditions. The results did not confirm the existence of a compensation point within a 95% confidence level, though we cannot completely exclude emission of NO2 under very low atmospheric concentrations. Induced stomatal stricture, or total closure, by changing light conditions, as well as by application of the plant hormone ABA (Abscisic Acid) caused a corresponding decrease of NO2 uptake. No loss of NO2 to plant surfaces was observed under stomatal closure and species dependent differences in uptake rates could be clearly related to stomatal behavior.

  10. The Fluorescent Properties of Dissolved Organic Matter and Assessment of Total Nitrogen in Overlying Water with Different Dissolved Oxygen Conditions.

    Science.gov (United States)

    Zhang Hua; Kuan, Wang; Song, Jian; Zhang, Yong; Huang, Ming; Huang, Jian; Zhu, Jing; Huang, Shan; Wang, Meng

    2016-03-01

    This paper used excitation-emission matrix spectroscopy (EEMs) to probe the fluorescence properties of dissolved organic matter (DOM) in the overlying water with different dissolved oxygen (DO) conditions, investigating the relationship between protein-like fluorescence intensity and total nitrogen concentration. The resulting fluorescence spectra revealed three protein-like components (high-excitation wavelength tyrosine, low-excitation wavelength tyrosine, low-excitation wavelength tryptophan) and two fulvic-like components (ultraviolet fulvic-like components, visible fulvic-like components) in the overlying water. Moreover, the protein-like components were dominant in the overlying water's DOM. The fluorescence intensity of the protein-like components decreased significantly after aeration. Two of the protein-like components--the low-excitation wavelength tyrosine and the low-excitation wavelength tryptophan--were more susceptible to degradation by microorganisms within the degradable organic matter with respect to the high-excitation wavelength tyrosine. In contrast, the ultraviolet and visible fulvic-like fluorescence intensity increased along with increasing DO concentration, indicating that the fulvic-like components were part of the refractory organics. The fluorescence indices of the DOM in the overlying water were between 1.65-1.80, suggesting that the sources of the DOM were related to terrigenous sediments and microbial metabolic processes, with the primary source being the contribution from microbial metabolism. The fluorescence indices increased along with DO growth, which showed that microbial biomass and microbial activity gradually increased with increasing DO while microbial metabolism also improved, which also increased the biogenic components in the overlying water. The fluorescence intensity of the high-excitation wavelength tyrosine peak A showed a good linear relationship with the total nitrogen concentration at higher DO concentrations of 2

  11. Enhanced acid rain and atmospheric deposition of nitrogen, sulfur and heavy metals in Northern China

    Science.gov (United States)

    Pan, Y.; Wang, Y.

    2013-12-01

    Atmospheric deposition is known to be important mechanism reducing air pollution. In response to the growing concern on the potential effects of the deposited material entering terrestrial and aquatic environments as well as their subsequent health effects, since 2007 we have established a 10-site monitoring network in Northern China, where particularly susceptible to severe air pollution. Wet and dry deposition was collected using an automatic wet-dry sampler. The presentation will focus on the new results of atmospheric deposition flux for a number of chemical species, such as nutrients (e.g. nitrogen and phosphorus), acidic matters (e.g. sulfur and proton), heavy metals and Polycyclic Aromatic Hydrocarbons, etc. This is to our knowledge the first detailed element budget study in the atmosphere across Northern China. We find that: (1) Over the 3 year period, 26% of precipitation events in the target area were more acid than pH 5.60 and these acidic events occurred in summer and autumn. The annual volume-weighted mean (VWM) pH value of precipitation was lower than 5.60 at most sites, which indicated the acidification of precipitation was not optimistic. The primary ions in precipitation were NH4+, Ca2+, SO42- and NO3-, with 10-sites-average concentrations of 221, 216, 216 and 80 μeq L-1, respectively. The ratio of SO42- to NO3- was 2.7; suggesting SO42- was the dominant acid component. (2) The deposited particles were neutral in general and the pH value increased from rural area to industrial and coastal sites. It is not surprising to note that the annual VWM pH value of precipitation was higher than 5.60 at three urban sites (Beijing and Tianjin mega cities) and one coastal site near the Bohai Bay, considering the fact that high buffer capacity of alkaline component, gas NH3 and mineral aerosols, at these sites compared to other places. (3) The 10-sites annual total deposition amounts for sulfur and nitrogen compounds were 60 and 65 kg N/S ha-1 yr-1

  12. Spatiotemporal variability of wet atmospheric nitrogen deposition to the Neuse River Estuary, North Carolina

    Energy Technology Data Exchange (ETDEWEB)

    Whitall, D.R.; Paerl, H.W. [University of North Carolina, Morehad City, NC (USA). Inst. of Marine Sciences

    2001-10-01

    Excessive nitrogen (N) loading to N-sensitive waters such as the Neuse River estuary (North Carolina) has been shown to promote changes in microbial and algal community composition and function (harmful algal blooms), hypoxia and anoxia, and fish kills. Previous studies have estimated that wet atmospheric deposition of nitrogen (WAD-N), as deposition of dissolved inorganic nitrogen (DIN: NO{sub 3}{sup -} NH{sub 3}/NH{sub 4}{sup +}) and dissolved organic nitrogen, may contribute at least 15% of the total externally supplied or 'new' N flux to the coastal waters of North Carolina. In a 3-yr study from June 1996 to June 1999, the weekly wet deposition of inorganic and organic N was counted at eleven sites on a northwest-southeast transect in the watershed. The annual mean total (wet DIN + wet organics) WAD-N flux for (15,026 Mg N/yr). Seasonally the spring (March-May) and summer (June - August) months contain the highest total weekly N depositions; this pattern appears to be driven by N concentration in precipitation. There is also spatial variability in WAD-N deposition; in general, the upper portion of the watershed receives the lowest annual deposition and the middle portion of the watershed receives the highest deposition. Based on a range of watershed N retention and in-stream riverine processing values, it was estimated that this flux contributes approximately 24% of the total 'new' N flux to the estuary. 61 refs., 4 figs., 4 tabs.

  13. Evaluation of the accuracy of thermal dissociation CRDS and LIF techniques for atmospheric measurement of reactive nitrogen species

    Science.gov (United States)

    Womack, Caroline C.; Neuman, J. Andrew; Veres, Patrick R.; Eilerman, Scott J.; Brock, Charles A.; Decker, Zachary C. J.; Zarzana, Kyle J.; Dube, William P.; Wild, Robert J.; Wooldridge, Paul J.; Cohen, Ronald C.; Brown, Steven S.

    2017-05-01

    The sum of all reactive nitrogen species (NOy) includes NOx (NO2 + NO) and all of its oxidized forms, and the accurate detection of NOy is critical to understanding atmospheric nitrogen chemistry. Thermal dissociation (TD) inlets, which convert NOy to NO2 followed by NO2 detection, are frequently used in conjunction with techniques such as laser-induced fluorescence (LIF) and cavity ring-down spectroscopy (CRDS) to measure total NOy when set at > 600 °C or speciated NOy when set at intermediate temperatures. We report the conversion efficiency of known amounts of several representative NOy species to NO2 in our TD-CRDS instrument, under a variety of experimental conditions. We find that the conversion efficiency of HNO3 is highly sensitive to the flow rate and the residence time through the TD inlet as well as the presence of other species that may be present during ambient sampling, such as ozone (O3). Conversion of HNO3 at 400 °C, nominally the set point used to selectively convert organic nitrates, can range from 2 to 6 % and may represent an interference in measurement of organic nitrates under some conditions. The conversion efficiency is strongly dependent on the operating characteristics of individual quartz ovens and should be well calibrated prior to use in field sampling. We demonstrate quantitative conversion of both gas-phase N2O5 and particulate ammonium nitrate in the TD inlet at 650 °C, which is the temperature normally used for conversion of HNO3. N2O5 has two thermal dissociation steps, one at low temperature representing dissociation to NO2 and NO3 and one at high temperature representing dissociation of NO3, which produces exclusively NO2 and not NO. We also find a significant interference from partial conversion (5-10 %) of NH3 to NO at 650 °C in the presence of representative (50 ppbv) levels of O3 in dry zero air. Although this interference appears to be suppressed when sampling ambient air, we nevertheless recommend regular

  14. The anthropogenic perturbation of the marine nitrogen cycle by atmospheric deposition: Nitrogen cycle feedbacks and the 15N Haber-Bosch effect

    Science.gov (United States)

    Yang, Simon; Gruber, Nicolas

    2016-10-01

    Over the last 100 years, anthropogenic emissions have led to a strong increase of atmospheric nitrogen deposition over the ocean, yet the resulting impacts and feedbacks are neither well understood nor quantified. To this end, we run a suite of simulations with the ocean component of the Community Earth System Model v1.2 forced with five scenarios of nitrogen deposition over the period from 1850 through 2100, while keeping all other forcings unchanged. Even though global oceanic net primary production increases little in response to this fertilization, the higher export and the resulting expansion of the oxygen minimum zones cause an increase in pelagic and benthic denitrification and burial by about 5%. In addition, the enhanced availability of fixed nitrogen in the surface ocean reduces global ocean N2 fixation by more than 10%. Despite the compensating effects through these negative feedbacks that eliminate by the year 2000 about 60% of the deposited nitrogen, the anthropogenic nitrogen input forced the upper ocean N budget into an imbalance of between 9 and 22 Tg N yr-1 depending on the deposition scenario. The excess nitrogen accumulates to highly detectable levels and causes in most areas a distinct negative trend in the δ15N of the oceanic fixed nitrogen pools—a trend we refer to as the 15N Haber-Bosch effect. Changes in surface nitrate utilization and the nitrogen feedbacks induce further changes in the δ15N of NO3-, making it a good but complex recorder of the overall impact of the changes in atmospheric deposition.

  15. Nitrogen concentrations and nitrogen isotopic compositions in leaves of Cinnamomum Camphora and Pinus massoniana (Lamb.) for indicating atmospheric nitrogen deposition in Guiyang (SW China)

    Science.gov (United States)

    Xu, Yu; Xiao, Huayun; Qu, Linglu

    2017-06-01

    Nitrogen (N) concentrations and δ15N signatures in soil and camphor (Cinnamomum Camphora) and Masson pine (Pinus massoniana Lamb.) leaves collected along an urban-rural gradient in Guiyang (SW China) were investigated systematically. N concentrations in camphor (1.01-2.37%) and Masson pine (0.99-2.42%) leaves showed a significant decrease from central Guiyang (0-6 km) to suburban areas (18-24 km), while slightly increased leaf N concentrations reemerged at areas more than 24 km from the city center. The δ15N values in camphor and Masson pine leaves also decreased from central Guiyang to the rural area, with more positive leaf δ15N in the urban area and 15N-depleted leaf δ15N in the rural area. No significant differences were observed for soil N concentrations and soil δ15N in these areas, which suggested that the decrease in leaf N concentrations was due to decreased atmospheric N deposition along the urban-rural gradient and that there were two isotopically different atmospheric N sources in Guiyang city: foliar δ15N values in urban areas were mainly influenced by 15N-enriched atmospheric NOx-N from traffic emissions, while those in rural areas were primarily affected by 15N-depleted atmospheric NHx-N from agricultural activities. However, the pattern of moss (collected ten years prior, with lower traffic density and wastewater treatment rate in the urban area) δ15N variation in the urban area (0-12 km) was contrary to that of the camphor and Masson pine leaves, indicating that the δ15N values in previously collected urban mosses were mainly controlled by isotopically light NHx-N from untreated wastes and sewage, but were much less affected by traffic. For the trees in the urban area, N concentrations in camphor and Masson pine leaves varied in parallel with their δ15N values (P deposition in the urban area. This indicated that the greater δ15N in urban camphor and Masson pine leaves reflected a higher contribution of NOx-N to N deposition. This study

  16. Phosphorus, and nitrogen co-doped carbon dots as a fluorescent probe for real-time measurement of reactive oxygen and nitrogen species inside macrophages.

    Science.gov (United States)

    Gong, Yunqian; Yu, Bin; Yang, Wen; Zhang, Xiaoling

    2016-05-15

    Phosphorus and nitrogen doped carbon dots (PN-CDs) were conveniently prepared by carbonization of adenosine-5'-triphosphate using a hydrothermal treatment. The PN-CDs with P/C atomic ratio of ca. 9.2/100 emit blue luminescence with high quantum yields of up to 23.5%. The PN-CDs were used as a novel sensing platform for live cell imaging of reactive oxygen species (ROS) and reactive nitrogen species (RNS), including ClO(-), ONOO(-), and NO in macrophages. The nanosensor design is based on our new finding that the strong fluorescence of the PN-CDs can be sensitively and selectively quenched by ROS and RNS both in vitro and in vivo. These results reveal that the PN-CDs can serve as a sensitive sensor for rapid imaging of ROS and RNS signaling with high selectivity and contrast. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Efficient synthesis of highly fluorescent nitrogen-doped carbon dots for cell imaging using unripe fruit extract of Prunus mume

    Energy Technology Data Exchange (ETDEWEB)

    Atchudan, Raji; Edison, Thomas Nesakumar Jebakumar Immanuel [School of Chemical Engineering, Yeungnam University, Gyeongsan 38541 (Korea, Republic of); Sethuraman, Mathur Gopalakrishnan, E-mail: mgsethu@gmail.com [Department of Chemistry, Gandhigram Rural Institute-Deemed University, Gandhigram 624 302, Tamilnadu (India); Lee, Yong Rok, E-mail: yrlee@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan 38541 (Korea, Republic of)

    2016-10-30

    Graphical abstract: The green synthesis of highly fluorescent N-CDs was achieved using the extract of unripe P. mume fruit as a carbon precursor by a one-pot simple hydrothermal-carbonization method. The resulting N-CDs were used as a staining agent for the fluorescence imaging of MDA-MB-231 cells. Display Omitted - Highlights: • The green synthesis of highly fluorescent N-CDs using the extract of unripe P. mume. • The N-CDs were synthesized by one-pot hydrothermal-carbonization method. • This method of synthesis is a simple, cost effective and eco-friendly route. • N-CDs will be a good alternative for fluorescent dyes and SQDs for bio-applications. - Abstract: Highly fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized using the extract of unripe Prunus mume (P. mume) fruit by a simple one step hydrothermal-carbonization method. The N-CDs were synthesized at different pH ranges, 2.3, 5, 7, and 9. The pH of the P. mume extract was adjusted using an aqueous ammonia solution (25%). The optical properties of N-CDs were examined by UV–vis and fluorescence spectroscopy. The N-CDs synthesized at pH 9 emitted high fluorescence intensity compared to other obtained N-CDs. The N-CDs synthesized at pH 9 was further characterized by high resolution transmission electron microscopy (HR-TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and Fourier transform-infra red (FT-IR) spectroscopy. HR-TEM showed that the average size of the synthesized N-CDs was approximately 9 nm and the interlayer distance was 0.21 nm, which was validated by XRD. The graphitic nature of the synthesized N-CDs were confirmed by Raman spectroscopy. XPS and FT-IR spectroscopy confirmed the doping of the nitrogen moiety over the synthesized CDs. The synthesized nitrogen doped CDs (N-CDs) were low toxicity and were used as a staining probe for fluorescence cell imaging.

  18. Nitrogen: a possible substitute for mercury as a UV-emitter for mercury-less low-pressure discharge fluorescent lamps using Penning-like energy transfer

    Science.gov (United States)

    Jinno, Masafumi; Takubo, Shuji; Hazata, Yuji; Kitsinelis, Spiros; Motomura, Hideki

    2005-09-01

    Nitrogen is well known as a UV-emitter because of its 2nd positive band lying around 350 nm. However, it is a molecular gas and when energy is stored in rotational or vibrational levels, the gas temperature can become high enough to melt even the glass tube. To avoid such problems the authors tried to use the Penning-like effect between the argon metastables and nitrogen C 3Πu states with very low partial pressure of nitrogen compared with that of the argon. By adding a very small amount of nitrogen to argon, the discharge changes drastically. Though pure argon discharge and pure nitrogen discharge are both unstable and easy to constrict, a small amount of nitrogen improves the stability of the discharge and emits the nitrogen 2nd positive band UV light by energy transfer from the argon metastable to the nitrogen molecule C 3Πu state. Nitrogen-added argon fluorescent lamps operated at 30 kHz of alternative square voltage wave achieve about 4500 cd m-2 at 3.75 W and at 9.3 kPa of pressure with good dimming characteristics. The maximum luminance should be higher than this because the input power is limited by the power supply. At this condition the luminous efficacy achieves 7.1 lm W-1. These results show a possibility of argon-nitrogen fluorescent lamps as mercury-less fluorescent lamps.

  19. Nitrogen: a possible substitute for mercury as a UV-emitter for mercury-less low-pressure discharge fluorescent lamps using Penning-like energy transfer

    Energy Technology Data Exchange (ETDEWEB)

    Jinno, Masafumi; Takubo, Shuji; Hazata, Yuji; Kitsinelis, Spiros; Motomura, Hideki [Department of Electrical and Electronic Engineering, Ehime University, 3 Bunkyo-Cho, Matsuyama 790-8577 (Japan)

    2005-09-07

    Nitrogen is well known as a UV-emitter because of its 2nd positive band lying around 350 nm. However, it is a molecular gas and when energy is stored in rotational or vibrational levels, the gas temperature can become high enough to melt even the glass tube. To avoid such problems the authors tried to use the Penning-like effect between the argon metastables and nitrogen C {sup 3}{pi}{sub u} states with very low partial pressure of nitrogen compared with that of the argon. By adding a very small amount of nitrogen to argon, the discharge changes drastically. Though pure argon discharge and pure nitrogen discharge are both unstable and easy to constrict, a small amount of nitrogen improves the stability of the discharge and emits the nitrogen 2nd positive band UV light by energy transfer from the argon metastable to the nitrogen molecule C {sup 3}{pi}{sub u} state. Nitrogen-added argon fluorescent lamps operated at 30 kHz of alternative square voltage wave achieve about 4500 cd m{sup -2} at 3.75 W and at 9.3 kPa of pressure with good dimming characteristics. The maximum luminance should be higher than this because the input power is limited by the power supply. At this condition the luminous efficacy achieves 7.1 lm W{sup -1}. These results show a possibility of argon-nitrogen fluorescent lamps as mercury-less fluorescent lamps.

  20. Monte Carlo analysis of field-dependent electron avalanche coefficients in nitrogen at atmospheric pressure

    Science.gov (United States)

    Nguyen, H. K.; Mankowski, J.; Dickens, J. C.; Neuber, A. A.; Joshi, R. P.

    2017-12-01

    Calculations of electron impact ionization of nitrogen gas at atmospheric pressure are presented based on the kinetic Monte Carlo technique. The emphasis is on energy partitioning between primary and secondary electrons, and three different energy sharing schemes have been evaluated. The ionization behavior is based on Wannier's classical treatment. Our Monte Carlo results for the field-dependent drift velocities match the available experimental data. More interestingly, the field-dependent first Townsend coefficient predicted by the Monte Carlo calculations is shown to be in close agreement with reported data for E/N values ranging as high as 4000 Td, only when a random assignment of excess energies between the primary and secondary particles is used.

  1. Torrefaction of corncob to produce charcoal under nitrogen and carbon dioxide atmospheres.

    Science.gov (United States)

    Li, Shu-Xian; Chen, Chang-Zhou; Li, Ming-Fei; Xiao, Xiao

    2017-10-12

    Corncob was torrefied under nitrogen and carbon dioxide atmospheres at 220-300 °C, obtaining solid products with mass yields of 69.38-95.03% and 67.20-94.99% and higher heating values of 16.58-24.77 MJ/kg and 16.68-24.10 MJ/kg, respectively. The changes of physicochemical properties of the charcoal was evaluated by many spectroscopies, contact angle determination, and combustion test. Hemicelluloses were not detected for the torrefaction under the hard conditions. As the severity increased, C concentration raised while H and O concentrations reduced. Combustion test showed that the burnout temperature of charcoal declined with the elevation of reaction temperature, and torrefaction at a high temperature shortened the time for the whole combustion process. Base on the data, torrefaction at 260 °C under carbon dioxide was recommended for the torrefaction of corncob. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Atmospheric nitrogen dioxide at ambient levels stimulates growth and development of horticultural plants

    Energy Technology Data Exchange (ETDEWEB)

    Adam, S.E.H.; Shigeto, J. [Hiroshima Univ., Hiroshima (Japan). Dept. of Mathematical and Life Sciences; Sakamoto, A.; Takahashi, M.; Morikawa, H. [Hiroshima Univ., Hiroshima (Japan). Dept. of Mathematical and Life Sciences, Core Research for Evolutional Science and Technology

    2008-02-15

    Studies have demonstrated that ambient levels of atmospheric nitrogen dioxide (NO{sub 2}) can cause Nicotiana plumbaginifolia to double its biomass as well as its cell contents. This paper examined the influence of NO{sub 2} on lettuce, sunflower, cucumber, and pumpkin plants. Plants were grown in environments supplemented with stable isotope-labelled NO{sub 2} for approximately 6 weeks and irrigated with nitrates. Measured growth parameters included leaf number, internode number, stem length, number of flower buds, and root length. Results of the study demonstrated that the addition of NO{sub 2} doubled the aboveground and belowground biomass of sunflowers, while only the aboveground biomass of pumpkin, cucumbers, and lettuces was doubled. Levels of carbon (C), nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were also doubled in the lettuce samples. A mass spectrometry analysis showed that only a small percentage of total plant N was derived from NO{sub 2}. It was concluded that exogenous NO{sub 2} additions function as a signal rather than as a significant nutrient source in horticultural plants. 22 refs., 2 tabs., 1 fig.

  3. Atmospheric nitrogen deposition in estuarine and coastal waters: Biogeochemical and water quality impacts

    Energy Technology Data Exchange (ETDEWEB)

    Paerl, H.W.; Peierls, B.L. [Univ. of North Carolina, Chapel Hill, NC (United States). Inst. of Marine Sciences; Fogel, M.L. [Carnegie Institution of Washington, DC (United States). Geophysical Lab.; Aguilar, C. [Univ. of North Carolina, Chapel Hill, NC (United States). Inst. of Marine Sciences]|[Carnegie Institution of Washington, DC (United States). Geophysical Lab.

    1994-12-31

    Atmospheric deposition (AD) is a significant source of biologically-available ``new`` nitrogen in N-limited estuarine and coastal ocean waters. From 10 to over 50% of ``new`` N inputs are attributable to AD in waters ``downwind`` of emissions. In situ microcosm and mesocosm bioassays indicate that this ``new`` N source can enhance microalgal primary production and may alter community composition. Relative to terrestrial and regenerated N inputs, the dominant AD-N sources, NO{sub 3}k{sup {minus}}, NH{sub 4}{sup {plus}}, and dissolves organic nitrogen (DON) reveal stable N isotope ratios ({delta}{sup 15}N) generally deplete in {sup 15}N. The relatively low {delta}{sup 15}N ratio of AD-N has been used as a tracer of the incorporation and fate of this ``new`` N source in receiving water. Diagnostic biomarker molecules, including proteins and pigments (chlorophylls), indicate rapid algal utilization and transformation of AD-N. Seasonal production and N isotope studies in mixed and stratified North Carolina Atlantic coastal and offshore (i.e. Gulf Stream) waters indicate a marked impact of AD-N on microbial production. AD-N is an important and thus far poorly recognized source of ``new`` N in N-limited waters; these waters characterized a large proportion of the world`s estuarine and coastal zones. AD-N may additionally play a role in recently-noted coastal eutrophication and algal nuisance bloom dynamics.

  4. Compact fluorescent lighting in Wisconsin: elevated atmospheric emission and landfill deposition post-EISA implementation.

    Science.gov (United States)

    Arendt, John D; Katers, John F

    2013-07-01

    The majority of states in the USA, including Wisconsin, have been affected by elevated air, soil and waterborne mercury levels. Health risks associated with mercury increase from the consumption of larger fish species, such as Walleye or Pike, which bio-accumulate mercury in muscle tissue. Federal legislation with the 2011 Mercury and Air Toxics Standards and the Wisconsin legislation on mercury, 2009 Wisconsin Act 44, continue to aim at lowering allowable levels of mercury emissions. Meanwhile, mercury-containing compact fluorescent lights (CFL) sales continue to grow as businesses and consumers move away from energy intensive incandescent light bulbs. An exchange in pollution media is occurring as airborne mercury emissions from coal-burning power plants, the largest anthropogenic source of mercury, are being reduced by lower energy demand and standards, while more universal solid waste containing mercury is generated each time a CFL is disposed. The treatment of CFLs as a 'universal waste' by the Environmental Protection Agency (EPA) led to the banning of non-household fluorescent bulbs from most municipal solid waste. Although the EPA encourages recycling of bulbs, industry currently recycles fluorescent lamps and CFLs at a rate of only 29%. Monitoring programs at the federal and state level have had only marginal success with industrial and business CFL recycling. The consumer recycling rate is even lower at only 2%. A projected increase in residential CFL use in Wisconsin owing to the ramifications of the Energy Independence and Security Act of 2007 will lead to elevated atmospheric mercury and landfill deposition in Wisconsin.

  5. Meta-analysis assessing potential of steady-state chlorophyll fluorescence for remote sensing detection of plant water, temperature and nitrogen stress

    Czech Academy of Sciences Publication Activity Database

    Ač, Alexander; Malenovský, Z.; Olejníčková, Julie; Gallé, A.; Rascher, U.; Mohammed, G.

    2015-01-01

    Roč. 168, oct (2015), s. 420-436 ISSN 0034-4257 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : steady-state chlorophyll fluorescence * passive sun-induced fluorescence * active laser-induced fluorescence * photosynthesis * stress * water * temperature * nitrogen * random-effects meta-analysis * FLEX satellite mission Subject RIV: EH - Ecology, Behaviour Impact factor: 5.881, year: 2015

  6. Lichen-based critical loads for atmospheric nitrogen deposition in Western Oregon and Washington Forests, USA.

    Science.gov (United States)

    Geiser, Linda H; Jovan, Sarah E; Glavich, Doug A; Porter, Matthew K

    2010-07-01

    Critical loads (CLs) define maximum atmospheric deposition levels apparently preventative of ecosystem harm. We present first nitrogen CLs for northwestern North America's maritime forests. Using multiple linear regression, we related epiphytic-macrolichen community composition to: 1) wet deposition from the National Atmospheric Deposition Program, 2) wet, dry, and total N deposition from the Communities Multi-Scale Air Quality model, and 3) ambient particulate N from Interagency Monitoring of Protected Visual Environments (IMPROVE). Sensitive species declines of 20-40% were associated with CLs of 1-4 and 3-9 kg N ha(-1)y(-1) in wet and total deposition. CLs increased with precipitation across the landscape, presumably from dilution or leaching of depositional N. Tight linear correlation between lichen and IMPROVE data suggests a simple screening tool for CL exceedance in US Class I areas. The total N model replicated several US and European lichen CLs and may therefore be helpful in estimating other temperate-forest lichen CLs. Published by Elsevier Ltd.

  7. Increased forest carbon storage with increased atmospheric CO2 despite nitrogen limitation: a game-theoretic allocation model for trees in competition for nitrogen and light.

    Science.gov (United States)

    Dybzinski, Ray; Farrior, Caroline E; Pacala, Stephen W

    2015-03-01

    Changes in resource availability often cause competitively driven changes in tree allocation to foliage, wood, and fine roots, either via plastic changes within individuals or through turnover of individuals with differing strategies. Here, we investigate how optimally competitive tree allocation should change in response to elevated atmospheric CO2 along a gradient of nitrogen and light availability, together with how those changes should affect carbon storage in living biomass. We present a physiologically-based forest model that includes the primary functions of wood and nitrogen. From a tree's perspective, wood is an offensive and defensive weapon used against neighbors in competition for light. From a biogeochemical perspective, wood is the primary living reservoir of stored carbon. Nitrogen constitutes a tree's photosynthetic machinery and the support systems for that machinery, and its limited availability thus reduces a tree's ability to fix carbon. This model has been previously successful in predicting allocation to foliage, wood, and fine roots along natural productivity gradients. Using game theory, we solve the model for competitively optimal foliage, wood, and fine root allocation strategies for trees in competition for nitrogen and light as a function of CO2 and nitrogen mineralization rate. Instead of down-regulating under nitrogen limitation, carbon storage under elevated CO2 relative to carbon storage at ambient CO2 is approximately independent of the nitrogen mineralization rate. This surprising prediction is a consequence of both increased competition for nitrogen driving increased fine root biomass and increased competition for light driving increased allocation to wood under elevated CO2 . © 2014 John Wiley & Sons Ltd.

  8. Hydrothermal Synthesis of Nitrogen-Doped Carbon Quantum Dots as Fluorescent Probes for the Detection of Dopamine.

    Science.gov (United States)

    Zhao, Chunxi; Jiao, Yang; Hua, Jianhao; Yang, Jian; Yang, Yaling

    2017-11-07

    Nitrogen-doped carbon quantum dots (N-CQDs) were synthesized though a facile, economical and straightforward hydrothermal method by using polyacrylamide as both carbon and nitrogen sources. The as-prepared N-CQDs offered high quantum yield of 23.1%, exhibited good water solubility and fluorescence properties. Moreover, the N-CQDs can be used as effective probes for sensitive and selective detection of dopamine. Fluorescence of N-CQDs was effectively quenched after the addition of dopamine owing to dopamine would be transformed into dopamine-quinone under alkaline conditions. A good linear relationship between fluorescence quenching and the concentration of dopamine in the range 0.1-200 μM was obtained with a low detection limit of 0.05 μM. The proposed method showed high selectivity for dopamine in the presence of potential interfering species. Moreover, this method was successfully applied to the determination of DA in urine sample with satisfactory recoveries.

  9. DART: Recent Advances in Remote Sensing Data Modeling With Atmosphere, Polarization, and Chlorophyll Fluorescence

    Science.gov (United States)

    Gastellu-Etchegorry, Jean-Phil; Lauret, Nicolas; Yin, Tiangang; Landier, Lucas; Kallel, Abdelaziz; Malenovsky, Zbynek; Bitar, Ahmad Al; Aval, Josselin; Benhmida, Sahar; Qi, Jianbo; hide

    2017-01-01

    To better understand the life-essential cycles and processes of our planet and to further develop remote sensing (RS) technology, there is an increasing need for models that simulate the radiative budget (RB) and RS acquisitions of urban and natural landscapes using physical approaches and considering the three-dimensional (3-D) architecture of Earth surfaces. Discrete anisotropic radiative transfer (DART) is one of the most comprehensive physically based 3-D models of Earth-atmosphere radiative transfer, covering the spectral domain from ultraviolet to thermal infrared wavelengths. It simulates the optical 3-DRB and optical signals of proximal, aerial, and satellite imaging spectrometers and laser scanners, for any urban and/or natural landscapes and for any experimental and instrumental configurations. It is freely available for research and teaching activities. In this paper, we briefly introduce DART theory and present recent advances in simulated sensors (LiDAR and cameras with finite field of view) and modeling mechanisms (atmosphere, specular reflectance with polarization and chlorophyll fluorescence). A case study demonstrating a novel application of DART to investigate urban landscapes is also presented.

  10. Atmospheric deposition of inorganic nitrogen in Spanish forests of Quercus ilex measured with ion-exchange resins and conventional collectors.

    Science.gov (United States)

    García-Gomez, Héctor; Izquieta-Rojano, Sheila; Aguillaume, Laura; González-Fernández, Ignacio; Valiño, Fernando; Elustondo, David; Santamaría, Jesús M; Àvila, Anna; Fenn, Mark E; Alonso, Rocío

    2016-09-01

    Atmospheric nitrogen deposition is one of the main threats for biodiversity and ecosystem functioning. Measurement techniques like ion-exchange resin collectors (IECs), which are less expensive and time-consuming than conventional methods, are gaining relevance in the study of atmospheric deposition and are recommended to expand monitoring networks. In the present work, bulk and throughfall deposition of inorganic nitrogen were monitored in three different holm oak forests in Spain during two years. The results obtained with IECs were contrasted with a conventional technique using bottle collectors and with a literature review of similar studies. The performance of IECs in comparison with the conventional method was good for measuring bulk deposition of nitrate and acceptable for ammonium and total dissolved inorganic nitrogen. Mean annual bulk deposition of inorganic nitrogen ranged 3.09-5.43 kg N ha(-1) according to IEC methodology, and 2.42-6.83 kg N ha(-1) y(-1) using the conventional method. Intra-annual variability of the net throughfall deposition of nitrogen measured with the conventional method revealed the existence of input pulses of nitrogen into the forest soil after dry periods, presumably originated from the washing of dry deposition accumulated in the canopy. Important methodological recommendations on the IEC method and discussed, compiled and summarized. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Nitrogen doped carbon nanodots as fluorescent probes for selective detection and quantification of Ferric(III) ions

    Science.gov (United States)

    Chin, Suk-Fun; Tan, Shao-Chien; Pang, Suh-Cem; Ng, Sing-Muk

    2017-11-01

    Nitrogen (N) doped carbon dots (N-CDs) that showed blue fluorescence with quantum yield (QY) of 12.25% were synthesized by one step microwave irradiation of lysine in ortho-phosphoric acid at 1000 W for 5 min. The as-synthesized N-CDs were successfully explored as fluorescent probes for selective detection of ferric (Fe3+) ions in aqueous condition with a linear range from 0.2 to 5.0 mM and a detection limit of 0.074 mM ± 0.081 (S/N = 3). The N-CDs exhibited high selectivity towards the detection of Fe3+ ions even in the presence of interfering ions. The N-CDs also demonstrated the potential of practical application for determining of Fe3+ ions concentration in real samples with high recovery rate and low relative standard deviation error.

  12. Field investigations of nitrogen dioxide (NO2 exchange between plants and the atmosphere

    Directory of Open Access Journals (Sweden)

    J. Kesselmeier

    2013-01-01

    Full Text Available The nitrogen dioxide (NO2 exchange between the atmosphere and needles of Picea abies L. (Norway Spruce was studied under uncontrolled field conditions using a dynamic chamber system. This system allows measurements of the flux density of the reactive NO-NO2-O3 triad and additionally of the non-reactive trace gases CO2 and H2O. For the NO2 detection a highly NO2 specific blue light converter was used, which was coupled to chemiluminescence detection of the photolysis product NO. This NO2 converter excludes known interferences with other nitrogen compounds, which occur by using more unspecific NO2 converters. Photo-chemical reactions of NO, NO2, and O3 inside the dynamic chamber were considered for the determination of NO2 flux densities, NO2 deposition velocities, as well as NO2 compensation point concentrations. The calculations are based on a bi-variate weighted linear regression analysis (y- and x-errors considered. The NO2 deposition velocities for spruce, based on projected needle area, ranged between 0.07 and 0.42 mm s−1. The calculated NO2 compensation point concentrations ranged from 2.4 ± 9.63 to 29.0 ± 16.30 nmol m−3 (0.05–0.65 ppb but the compensation point concentrations were all not significant in terms of compensation point concentration is unequal to zero. These data challenge the existence of a NO2 compensation point concentration for spruce. Our study resulted in lower values of NO2 gas exchange flux densities, NO2 deposition velocities and NO2 compensation point concentrations in comparison to most previous studies. It is essential to use a more specific NO2 analyzer than used in previous studies and to consider photo-chemical reactions between NO, NO2, and O3 inside the chamber.

  13. A global assessment of forest surface albedo and its relationships with climate and atmospheric nitrogen deposition.

    Science.gov (United States)

    Leonardi, Stefano; Magnani, Federico; Nolè, Angelo; Van Noije, Twan; Borghetti, Marco

    2015-01-01

    We present a global assessment of the relationships between the short-wave surface albedo of forests, derived from the MODIS satellite instrument product at 0.5° spatial resolution, with simulated atmospheric nitrogen deposition rates (Ndep ), and climatic variables (mean annual temperature Tm and total annual precipitation P), compiled at the same spatial resolution. The analysis was performed on the following five forest plant functional types (PFTs): evergreen needle-leaf forests (ENF); evergreen broad-leaf forests (EBF); deciduous needle-leaf forests (DNF); deciduous broad-leaf forests (DBF); and mixed-forests (MF). Generalized additive models (GAMs) were applied in the exploratory analysis to assess the functional nature of short-wave surface albedo relations to environmental variables. The analysis showed evident correlations of albedo with environmental predictors when data were pooled across PFTs: Tm and Ndep displayed a positive relationship with forest albedo, while a negative relationship was detected with P. These correlations are primarily due to surface albedo differences between conifer and broad-leaf species, and different species geographical distributions. However, the analysis performed within individual PFTs, strengthened by attempts to select 'pure' pixels in terms of species composition, showed significant correlations with annual precipitation and nitrogen deposition, pointing toward the potential effect of environmental variables on forest surface albedo at the ecosystem level. Overall, our global assessment emphasizes the importance of elucidating the ecological mechanisms that link environmental conditions and forest canopy properties for an improved parameterization of surface albedo in climate models. © 2014 John Wiley & Sons Ltd.

  14. Atmospheric NH3 and NO2 concentration and nitrogen deposition in an agricultural catchment of Eastern China.

    Science.gov (United States)

    Yang, Rong; Hayashi, Kentaro; Zhu, Bin; Li, Feiyue; Yan, Xiaoyuan

    2010-09-15

    To assess the atmospheric environmental impacts of anthropogenic reactive nitrogen in the fast-developing Eastern China region, we measured atmospheric concentrations of nitrogen dioxide (NO(2)) and ammonia (NH(3)) as well as the wet deposition of inorganic nitrogen (NO(3)(-) and NH(4)(+)) and dissolved organic nitrogen (DON) levels in a typical agricultural catchment in Jiangsu Province, China, from October 2007 to September 2008(.) The annual average gaseous concentrations of NO(2) and NH(3) were 42.2 microg m(-3) and 4.5 microg m(-3) (0 degree C, 760 mm Hg), respectively, whereas those of NO(3)(-), NH(4)(+), and DON in the rainwater within the study catchment were 1.3, 1.3, and 0.5 mg N L(-1), respectively. No clear difference in gaseous NO(2) concentrations and nitrogen concentrations in collected rainwater was found between the crop field and residential sites, but the average NH(3) concentration of 5.4 microg m(-3) in residential sites was significantly higher than that in field sites (4.1 microg m(-3)). Total depositions were 40 kg N ha(-1) yr(-1) for crop field sites and 30 kg N ha(-1) yr(-1) for residential sites, in which dry depositions (NO(2) and NH(3)) were 7.6 kg N ha(-1) yr(-1) for crop field sites and 1.9 kg N ha(-1) yr(-1) for residential sites. The DON in the rainwater accounted for 16% of the total wet nitrogen deposition. Oxidized N (NO(3)(-) in the precipitation and gaseous NO(2)) was the dominant form of nitrogen deposition in the studied region, indicating that reactive forms of nitrogen created from urban areas contribute greatly to N deposition in the rural area evaluated in this study. Copyright 2010 Elsevier B.V. All rights reserved.

  15. Sensitivity of modeled atmospheric nitrogen species and nitrogen deposition to variations in sea salt emissions in the North Sea and Baltic Sea regions

    Directory of Open Access Journals (Sweden)

    D. Neumann

    2016-03-01

    Full Text Available Coarse sea salt particles are emitted ubiquitously from the ocean surface by wave-breaking and bubble-bursting processes. These particles impact the atmospheric chemistry by affecting the condensation of gas-phase species and, thus, indirectly the nucleation of new fine particles, particularly in regions with significant air pollution. In this study, atmospheric particle concentrations are modeled for the North Sea and Baltic Sea regions in northwestern Europe using the Community Multiscale Air Quality (CMAQ modeling system and are compared to European Monitoring and Evaluation Programme (EMEP measurement data. The sea salt emission module is extended by a salinity-dependent scaling of the sea salt emissions because the salinity in large parts of the Baltic Sea is very low, which leads to considerably lower sea salt mass emissions compared to other oceanic regions. The resulting improvement in predicted sea salt concentrations is assessed. The contribution of surf zone emissions is considered separately. Additionally, the impacts of sea salt particles on atmospheric nitrate and ammonium concentrations and on nitrogen deposition are evaluated. The comparisons with observational data show that sea salt concentrations are commonly overestimated at coastal stations and partly underestimated farther inland. The introduced salinity scaling improves the predicted Baltic Sea sea salt concentrations considerably. The dates of measured peak concentrations are appropriately reproduced by the model. The impact of surf zone emissions is negligible in both seas. Nevertheless, they might be relevant because surf zone emissions were cut at an upper threshold in this study. Deactivating sea salt leads to minor increases in NH3 +  NH4+ and HNO3 +  NO3− and a decrease in NO3− concentrations. However, the overall effect on NH3 +  NH4+ and HNO3 +  NO3− concentrations is smaller than the deviation from the measurements. Nitrogen wet deposition is

  16. Nitrogen evolution within the Earth's atmosphere-mantle system assessed by recycling in subduction zones

    Science.gov (United States)

    Mallik, Ananya; Li, Yuan; Wiedenbeck, Michael

    2018-01-01

    Understanding the evolution of nitrogen (N) across Earth's history requires a comprehensive understanding of N's behaviour in the Earth's mantle - a massive reservoir of this volatile element. Investigation of terrestrial N systematics also requires assessment of its evolution in the Earth's atmosphere, especially to constrain the N content of the Archaean atmosphere, which potentially impacted water retention on the post-accretion Earth, potentially causing enough warming of surface temperatures for liquid water to exist. We estimated the proportion of recycled N in the Earth's mantle today, the isotopic composition of the primitive mantle, and the N content of the Archaean atmosphere based on the recycling rates of N in modern-day subduction zones. We have constrained recycling rates in modern-day subduction zones by focusing on the mechanism and efficiency of N transfer from the subducting slab to the sub-arc mantle by both aqueous fluids and slab partial melts. We also address the transfer of N by aqueous fluids as per the model of Li and Keppler (2014). For slab partial melts, we constrained the transfer of N in two ways - firstly, by an experimental study of the solubility limit of N in melt (which provides an upper estimate of N uptake by slab partial melts) and, secondly, by the partitioning of N between the slab and its partial melt. Globally, 45-74% of N introduced into the mantle by subduction enters the deep mantle past the arc magmatism filter, after taking into account the loss of N from the mantle by degassing at mid-ocean ridges, ocean islands and back-arcs. Although the majority of the N in the present-day mantle remains of primordial origin, our results point to a significant, albeit minor proportion of mantle N that is of recycled origin (17 ± 8% or 12 ± 5% of N in the present-day mantle has undergone recycling assuming that modern-style subduction was initiated 4 or 3 billion years ago, respectively). This proportion of recycled N is enough to

  17. Assessment of nitrogen and phosphorus loading by atmospheric dry deposition to the Lagos Lagoon, Nigeria.

    Science.gov (United States)

    Olayinka, Kehinde O; Oladosu, Najeem O; Abayomi, Akeem A; Alo, Babajide I

    2016-07-01

    Surface water pollution has been found to be considerably driven by the contributions of airborne particles, open-air waste burning and fossil fuel combustion, ammonia volatilization from excreta, fertilizer and derivatives from explosive factories. Atmospheric deposition into the Lagos Lagoon is suspected to be a major contributor to the nutrient levels of the lagoon. Atmospheric dry nutrient deposition was monitored at six stations around the Lagos Lagoon from January to June 2012 in order to estimate the contribution of atmospheric deposits into the lagoon's nutrient cycles. Species of phosphorus (P) and nitrogen (N) in the lagoon water were analyzed by colorimetric methods. Mean [NO(-) 3 + NO(-) 2]-N was 3.08 ± 2.10 mg m(-2) day(-1) (0.55-8.73 mg m(-2) day(-1)). The (NO(-) 3 + NO(-) 2)-N was only about 2 % of total N but [NH(+) 4 + organic]-N was approximately 38 % of total N. Particulate N was about 60 % of total N. Average total N was 144 ± 94.9 mg m(-2) day(-1) (48.0-285 mg m(-2) day(-1)). Average soluble reactive P was significantly lower than [NO(-) 3 + NO(-) 2]-N averaging about 0.12 ± 0.12 mg m(-2) day(-1). Soluble reactive P (SRP) was less than 2 % of total P but soluble organic P was about 86 % of total P. Particulate P accounted for about 12 % of total P. Average total P was 4.56 ± 10.1 mg m(-2) day(-1) (0.48-31.6 mg m(-2) day(-1)). This study shows that atmospheric deposition of nutrients into the Lagos Lagoon is taking place and this may represent a considerable proportion of the total nutrient loading of the lagoon.

  18. Modeling of recovery mechanism of ozone zero phenomenaby adding small amount of nitrogen in atmospheric pressure oxygen dielectric barrier discharges

    Science.gov (United States)

    Akashi, Haruaki; Yoshinaga, Tomokazu

    2013-09-01

    Ozone zero phenomena in an atmospheric pressure oxygen dielectric barrier discharges have been one of the major problems during a long time operation of ozone generators. But it is also known that the adding a small amount of nitrogen makes the recover from the ozone zero phenomena. To make clear the mechanism of recovery, authors have been simulated the discharges with using the results of Ref. 3. As a result, the recovery process can be seen and ozone density increased. It is found that the most important species would be nitrogen atoms. The reaction of nitrogen atoms and oxygen molecules makes oxygen atoms which is main precursor species of ozone. This generation of oxygen atoms is effective to increase ozone. The dependence of oxygen atom density (nO) and nitrogen atom density (nN) ratio was examined in this paper. In the condition of low nN/nO ratio case, generation of nitrogen oxide is low, and the quenching of ozone by the nitrogen oxide would be low. But in the high ratio condition, the quenching of ozone by nitrogen oxide would significant. This work was supported by KAKENHI(23560352).

  19. Atmospheric nitrogen desposition to the Neuse River watershed: Fluxes, sources and spatiotemporal variability

    Science.gov (United States)

    Whitall, David Richard

    Atmospheric deposition of nitrogen (AD-N), as wet and dry deposition of dissolved inorganic nitrogen (DIN: NO3- , NH3/NH4+) and dissolved organics, contributes >20% of the total externally-supplied or "new" N flux to the waterways of the Neuse River basin (North Carolina). Excessive nitrogen (N) loading to N-sensitive waters such as the Neuse River Estuary has been linked to changes in microbial and algal community composition and function (harmful algal blooms), hypoxia/anoxia, and fish kills. In a three year study from June 1996 to June 1999, the weekly wet deposition of inorganic and organic N was calculated at eleven sites on a northwest-southeast transect in the watershed. The annual mean total (wet + dry) AD-N flux was calculated to be 1732 mg/m2/yr. Nitrate was the most prevalent chemical species in deposition, followed by ammonium and organics. Seasonally, the spring (March--May)and summer (June--August) months contained the highest total weekly N deposition; this does not appear to be driven by precipitation amount. There was spatial variability in AD-N deposition; in general, the upper portion of the watershed receives the lowest annual deposition. Estimates of watershed N retention and in-stream riverine processing revealed that this flux contributed from 27--58% of the total "new" N flux to the estuary, with direct deposition to the estuary surface accounting for 10% of the total "new" N flux. Sites in the middle portion of the basin had a significantly lower delta 15NH4+, suggesting that they were more impacted by NH3 from animal waste than sites in the upper and lower portions of the basin. Meteorological modeling of air parcel back trajectories did not correlate well with AD-N flux from those parcels, but there was some evidence to suggest that a large portion of this AD-N may have originated outside of North Carolina, making managing this nutrient flux a regional rather than a state issue. AD-N is an important source of "new" N to the Neuse River

  20. Staggering reductions in atmospheric nitrogen dioxide across Canada in response to legislated transportation emissions reductions

    Science.gov (United States)

    Reid, Holly; Aherne, Julian

    2016-12-01

    It is well established that atmospheric nitrogen dioxide (NO2), associated mainly with emissions from transportation and industry, can have adverse effects on both human and ecosystem health. Specifically, atmospheric NO2 plays a role in the formation of ozone, and in acidic and nutrient deposition. As such, international agreements and national legislation, such as the On-Road Vehicle and Engine Emission Regulations (SOR/2003-2), and the Federal Agenda on Cleaner Vehicles, Engines and Fuel have been put into place to regulate and limit oxidized nitrogen emissions. The objective of this study was to assess the response of ambient air concentrations of NO2 across Canada to emissions regulations. Current NO2 levels across Canada were examined at 137 monitoring sites, and long-term annual and quarterly trends were evaluated for 63 continuous monitoring stations that had at least 10 years of data during the period 1988-2013. A non-parametric Mann-Kendall test (Z values) and Sen's slope estimate were used to determine monotonic trends; further changepoint analysis was used to determine periods with significant changes in NO2 air concentration and emissions time-series data. Current annual average NO2 levels in Canada range between 1.16 and 14.96 ppb, with the national average being 8.43 ppb. Provincially, average NO2 ranges between 3.77 and 9.25 ppb, with Ontario and British Columbia having the highest ambient levels of NO2. Long-term tend analysis indicated that the annual average NO2 air concentration decreased significantly at 87% of the stations (55 of 63), and decreased non-significantly at 10% (5 of 63) during the period 1998-2013. Concentrations increased (non-significantly) at only 3% (2 of 63) of the sites. Quarterly long-term trends showed similar results; significant decreases occurred at 84% (January-March), 88% (April-June), 83% (July-September), and 81% (October-December) of the sites. Declines in transportation emissions had the most influence on NO2 air

  1. Atmospheric Nitrogen Deposition to the Oceans: Observation- and Model-Based Estimates

    Science.gov (United States)

    Baker, Alex

    2016-04-01

    The reactive nitrogen (Nr) burden of the atmosphere has been increased by a factor of 3-4 by anthropogenic activity since the Industrial Revolution. This has led to large increases in the deposition of nitrate and ammonium to the surface waters of the open ocean, particularly downwind of major human population centres, such as those in North America, Europe and Southeast Asia. In oligotrophic waters, this deposition has the potential to significantly impact marine productivity and the global carbon cycle. Global-scale understanding of N deposition to the oceans is reliant on our ability to produce effective models of reactive nitrogen emission, atmospheric chemistry, transport and deposition (including deposition to the land surface). Over land, N deposition models can be assessed using comparisons to regional monitoring networks of precipitation chemistry (notably those located in North America, Europe and Southeast Asia). No similar datasets exist which would allow observation - model comparisons of wet deposition for the open oceans, because long-term wet deposition records are available for only a handful of remote island sites and rain collection over the open ocean itself is logistically very difficult. In this work we attempt instead to use ~2800 observations of aerosol nitrate and ammonium concentrations, acquired from sampling aboard ships in the period 1995 - 2012, to assess the performance of modelled N deposition fields over the remote ocean. This database is non-uniformly distributed in time and space. We selected three ocean regions (the eastern tropical North Atlantic, the northern Indian Ocean and northwest Pacific) where we considered the density and distribution of observational data is sufficient to provide effective comparison to the model ensemble. Our presentation will focus on the eastern tropical North Atlantic region, which has the best data coverage of the three. We will compare dry deposition fluxes calculated from the observed nitrate

  2. Effects of stepwise nitrogen depletion on carotenoid content, fluorescence parameters and the cellular stoichiometry of Chlorella vulgaris

    Science.gov (United States)

    Zhang, Ping; Li, Zhe; Lu, Lunhui; Xiao, Yan; Liu, Jing; Guo, Jinsong; Fang, Fang

    2017-06-01

    Stressful conditions can stimulate the accumulation of carotenoids in some microalgae. To obtain more knowledge of the stress response, we studied the effects of different N concentrations on unicellular content of carotenoids using Raman spectroscopic technique; cellular stoichiometric changes and the fluorescence parameters of Chlorella vulgaris were concomitantly studied. Initially, we optimized the Raman scattering conditions and demonstrated the feasibility of unicellular carotenoid analysis by Raman spectroscopic technique. The results showed that an integration time of 10 s, laser power at 0.1 mW and an accumulation time of 1 were the optimum conditions, and the peak height at 1523 cm- 1 scaled linearly with the carotenoid content in the range of 0.625-1440 mg/L with a recovery rate of 97% 103%. In the experiment, seven different nitrogen levels ranging from 0 to 2.48 × 105 μg/L were imposed. Samples were taken at the start, exponential phase and end of the experiment. The results showed that nitrogen stress can facilitate the synthesis of carotenoids, while at the same time, excessive nitrogen stress led to lower proliferative and photosynthetic activity. Compared with carotenoids, chlorophylls were more sensitive to nitrogen stress; it declined dramatically as stress processed. There existed no significant differences for Fv/Fm among different nitrogen levels during the exponential phase, while in the end, it declined and a significant difference appeared between cells in 2.48 × 105 μg/L N and other experimental levels. Photosynthetic efficiency, namely the C/N mole ratio in algal cells, didnot significantly change during the exponential phase; however, apparent increases ultimately occurred, except for the stable C/N in BG11 medium. This increase matched well with the carotenoid decline, indicating that an increasing cellular C/N mole ratio can be used as an indicator of excessive stress in carotenoid production. Besides, there also existed an inverse

  3. Analysis of nitrogen-based explosives with desorption atmospheric pressure photoionization mass spectrometry.

    Science.gov (United States)

    Kauppila, T J; Flink, A; Pukkila, J; Ketola, R A

    2016-02-28

    Fast methods that allow the in situ analysis of explosives from a variety of surfaces are needed in crime scene investigations and home-land security. Here, the feasibility of the ambient mass spectrometry technique desorption atmospheric pressure photoionization (DAPPI) in the analysis of the most common nitrogen-based explosives is studied. DAPPI and desorption electrospray ionization (DESI) were compared in the direct analysis of trinitrotoluene (TNT), trinitrophenol (picric acid), octogen (HMX), cyclonite (RDX), pentaerythritol tetranitrate (PETN), and nitroglycerin (NG). The effect of different additives in DAPPI dopant and in DESI spray solvent on the ionization efficiency was tested, as well as the suitability of DAPPI to detect explosives from a variety of surfaces. The analytes showed ions only in negative ion mode. With negative DAPPI, TNT and picric acid formed deprotonated molecules with all dopant systems, while RDX, HMX, PETN and NG were ionized by adduct formation. The formation of adducts was enhanced by addition of chloroform, formic acid, acetic acid or nitric acid to the DAPPI dopant. DAPPI was more sensitive than DESI for TNT, while DESI was more sensitive for HMX and picric acid. DAPPI could become an important method for the direct analysis of nitroaromatics from a variety of surfaces. For compounds that are thermally labile, or that have very low vapor pressure, however, DESI is better suited. Copyright © 2016 John Wiley & Sons, Ltd.

  4. The effects of atmospheric nitrogen deposition on terrestrial and freshwater biodiversity

    Science.gov (United States)

    Baron, Jill S.; Barber, Mary C.; Adams, Mark; Agboola, Julius I.; Allen, Edith B.; Bealey, William J.; Bobbink, Roland; Bobrovsky, Maxim V.; Bowman, William D.; Branquinho, Cristina; Bustamente, Mercedes M. C.; Clark, Christopher M.; Cocking, Edward C.; Cruz, Cristina; Davidson, Eric A.; Denmead, O. Tom; Dias, Teresa; Dise, Nancy B.; Feest, Alan; Galloway, James N.; Geiser, Linda H.; Gilliam, Frank S.; Harrison, Ian J.; Khanina, Larisa G.; Lu, Xiankai; Manrique, Esteban; Ochoa-Hueso, Raul; Ometto, Jean P. H. B.; Payne, Richard; Scheuschner, Thomas; Sheppard, Lucy J.; Simpson, Gavin L.; Singh, Y. V.; Stevens, Carly J.; Strachan, Ian; Sverdrup, Harald; Tokuchi, Naoko; van Dobben, Hans; Woodin, Sarah

    2014-01-01

    This chapter reports the findings of a Working Group on how atmospheric nitrogen (N) deposition affects both terrestrial and freshwater biodiversity. Regional and global scale impacts on biodiversity are addressed, together with potential indicators. Key conclusions are that: the rates of loss in biodiversity are greatest at the lowest and initial stages of N deposition increase; changes in species compositions are related to the relative amounts of N, carbon (C) and phosphorus (P) in the plant soil system; enhanced N inputs have implications for C cycling; N deposition is known to be having adverse effects on European and North American vegetation composition; very little is known about tropical ecosystem responses, while tropical ecosystems are major biodiversity hotspots and are increasingly recipients of very high N deposition rates; N deposition alters forest fungi and mycorrhyzal relations with plants; the rapid response of forest fungi and arthropods makes them good indicators of change; predictive tools (models) that address ecosystem scale processes are necessary to address complex drivers and responses, including the integration of N deposition, climate change and land use effects; criteria can be identified for projecting sensitivity of terrestrial and aquatic ecosystems to N deposition. Future research and policy-relevant recommendations are identified.

  5. Dark hydrogen production in nitrogen atmosphere - An approach for sustainability by marine cyanobacterium Leptolyngbya valderiana BDU 20041

    Energy Technology Data Exchange (ETDEWEB)

    Prabaharan, D.; Arun Kumar, D.; Uma, L.; Subramanian, G. [National Facility for Marine Cyanobacteria (Sponsored by DBT, Govt. of India), Department of Marine Biotechnology, Bharathidasan University, Tiruchirapalli 620 024 (India)

    2010-10-15

    Biological hydrogen production is an ideal system for three main reasons i) forms a renewable energy source, ii) gives clean fuel and iii) serves as a good supplement to oil reserves. The major challenges faced in biological hydrogen production are the presence of uptake hydrogenase and lack of sustainability in the cyanobacterial hydrogen production system. Three different marine cyanobacterial species viz. Leptolyngbya valderiana BDU 20041, Dichothrix baueriana BDU 40481 and Nostoc calcicola BDU 40302 were studied for their potential use in hydrogen production. Among these, L. valderiana BDU 20041, was found to produce hydrogen even in 100% nitrogen atmosphere which was 85% of the hydrogen produced in argon atmosphere. This is the first report of such a high rate of production of hydrogen in a nitrogen atmosphere by a cyanobacterium, which makes it possible to develop sustained hydrogen production systems. L. valderiana BDU 20041, a dark hydrogen producer uses the reductant essentially supplied by the respiratory pathway for hydrogen production. Using inhibitors, this organism was found to produce hydrogen due to the activities of both nitrogenase and bidirectional hydrogenase, while it had no 'uptake' hydrogenase activity. The other two organisms though had low levels of bidirectional hydrogenase, possessed considerable 'uptake' hydrogenase activity and hence could not release much hydrogen either in argon or nitrogen atmosphere. (author)

  6. Atmospheric NO2: in situ laser-induced fluorescence detection atparts per trillion mixing ratios

    Energy Technology Data Exchange (ETDEWEB)

    Thornton, Joel A.; Wooldridge, Paul J.; Cohen, Ronald C.

    1999-08-04

    NO2 affects the abundance of O3 and OH throughout theatmosphere, exerting influence over stratospheric ozone, on the oxidativecapacity of the atmosphere, on the greenhouse effect, on production oforganic and inorganic aerosol, and on production of photochemical smog.In the troposphere, NO2 mixing ratios vary from 100s of parts per billion(ppb) in cities to below 10 parts per trillion (ppt) in remote locations.We describe a laser-induced fluorescence instrument designed for accurate(+-5 percent, 1s), continuous, autonomous, in situ observations of NO2with the sensitivity (15 ppt/10 secat S/N=2) and portability necessary tostudy NO2 anywhere in the troposphere. The technique is advantageousbecause it is spectroscopically specific and direct in that it does notrequire conversion of NO2 into another species (e.g., NO) prior todetection eliminating a class of potential interferences. Performance ofthe instrument is illustrated with 15 weeks (July-Oct 1998) ofobservations at the University of California, Blodgett Forest fieldstation located in the foothills of the Sierra Nevada and 4 weeks (June15-July 15, 1999) in Nashville, TN during the Southern Oxidants Study.Ambient concentrations of NO2 at Blodgett Forest varied from below 50 pptto 4000 ppt and NO2 ranged from 5 to 50 percent of total reactivenitrogen, while in Nashville, TN concentrations ranged from 1 ppb to 75ppb.

  7. Characterization of aerosol in the atmosphere at Syowa Station by X-ray fluorescence spectrometry (XRF

    Directory of Open Access Journals (Sweden)

    Tomoki Aoyama

    2010-12-01

    Full Text Available The particle size distribution has been continuously measured by optical particle counter at Syowa Station. Physical and chemical properties of particulate matter have been analyzed in the laboratory after arriving in Japan. However, the properties of particles may be changed in this case. In the present work, the atmospheric particulate matter at Syowa Station, Antarctica was characterized by X-ray fluorescence spectroscopy (XRF at Syowa Station. The advantages of this method have non destructive, rapid and simple analysis. The particle samples were collected on a Teflon filter; the obtained particles were measured by XRF (HORIBA, X-ray Analytical Microscope XGT-5000 on site soon for elemental analysis. The obtained results show that collected particles mainly contain sea salt (Na, Mg, Cl, K, Ca and soil (Si, Fe origin components. The particles from sea salt and soil origin increased under blizzard and strong wind condition. Sulfur increased in summer, and decreased in winter while particles from sea salt decreased in summer.

  8. Nitrogen cycling in the suboxic Arabian Sea: Implications for atmospheric chemistry and climate

    Digital Repository Service at National Institute of Oceanography (India)

    Naqvi, S.W.A.

    . This reinforces the view that the ocean oscillates between a net source and a net sink of combined nitrogen on geological time scales and that the resultant changes in the combined nitrogen on geological time and that the resultant changes in the combined nitrogen...

  9. Using nitrogen concentration and isotopic composition in lichens to spatially assess the relative contribution of atmospheric nitrogen sources in complex landscapes.

    Science.gov (United States)

    Pinho, P; Barros, C; Augusto, S; Pereira, M J; Máguas, C; Branquinho, C

    2017-11-01

    Reactive nitrogen (Nr) is an important driver of global change, causing alterations in ecosystem biodiversity and functionality. Environmental assessments require monitoring the emission and deposition of both the amount and types of Nr. This is especially important in heterogeneous landscapes, as different land-cover types emit particular forms of Nr to the atmosphere, which can impact ecosystems distinctively. Such assessments require high spatial resolution maps that also integrate temporal variations, and can only be feasibly achieved by using ecological indicators. Our aim was to rank land-cover types according to the amount and form of emitted atmospheric Nr in a complex landscape with multiple sources of N. To do so, we measured and mapped nitrogen concentration and isotopic composition in lichen thalli, which we then related to land-cover data. Results suggested that, at the landscape scale, intensive agriculture and urban areas were the most important sources of Nr to the atmosphere. Additionally, the ocean greatly influences Nr in land, by providing air with low Nr concentration and a unique isotopic composition. These results have important consequences for managing air pollution at the regional level, as they provide critical information for modeling Nr emission and deposition across regional as well as continental scales. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Precise measurement of the absolute fluorescence yield of nitrogen in air. Consequences on the detection of ultra-high energy cosmic rays; Mesure precise du rendement absolu de la fluorescence de l'azote dans l'air. Consequences sur la detection des rayons cosmiques d'ultra-haute energie

    Energy Technology Data Exchange (ETDEWEB)

    Lefeuvre, G

    2006-07-15

    The study of the energy spectrum of ultra-high energy cosmic rays (E > 10{sup 20} eV) requires to determine the energy with much more precision than what is currently achieved. The shower of particles created in the atmosphere can be detected either by sampling particle on the ground, or by detecting the fluorescence induced by the excitation of nitrogen by shower electrons. At present, the measurement of the fluorescence is the simplest and the most reliable method, since it does not call upon hadronic physics laws at extreme energies, a field still inaccessible to accelerators. The precise knowledge of the conversion factor between deposited energy and the number of fluorescence photons produced (the yield) is thus essential. Up to now, it has been determined with an accuracy of 15 % only. This main goal of this work is to measure this yield to better than 5 per cent. To do this, 1 MeV electrons from a radioactive source excite nitrogen of the air. The accuracy has been reached thanks to the implementation of a new method for the absolute calibration of the photomultipliers detecting the photons, to better than 2 per cent. The fluorescence yield, measured and normalized to 0.85 MeV, 760 mmHg and 15 Celsius degrees, is (4.23 {+-} 0.20) photons per meter, or (20.46 {+-} 0.98) photons per deposited MeV. In addition, and for the first time, the absolute fluorescence spectrum of nitrogen excited by a source has been measured with an optical grating spectrometer. (author)

  11. Chemical redox modulated fluorescence of nitrogen-doped graphene quantum dots for probing the activity of alkaline phosphatase.

    Science.gov (United States)

    Liu, JingJing; Tang, Duosi; Chen, Zhitao; Yan, Xiaomei; Zhong, Zhou; Kang, Longtian; Yao, Jiannian

    2017-08-15

    Alkaline phosphatase (ALP) as an essential enzyme plays an important role in clinical diagnoses and biomedical researches. Hence, the development of convenient and sensitivity assay for monitoring ALP is extremely important. In this work, on the basis of chemical redox strategy to modulate the fluorescence of nitrogen-doped graphene quantum dots (NGQDs), a novel label-free fluorescent sensing system for the detection of alkaline phosphatase (ALP) activity has been developed. The fluorescence of NGQDs is firstly quenched by ultrathin cobalt oxyhydroxide (CoOOH) nanosheets, and then restored by ascorbic acid (AA), which can reduce CoOOH to Co2+, thus the ALP can be monitored based on the enzymatic hydrolysis of L-ascorbic acid-2-phosphate (AAP) by ALP to generate AA. Quantitative evaluation of ALP activity in a range from 0.1 to 5U/L with the detection limit of 0.07U/L can be realized in this sensing system. Endowed with high sensitivity and selectivity, the proposed assay is capable of detecting ALP in biological system with satisfactory results. Meanwhile, this sensing system can be easily extended to the detection of various AA-involved analytes. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. The Relationship between Nitrogen Dioxide Concentrations in the Atmosphere Measured by the Sodium Arsenite Method and the Chemiluminescence Method

    Directory of Open Access Journals (Sweden)

    Sivapan Choo-in

    2015-01-01

    Full Text Available The relationship between the nitrogen dioxide concentration measured by the Sodium Arsenite method and the Chemiluminescence method, aimed at developing a device for measuring nitrogen dioxide in the atmosphere by means of the Sodium Arsenite method and studying the correlation between the concentration of nitrogen dioxide in the atmosphere which was measured by Sodium Arsenite method and the Chemiluminescense method done by the Pollution Control Department, Thailand. In this research sampling collection of nitrogen dioxide concentration in various conditions by the Sodium Arsenite method was compared with that by the Chemiluminescence method done by the pollution control Department at the Air Quality Measurement Station at the Din Dang district, Bangkok. It was done by one-hour average value totaling of thirty data. The research result found that the sampling collection with the flowing rate of 160 ml/min and the absorption reagent with mixture of 0.2 M sodium hydroxide and 0.015 M sodium arsenite had the highest relationship to the measurement result done by the Pollution Control Department at a statistical significance level of 0.05 with the value of correlation coefficient at 0.658 which had a high relation.

  13. A Long-term Forest Fertilization Experiment to Understand Ecosystem Responses to Atmospheric Nitrogen Deposition

    Science.gov (United States)

    Baron, J.; Advani, S. M.; Allen, J.; Boot, C.; Denef, K.; Denning, S.; Hall, E.; Moore, J. C.; Reuth, H.; Ryan, M. G.; Shaw, E.

    2016-12-01

    Long-term field experiments can reveal changes in ecosystem processes that may not be evident in short-term studies. Short-term measurements or experiments may have narrower objectives or unrealistic treatments in order to see a change, whereas long-term studies can reveal complex interactions that take longer to manifest. We report results from a long-term experiment (1996 to present) in subalpine forests to simulate the consequences of sustained atmospheric nitrogen (N) deposition. Loch Vale watershed in Rocky Mountain National Park, the location of the experiment, has received an order of magnitude greater atmospheric N deposition than estimated background since mid-20th Century. Augmenting that, in 1996 we began adding 25 kg NH4NO3 ha-1 yr-1 to three 30m x 30m old-growth Engelmann spruce and subalpine fir plots. Treated stands were matched by nearby controls. N addition caused rapid leaching of nitrate and cations from soils, and increased N mineralization and nitrification rates. These observations in the fertilized plots have been sustained over time. Soluble aluminum concentrations do not differ significantly between fertilized and control plots, but treated soils are now markedly more acidic (pH of 4.7) than original soil and controls (pH of 5.1); further acidification might increase aluminum leaching. Effects on soil carbon were complex, mediated by reductions in total microbial biomass, decreases in arbuscular mychorrizal and saprotropic fungi, and increased potential rates of N enzyme degrading activities. Initial soil C:N of 24 was lower than similar soils in low N deposition stands (C:N of 36). The C:N declined to 22 with treatment. Fertilized plots lost 11% soil C, but the mechanism is unclear. We did not measure changes in C inputs from litter, microbial biomass, or plant uptake, but there was no change in summer CO2 flux, measured in 2003, 2004, and 2014. Leaching of DOC from fertilized plots was elevated throughout the experiment, providing one

  14. Langmuir probe diagnostics of an atmospheric pressure, vortex-stabilized nitrogen plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Prevosto, L.; Mancinelli, B. R. [Grupo de Descargas Electricas, Departamento Ingenieria Electromecanica, Facultad Regional Venado Tuerto (UTN), Laprida 651, (2600) Venado Tuerto, Santa Fe (Argentina); Kelly, H. [Grupo de Descargas Electricas, Departamento Ingenieria Electromecanica, Facultad Regional Venado Tuerto (UTN), Laprida 651, (2600) Venado Tuerto, Santa Fe (Argentina) and Instituto de Fisica del Plasma (CONICET), Departamento de Fisica, Facultad de Ciencias Exactas y Naturales UBA Ciudad Universitaria Pab. I, (1428) Buenos Aires (Argentina)

    2012-09-15

    Langmuir probe measurements in an atmospheric pressure direct current (dc) plasma jet are reported. Sweeping probes were used. The experiment was carried out using a dc non-transferred arc torch with a rod-type cathode and an anode of 5 mm diameter. The torch was operated at a nominal power level of 15 kW with a nitrogen flow rate of 25 Nl min{sup -1}. A flat ion saturation region was found in the current-voltage curve of the probe. The ion saturation current to a cylindrical probe in a high-pressure non local thermal equilibrium (LTE) plasma was modeled. Thermal effects and ionization/recombination processes inside the probe perturbed region were taken into account. Averaged radial profiles of the electron and heavy particle temperatures as well as the electron density were obtained. An electron temperature around 11 000 K, a heavy particle temperature around 9500 K and an electron density of about 4 Multiplication-Sign 10{sup 22} m{sup -3}, were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found throughout the plasma jet. The electron and heavy particle temperature profiles showed good agreement with those reported in the literature by using spectroscopic techniques. It was also found that the temperature radial profile based on LTE was very close to that of the electrons. The calculations have shown that this method is particularly useful for studying spraying-type plasma jets characterized by electron temperatures in the range 9000-14 000 K.

  15. Acclimation of nitrogen uptake capacity of rice to elevated atmospheric CO2 concentration

    Science.gov (United States)

    Shimono, Hiroyuki; Bunce, James A.

    2009-01-01

    Background and Aims Nitrogen (N) is a major factor affecting yield gain of crops under elevated atmospheric carbon dioxide concentrations [CO2]. It is well established that elevated [CO2] increases root mass, but there are inconsistent reports on the effects on N uptake capacity per root mass. In the present study, it was hypothesized that the responses of N uptake capacity would change with the duration of exposure to elevated [CO2]. Methods The hypothesis was tested by measuring N uptake capacity in rice plants exposed to long-term and short-term [CO2] treatments at different growth stages in plants grown under non-limiting N conditions in hydroponic culture. Seasonal changes in photosynthesis rate and transpiration rate were also measured. Key Results In the long-term [CO2] study, leaf photosynthetic responses to intercellular CO2 concentration (Ci) were not affected by elevated [CO2] before the heading stage, but the initial slope in this response was decreased by elevated [CO2] at the grain-filling stage. Nitrate and ammonium uptake capacities per root dry weight were not affected by elevated [CO2] at panicle initiation, but thereafter they were reduced by elevated [CO2] by 31–41 % at the full heading and mid-ripening growth stages. In the short-term study (24 h exposures), elevated [CO2] enhanced nitrate and ammonium uptake capacities at the early vegetative growth stage, but elevated [CO2] decreased the uptake capacities at the mid-reproductive stage. Conclusions This study showed that N uptake capacity was downregulated under long-term exposure to elevated [CO2] and its response to elevated [CO2] varied greatly with growth stage. PMID:18952623

  16. Observations of atmospheric nitrogen and phosphorus deposition during the period of algal bloom formation in northern Lake Taihu, China.

    Science.gov (United States)

    Zhai, Shuijing; Yang, Longyuan; Hu, Weiping

    2009-09-01

    Cyanobacterial blooms in Lake Taihu occurred at the end of April 2007 and had crucial impacts on the livelihood of millions of people living there. Excessive nutrients may promote bloom formation. Atmospheric nitrogen (N) and phosphorus (P) deposition appears to play an important role in algal bloom formation. Bulk deposition and rain water samples were collected respectively from May 1 to November 30, 2007, the period of optimal algal growth, to measure the bulk atmospheric deposition rate, wet deposition rate, and dry deposition rate for total nitrogen (TN; i.e., all species of nitrogen), and total phosphorus (TP; i.e., all species of phosphorus), in northern Lake Taihu, China. The trends of the bulk atmospheric deposition rate for TN and the wet deposition rate for TN showed double peaks during the observation period and distinct influence with plum rains and typhoons. Meanwhile, monthly bulk atmospheric deposition rates for TP showed little influence of annual precipitation. However, excessive rain may lead to high atmospheric N and P deposition rates. In bulk deposition samples, the average percentage of total dissolved nitrogen accounting for TN was 91.2% and changed little with time. However, the average percentage of total dissolved phosphorus accounting for TP was 65.6% and changed substantially with time. Annual bulk atmospheric deposition rates of TN and TP during 2007 in Lake Taihu were estimated to be 2,976 and 84 kg km(-2) a(-1), respectively. The results showed decreases of 34.4% and 78.7%, respectively, compared to 2002-2003. Annual bulk deposition load of TN for Lake Taihu was estimated at 6,958 t a(-1) in 2007 including 4,642 t a(-1) of wet deposition, lower than the values obtained in 2002-2003. This may be due to measures taken to save energy and emission control regulations in the Yangtze River Delta. Nevertheless, high atmospheric N and P deposition loads helped support cyanobacterial blooms in northern Lake Taihu during summer and autumn, the

  17. Temporal characteristics of atmospheric ammonia and nitrogen dioxide over China based on emission data, satellite observations and atmospheric transport modeling since 1980

    Science.gov (United States)

    Liu, Lei; Zhang, Xiuying; Xu, Wen; Liu, Xuejun; Li, Yi; Lu, Xuehe; Zhang, Yuehan; Zhang, Wuting

    2017-08-01

    China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen (Nr). Atmospheric ammonia (NH3) and nitrogen dioxide (NO2) are the most important precursors for Nr compounds (including N2O5, HNO3, HONO and particulate NO3- and NH4+) in the atmosphere. Understanding the changes in NH3 and NO2 has important implications for the regulation of anthropogenic Nr emissions and is a requirement for assessing the consequence of environmental impacts. We conducted the temporal trend analysis of atmospheric NH3 and NO2 on a national scale since 1980 based on emission data (during 1980-2010), satellite observation (for NH3 since 2008 and for NO2 since 2005) and atmospheric chemistry transport modeling (during 2008-2015).Based on the emission data, during 1980-2010, significant continuous increasing trends in both NH3 and NOx were observed in REAS (Regional Emission inventory in Asia, for NH3 0.17 and for NOx 0.16 kg N ha-1 yr-2) and EDGAR (Emissions Database for Global Atmospheric Research, for NH3 0.24 and for NOx 0.17 kg N ha-1 yr-2) over China. Based on the satellite data and atmospheric chemistry transport model (CTM) MOZART-4 (Model for Ozone and Related chemical Tracers, version 4), the NO2 columns over China increased significantly from 2005 to 2011 and then decreased significantly from 2011 to 2015; the satellite-retrieved NH3 columns from 2008 to 2014 increased at a rate of 2.37 % yr-1. The decrease in NO2 columns since 2011 may result from more stringent strategies taken to control NOx emissions during the 12th Five Year Plan, while no control policy has focused on NH3 emissions. Our findings provided an overall insight into the temporal trends of both NO2 and NH3 since 1980 based on emission data, satellite observations and atmospheric transport modeling. These findings can provide a scientific background for policy makers that are attempting to control atmospheric pollution in China. Moreover, the multiple datasets

  18. Temporal characteristics of atmospheric ammonia and nitrogen dioxide over China based on emission data, satellite observations and atmospheric transport modeling since 1980

    Directory of Open Access Journals (Sweden)

    L. Liu

    2017-08-01

    Full Text Available China is experiencing intense air pollution caused in large part by anthropogenic emissions of reactive nitrogen (Nr. Atmospheric ammonia (NH3 and nitrogen dioxide (NO2 are the most important precursors for Nr compounds (including N2O5, HNO3, HONO and particulate NO3− and NH4+ in the atmosphere. Understanding the changes in NH3 and NO2 has important implications for the regulation of anthropogenic Nr emissions and is a requirement for assessing the consequence of environmental impacts. We conducted the temporal trend analysis of atmospheric NH3 and NO2 on a national scale since 1980 based on emission data (during 1980–2010, satellite observation (for NH3 since 2008 and for NO2 since 2005 and atmospheric chemistry transport modeling (during 2008–2015.Based on the emission data, during 1980–2010, significant continuous increasing trends in both NH3 and NOx were observed in REAS (Regional Emission inventory in Asia, for NH3 0.17 and for NOx 0.16 kg N ha−1 yr−2 and EDGAR (Emissions Database for Global Atmospheric Research, for NH3 0.24 and for NOx 0.17 kg N ha−1 yr−2 over China. Based on the satellite data and atmospheric chemistry transport model (CTM MOZART-4 (Model for Ozone and Related chemical Tracers, version 4, the NO2 columns over China increased significantly from 2005 to 2011 and then decreased significantly from 2011 to 2015; the satellite-retrieved NH3 columns from 2008 to 2014 increased at a rate of 2.37 % yr−1. The decrease in NO2 columns since 2011 may result from more stringent strategies taken to control NOx emissions during the 12th Five Year Plan, while no control policy has focused on NH3 emissions. Our findings provided an overall insight into the temporal trends of both NO2 and NH3 since 1980 based on emission data, satellite observations and atmospheric transport modeling. These findings can provide a scientific background for policy makers that are attempting to control atmospheric

  19. Intrinsic gettering of Czochralski silicon annealed in argon and nitrogen atmosphere

    Science.gov (United States)

    Shui, Qiong; Yang, Deren; Li, Liben; Pi, Xiaodong; Que, Duanlin

    2001-12-01

    The intrinsic gettering of nitrogen-doped Czochralski (NCZ) and nitrogen-undoped Czochralski (CZ) silicon annealed in argon and nitrogen ambient has been investigated by three-step annealing. It is found that the threshold oxygen concentration for effective precipitation is about 4.8×10 17 cm -3 at 1150°C. No difference of the denuded zone (DZ) width between the NCZ and CZ silicon samples was found when they were annealed in argon ambient. However, a few of small etching pits occurred in the DZ region for both of NCZ and CZ silicon samples. It is suggested that nitrogen could diffuse into the DZ region and form N-O complexes as heterogeneous nuclei, which can enhance oxygen precipitates, when the samples were annealed in nitrogen ambient.

  20. Attributes for NHDPlus Catchments (Version 1.1) for the Conterminous United States: Normalized Atmospheric Deposition for 2002, Total Inorganic Nitrogen

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This data set represents the average normalized atmospheric (wet) deposition, in kilograms, of Total Inorganic Nitrogen for the year 2002 compiled for every...

  1. [Effects of elevated atmospheric CO2 concentration on mung bean leaf photosynthesis and chlorophyll fluorescence parameters].

    Science.gov (United States)

    Hao, Xing-yu; Han, Xue; Li, Ping; Yang, Hong-bin; Lin, Er-da

    2011-10-01

    By using free air CO2 enrichment (FACE) system, a pot experiment under field condition was conducted to study the effects of elevated CO2 concentration (550 +/- 60 micromol mol(-1)) on the leaf photosynthesis and chlorophyll fluorescence parameters of mung bean. Comparing with the control (CO2 concentration averagely 389 +/- 40 micromol mol(-1)), elevated CO2 concentration increased the leaf intercellular CO2 concentration (Ci) and net photosynthesis rate (P(n)) at flowering and pod growth stage by 9.8% and 11.7%, decreased the stomatic conductance (G(s)) and transpiration rate (T(r)) by 32.0% and 24.6%, respectively, and increased the water use efficiency (WUE) by 83.5%. Elevated CO2 concentration had lesser effects on the minimal fluorescence (F0), maximal fluorescence (F(m)), variable fluorescence (F(v)), ratio of variable fluorescence to minimal fluorescence (F(v)/F0), and ratio of variable fluorescence to maximal fluorescence (F(v)/F(m)) at bud stage, but increased the F0 at pod filling stage by 19.1% and decreased the Fm, F(v), F(v)/F0, and F(v)/F(m) by 9.0%, 14.3%, 25.8% , and 6.2%, respectively. These results suggested that elevated CO2 concentration could damage the structure of leaf photosystem II and consequently decrease the leaf photosynthetic capacity in the late growth phase of mung bean.

  2. Elevated atmospheric CO2 and increased nitrogen deposition : effects on C and N metabolism and growth of the peat moss Sphagnum recurvum P. Beauv. var. mucronatum (Russ.) Warnst

    NARCIS (Netherlands)

    van der Heijden, E; Verbeek, S.K.; Kuiper, P.J C

    Sphagnum bogs play an important role when considering the impacts of global change on global carbon and nitrogen cycles. Sphagnum recurvum P. Beauv. var. mucronatum (Russ.) was grown at 360 (ambient) and 700 mu L L-1 (elevated) atmospheric [CO2] in combination with different nitrogen deposition

  3. Spatiotemporal patterns of correlation between atmospheric nitrogen dioxide and aerosols over South Asia

    Science.gov (United States)

    ul-Haq, Zia; Tariq, Salman; Ali, Muhammad

    2017-10-01

    An accurate knowledge is needed on the complex relation between atmospheric trace gasses and aerosol variability and their sources to explain trace gases-aerosols-climate interaction and next-generation modeling of climate change and air quality. In this regard, we have used tropospheric Nitrogen Dioxide (NO2), Aerosol Optical Depth (AOD) and Angstrom Exponent (AE) obtained from satellite-based Ozone Monitoring Instrument (OMI)/Aura and Moderate-Resolution Imaging Spectroradiometer (MODIS)/Aqua over South Asia. NO2-AOD correlation with coefficient r = 0.49 is determined over the landmass of South Asia during 2005-2015. Yearly mean NO2-AOD correlation over South Asia shows large variations ranging from r = 0.32 to 0.86 in 2008 and 2009, respectively. The highest correlation ( r = 0.66) is seen over eastern regions of Bangladesh and India, as well as adjoining areas of western Myanmar mostly linked to anthropogenic activities. A significant correlation ( r = 0.59) associated with natural causes is found over some parts of Sistan region, located at the borders of Iran, Pakistan and Afghanistan, and adjoining territory. We find significant positive correlations for monsoon and post-monsoon seasons with r = 0.50 and r = 0.61, respectively. A linear regression on the annual correlation coefficients data suggests that NO2-AOD correlation is strengthening with an increase of 12.9% over South Asia during the study period. The spatial distribution of data slopes reveals positive trends in NO2-AOD correlation over megacities Lahore, Dhaka, Mumbai and Kolkata linked to growing anthropogenic activities. Singrauli city (India) has the highest correlation ( r = 0.62) and 35% increase in correlation coefficient value per year. A negative correlation is observed for megacity Karachi ( r = -0.37) suggesting the non-commonality of NO2 and aerosols emission sources. AE has also been used to discuss its correlation with NO2 over the areas with dominance of fine-mode aerosols.

  4. Atmospheric wet deposition of sulfur and nitrogen in Jiuzhaigou National Nature Reserve, Sichuan Province, China.

    Science.gov (United States)

    Qiao, Xue; Xiao, Weiyang; Jaffe, Daniel; Kota, Sri Harsha; Ying, Qi; Tang, Ya

    2015-04-01

    In the last two decades, remarkable ecological changes have been observed in Jiuzhaigou National Nature Reserve (JNNR). Some of these changes might be related to excessive deposition of sulfur (S) and nitrogen (N), but the relationship has not been quantified due to lack of monitoring data, particularly S and N deposition data. In this study, we investigated the concentrations, fluxes, and sources of S and N wet deposition in JNNR from April 2010 to May 2011. The results show that SO4(2-), NO3-, and NH4+ concentrations in the wet deposition were 39.4-170.5, 6.2-34.8, and 0.2-61.2 μeq L(-1), with annual Volume-Weighted Mean (VWM) concentrations of 70.5, 12.7, and 13.4 μeq L(-1), respectively. Annual wet deposition fluxes of SO4(2-), NO3-, and NH4+ were 8.06, 1.29, and 1.39 kg S(N)ha(-1), respectively, accounting for about 90% of annual atmospheric inputs of these species at the monitoring site. The results of Positive Matrix Factorization (PMF) analysis show that fossil fuel combustion, agriculture, and aged sea salt contributed to 99% and 83% of annual wet deposition fluxes of SO4(2-) and NO3-, respectively. Agriculture alone contributed to 89% of annual wet deposition flux of NH4+. Although wet deposition in JNNR was polluted by anthropogenic acids, the acidity was largely neutralized by the Ca2+ from crust and 81% of wet deposition samples had a pH higher than 6.00. However, acid rain mainly caused by SO4(2-) continued to occur in the wet season, when ambient alkaline dust concentration was lower. Since anthropogenic emissions have elevated S and N deposition and caused acid rain in JNNR, further studies are needed to better quantify the regional sources and ecological effects of S and N deposition for JNNR. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Nitrogen accumulation and partitioning in a High Arctic tundra ecosystem from extreme atmospheric N deposition events

    Energy Technology Data Exchange (ETDEWEB)

    Choudhary, Sonal, E-mail: S.Choudhary@sheffield.ac.uk [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Management School, University of Sheffield, Conduit Road, Sheffield S10 1FL (United Kingdom); Blaud, Aimeric [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); Osborn, A. Mark [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom); School of Applied Sciences, RMIT University, PO Box 71, Bundoora, VIC 3083 (Australia); Press, Malcolm C. [School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Manchester Metropolitan University, Manchester, M15 6BH (United Kingdom); Phoenix, Gareth K. [Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN (United Kingdom)

    2016-06-01

    Arctic ecosystems are threatened by pollution from recently detected extreme atmospheric nitrogen (N) deposition events in which up to 90% of the annual N deposition can occur in just a few days. We undertook the first assessment of the fate of N from extreme deposition in High Arctic tundra and are presenting the results from the whole ecosystem {sup 15}N labelling experiment. In 2010, we simulated N depositions at rates of 0, 0.04, 0.4 and 1.2 g N m{sup −2} yr{sup −1}, applied as {sup 15}NH{sub 4}{sup 15}NO{sub 3} in Svalbard (79{sup °}N), during the summer. Separate applications of {sup 15}NO{sub 3}{sup −} and {sup 15}NH{sub 4}{sup +} were also made to determine the importance of N form in their retention. More than 95% of the total {sup 15}N applied was recovered after one growing season (~ 90% after two), demonstrating a considerable capacity of Arctic tundra to retain N from these deposition events. Important sinks for the deposited N, regardless of its application rate or form, were non-vascular plants > vascular plants > organic soil > litter > mineral soil, suggesting that non-vascular plants could be the primary component of this ecosystem to undergo measurable changes due to N enrichment from extreme deposition events. Substantial retention of N by soil microbial biomass (70% and 39% of {sup 15}N in organic and mineral horizon, respectively) during the initial partitioning demonstrated their capacity to act as effective buffers for N leaching. Between the two N forms, vascular plants (Salix polaris) in particular showed difference in their N recovery, incorporating four times greater {sup 15}NO{sub 3}{sup −} than {sup 15}NH{sub 4}{sup +}, suggesting deposition rich in nitrate will impact them more. Overall, these findings show that despite the deposition rates being extreme in statistical terms, biologically they do not exceed the capacity of tundra to sequester pollutant N during the growing season. Therefore, current and future extreme events

  6. Sulfur and nitrogen co-doped carbon dots sensors for nitric oxide fluorescence quantification.

    Science.gov (United States)

    Simões, Eliana F C; Leitão, João M M; Esteves da Silva, Joaquim C G

    2017-04-01

    Microwave synthetized sulfur and nitrogen co-doped carbon dots responded selectively to nitric oxide (NO) at pH 7. Citric acid, urea and sodium thiosulfate in the proportion of 1:1:3 were used respectively as carbon, nitrogen and sulfur sources in the carbon dots microwave synthesis. For this synthesis, the three compounds were diluted in 15 mL of water and exposed for 5 min to a microwave radiation of 700 W. It is observed that the main factor contributing to the increased sensitivity and selectivity response to NO at pH 7 is the sodium thiosulfate used as sulfur source. A linear response range from 1 to 25 μM with a sensitivity of 16 μM-1 and a detection limit of 0.3 μM were obtained. The NO quantification capability was assessed in standard and in fortified serum solutions. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Production of TiN thin films by N2-laser-ablated Ti atoms in nitrogen gas atmospheres

    Science.gov (United States)

    Castell, R.; Ruiz, A.; Castell, C.; Suárez, C.

    Laser ablation has proven to be an important technique for thin film deposition because of the high velocity heating and quenching of materials. We have used a nitrogen laser, which is capable of producing nanosecond pulses of intense UV (337.1 nm) radiation to generate high-temperature and high-electron-density plasmas when strongly focused on titanium targets. Laser beam pulses with a peak energy of 32 J/cm2 and a power density of 1.6 GW/cm2 were used in this experiment. As ablated Ti species are allowed to expand further in a nitrogen atmosphere, they cool down and eventually dissipate. In this sequence, they meet a substrate where condensation, nucleation, and growth processes yield TiN thin films because of the reaction with the nitrogen gas. Thin film depositions were made on stainless steel (AISI 1020 and AISI 304) substrates at nitrogen gas pressures ranging from 10-1 Pa to 200 Pa and for different distances between the substrate and the spot where the laser beam was focused upon the target. For rather short distances (less than 7 mm), optical microscopy shows the effect of a further plasma-thin film interaction, while at larger distances, the depositions exhibit a regular film condensation from the vapor. Microstructure characterization of the thin film deposited was done by several techniques. The typical cubic TiN phase was identified by transmission electron microscopy (TEM) and energy dispersion spectroscopy (EDS).

  8. Total atmospheric deposition of reduced nitrogen in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of wet and dry deposition of reduced nitrogen in the Pacific Northwest...

  9. Total atmospheric deposition of oxidized nitrogen in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of wet and dry deposition of oxidized nitrogen in the Pacific...

  10. EnviroAtlas - Atmospheric Nitrogen Deposition by 12-digit HUC for the Conterminous United States (2002)

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset includes annual nitrogen and sulfur deposition within each 12-digit HUC subwatershed for the year 2002. Values are provided for total...

  11. Total atmospheric deposition of oxidized and reduced nitrogen in the United States Pacific Northwest for 2002

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This spatial data set was created by the U.S. Geological Survey (USGS) to represent the amount of wet and dry deposition of oxidized and reduced nitrogen in the...

  12. EnviroAtlas - Atmospheric Nitrogen Deposition by 12-digit HUC for the Conterminous United States (2006)

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset includes annual nitrogen and sulfur deposition within each 12-digit HUC subwatershed for the year 2006. Values are provided for total...

  13. Controlled production of atomic oxygen and nitrogen in a pulsed radio-frequency atmospheric-pressure plasma

    Science.gov (United States)

    Dedrick, J.; Schröter, S.; Niemi, K.; Wijaikhum, A.; Wagenaars, E.; de Oliveira, N.; Nahon, L.; Booth, J. P.; O’Connell, D.; Gans, T.

    2017-11-01

    Radio-frequency driven atmospheric pressure plasmas are efficient sources for the production of reactive species at ambient pressure and close to room temperature. Pulsing the radio-frequency power input provides additional control over species production and gas temperature. Here, we demonstrate the controlled production of highly reactive atomic oxygen and nitrogen in a pulsed radio-frequency (13.56 MHz) atmospheric-pressure plasma, operated with a small 0.1 % air-like admixture (N2 /O2 at 4:1 ) through variations in the duty cycle. Absolute densities of atomic oxygen and nitrogen are determined through vacuum-ultraviolet absorption spectroscopy using the DESIRS beamline at the SOLEIL synchrotron coupled with a high resolution Fourier-transform spectrometer. The neutral-gas temperature is measured using nitrogen molecular optical emission spectroscopy. For a fixed applied-voltage amplitude (234 V), varying the pulse duty cycle from 10% to 100% at a fixed 10 kHz pulse frequency enables us to regulate the densities of atomic oxygen and nitrogen over the ranges of (0.18+/-0.03) –(3.7+/-0.1)× 1020 m-3 and (0.2+/-0.06) –(4.4+/-0.8) × 1019 m-3 , respectively. The corresponding 11 K increase in the neutral-gas temperature with increased duty cycle, up to a maximum of (314+/-4) K, is relatively small. This additional degree of control, achieved through regulation of the pulse duty cycle and time-averaged power, could be of particular interest for prospective biomedical applications.

  14. Downsizing of Georgia Tech's Airborne Fluorescence Spectrometer (AFS) for the Measurement of Nitrogen Oxides

    Science.gov (United States)

    Sandholm, Scott

    1998-01-01

    This report addresses the Tropospheric Trace Gas and Airborne Measurements (TTGAMG) endeavors to further downsize and stabilize the Georgia Institute of Technology's Airborne Laser Induced Fluorescence Experiment (GITALIFE). It will mainly address the TTGAMG successes and failures as participants in the summer 1998 Wallops Island test flights on board the P3-B. Due to the restructuring and reorganization of the TTGAMG since the original funding of this grant, some of the objectives and time lines of the deliverables have been changed. Most of these changes have been covered in the preceding annual report. We are anticipating getting back on track with the original proposal's downsizing effort this summer, culminating in the GITALIFE no longer occupying a high bay rack and the loss of several hundred pounds.

  15. Applying MERLIN for modelling nitrate leaching in a nitrogen saturated Douglas fir forest in the Netherlands after decreased atmospheric nitrogen input

    Directory of Open Access Journals (Sweden)

    A. Tietema

    1998-01-01

    Full Text Available The MERLIN model was applied on the results of a field-scale manipulation experiment with decreased nitrogen (N deposition in an N saturated forest ecosystem in the Netherlands. The aim was to investigate the mechanisms that could explain the observed rapid response of nitrate as a result of the decreased N input. Calibrating the model to pre-treatment data revealed that, despite the high atmospheric N input, the trees relied on N mineralised from refractory organic matter (ROM for their growth. MERLIN could simulate only the fast response of nitrate leaching after decreased input if this ROM mineralisation rate was decreased strongly at the time of the manipulation experiment.

  16. High sensitive and high temporal and spatial resolved image of reactive species in atmospheric pressure surface discharge reactor by laser induced fluorescence

    Science.gov (United States)

    Gao, Liang; Feng, Chun-Lei; Wang, Zhi-Wei; Ding, Hongbin

    2017-05-01

    The current paucity of spatial and temporal characterization of reactive oxygen and nitrogen species (RONS) concentration has been a major hurdle to the advancement and clinical translation of low temperature atmospheric plasmas. In this study, an advanced laser induced fluorescence (LIF) system has been developed to be an effective antibacterial surface discharge reactor for the diagnosis of RONS, where the highest spatial and temporal resolution of the LIF system has been achieved to ˜100 μm scale and ˜20 ns scale, respectively. Measurements on an oxidative OH radical have been carried out as typical RONS for the benchmark of the whole LIF system, where absolute number density calibration has been performed on the basis of the laser Rayleigh scattering method. Requirements for pixel resolved spatial distribution and outer plasma region detection become challenging tasks due to the low RONS concentration (˜ppb level) and strong interference, especially the discharge induced emission and pulsed laser induced stray light. In order to design the highly sensitive LIF system, a self-developed fluorescence telescope, the optimization of high precision synchronization among a tunable pulsed laser, a surface discharge generator, intensified Charge Coupled Device (iCCD) camera, and an oscilloscope have been performed. Moreover, an image BOXCAR approach has been developed to remarkably improve the sensitivity of the whole LIF system by optimizing spatial and temporal gating functions via both hardware and software, which has been integrated into our automatic control and data acquisition system on the LabVIEW platform. In addition, a reciprocation averaging measurement has been applied to verify the accuracy of the whole LIF detecting system, indicating the relative standard deviation of ˜3%.

  17. [Effects of elevated atmospheric CO2 concentration and nitrogen addition on the growth of Calamagrostis angustifolia in Sanjiang Plain freshwater marsh].

    Science.gov (United States)

    Zhao, Guang-Ying; Liu, Jing-Shuang; Wang, Yang

    2011-06-01

    By using open top chamber, an experiment with two levels of atmospheric CO2 concentration (350 and 700 micromol x mol(-1)) and three levels of nitrogen supply (0, 5, and 15 g N x m(-2)) was conducted to investigate the effects of elevated atmospheric CO2 and nitrogen supply on the growth of Calamagrostis angustifolia in the freshwater marsh of Sanjiang Plain. Under elevated atmospheric CO2 concentration, the phenophase of C. angustifolia advanced. Jointing stage was advanced by 1-2 d, and maturity stage was advanced by 3 d. Elevated atmospheric CO2 promoted the tillering of C. angustifolia, with the increment of tiller number under 0, 5, and 15 g x m(-2) of nitrogen supply being 8.2% (P 0.05), respectively. Elevated atmospheric CO2 also promoted the aboveground biomass at jointing and heading stages, the increment being 12.4% and 20.9% (P CO2 concentration depended on nitrogen supply level. Under sufficient nitrogen supply, the promotion effect of elevated atmospheric CO2 concentration on the biomass of C. angustifolia was higher.

  18. Abrupt recent trend changes in atmospheric nitrogen dioxide over the Middle East

    KAUST Repository

    Lelieveld, J.

    2015-08-21

    Nitrogen oxides, released from fossil fuel use and other combustion processes, affect air quality and climate. From the mid-1990s onward, nitrogen dioxide (NO2) has been monitored from space, and since 2004 with relatively high spatial resolution by the Ozone Monitoring Instrument. Strong upward NO2 trends have been observed over South and East Asia and the Middle East, in particular over major cities. We show, however, that a combination of air quality control and political factors, including economical crisis and armed conflict, has drastically altered the emission landscape of nitrogen oxides in the Middle East. Large changes, including trend reversals, have occurred since about 2010 that could not have been predicted and therefore are at odds with emission scenarios used in projections of air pollution and climate change in the early 21st century.

  19. Comparative planetary nitrogen atmospheres: Density and thermal structures of Pluto and Triton

    Science.gov (United States)

    Strobel, Darrell F.; Zhu, Xun

    2017-07-01

    Both atmospheres of Pluto and Neptune's largest satellite Triton have cold surfaces with surface gravitational accelerations and atmospheric surface pressures of comparable magnitude. To study their atmospheres we have updated Zhu et al. (2014) model for Pluto's atmosphere by adopting Voigt line profiles in the radiation module with the latest spectral database and extended the model to Triton's atmosphere by including additional parameterized heating due to the magnetospheric electron transport and energy deposition. The CH4 mixing ratio profiles play central roles in differentiating the atmospheres of Pluto and Triton. On Pluto the surface CH4 mole fraction is in the range of 0.3-0.8%, sufficiently high to ensure that it is well mixed in the lower atmosphere and not subject to photochemical destruction. Near the exobase CH4 attains comparable density to N2 due to gravitational diffusive separation and escapes at 500 times the N2 rate (= 1 × 1023 N2 s-1). In Triton's atmosphere, the surface CH4 mole fraction is on the order of 0.015%, sufficiently low to ensure that it is photochemically destroyed irreversibly in the lower atmosphere and that N2 remains the major species, even at the exobase. With solar EUV power only, Triton's upper thermosphere is too cold and magnetospheric heating, approximately comparable to the solar EUV power, is needed to bring the N2 tangential column number density in the 500-800 km range up to values derived from the Voyager 2 UVS observations (Broadfoot et al., 1989). Due to their cold exobase temperatures relative to the gravitational potential energy wells that N2 resides in, atmospheric escape from Triton and Pluto is not dominated by N2 Jeans escape but by CH4 from Pluto and H, C, N and H2 from Triton. The atmospheric thermal structure near the exobase is sensitive to the atmospheric escape rate only when it is significantly greater than 2 × 1027 amu s-1, above which enhanced Jeans escape and larger radial velocity adiabatically

  20. [Effects of atmospheric CO2 concentration enhancement and nitrogen application rate on wheat grain yield and quality].

    Science.gov (United States)

    Cui, Hao; Shi, Zu-liang; Cai, Jian; Jiang, Dong; Cao, Wei-xing; Dai, Ting-bo

    2011-04-01

    FACE platform was applied to study the effects of elevated atmospheric CO2 concentration on wheat grain yield and quality under two nitrogen (N) application rates. Elevated atmospheric CO2 concentration and applying N increased the grain yield, spike number, grain number per spike, and biomass significantly, but elevated CO2 concentration had no significant effects on harvest index (HI). Under elevated CO2 concentration, there was a significant decrease in the protein, gliadin, gluteinin, and glutein contents of the grain and the sedimentation value of the flour, and a significant increase in the starch and its components contents of the grain; under N application, an inverse was observed. The dough stability time and the dough viscosity characteristics, such as peak viscosity, final viscosity, and setback value, increased significantly under elevated CO2 concentration and high N application rate. The interaction of atmospheric CO2 concentration and N application rate had significantly positive effects on wheat grain yield and biomass, but less effect on grain quality. Therefore, with elevated atmospheric CO2 concentration in the future, maintaining a higher N application level would benefit wheat grain yield and paste characteristics, and mitigate the decline of grain quality.

  1. Sustained effects of atmospheric [CO2] and nitrogen availability on forest soil CO2 efflux

    Science.gov (United States)

    A. Christopher Oishi; Sari Palmroth; Kurt H. Johnsen; Heather R. McCarthy; Ram. Oren

    2014-01-01

    Soil CO2 efflux (Fsoil) is the largest source of carbon from forests and reflects primary productivity as well as how carbon is allocated within forest ecosystems. Through early stages of stand development, both elevated [CO2] and availability of soil nitrogen (N; sum of mineralization, deposition, and fixation) have been shown to increase gross primary productivity,...

  2. Does chronic nitrogen deposition during biomass growth affect atmospheric emissions from biomass burning?

    Science.gov (United States)

    Michael R Giordano; Joey Chong; David R Weise; Akua A Asa-Awuku

    2016-01-01

    Chronic nitrogen deposition has measureable impacts on soil and plant health.We investigate burning emissions from biomass grown in areas of high and low NOx deposition. Gas and aerosolphase emissions were measured as a function of photochemical aging in an environmental chamber at UC-Riverside. Though aerosol chemical speciation was not...

  3. The Solar Photospheric Nitrogen Abundance : Determination with 3D and 1D Model Atmospheres

    NARCIS (Netherlands)

    Maiorca, E.; Caffau, E.; Bonifacio, P.; Busso, M.; Faraggiana, R.; Steffen, M.; Ludwig, H. -G.; Kamp, I.

    2009-01-01

    We present a new determination of the solar nitrogen abundance making use of 3D hydrodynamical modelling of the solar photosphere, which is more physically motivated than traditional static 1D models. We selected suitable atomic spectral lines, relying on equivalent width measurements already

  4. Design and construction of prototype transversely excited atmospheric (TEA nitrogen laser energized by a high voltage electrical discharge

    Directory of Open Access Journals (Sweden)

    Mukhtar Hussain

    2015-07-01

    Full Text Available The present study reports design and construction, of a prototype of Transversely Excited Atmospheric (TEA nitrogen laser, and a high voltage power supply to excite N2 gas in air, while air is used as an active lasing medium. A Blumlein line discharge circuit is used for operation of this laser. The high voltage is generated by a fly back transformer based power supply varying from 10 kV to 20 kV. The wavelength (337.1 nm of TEA nitrogen laser is measured employing a standard commercial spectrometer and the laser output energy of 300 μJ is measured from the constructed system. Different parameters such as beam profile, laser output spectrum, laser efficiency, and variation of E/P (Electrical field/Pressure value with respect to input voltage and electrodes separations are studied in order to optimize the overall operational efficiency of present nitrogen laser. The analysis of the high voltage prototype appeared in this designed source has also been made and described in this paper.

  5. Projected change in atmospheric nitrogen deposition to the Baltic Sea towards 2020

    Directory of Open Access Journals (Sweden)

    C. Geels

    2012-03-01

    Full Text Available The ecological status of the Baltic Sea has for many years been affected by the high input of both waterborne and airborne nutrients. The focus here is on the airborne input of nitrogen (N and the projected changes in this input, assuming the new National Emission Ceilings directive (NEC-II, currently under negotiation in the EU, is fulfilled towards the year 2020. With a set of scenario simulations, the Danish Eulerian Hemispheric Model (DEHM has been used to estimate the development in nitrogen deposition based on present day meteorology combined with present day (2007 or future (2020 anthropogenic emissions. Applying a so-called tagging method in the DEHM model, the contribution from ship traffic and from each of the nine countries with coastlines to the Baltic Sea has been assessed. The annual deposition to the Baltic Sea is estimated to 203 k tonnes N for the present day scenario (2007 and 165 k tonnes N in the 2020 scenario, giving a projected reduction of 38 k tonnes N in the annual load in 2020. This equals a decline in nitrogen deposition of 19%. The results from 20 model runs using the tagging method show that of the total nitrogen deposition in 2007, 52% came from emissions within the bordering countries. By 2020, this is projected to decrease to 48%. For some countries the projected decrease in nitrogen deposition arising from the implementation of the NEC-II directive will contribute significantly to compliance with the reductions agreed on in the provisional reduction targets of the Baltic Sea Action Plan. This underlines the importance of including projections like the current in future updates of the Baltic Sea Action Plan.

  6. Fluorescence from atmospheric aerosol detected by a lidar indicates biogenic particles in the lowermost stratosphere

    Directory of Open Access Journals (Sweden)

    F. Immler

    2005-01-01

    Full Text Available With a lidar system that was installed in Lindenberg/Germany, we observed in June 2003 an extended aerosol layer at 13km altitude in the lowermost stratosphere. This layer created an inelastic backscatter signal that we detected with a water vapour Raman channel, but that was not produced by Raman scattering. Also, we find evidence for inelastic scattering from a smoke plume from a forest fire that we observed in the troposphere. We interpret the unexpected properties of these aerosols as fluorescence induced by the laser beam at organic components of the aerosol particles. Fluorescence from ambient aerosol had not yet been considered detectable by lidar systems. However, organic compounds such as polycyclic aromatic hydrocarbons sticking to the aerosol particles, or bioaerosol such as bacteria, spores or pollen fluoresce when excited with UV-radiation in a way that is detectable by our lidar system. Therefore, we conclude that fluorescence from organic material released by biomass burning creates, inelastic backscatter signals that we measured with our instrument and thus demonstrate a new and powerful way to characterize aerosols by a remote sensing technique. The stratospheric aerosol layer that we have observed in Lindenberg for three consecutive days is likely to be a remnant from Siberian forest fire plumes lifted across the tropopause and transported around the globe.

  7. Atmospheric nitrogen uptake by soyabean cultivars in combination with Bradyrhizobium japonicum strains

    Directory of Open Access Journals (Sweden)

    A. D. P Botha

    1997-07-01

    Full Text Available A pot experiment was conducted, using three soyabean (Giycinc max (L. Merrill cultivars (Forrest, Prima and A5409 inoculated at planting, with no (0 and two Bradyrhizobium japonicum strains (WB1 and WB74. The objectives were to investigate the effect of cultivar-rhizobial strain combinations on biomass and N derived from the atmosphere (Ndfa and to compare the atmospheric N uptake determined by the isolope technique, with the conventional method.

  8. Analysis of High Frequency Site-Specific Nitrogen and Oxygen Isotopic Composition of Atmospheric Nitrous Oxide at Mace Head, Ireland

    Science.gov (United States)

    McClellan, M. J.; Harris, E. J.; Olszewski, W.; Ono, S.; Prinn, R. G.

    2014-12-01

    Atmospheric nitrous oxide (N2O) significantly impacts Earth's climate due to its dual role as an inert potent greenhouse gas in the troposphere and as a reactive source of ozone-destroying nitrogen oxides in the stratosphere. However, there remain significant uncertainties in the global budget of this gas. The marked spatial divide in its reactivity means that all stages in the N2O life cycle—emission, transport, and destruction—must be examined to understand the overall effect of N2O on climate. Source and sink processes of N2O lead to varying concentrations of N2O isotopologues (14N14N16O, 14N15N16O, 15N14N16O, and 14N14N18O being measured) due to preferential isotopic production and elimination in different environments. Estimation of source and sink fluxes can be improved by combining isotopically resolved N2O observations with simulations using a chemical transport model with reanalysis meteorology and treatments of isotopic signatures of specific surface sources and stratospheric intrusions. We present the first few months of site-specific nitrogen and oxygen isotopic composition data from the Stheno-TILDAS instrument (Harris et al, 2013) at Mace Head, Ireland and compare these to results from MOZART-4 (Model for Ozone and Related Chemical Tracers, version 4) chemical transport model runs including N2O isotopic fractionation processes and reanalysis meterological fields (NCEP/NCAR, MERRA, and GEOS-5). This study forms the basis for future inverse modeling experiments that will improve the accuracy of isotopically differentiated N2O emission and loss estimates. Ref: Harris, E., D. Nelson, W. Olszewski, M. Zahniser, K. Potter, B. McManus, A. Whitehill, R. Prinn, and S. Ono, Development of a spectroscopic technique for continuous online monitoring of oxygen and site-specific nitrogen isotopic composition of atmospheric nitrous oxide, Analytical Chemistry, 2013; DOI: 10.1021/ac403606u.

  9. The Role of Nitrogen Dynamics in the Responses of Terrestrial Carbon Dynamics to Changes in Atmospheric Carbon Dioxide, Climate, and Land Use

    Science.gov (United States)

    McGuire, A. D.; Melillo, J.; Kicklighter, D.; Joyce, L.

    2007-12-01

    While it has long been appreciated that alterations of the nitrogen cycle can substantially affect the carbon dynamics of terrestrial ecosystems, most large-scale models of terrestrial carbon dynamics have ignored carbon-nitrogen interactions in making projections of how carbon dynamics will respond to changes in atmospheric carbon dioxide, climate, and land use. Numerous experimental studies have documented that the uptake of carbon by terrestrial ecosystems is enhanced by nitrogen fertilization under baseline and elevated atmospheric carbon dioxide concentrations. Ecosystem warming studies often identify that the uptake of carbon is enhanced when mineralization of soil organic nitrogen increases in response to warming, but the response often depends on how warming affects soil moisture. Nitrogen amendments are a standard practice in heavily managed agro-forestry ecosystems because of the enhanced response of plant growth to nitrogen fertilization. We have used the Terrestrial Ecosystem Model (TEM) as a tool to explore the regional and global implications of how carbon-nitrogen interactions may influence the responses of terrestrial carbon dynamics to environmental change and land use. Comparisons of the model with and without nitrogen dynamics indicate that the response of carbon uptake to increases in atmospheric carbon dioxide are clearly constrained by nitrogen dynamics. In contrast, carbon uptake is enhanced in situations in which warming enhances the mineralization of soil organic nitrogen, and this response can lead to increases in vegetation carbon storage that are greater than losses of carbon from increases in decomposition of soil organic matter. Land use can result in substantial depletion of nitrogen from terrestrial ecosystems in the harvest of agricultural products. As substantial sink activity is associated with forest re-growth after agricultural land abandonment, we conducted simulations with TEM in the eastern United State to evaluate to role of

  10. Nitrogen distribution and cycling through water flows in a subtropical bamboo forest under high level of atmospheric deposition.

    Directory of Open Access Journals (Sweden)

    Li-hua Tu

    Full Text Available BACKGROUND: The hydrological cycle is an important way of transportation and reallocation of reactive nitrogen (N in forest ecosystems. However, under a high level of atmospheric N deposition, the N distribution and cycling through water flows in forest ecosystems especially in bamboo ecosystems are not well understood. METHODOLOGY/PRINCIPAL FINDINGS: In order to investigate N fluxes through water flows in a Pleioblastus amarus bamboo forest, event rainfall/snowfall (precipitation, PP, throughfall (TF, stemflow (SF, surface runoff (SR, forest floor leachate (FFL, soil water at the depth of 40 cm (SW1 and 100 cm (SW2 were collected and measured through the whole year of 2009. Nitrogen distribution in different pools in this ecosystem was also measured. Mean N pools in vegetation and soil (0-1 m were 351.7 and 7752.8 kg ha(-1. Open field nitrogen deposition at the study site was 113.8 kg N ha(-1 yr(-1, which was one of the highest in the world. N-NH4(+, N-NO3(- and dissolved organic N (DON accounted for 54%, 22% and 24% of total wet N deposition. Net canopy accumulated of N occurred with N-NO3(- and DON but not N-NH4(+. The flux of total dissolved N (TDN to the forest floor was greater than that in open field precipitation by 17.7 kg N ha(-1 yr(-1, due to capture of dry and cloudwater deposition net of canopy uptake. There were significant negative exponential relationships between monthly water flow depths and monthly mean TDN concentrations in PP, TF, SR, FFL and SW1. CONCLUSIONS/SIGNIFICANCE: The open field nitrogen deposition through precipitation is very high over the world, which is the main way of reactive N input in this bamboo ecosystem. The water exchange and N consume mainly occurred in the litter floor layer and topsoil layer, where most of fine roots of bamboo distributed.

  11. Synthesis of fluorescent diblock copolymer nanoparticle supported ...

    Indian Academy of Sciences (India)

    ROP of caprolactonewas carried out at 160 ∘ C for 2 h under nitrogen atmosphere in the presence of stannous octoate (Sn(Oct) 2 ) as a catalyst followed by the ROP of tetrahydrofuran in the presence of phthalicanhydride as a co-monomer. Thus, synthesized fluorescent DBCNC was characterized by various analytical tools ...

  12. Low atmospheric nitrogen loads lead to grass encroachment in coastal dunes, but only on acid soils

    OpenAIRE

    Remke, E.; Brouwer, E.; Kooijman, A.; Blindow, I.; Roelofs, J.G.M.

    2009-01-01

    The impact of atmospheric N-deposition on succession from open sand to dry, lichen-rich, short grassland, and tall grass vegetation dominated by Carex arenaria was surveyed in 19 coastal dune sites along the Baltic Sea. Coastal dunes with acid or slightly calcareous sand reacted differently to atmospheric wet deposition of 5-8 kg N ha(-1) y(-1). Accelerated acidification, as well as increased growth of Carex and accumulation of organic matter, was observed only at acid sites with pH(NaCl) of ...

  13. Atmospheric CO2 and O3 alter competition for soil nitrogen in developing forests

    Science.gov (United States)

    Donald R. Zak; Mark E. Kubiske; Kurt S. Pregitzer; Andrew J. Burton

    2012-01-01

    Plant growth responses to rising atmospheric CO2 and O3 vary among genotypes and between species, which could plausibly influence the strength of competitive interactions for soil N. Ascribable to the size-symmetric nature of belowground competition, we reasoned that differential growth responses to CO2...

  14. Low atmospheric nitrogen loads lead to grass encroachment in coastal dunes, but only on acid soils

    NARCIS (Netherlands)

    Remke, E.; Brouwer, E.; Kooijman, A.; Blindow, I.; Roelofs, J.G.M.

    2009-01-01

    The impact of atmospheric N-deposition on succession from open sand to dry, lichen-rich, short grassland, and tall grass vegetation dominated by Carex arenaria was surveyed in 19 coastal dune sites along the Baltic Sea. Coastal dunes with acid or slightly calcareous sand reacted differently to

  15. A fluorescent probe based on nitrogen doped graphene quantum dots for turn off sensing of explosive and detrimental water pollutant, TNP in aqueous medium

    Science.gov (United States)

    Kaur, Manjot; Mehta, Surinder K.; Kansal, Sushil Kumar

    2017-06-01

    This paper reports the carbonization assisted green approach for the fabrication of nitrogen doped graphene quantum dots (N-GQDs). The obtained N-GQDs displayed good water dispersibility and stability in the wide pH range. The as synthesized N-GQDs were used as a fluorescent probe for the sensing of explosive 2,4,6-trinitrophenol (TNP) in aqueous medium based on fluorescence resonance energy transfer (FRET), molecular interactions and charge transfer mechanism. The quenching efficiency was found to be linear in proportion to the TNP concentration within the range of 0-16 μM with detection limit (LOD) of 0.92 μM. The presented method was successfully applied to the sensing of TNP in tap and lake water samples with satisfactory results. Thus, N-GQDs were used as a selective, sensitive and turn off fluorescent sensor for the detection of perilous water contaminant i.e. TNP.

  16. Contribution of atmospheric nitrogen deposition to diffuse pollution in a typical hilly red soil catchment in southern China.

    Science.gov (United States)

    Shen, Jianlin; Liu, Jieyun; Li, Yong; Li, Yuyuan; Wang, Yi; Liu, Xuejun; Wu, Jinshui

    2014-09-01

    Atmospheric nitrogen (N) deposition is currently high and meanwhile diffuse N pollution is also serious in China. The correlation between N deposition and riverine N export and the contribution of N deposition to riverine N export were investigated in a typical hilly red soil catchment in southern China over a two-year period. N deposition was as high as 26.1 to 55.8kgN/(ha·yr) across different land uses in the studied catchment, while the riverine N exports ranged from 7.2 to 9.6kgN/(ha·yr) in the forest sub-catchment and 27.4 to 30.3kgN/(ha·yr) in the agricultural sub-catchment. The correlations between both wet N deposition and riverine N export and precipitation were highly positive, and so were the correlations between NH4(+)-N or NO3(-)-N wet deposition and riverine NH4(+)-N or NO3(-)-N exports except for NH4(+)-N in the agricultural sub-catchment, indicating that N deposition contributed to riverine N export. The monthly export coefficients of atmospheric deposited N from land to river in the forest sub-catchment (with a mean of 14%) presented a significant positive correlation with precipitation, while the monthly contributions of atmospheric deposition to riverine N export (with a mean of 18.7% in the agricultural sub-catchment and a mean of 21.0% in the whole catchment) were significantly and negatively correlated with precipitation. The relatively high contribution of N deposition to diffuse N pollution in the catchment suggests that efforts should be done to control anthropogenic reactive N emissions to the atmosphere in hilly red soil regions in southern China. Copyright © 2014. Published by Elsevier B.V.

  17. Kinematic evidence that atmospheric nitrogen dioxide increases the rates of cell proliferation and enlargement to stimulate leaf expansion in Arabidopsis.

    Science.gov (United States)

    Takahashi, Misa; Morikawa, Hiromichi

    2015-01-01

    To elucidate the stimulation of leaf growth by atmospheric nitrogen dioxide (NO2), we performed a kinematic analysis of the eighth leaves of Arabidopsis thaliana (accession C24) plants grown for 17-35 days after sowing in the presence or absence of 50 ppb NO2 (designated +NO2 plants and -NO2 plants, respectively). We found that the peak and mean values of the relative rates of leaf expansion, cell division and cell expansion were always greater in +NO2 plants than in -NO2 plants. No evidence for prolonged duration was obtained. Thus, NO2 treatment increased the rates of both cell proliferation and enlargement to increase leaf size. Furthermore, a fold-change analysis showed that cell proliferation and enlargement differentially regulated NO2-induced leaf expansion.

  18. Flexible reduced graphene oxide supercapacitor fabricated using a nitrogen dc-pulse atmospheric-pressure plasma jet

    Science.gov (United States)

    Yang, Cheng-Han; Kuok, Fei-Hong; Liao, Chen-Yu; Wan, Ting-Hao; Chen, Chieh-Wen; Hsu, Cheng-Che; Cheng, I.-Chun; Chen, Jian-Zhang

    2017-02-01

    We use a nitrogen dc-pulse atmospheric-pressure plasma jet to fabricate a flexible reduced graphene oxide (rGO) supercapacitor with polyvinyl alcohol (PVA)/sulfuric acid (H2SO4) gel electrolyte. An areal capacitance of 47.03 mF · cm-2 (evaluated using cyclic voltammetry (CV) under a potential scan rate of 2 mV · s-1) is achieved. The supercapacitor can be operated without apparent degradation under bending with a bending radius of 0.55 cm. After a 1000 cycle CV stability test, the capacitance retention rate is 100% when flat and is 98.6% under bending (bending radius  =  0.55 cm), indicating promising stability of the APPJ-processed flexible supercapacitor.

  19. Concentrations and nitrogen isotope compositions of free amino acids in Pinus massoniana (Lamb.) needles of different ages as indicators of atmospheric nitrogen pollution

    Science.gov (United States)

    Xu, Yu; Xiao, Huayun

    2017-09-01

    Free amino acid δ15N values and concentrations of current-year new (new), current-year mature (middle-age) and previous-year (old) Pinus massoniana (Lamb.) needles were determined for five sites with different distances from a highway in a forest in Guiyang (SW China). Needle free amino acid concentrations decreased with increasing distance from the highway, and only the free amino acid concentrations (total free amino acid, arginine, γ-aminobutyric acid, valine, alanine and proline) in the middle-aged needles demonstrated a strong correlation with distance from the highway, indicating that free amino acid concentrations in middle-aged needles may be a more suitable indicator of nitrogen (N) deposition compared to new and old needles. Needle free amino acid δ15N values were more positive near the highway compared to the more distant sites and increased with increasing needle age, indicating that N deposition in this site may be dominated by isotopically heavy NOx-N from traffic emissions. In sites beyond 400 m from the highway, the δ15N values of total free amino acids, histidine, glutamine, proline, alanine, aspartate, isoleucine, lysine, arginine and serine in each age of needle were noticeably negative compared to their respective δ15N values near the highway. This suggested that needle free amino acid δ15N values from these sites were more affected by 15N-depleted atmospheric NHx-N from soil emissions. This result was further supported by the similarity in the negative moss δ15N values at these sites to the δ15N values of soil-derived NHx-N. Needle free amino acid δ15N values therefore have the potential to provide information about atmospheric N sources. We conclude that needle free amino acid concentrations are sensitive indicators of N deposition and that the age-related free amino acid δ15N values in needles can efficiently reflect atmospheric N sources. This would probably promote the application of the combined plant tissue amino acid

  20. Influence of the flux composition and state of the gas atmosphere over the kinetics of nitrogen absorption by steels and alloys at the arc slag remelting

    Energy Technology Data Exchange (ETDEWEB)

    Medovar, B.I.; Medovar, L.B.; Saenko, V.Ya.; Pomarin, Yu.M.; Chernets, A.V. [Academy of Sci., Kiev (Ukraine). Sci. and Eng. Center of Electroslag Technol.

    1999-07-01

    In the work are represented the results of fundamental investigations of the kinetics of nitrogen absorption depending on state of the gas atmosphere and composition of the flux applied at the induction and arc melting. Are given the calculated and experimental relations of nitrogen absorption by liquid metal from the gas phase within the atmosphere of nitrogen with different concentration of oxygen, performed on the basis of application of modern methods of levitation and arc meltings. It is shown that along with increasing of the oxygen content in the gas phase reduces the speed of nitrogen absorption independently from the applied means of melting (the induction or arc one). The data obtained on the grounds of the theoretical calculations and laboratory investigations have been confirmed by the results of the experimental and industrial testing with respect the arc slag remelting technology (ASR). It is shown that chemical composition of the flux considerably influences over the kinetics of nitrogen absorption by liquid metal, and along with increasing the quantity of oxides in it reduces the speed of nitrogen absorption by metal. It has been also established the dependence of the grade of metal saturation with nitrogen at the ASR for different depth of the slag pool. The investigations having been carried out allowed detect and precise the extent of influence of different technological parameters over saturation of metal with nitrogen and showed that keeping to optimum technological schedules of remelting it is possible alloy metal by nitrogen from the gas phase until the concentrations close to standard solubility and confirmed high effectiveness of the means of nitrogen alloying immediately from the gas phase within the ASR process. (orig.)

  1. Cellular attachment and differentiation on titania nanotubes exposed to air- or nitrogen-based non-thermal atmospheric pressure plasma.

    Directory of Open Access Journals (Sweden)

    Hye Yeon Seo

    Full Text Available The surface topography and chemistry of titanium implants are important factors for successful osseointegration. However, chemical modification of an implant surface using currently available methods often results in the disruption of topographical features and the loss of beneficial effects during the shelf life of the implant. Therefore, the aim of this study was to apply the recently highlighted portable non-thermal atmospheric pressure plasma jet (NTAPPJ, elicited from one of two different gas sources (nitrogen and air, to TiO2 nanotube surfaces to further improve their osteogenic properties while preserving the topographical morphology. The surface treatment was performed before implantation to avoid age-related decay. The surface chemistry and morphology of the TiO2 nanotube surfaces before and after the NTAPPJ treatment were determined using a field-emission scanning electron microscope, a surface profiler, a contact angle goniometer, and an X-ray photoelectron spectroscope. The MC3T3-E1 cell viability, attachment and morphology were confirmed using calcein AM and ethidium homodimer-1 staining, and analysis of gene expression using rat mesenchymal stem cells was performed using a real-time reverse-transcription polymerase chain reaction. The results indicated that both portable nitrogen- and air-based NTAPPJ could be used on TiO2 nanotube surfaces easily and without topographical disruption. NTAPPJ resulted in a significant increase in the hydrophilicity of the surfaces as well as changes in the surface chemistry, which consequently increased the cell viability, attachment and differentiation compared with the control samples. The nitrogen-based NTAPPJ treatment group exhibited a higher osteogenic gene expression level than the air-based NTAPPJ treatment group due to the lower atomic percentage of carbon on the surface that resulted from treatment. It was concluded that NTAPPJ treatment of TiO2 nanotube surfaces results in an increase in

  2. Kinetics of organic molecules in pulsed plasmas of nitrogen or N2/O2 mixtures at near atmospheric pressure

    Science.gov (United States)

    Pasquiers, S.; Blin-Simiand, N.; Magne, L.

    2013-12-01

    In plasmas of atmospheric gases, the kinetics of some aliphatic organic molecules belonging to the hydrocarbons (propene, propane), aldehydes (acetaldehyde) and ketones (acetone) families were studied using a photo-triggered discharge (homogeneous plasma). It was shown that quenchings of N2 metastable states, A\\,^{3}\\Sigma_{u}^{+} and the group of singlets a'\\,^{1}\\Sigma_{u}^{-} , a 1Πg and w 1Δu, are important processes for the decomposition of such molecules. It plays a fundamental role in the nitrogen plasma, but it is also present in air. At low temperature, the oxidation reactions by the oxygen atom or by the hydroxyl radical are not always sufficiently effective to induce an increase of the molecule decomposition when oxygen is added to the nitrogen/organic mixture. For most cases, quenching processes appear purely dissociative. However, recent results obtained for propene lead to the conclusion that a non-dissociative exit route could exist. The quenching of the singlet states induces a break of the double bound C = O for the acetaldehyde and acetone molecules. Some kinetic analogies appear between filamentary and homogeneous plasmas, which could be very useful to get a comprehensive understanding of the physico-chemical processes in dielectric barriers or corona discharges used for various applications.

  3. Global carbon - nitrogen - phosphorus cycle interactions: A key to solving the atmospheric CO2 balance problem?

    Science.gov (United States)

    Peterson, B. J.; Mellillo, J. M.

    1984-01-01

    If all biotic sinks of atmospheric CO2 reported were added a value of about 0.4 Gt C/yr would be found. For each category, a very high (non-conservative) estimate was used. This still does not provide a sufficient basis for achieving a balance between the sources and sinks of atmospheric CO2. The bulk of the discrepancy lies in a combination of errors in the major terms, the greatest being in a combination of errors in the major terms, the greatest being in the net biotic release and ocean uptake segments, but smaller errors or biases may exist in calculations of the rate of atmospheric CO2 increase and total fossil fuel use as well. The reason why biotic sinks are not capable of balancing the CO2 increase via nutrient-matching in the short-term is apparent from a comparison of the stoichiometry of the sources and sinks. The burning of fossil fuels and forest biomass releases much more CO2-carbon than is sequestered as organic carbon.

  4. Noble gases, nitrogen, and methane from the deep interior to the atmosphere of Titan

    Science.gov (United States)

    Glein, Christopher R.

    2015-04-01

    Titan's thick N2-CH4 atmosphere is unlike any in the Solar System, and its origin has been shrouded in mystery for over half a century. Here, I perform a detailed analysis of chemical and isotopic data from the Cassini-Huygens mission to develop the hypothesis that Titan's (non-photochemical) atmospheric gases came from deep within. It is suggested that Titan's CH4, N2, and noble gases originated in a rocky core buried inside the giant satellite, and hydrothermal and cryovolcanic processes were critical to the creation of Titan's atmosphere. Mass balance and chemical equilibrium calculations demonstrate that all aspects of this hypothesis can be considered geochemically plausible with respect to contemporary observational, experimental, and theoretical knowledge. Specifically, I show that a rocky core with a bulk noble gas content similar to that in CI carbonaceous meteorites would contain sufficient 36Ar and 22Ne to explain their reported abundances. I also show that Henry's law constants for noble gases in relevant condensed phases can be correlated with the size of their atoms, which leads to expected mixing ratios for 84Kr (∼0.2 ppbv) and 132Xe (∼0.01 ppbv) that can explain why these species have yet to be detected (Huygens upper limit <10 ppbv). The outgassing of volatiles into Titan's atmosphere may be restricted by the stability of clathrate hydrates in Titan's interior. The noble gas geochemistry also provides significant new insights into the origin of N2 and CH4 on Titan, as I find that Ar and N2, and Kr and CH4 should exhibit similar phase partitioning behavior on Titan. One implication is that over 95% of Titan's N2 may still reside in the interior. Another key result is that the upper limit from the Huygens GC-MS on the Kr/CH4 ratio in Titan's atmosphere is far too low to be consistent with accretion of primordial CH4 clathrate, which motivates me to consider endogenic production of CH4 from CO2 as a result of geochemical reactions between liquid

  5. Investigation of potential interferences in the detection of atmospheric ROx radicals by laser-induced fluorescence under dark conditions

    Science.gov (United States)

    Fuchs, Hendrik; Tan, Zhaofeng; Hofzumahaus, Andreas; Broch, Sebastian; Dorn, Hans-Peter; Holland, Frank; Künstler, Christopher; Gomm, Sebastian; Rohrer, Franz; Schrade, Stephanie; Tillmann, Ralf; Wahner, Andreas

    2016-04-01

    Direct detection of highly reactive, atmospheric hydroxyl radicals (OH) is widely accomplished by laser-induced fluorescence (LIF) instruments. The technique is also suitable for the indirect measurement of HO2 and RO2 peroxy radicals by chemical conversion to OH. It requires sampling of ambient air into a low-pressure cell, where OH fluorescence is detected after excitation by 308 nm laser radiation. Although the residence time of air inside the fluorescence cell is typically only on the order of milliseconds, there is potential that additional OH is internally produced, which would artificially increase the measured OH concentration. Here, we present experimental studies investigating potential interferences in the detection of OH and peroxy radicals for the LIF instruments of Forschungszentrum Jülich for nighttime conditions. For laboratory experiments, the inlet of the instrument was over flowed by excess synthetic air containing one or more reactants. In order to distinguish between OH produced by reactions upstream of the inlet and artificial signals produced inside the instrument, a chemical titration for OH was applied. Additional experiments were performed in the simulation chamber SAPHIR where simultaneous measurements by an open-path differential optical absorption spectrometer (DOAS) served as reference for OH to quantify potential artifacts in the LIF instrument. Experiments included the investigation of potential interferences related to the nitrate radical (NO3, N2O5), related to the ozonolysis of alkenes (ethene, propene, 1-butene, 2,3-dimethyl-2-butene, α-pinene, limonene, isoprene), and the laser photolysis of acetone. Experiments studying the laser photolysis of acetone yield OH signals in the fluorescence cell, which are equivalent to 0.05 × 106 cm-3 OH for a mixing ratio of 5 ppbv acetone. Under most atmospheric conditions, this interference is negligible. No significant interferences were found for atmospheric concentrations of reactants

  6. [Effect of atmospheric CO2 concentration and nitrogen application level on absorption and transportation of nutrient elements in oilseed rape].

    Science.gov (United States)

    Wang, Wen-ming; Zhang, Zhen-hua; Song, Hai-xing; Liu, Qiang; Rong, Xiang-min; Guan, Chun-yun; Zeng, Jing; Yuan, Dan

    2015-07-01

    Effect of elevated atmospheric-CO2 (780 µmol . mol-1) on the absorption and transportation of secondary nutrient elements (calcium, magnesium, sulphur) and micronutrient elements (iron, manganese, zinc, molybdenum and boron) in oilseed rape at the stem elongation stage were studied by greenhouse simulated method. Compared with the ambient CO2 condition, the content of Zn in stem was increased and the contents of other nutrient elements were decreased under the elevated atmospheric-CO2 with no nitrogen (N) application; the contents of Ca, S, B and Zn were increased, and the contents of Mg, Mn, Mo and Fe were decreased under the elevated atmospheric CO2 with N application (0.2 g N . kg-1 soil); except the content of Mo in leaf was increased, the contents of other nutrient elements were decreased under the elevated atmospheric-CO2 with two levels of N application. Compared with the ambient CO2 condition, the amounts of Ca and S relative to the total amount of secondary nutrient elements in stem and the amounts of B and Zn relative to the total amount of micronutrient elements in stem were increased under the elevated-CO2 treatment with both levels of N application, and the corresponding values of Mg, Fe, Mn and Mo were decreased; no-N application treatment increased the proportion of Ca distributed into the leaves, and the proportion of Mg distributed into leaves was increased by the normal-N application level; the proportions of Mn, Zn and Mo distributed into the leaves were increased at both N application levels. Without N application, the elevation of atmospheric CO2 increased the transport coefficients of SFe, Mo and SS,B, but decreased the transport coefficients of SMg,Fe, SMg, Mn and SS,Fe, indicating the proportions of Mo, S transported into the upper part of plant tissues was higher than that of Fe, and the corresponding value of B was higher than that observed for S, the corresponding value of Mg was higher than that of Fe and Mn. Under normal-N application

  7. Ultraviolet pulsed laser irradiation of multi-walled carbon nanotubes in nitrogen atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Pérez del Pino, Ángel, E-mail: aperez@icmab.es; Cabana, Laura; Tobias, Gerard [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Científicas (ICMAB-CSIC), Campus UAB, 08193 Bellaterra (Spain); György, Enikö [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Científicas (ICMAB-CSIC), Campus UAB, 08193 Bellaterra (Spain); National Institute for Lasers, Plasma and Radiation Physics, P. O. Box MG 36, 76900 Bucharest V (Romania); Ballesteros, Belén [ICN2—Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona (Spain)

    2014-03-07

    Laser irradiation of randomly oriented multi-walled carbon nanotube (MWCNT) networks has been carried out using a pulsed Nd:YAG UV laser in nitrogen gas environment. The evolution of the MWCNT morphology and structure as a function of laser fluence and number of accumulated laser pulses has been studied using electron microscopies and Raman spectroscopy. The observed changes are discussed and correlated with thermal simulations. The obtained results indicate that laser irradiation induces very fast, high temperature thermal cycles in MWCNTs which produce the formation of different nanocarbon forms, such as nanodiamonds. Premelting processes have been observed in localized sites by irradiation at low number of laser pulses and low fluence values. The accumulation of laser pulses and the increase in the fluence cause the full melting and amorphization of MWCNTs. The observed structural changes differ from that of conventional high temperature annealing treatments of MWCNTs.

  8. The photosynthesis - leaf nitrogen relationship at ambient and elevated atmospheric carbon dioxide: a meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Andrew G. Peterson; J. Timothy Ball; Yiqi Luo; Christopher B. Field; Peter B. Reich; Peter S. Curtis; Kevin L. Griffin; Carla S Gunderson; Richard J. Norby; David T. Tissue; Manfred Forstreuter; Ana Rey; Christoph S. Vogel; CMEAL collaboration

    1998-09-25

    Estimation of leaf photosynthetic rate (A) from leaf nitrogen content (N) is both conceptually and numerically important in models of plant, ecosystem and biosphere responses to global change. The relationship between A and N has been studied extensively at ambient CO{sub 2} but much less at elevated CO{sub 2}. This study was designed to (1) assess whether the A-N relationship was more similar for species within than between community and vegetation types, and (2) examine how growth at elevated CO{sub 2} affects the A-N relationship. Data were obtained for 39 C{sub 3} species grown at ambient CO{sub 2} and 10 C{sub 3} species grown at ambient and elevated CO{sub 2}. A regression model was applied to each species as well as to species pooled within different community and vegetation types. Cluster analysis of the regression coefficients indicated that species measured at ambient CO{sub 2} did not separate into distinct groups matching community or vegetation type. Instead, most community and vegetation types shared the same general parameter space for regression coefficients. Growth at elevated CO{sub 2} increased photosynthetic nitrogen use efficiency for pines and deciduous trees. When species were pooled by vegetation type, the A-N relationship for deciduous trees expressed on a leaf-mass bask was not altered by elevated CO{sub 2}, while the intercept increased for pines. When regression coefficients were averaged to give mean responses for different vegetation types, elevated CO{sub 2} increased the intercept and the slope for deciduous trees but increased only the intercept for pines. There were no statistical differences between the pines and deciduous trees for the effect of CO{sub 2}. Generalizations about the effect of elevated CO{sub 2} on the A-N relationship, and differences between pines and deciduous trees will be enhanced as more data become available.

  9. Elevated Atmospheric CO2 and Warming Stimulates Growth and Nitrogen Fixation in a Common Forest Floor Cyanobacterium under Axenic Conditions

    Directory of Open Access Journals (Sweden)

    Zoë Lindo

    2017-03-01

    Full Text Available The predominant input of available nitrogen (N in boreal forest ecosystems originates from moss-associated cyanobacteria, which fix unavailable atmospheric N2, contribute to the soil N pool, and thereby support forest productivity. Alongside climate warming, increases in atmospheric CO2 concentrations are expected in Canada’s boreal region over the next century, yet little is known about the combined effects of these factors on N fixation by forest floor cyanobacteria. Here we assess changes in N fixation in a common forest floor, moss-associated cyanobacterium, Nostoc punctiforme Hariot, under elevated CO2 conditions over 30 days and warming combined with elevated CO2 over 90 days. We measured rates of growth and changes in the number of specialized N2 fixing heterocyst cells, as well as the overall N fixing activity of the cultures. Elevated CO2 stimulated growth and N fixation overall, but this result was influenced by the growth stage of the cyanobacteria, which in turn was influenced by our temperature treatments. Taken together, climate change factors of warming and elevated CO2 are expected to stimulate N2 fixation by moss-associated cyanobacteria in boreal forest systems.

  10. Lake-specific responses to elevated atmospheric nitrogen deposition in the Colorado Rocky Mountains, U.S.A.

    Science.gov (United States)

    Nydick, K.R.; LaFrancois, B.M.; Baron, J.S.; Johnson, B.M.

    2003-01-01

    We explored variability among subalpine lakes sharing very similar climate and atmospheric conditions, but differing in watershed characteristics, hydrology, and food web structure. Special attention was given to nitrogen (N) dynamics because the study area receives some of the highest levels of atmospheric N deposition in the Rocky Mountains. We asked if the effect of regional N deposition would be manifested uniformly among neighboring lakes both in terms of ambient conditions and responses to greater nutrient inputs. Catchment vegetation appeared to be the main determinant of ambient nitrate (NO3), phosphate (PO4), and dissolved organic carbon (DOC) concentrations, although in-lake differences in recycling produced variable and contrasting NH4 levels. Phytoplankton chlorophyll a temporarily responded to early season NO3 peaks in the lakes with rocky watersheds, but chlorophyll means over the ice-free season were remarkably similar among lakes despite differences in both nutrient supply and zooplankton grazing. In most cases, phosphorus was limiting to phytoplankton growth, although the importance of N deficiencies was greater in lakes with forested watersheds and fringing wetlands.

  11. Spatial variation of atmospheric nitrogen deposition and critical loads for aquatic ecosystems in the Greater Yellowstone Area.

    Science.gov (United States)

    Nanus, L; McMurray, J A; Clow, D W; Saros, J E; Blett, T; Gurdak, J J

    2017-04-01

    Current and historic atmospheric nitrogen (N) deposition has impacted aquatic ecosystems in the Greater Yellowstone Area (GYA). Understanding the spatial variation in total atmospheric deposition (wet + dry) of N is needed to estimate air pollution deposition critical loads for sensitive aquatic ecosystems. This is particularly important for areas that have an increasing contribution of ammonia dry deposition to total N (TN), such as the GYA. High resolution geostatistical models and maps of TN deposition (wet + dry) were developed using a variety of techniques including ordinary kriging in a geographic information system, to evaluate spatial variability and identify areas of elevated loading of pollutants for the GYA. TN deposition estimates in the GYA range from <1.4 to 7.5 kg N ha-1 yr-1 and show greater variability than wet inorganic N deposition. Critical loads of TN deposition (CLTNdep) for nutrient enrichment in aquatic ecosystems range from less than 1.5 ± 1.0 kg N ha-1 yr-1 to over 4.0 ± 1.0 kg N ha-1 yr-1 and variability is controlled by differences in basin characteristics. The lowest CLTNdep estimates occurred in high elevation basins within GYA Wilderness boundaries. TN deposition maps were used to identify critical load exceedances for aquatic ecosystems. Estimated CLTNdep exceedances for the GYA range from 17% to 48% depending on the surface water nitrate (NO3-) threshold. Based on a NO3- threshold of 1.0 μmol L-1, TN deposition exceeds CLTNdep in approximately 30% of the GYA. These predictive models and maps can be used to help identify and protect sensitive ecosystems that may be impacted by excess atmospheric N deposition. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. An “on-off-on” fluorescent nanoprobe for recognition of chromium(VI) and ascorbic acid based on phosphorus/nitrogen dual-doped carbon quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Xiaojuan, E-mail: gxj1124@sxu.edu.cn [Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Liu, Yang; Yang, Zhenhua; Shuang, Shaomin [Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Zhang, Zeyu [Faculty of Science, Beijing University of Chemical Technology, Beijing, 100029 (China); Dong, Chuan, E-mail: dc@sxu.edu.cn [Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China)

    2017-05-22

    Chromium (VI) [Cr(VI)] is a harsh environmental contaminates and has been proved to be highly toxic, carcinogenic and mutagenic. Therefore, developing an inexpensive, good selective and highly sensitive nanoprobe for the detection of Cr(VI) is in urgent demand. Recently, the highly fluorescent carbon quantum dots (CQDs) have been successfully utilized as efficient fluorescent nanoprobes for the detection of ions, pH and molecular substances. In this work, an “on-off” fluorescence phosphorus/nitrogen dual-doped CQDs (PNCQDs) probe was developed for the determination of Cr(VI) based on inner filter effect (IFE). The proposed PNCQDs nanoprobe shows its distinct merits of simplicity, convenience, fast implementation, good selectivity and high sensitivity towards Cr(VI), allowing its potential application in the determination of Cr(VI) in environment and biosystem. In addition, the chelation effect of the functional groups in reductant and Cr(VI), and the easy-conversion of Cr(VI) to reduced states (i.e. Cr(III) and Cr(0)) by reductants makes the minimization of IFE with a concomitant recovery of PNCQDs fluorescence possible. Hence, the PNCQDs/Cr(VI) hybrid was used as an “off-on” fluorescence probe for sensing ascorbic acid (AA), which is a model reductant. For the detection of Cr(VI), the linear range and the limit of detection achieved were 1.5–30 μmol/L and 23 nmol/L, respectively. For the detection of AA, the linear range and the limit of detection obtained were 5.0–200 μmol/L and 1.35 μmol/L, respectively. The as-constructed “on-off-on” PNCQDs fluorescent nanoprobe was successfully applied for detecting Cr(VI) and AA in biosystem. Furthermore, the as-constructed fluorescent sensing system was successfully applied to the analyses of AA in fresh fruits and in commercial fruit juices with satisfactory results. - Highlights: • Fast synthesis of phosphorus/nitrogen dual-doped CQDs (PNCQDs) by acid-base neutralization carbonization method.

  13. Photosynthetic acclimation of overstory Populus tremuloides and understory Acer saccharum to elevated atmospheric CO2 concentration: interactions with shade and soil nitrogen

    Science.gov (United States)

    Mark E. Kubiske; Donald R. Zak; Kurt S. Pregitzer; Yu Takeuchi

    2002-01-01

    We exposed Populus tremuloides Michx. and Acer saccharum Marsh. to a factorial combination of ambient and elevated atmospheric CO2 concentrations ([CO2]) and high-nitrogen (N) and low-N soil treatments in open-top chambers for 3 years. Our objective was to compare photosynthetic...

  14. Effects of elevated atmospheric CO2 concentration and increased nitrogen deposition on growth and chemical composition of ombrotrophic Sphagnum balticum and oligo-mesotrophic Sphagnum papillosum

    NARCIS (Netherlands)

    Van der Heijden, E; Jauhiainen, J; Silvola, J; Vasander, H; Kuiper, PJC

    2000-01-01

    The ombrotrophic Sphagnum balticum (Russ.) C. Jens. and the oligo-mesotrophic Sphagnum papillosum Lindb. were grown at ambient (360 mu l l(-1)) and at elevated (720 mu l l(-1)) atmospheric CO2 concentrations and at different nitrogen deposition rates, varying between 0 and 30kg N ha(-1) yr(-1), The

  15. Total reflection X-ray fluorescence analysis of pollen as an indicator for atmospheric pollution

    Energy Technology Data Exchange (ETDEWEB)

    Pepponi, G. E-mail: pepponi@itc.it; Lazzeri, P.; Coghe, N.; Bersani, M.; Gottardini, E.; Cristofolini, F.; Clauser, G.; Torboli, A

    2004-08-31

    The viability of pollen is affected by environmental pollution and its use as a bio-indicator is proposed. Such effects can be observed and quantified by biological tests. However, a more accurate identification of the agents affecting the viability is required in order to validate the biological assay for environmental monitoring. The chemical analysis of pollen is meant to ascertain the existence of a correlation between its reduced biological functions and the presence of pollutants. Moreover, such biological systems act as accumulators and allow the detection and quantification of species present in the environment at low concentrations. Total reflection X-ray fluorescence analysis (TXRF) has been chosen for the investigation due to its high sensitivity, multielement capability and wide dynamic range. Corylus avellana L. (hazel) pollen has been collected in areas with different anthropic impact in the province of Trento, Italy. For the TXRF measurements, a liquid sample is needed, especially if a quantitative analysis is required. In the present work, the analysis after a microwave digestion has been compared with the analysis of a suspension of the pollen samples. In both cases, an internal standard has been used for the quantification. The concentrations of 17 elements ranging from Al to Pb have been determined in 13 samples. Analysis of the suspensions showed to be comparable to that of digested samples in terms of spectral quality, but the latter preparation method gave better reproducibility. Sub-ppm lowest limits of detection were obtained for iron and heavier elements detected.

  16. Nitrogen-doped carbon quantum dots as a fluorescence probe combined with magnetic solid-phase extraction purification for analysis of folic acid in human serum.

    Science.gov (United States)

    Wang, Meng; Jiao, Yang; Cheng, Chunsheng; Hua, Jianhao; Yang, Yaling

    2017-12-01

    A novel and sensitive method based on nitrogen-doped carbon quantum dots as a fluorescence probe coupled with magnetic solid-phase extraction (MSPE) purification for analysis of folic acid (FA) in human serum samples has been established for the first time. In the developed system, magnetic nanoparticles coated with hexanoic acid (Fe3O4@C6) were synthesized by a one-step chemical co-precipitation method with good magnetic properties and dispersibility for sample purification, and it is better to be separated from the sample. High fluorescence nitrogen-doped carbon quantum dots (N-CQDs), simply prepared using a one-step hydrothermal method with nitrilotriacetic acid, could be selectively quenched by FA. Based on this phenomenon, a fluorescence assay was proposed for specific determination of FA. Various operational experiment parameters have been studied and optimized in detail. Under the optimum experimental conditions, the detection limit of the proposed method for FA was evaluated to be 0.5 nM (S/N = 3), while the relative standard deviation (RSD) was 1.2% (n = 6). Finally, the proposed method was applied for determination of trace levels of FA from human serum samples and quantitative recoveries were achieved within the range of 95.7-103.5%. All of the results showed that the proposed method had significant application in further research. Graphical abstract Schematic of synthesis of N-CQDs and schematic of suggested mode for analysis of folic acid (FA).

  17. Nitrogen-doped carbon quantum dots: facile synthesis and application as a "turn-off" fluorescent probe for detection of Hg2+ ions.

    Science.gov (United States)

    Zhang, Ruizhong; Chen, Wei

    2014-05-15

    A facile, economical and straightforward hydrothermal strategy is used to prepare highly luminescent nitrogen-doped carbon quantum dots (N-CQDs) by using folic acid as both carbon and nitrogen sources. The as-prepared N-CQDs have an average size of 4.5 ± 1.0 nm and exhibit excitation wavelength-dependent fluorescence with the maximum emission and excitation at 390 and 470 nm, respectively. Furthermore, due to the effective quenching effect of Hg(2+) ions, such N-CQDs are found to serve as an effective fluorescent sensing platform for lable-free sensitive detection of Hg(2+) ions with a detection limit of 0.23 μM. The selectivity experiments reveal that the fluorescent sensor is specific for Hg(2+) even with interference by high concentrations of other metal ions. Most importantly, the N-CQDs-based Hg(2+) ions sensor can be successfully applied to the determination of Hg(2+) in tap water and real lake water samples. With excellent sensitivity and selectivity, such stable and cheap carbon materials are potentially suitable for monitoring of Hg(2+) in environmental application. © 2013 Elsevier B.V. All rights reserved.

  18. Atmospheric nitrogen deposition in the Yangtze River basin: Spatial pattern and source attribution.

    Science.gov (United States)

    Xu, Wen; Zhao, Yuanhong; Liu, Xuejun; Dore, Anthony J; Zhang, Lin; Liu, Lei; Cheng, Miaomiao

    2018-01-01

    The Yangtze River basin is one of the world's hotspots for nitrogen (N) deposition and likely plays an important role in China's riverine N output. Here we constructed a basin-scale total dissolved inorganic N (DIN) deposition (bulk plus dry) pattern based on published data at 100 observational sites between 2000 and 2014, and assessed the relative contributions of different reactive N (N r ) emission sectors to total DIN deposition using the GEOS-Chem model. Our results show a significant spatial variation in total DIN deposition across the Yangtze River basin (33.2 kg N ha -1 yr -1 on average), with the highest fluxes occurring mainly in the central basin (e.g., Sichuan, Hubei and Hunan provinces, and Chongqing municipality). This indicates that controlling N deposition should build on mitigation strategies according to local conditions, namely, implementation of stricter control of N r emissions in N deposition hotspots but moderate control in the areas with low N deposition levels. Total DIN deposition in approximately 82% of the basin area exceeded the critical load of N deposition for semi-natural ecosystems along the basin. On the basin scale, the dominant source of DIN deposition is fertilizer use (40%) relative to livestock (11%), industry (13%), power plant (9%), transportation (9%), and others (18%, which is the sum of contributions from human waste, residential activities, soil, lighting and biomass burning), suggesting that reducing NH 3 emissions from improper fertilizer (including chemical and organic fertilizer) application should be a priority in curbing N deposition. This, together with distinct spatial variations in emission sector contributions to total DIN deposition also suggest that, in addition to fertilizer, major emission sectors in different regions of the basin should be considered when developing synergistic control measures. Copyright © 2017. Published by Elsevier Ltd.

  19. Changes in susceptibility of beech (Fagus sylvatica) seedlings towards Phytophthora citricola under the influence of elevated atmospheric CO2 and nitrogen fertilization.

    Science.gov (United States)

    Fleischmann, F; Raidl, S; Osswald, W F

    2010-04-01

    The growth-differentiation balance hypothesis (GDBH) predicts changes in susceptibility of plants against herbivores with changing resource availability. In the presented study we tested the validity of the GDBH for trees infected with a root pathogen. For this purpose Fagus sylvatica seedlings grown under different atmospheric CO(2)- and soil nitrogen regimes were infected with the root pathogen Phytophthora citricola. High nitrogen supply increased total biomass of beech regardless of the CO(2)-treatment, whereas elevated CO(2) enhanced biomass only in the high nitrogen treatment. The responses of beech under the different growing regimes to the Phytophthora root infection were not in line with the predictions of the GDBH. Enhanced susceptibility of beech against P. citricola was found in seedlings grown under elevated CO(2) and low nitrogen supply. Fifteen months after inoculation these plants were characterized by enhanced water use efficiency, by altered root-shoot ratios, and by enhanced specific root tip densities. 2009 Elsevier Ltd. All rights reserved.

  20. Measurement and Modeling of Site-specific Nitrogen and Oxygen Isotopic Composition of Atmospheric Nitrous Oxide at Mace Head, Ireland

    Science.gov (United States)

    McClellan, M. J.; Saikawa, E.; Prinn, R. G.; Ono, S.

    2015-12-01

    Global mixing ratios of atmospheric nitrous oxide (N2O), a potent greenhouse gas, have increased nearly linearly from the beginning of the modern industrial period to today, with the current global average in excess of 325 ppb. This increase can be largely attributed to anthropogenic activity above the level of N2O emissions from natural biotic sources. The effect of N2O on Earth's climate is twofold: in the troposphere, N2O is radiatively active and chemically inert, while it serves as a reactive source of ozone-destroying nitrogen oxides in the stratosphere. The marked altitudinal divide in its reactivity means that all stages in the N2O life cycle—emission, transport, and destruction—must be examined to understand the overall effect of N2O on Earth's climate. However, the understanding of the total impact of N2O is incomplete, as there remain significant uncertainties in the global budget of this gas. Due to unique isotopic substitutions (15N and 18O) made by different N2O sources and stratospheric chemical reactions, the measurement of N2O isotopic ratios in ambient air can help identify the distribution and magnitude of distinct source types. We present the first year of site-specific nitrogen and oxygen isotopic composition data from the MIT Stheno-tunable infrared direct absorption spectroscopy (TILDAS) instrument at Mace Head, Ireland. Aided by the Stheno preconcentration system, Stheno-TILDAS can achieve measurement precisions of 0.10‰ or greater for all isotopic ratios (δ15N and δ18O) in ambient N2O. We further compare these data to the results from Model for Ozone and Related Tracers version 4 (MOZART-4) simulations, including N2O isotopic fractionation processes and MERRA/GEOS-5 reanalysis meteorological fields. These results will form the basis of future Bayesian inverse modeling simulations that will constrain global N2O source, circulation, and sink dynamics better.

  1. Atmospheric Pressure Plasma CVD of Amorphous Hydrogenated Silicon Carbonitride (a-SiCN:H) Films Using Triethylsilane and Nitrogen

    Energy Technology Data Exchange (ETDEWEB)

    Srinivasan Guruvenket; Steven Andrie; Mark Simon; Kyle W. Johnson; Robert A. Sailer

    2011-10-04

    Amorphous hydrogenated silicon carbonitride (a-SiCN:H) thin films are synthesized by atmospheric pressure plasma enhanced chemical vapor (AP-PECVD) deposition using the Surfx Atomflow{trademark} 250D APPJ source with triethylsilane (HSiEt{sub 3}, TES) and nitrogen as the precursor and the reactive gases, respectively. The effect of the substrate temperature (T{sub s}) on the growth characteristics and the properties of a-SiCN:H films was evaluated. The properties of the films were investigated via scanning electron microscopy (SEM), atomic force microscopy (AFM) for surface morphological analyses, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) for chemical and compositional analyses; spectroscopic ellipsometry for optical properties and thickness determination and nanoindentation to determine the mechanical properties of the a-SiCN:H films. Films deposited at low T{sub s} depict organic like features, while the films deposited at high T{sub s} depict ceramic like features. FTIR and XPS studies reveal that an increases in T{sub s} helps in the elimination of organic moieties and incorporation of nitrogen in the film. Films deposited at T{sub s} of 425 C have an index of refraction (n) of 1.84 and hardness (H) of 14.8 GPa. A decrease in the deposition rate between T{sub s} of 25 and 250 C and increase in deposition rate between T{sub s} of 250 and 425 C indicate that the growth of a-SiCN:H films at lower T{sub s} are surface reaction controlled, while at high temperatures film growth is mass-transport controlled. Based on the experimental results, a potential route for film growth is proposed.

  2. The Influence of Nitrogen Dioxide on Arrhythmias in Spain and Its Relationship with Atmospheric Circulation.

    Science.gov (United States)

    Santurtún, Ana; Sanchez-Lorenzo, Arturo; Villar, Alejandro; Riancho, José A; Zarrabeitia, María T

    2017-01-01

    Epidemiological studies suggest that increased ambient NO2 concentrations are associated with cardiovascular disease. However, none of them have examined the association between ambient air pollution and cardiac arrhythmias in the general population in Spain. This paper assesses the short-term association between the aforementioned air pollutant and hospital admissions for arrhythmia in nine different regions of Spain during a 6-year period (2005-2010), and the possible season-specific effects of the compound on this pathology, by performing a time-series analysis based on Poisson regression models. The results show statistically significant positive relationship increases between arrhythmia admissions and increments in NO2 concentration during the whole year, most notably in wintertime. Moreover, while trying to establish a threshold for NO2 concentration above which the incidence of arrhythmia episodes increases significantly, this study reveals that hospital admissions increased linearly in response to an increase in as we move to higher NO2 concentration levels. Finally, an analysis of NO2 concentrations and their relationship with atmospheric circulation is performed, showing higher values of NO2 under anticyclonic conditions during winter that could be used for implementing pollution level alert protocols depending on forecast circulation patterns.

  3. Cu2 + modulated nitrogen-doped grapheme quantum dots as a turn-off/on fluorescence sensor for the selective detection of histidine in biological fluid

    Science.gov (United States)

    Wang, Zhiyu; Fan, ZheFeng

    2018-01-01

    A highly sensitive sensor for detection of histidine (His) based on the nitrogen-doped graphene quantum dots (N-GQDs)-Cu2 + system has been designed. The N-GQDs were synthesized by one-step hydrothermal approach according to previous report. The fluorescence of N-GQDs can be effectively quenched by Cu2 + due to the binding between Cu2 + and functional groups on the surface of N-GQDs. The high affinity of His to Cu2 + enables Cu2 + to be dissociated from the surface of N-GQDs and recovering the fluorescence. The sensor displayed a sensitive response to His in the concentration range of 0-35 μmol L- 1, with a detection limit of 72.2 nmol L- 1. The proposed method is successfully applied to detect His in samples with a recovery range of 96-102%.

  4. Solid-phase synthesis of highly fluorescent nitrogen-doped carbon dots for sensitive and selective probing ferric ions in living cells.

    Science.gov (United States)

    Zhang, Haijuan; Chen, Yonglei; Liang, Meijuan; Xu, Laifang; Qi, Shengda; Chen, Hongli; Chen, Xingguo

    2014-10-07

    Carbon quantum dots (C-Dots) have drawn extensive attention in recent years due to their stable physicochemical and photochemical properties. However, the development of nitrogen-doped carbon quantum dots (N-doped C-Dots) is still on its early stage. In this paper, a facile and high-output solid-phase synthesis approach was proposed for the fabrication of N-doped, highly fluorescent carbon quantum dots. The obtained N-doped C-Dots exhibited a strong blue emission with an absolute quantum yield (QY) of up to 31%, owing to fluorescence enhancement effect of introduced N atoms into carbon dots. The strong coordination of oxygen-rich groups on N-doped C-Dots to Fe(3+) caused fluorescence quenching via nonradiative electron-transfer, leading to the quantitative detection of Fe(3+). The probe exhibited a wide linear response concentration range (0.01-500 μM) to Fe(3+) with a detection limit of 2.5 nM. Significantly, the N-doped C-Dots possess negligible cytotoxicity, excellent biocompatibility, and high photostability. All these features are favorable for label-free monitoring of Fe(3+) in complex biological samples. It was then successfully applied for the fluorescence imaging of intracellular Fe(3+). As an efficient chemosensor, the N-doped C-Dots hold great promise to broaden applications in biological systems.

  5. Nitrogen-rich functional groups carbon nanoparticles based fluorescent pH sensor with broad-range responding for environmental and live cells applications.

    Science.gov (United States)

    Shi, Bingfang; Su, Yubin; Zhang, Liangliang; Liu, Rongjun; Huang, Mengjiao; Zhao, Shulin

    2016-08-15

    A nitrogen-rich functional groups carbon nanoparticles (N-CNs) based fluorescent pH sensor with a broad-range responding was prepared by one-pot hydrothermal treatment of melamine and triethanolamine. The as-prepared N-CNs exhibited excellent photoluminesence properties with an absolute quantum yield (QY) of 11.0%. Furthermore, the N-CNs possessed a broad-range pH response. The linear pH response range was 3.0 to 12.0, which is much wider than that of previously reported fluorescent pH sensors. The possible mechanism for the pH-sensitive response of the N-CNs was ascribed to photoinduced electron transfer (PET). Cell toxicity experiment showed that the as-prepared N-CNs exhibited low cytotoxicity and excellent biocompatibility with the cell viabilities of more than 87%. The proposed N-CNs-based pH sensor was used for pH monitoring of environmental water samples, and pH fluorescence imaging of live T24 cells. The N-CNs is promising as a convenient and general fluorescent pH sensor for environmental monitoring and bioimaging applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Using Fluorescence to Determine the Fate and Bio-reactivity of Dissolved and Particulate Organic Nitrogen in the Neuse River Estuary, North Carolina, USA

    Science.gov (United States)

    Hounshell, A.; Peierls, B. L.; Paerl, H. W.; Osburn, C. L.; Abare, B.

    2016-02-01

    Both terrestrial and autochthonous organic matter in estuarine ecosystems have received increased attention as potential substrates for microbial metabolism and nutrient sources for supporting phytoplankton production, particularly as nitrogen (N) sources in these N-sensitive systems. The fate and bio-reactivity of organic matter within the Neuse River Estuary, North Carolina, USA was examined during nutrient addition bioassays in summer and fall 2014 and summer 2015. In addition to inorganic nutrient additions, the tested terrestrial organic matter sources included river dissolved organic matter, poultry litter extract, and wastewater treatment effluent. Using excitation emission matrices (EEMs) and parallel factor analysis (PARAFAC), identified fluorescent signatures for both dissolved and particulate organic matter were used as a proxy for organic nitrogen. Separate PARAFAC models based on particulate plus dissolved and dissolved organic matter only were generated using bioassay samples. Components identified in each model showed similarities to modeled components previously generated from in situ Neuse River Estuary samples, although some components were unique indicating potential differences in production and degradation pathways in the experimental system. By correlating the modeled fluorescent signatures with other biogeochemical parameters, including phytoplankton production and biomass, the role of organic matter, specifically organic N, in sustaining primary production and nutrient cycling was explored. Preliminary results indicate in situ autochthonous production of organic matter fluorescence due to both phytoplankton and bacterial production and potential biologic degradation of several fluorescent components identified by PARAFAC. The hypothesized results have important implications for managing organic matter (specifically organic N) loading to N-sensitive estuaries downstream from watersheds undergoing rapid agricultural and urban expansion.

  7. Snowpack-atmosphere gas exchanges of carbon dioxide, ozone, and nitrogen oxides at a hardwood forest site in northern Michigan

    Directory of Open Access Journals (Sweden)

    Brian Seok

    2015-03-01

    Full Text Available Abstract Snowpack-atmosphere gas exchanges of CO2, O3, and NOx (NO + NO2 were investigated at the University of Michigan Biological Station (UMBS, a mid-latitude, low elevation hardwood forest site, during the 2007–2008 winter season. An automated trace gas sampling system was used to determine trace gas concentrations in the snowpack at multiple depths continuously throughout the snow-covered period from two adjacent plots. One natural plot and one with the soil covered by a Tedlar sheet were setup for investigating whether the primary source of measured trace gases was biogenic (i.e., from the soil or non-biogenic (i.e., from the snowpack. The results were compared with the “White on Green” study conducted at the Niwot Ridge (NWT Long Term Ecological Research site in Colorado. The average winter CO2 flux ± s.e. from the soil at UMBS was 0.54 ± 0.037 µmol m-2 s-1 using the gradient diffusion method and 0.71 ± 0.012 µmol m-2 s-1 using the eddy covariance method, and in a similar range as found for NWT. Observed snowpack-O3 exchange was also similar to NWT. However, nitrogen oxides (NOx fluxes from snow at UMBS were 10 times smaller than those at NWT, and fluxes were bi-directional with the direction of the flux dependent on NOx concentrations in ambient air. The compensation point for the change in the direction of NOx flux was estimated to be 0.92 nmol mol-1. NOx in snow also showed diurnal dependency on incident radiation. These NOx dynamics in the snow at UMBS were notably different compared to NWT, and primarily determined by snow-atmosphere interactions rather than by soil NOx emissions.

  8. A Thermodynamic Approach to Soil-Plant-Atmosphere Modeling: From Metabolic Biochemical Processes to Water-Carbon-Nitrogen Balance

    Science.gov (United States)

    Clavijo, H. W.

    2016-12-01

    Modeling the soil-plant-atmosphere continuum has been central part of understanding interrelationships among biogeochemical and hydrological processes. Theory behind of couplings Land Surface Models (LSM) and Dynamical Global Vegetation Models (DGVM) are based on physical and physiological processes connected by input-output interactions mainly. This modeling framework could be improved by the application of non-equilibrium thermodynamic basis that could encompass the majority of biophysical processes in a standard fashion. This study presents an alternative model for plant-water-atmosphere based on energy-mass thermodynamics. The system of dynamic equations derived is based on the total entropy, the total energy balance for the plant, the biomass dynamics at metabolic level and the water-carbon-nitrogen fluxes and balances. One advantage of this formulation is the capability to describe adaptation and evolution of dynamics of plant as a bio-system coupled to the environment. Second, it opens a window for applications on specific conditions from individual plant scale, to watershed scale, to global scale. Third, it enhances the possibility of analyzing anthropogenic impacts on the system, benefiting from the mathematical formulation and its non-linearity. This non-linear model formulation is analyzed under the concepts of qualitative system dynamics theory, for different state-space phase portraits. The attractors and sources are pointed out with its stability analysis. Possibility of bifurcations are explored and reported. Simulations for the system dynamics under different conditions are presented. These results show strong consistency and applicability that validates the use of the non-equilibrium thermodynamic theory.

  9. Changes in fungal community composition in response to elevated atmospheric CO2 and nitrogen fertilization varies with soil horizon

    Directory of Open Access Journals (Sweden)

    Carolyn F Weber

    2013-04-01

    Full Text Available Increasing levels of atmospheric carbon dioxide (CO2 and rates of nitrogen (N-deposition to forest ecosystems are predicted to alter the structure and function of soil fungal communities, but the spatially heterogeneous distribution of soil fungi has hampered investigations aimed at understanding such impacts. We hypothesized that soil physical and chemical properties and fungal community composition would be differentially impacted by elevated atmospheric CO2 (eCO2 and N-fertilization in spatially separated field samples, in the forest floor, 0-2 cm, 2-5 cm and 5-10 cm depth intervals in a loblolly pine Free-Air-Carbon Dioxide Enrichment (FACE experiment. In all soils, quantitative PCR-based estimates of fungal biomass were highest in the forest floor. Fungal richness, based on pyrosequencing of the fungal ribosomal large subunit gene, increased in response to N-fertilization in 0-2 cm and forest floor intervals. Composition shifted in forest floor, 0-2 cm and 2-5 cm intervals in response to N-fertilization, but the shift was most distinct in the 0-2 cm interval, in which the largest number of statistically significant changes in soil chemical parameters (i.e phosphorus, organic matter, calcium, pH was also observed. In the 0-2 cm interval, increased recovery of sequences from the Thelephoraceae, Tricholomataceae, Hypocreaceae, Clavicipitaceae, and Herpotrichiellaceae families and decreased recovery of sequences from the Amanitaceae correlated with N-fertilization. In this same depth interval, Amanitaceae, Tricholomataceae and Herpotriciellaceae sequences were recovered less frequently from soils exposed to eCO2 relative to ambient conditions. These results demonstrated that vertical stratification should be taken into consideration in future efforts to elucidate environmental impacts on fungal communities and their feedbacks on ecosystem processes.

  10. Modelling the effects of atmospheric sulphur and nitrogen deposition on selected lakes and streams of the Central Alps (Italy

    Directory of Open Access Journals (Sweden)

    M. Rogora

    2003-01-01

    Full Text Available The dynamic model MAGIC was calibrated and applied to selected sites in north-western Italy (3 rivers, 10 alpine lakes to predict the future response of surface water to different scenarios of atmospheric deposition of S and N compounds. Results at the study sites suggest that several factors other than atmospheric deposition may influence the long-term changes in surface water chemistry. At present the lumped approach of dynamic models such as MAGIC cannot represent all the processes occurring at the catchment scale. Climate warming in particular and its effects on surface water chemistry proved to be important in the study area. Furthermore the river catchments considered here showed clear signs of N saturation. This condition and the increasing concentrations of NO3 in river water were simulated using N dynamics recently included in MAGIC. The modelling performed in this study represents the first application of MAGIC to Italian sites. The results show that inclusion of other factors specific to the Mediterranean area, such as dust deposition and climate change, may improve the fit to observed data and the reliability of the model forecast. Despite these limitations, the model captured well the main trends in chemical data in both rivers and lakes. The outputs clearly demonstrate the benefits of achieving the emission reductions in both S and N compounds as agreed under the Gothenburg Protocol rather than making no further emission reductions. It was also clear that, besides the substantial reduction of SO4 deposition from the peak levels of the 1980s, N deposition must also be reduced in the near future to protect freshwaters from further acidification. Keywords: MAGIC, northern Italy, acidification, recovery, nitrogen saturation

  11. Transport and deposition of nitrogen oxides and ozone in the atmospheric surface layer

    Science.gov (United States)

    Li, Yongxian

    Tropospheric ozone is an important photochemical air pollutant, which increases respiratory-related diseases, decreases crop yields, and causes other environmental problems. This research has focused on the measurement of soil biogenic emissions of nitric oxide (NO), one of the precursors for ozone formation, from intensively managed soils in the Southeast US, and examined the transport and deposition of NOx (NO + NO2) and ozone in the atmospheric surface layer, and the effects of NO emissions and its chemical reactions on ozone flux and deposition to the earth's surface. Emissions of nitric oxide were measured from an intensively managed agricultural soil, in the lower coastal plain of North Carolina (near Plymouth, NC), using a dynamic chamber technique. Measurements of soil NO emissions in several crop canopies were conducted at four different sites in North Carolina during late spring and summer of 1994-1996. The turbulent fluxes of NO2 and O3 at 5 m and 10 m above the ground were measured using the eddy-correlation technique near Plymouth, NC during late spring of 1995 and summer of 1996, concurrent with measurements of soil NO emissions using the dynamic chamber system. Soil NO emission from within the corn field was high averaging approximately 35 ng N/m2/s during the measurement period of 1995. In another study, vertical measurements of ozone were made on a 610 m tall tower located 15 km Southeast of Raleigh, NC during the summers of 1993-1997, as part of an effort by the State of North Carolina to develop a State Implementation Plan (SIP) for ozone control in the Raleigh Metropolitan Statistical Area. A strong correlation was observed between the nighttime and early morning ozone concentrations in the residual layer (CR) above the NBL and the maximum ground level concentration (C o max) the following afternoon. Based on this correlation, an empirical regression equation (Co max = 27.67*exp(0.016 CR)) was developed for predicting maximum ground level ozone

  12. Combined Tree-Ring Carbon and Nitrogen Isotopes to infer past atmospheric deposition in Northeastern Alberta

    Science.gov (United States)

    Savard, M. M.; Bégin, C.; Marion, J.

    2013-12-01

    Monitoring atmospheric emissions from industrial centers in North America is significantly younger than the emitting activities themselves. Attention should be placed on SOx and NOx emissions as they have been increasing over the last 15 years in western Canada. In Northeastern Alberta in particular, two distinct diffuse pollution contexts deserve attention: the Lower Athabasca Oil Sands (OS) district (north of Fort McMurray), and the coal fired power plant (CFPP) area (west of Edmonton). The NOx and SO2 emissions started in 1967 and 1956, but the direct air quality monitoring has been initiated in 1997 and 1985, in these respective contexts. In an attempt to address the gap in emission and deposition monitoring, we explored the δ13C and δ15N patterns of spruce trees (Picea glauca and Picea mariana) growing in four stands in the OS district and one stand, in the CFPP area. Tree-ring series collected from these five sites all covering the 1880-2010 period were analyzed and their δ13C and δ15N values examined along with the climatic parameters and SOx and NOx emission proxies. For two stands in the OS district where soil drainage was poor δ15N series did not vary significantly, but the intermediate and long-term δ13C and δ15N trends inversely correlate in the three other studied stands. For these three sites statistical analyses for the pre-operation calibration periods (1910-1961 and 1900-1951) allowed developing transfer functions and predicting the natural δ13C and δ15N responses to climatic conditions for the operation periods. The measured series all depart from the modeled natural trends, depicting anomalies. Interestingly, the anomalies in the two regions can be nicely reproduced by multiple-regression models combining local climatic parameters with acidifying emissions. Notwithstanding the significant inverse correlations between the δ13C and δ15N series for the three well drained sites and their link to acidifying emissions, it is too early to

  13. Effect of nitrogen addition to ozone generation characteristics by diffuse and filamentary dielectric barrier discharges at atmospheric pressure

    Science.gov (United States)

    Osawa, Naoki; Tsuji, Takafumi; Ogiso, Ryota; Yoshioka, Yoshio

    2017-05-01

    Ozone is widely used for gas treatment, advanced oxidation processes, microorganisms inactivation, etc. In this research, we investigated the effect of nitrogen addition to ozone generation characteristics by atmospheric pressure Townsend discharge (APTD) type and filamentary dielectric barrier discharge (DBD) type ozone generators. The result showed that the ozone generated by the filamentary DBD increases rapidly with the increase of O2 content, and is higher than that by the APTD. On the other hand, it is interesting that the ozone generated by the APTD gradually decreases with the increase of O2 content. In order to clarify why the characteristics of ozone generation by the two kinds of discharge modes showed different dependency to the N2 content, we analyzed the exhaust gas composition using FTIR spectroscopy and calculated the rate coefficients using BOLSIG+ code. As a result, we found that although O2 content decreased with increasing N2 content, additional O atoms produced by excited N2 molecules contribute to ozone generation in case of APTD. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder

  14. Nitrogen isotopes as indicators of NOx source contributions to atmospheric nitrate deposition across the midwestern and northeastern United States

    Science.gov (United States)

    Elliott, E.M.; Kendall, C.; Wankel, Scott D.; Burns, Douglas A.; Boyer, E.W.; Harlin, K.; Bain, D.J.; Butler, T.J.

    2007-01-01

    Global inputs of NOx are dominated by fossil fuel combustion from both stationary and vehicular sources and far exceed natural NOx sources. However, elucidating NOx sources to any given location remains a difficult challenge, despite the need for this information to develop sound regulatory and mitigation strategies. We present results from a regional-scale study of nitrogen isotopes (??15N) in wet nitrate deposition across 33 sites in the midwestern and northeastern U.S. We demonstrate that spatial variations in ??15N are strongly correlated with NOx emissions from surrounding stationary sources and additionally that ??15N is more strongly correlated with surrounding stationary source NOx emissions than pH, SO 42-, or NO3- concentrations. Although emission inventories indicate that vehicle emissions are the dominant NOx source in the eastern U.S., our results suggest that wet NO 3- deposition at sites in this study is strongly associated with NOx emissions from stationary sources. This suggests that large areas of the landscape potentially receive atmospheric NOy deposition inputs in excess of what one would infer from existing monitoring data alone. Moreover, we determined that spatial patterns in ??15N values are a robust indicator of stationary NOx contributions to wet NO3- deposition and hence a valuable complement to existing tools for assessing relationships between NO 3- deposition, regional emission inventories, and for evaluating progress toward NOx reduction goals. ?? 2007 American Chemical Society.

  15. Selective enhancement of the fluorescent pseudomonad population after amending the recirculating nutrient solution of hydroponically grown plants with a nitrogen stabilizer.

    Science.gov (United States)

    Pagliaccia, D; Merhaut, D; Colao, M C; Ruzzi, M; Saccardo, F; Stanghellini, M E

    2008-10-01

    Fluorescent pseudomonads have been associated, via diverse mechanisms, with suppression of root disease caused by numerous fungal and fungal-like pathogens. However, inconsistent performance in disease abatement, after their employment, has been a problem. This has been attributed, in part, to the inability of the biocontrol bacterium to maintain a critical threshold population necessary for sustained biocontrol activity. Our results indicate that a nitrogen stabilizer (N-Serve, Dow Agrosciences) selectively and significantly enhanced, by two to three orders of magnitude, the resident population of fluorescent pseudomonads in the amended (i.e., 25 microg ml(-1) nitrapyrin, the active ingredient) and recycled nutrient solution used in the cultivation of hydroponically grown gerbera and pepper plants. Pseudomonas putida was confirmed as the predominant bacterium selectively enhanced. Terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rDNA suggested that N-Serve selectively increased P. putida and reduced bacterial diversity 72 h after application. In vitro tests revealed that the observed population increases of fluorescent pseudomonads were preceded by an early growth suppression of indigenous aerobic heterotrophic bacteria (AHB) population. Interestingly, the fluorescent pseudomonad population did not undergo this decrease, as shown in competition assays. Xylene and 1,2,4-trimethylbenzene (i.e., the inert ingredients in N-Serve) were responsible for a significant percentage of the fluorescent pseudomonad population increase. Furthermore, those increases were significantly higher when the active ingredient (i.e., nitrapyrin) and the inert ingredients were combined, which suggests a synergistic response. P. putida strains were screened for the ability to produce antifungal compounds and for the antifungal activity against Pythium aphanidermatum and Phytophthora capsici. The results of this study suggest the presence of diverse mechanisms with

  16. Quenching of the OH and nitrogen molecular emission by methane addition in an Ar capacitively coupled plasma to remove spectral interference in lead determination by atomic fluorescence spectrometry

    Science.gov (United States)

    Frentiu, T.; Ponta, M.; Mihaltan, A. I.; Darvasi, E.; Frentiu, M.; Cordos, E.

    2010-07-01

    A new method is proposed to remove the spectral interference on elements in atomic fluorescence spectrometry by quenching of the molecular emission of the OH radical (A 2Σ + → X 2Π) and N 2 second positive system (C 3Π u → B 3Σ g) in the background spectrum of medium power Ar plasmas. The experiments were carried out in a radiofrequency capacitively coupled plasma (275 W, 27.12 MHz) by CH 4 addition. The quenching is the result of the high affinity of OH radical for a hydrogen atom from the CH 4 molecule and the collisions of the second kind between nitrogen excited molecules and CH 4, respectively. The decrease of the emission of N 2 second positive system in the presence of CH 4 is also the result of the deactivation of the metastable argon atoms that could excite the nitrogen molecules. For flow rates of 0.7 l min - 1 Ar with addition of 7.5 ml min - 1 CH 4, the molecular emission of OH and N 2 was completely removed from the plasma jet spectrum at viewing heights above 60 mm. The molecular emission associated to CH and CH 2 species was not observed in the emission spectrum of Ar/CH 4 plasma in the ultraviolet range. The method was experimented for the determination of Pb at 283.31 nm by atomic fluorescence spectrometry with electrodeless discharge lamp and a multichannel microspectrometer. The detection limit was 35 ng ml - 1 , 2-3 times better than in atomic emission spectrometry using the same plasma source, and similar to that in hollow cathode lamp microwave plasma torch atomic fluorescence spectrometry.

  17. The camera of the Pierre Auger Observatory Fluorescence Detector

    CERN Document Server

    Ambrosio, M; Bracci, F; Facal, P; Fonte, R; Gallo, G; Kemp, E; Matthiae, Giorgio; Nicotra, D; Privitera, P; Raia, G; Tusi, E; Vitali, G

    2002-01-01

    The Fluorescence Detector of the Pierre Auger Observatory is a set of telescopes which measure the fluorescence light emitted by atmospheric nitrogen stimulated by the cosmic-ray showers. The Camera is an array of photomultipliers positioned on the telescope focal surface. We describe the main features of the camera: the hexagonal pixels geometry on the spherical focal surface; the light collectors which complement the photomultipliers; the photomultipliers test.

  18. Properties of nitrogen fertilization are decisive in determining the effects of elevated atmospheric CO2 on the activity of nitrate reductase in plants.

    Science.gov (United States)

    Zhang, Ranran; Du, Shaoting

    2016-01-01

    The concentration of atmospheric CO2 is predicted to double by the end of this century. The response of higher plants to an increase in atmospheric CO2 often includes a change in nitrate reductase (NR) activity. In a recent study, we showed that, under elevated CO2 levels, NR induction in low-nitrate plants and NR inhibition in high-nitrate plants are regulated by nitric oxide (NO) generated via nitric oxide synthases. This finding provides an explanation for the diverse responses of plants to elevated CO2 levels, and suggests that the use of nitrogen fertilizers on soil will have a major influence on the nitrogen assimilation capacity of plants in response to CO2 elevation.

  19. An "on-off-on" fluorescent nanoprobe for recognition of chromium(VI) and ascorbic acid based on phosphorus/nitrogen dual-doped carbon quantum dot.

    Science.gov (United States)

    Gong, Xiaojuan; Liu, Yang; Yang, Zhenhua; Shuang, Shaomin; Zhang, Zeyu; Dong, Chuan

    2017-05-22

    Chromium (VI) [Cr(VI)] is a harsh environmental contaminates and has been proved to be highly toxic, carcinogenic and mutagenic. Therefore, developing an inexpensive, good selective and highly sensitive nanoprobe for the detection of Cr(VI) is in urgent demand. Recently, the highly fluorescent carbon quantum dots (CQDs) have been successfully utilized as efficient fluorescent nanoprobes for the detection of ions, pH and molecular substances. In this work, an "on-off" fluorescence phosphorus/nitrogen dual-doped CQDs (PNCQDs) probe was developed for the determination of Cr(VI) based on inner filter effect (IFE). The proposed PNCQDs nanoprobe shows its distinct merits of simplicity, convenience, fast implementation, good selectivity and high sensitivity towards Cr(VI), allowing its potential application in the determination of Cr(VI) in environment and biosystem. In addition, the chelation effect of the functional groups in reductant and Cr(VI), and the easy-conversion of Cr(VI) to reduced states (i.e. Cr(III) and Cr(0)) by reductants makes the minimization of IFE with a concomitant recovery of PNCQDs fluorescence possible. Hence, the PNCQDs/Cr(VI) hybrid was used as an "off-on" fluorescence probe for sensing ascorbic acid (AA), which is a model reductant. For the detection of Cr(VI), the linear range and the limit of detection achieved were 1.5-30 μmol/L and 23 nmol/L, respectively. For the detection of AA, the linear range and the limit of detection obtained were 5.0-200 μmol/L and 1.35 μmol/L, respectively. The as-constructed "on-off-on" PNCQDs fluorescent nanoprobe was successfully applied for detecting Cr(VI) and AA in biosystem. Furthermore, the as-constructed fluorescent sensing system was successfully applied to the analyses of AA in fresh fruits and in commercial fruit juices with satisfactory results. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. A new Open Top Chamber designed to test in situ effects of climatic and atmospheric changes on nitrogen fixation in boreal forest floor mosses

    Science.gov (United States)

    Bringuier, Charline; Bradley, Robert; Bellenger, Jean-Philippe; Morin, Hubert; Lindo, Zoë

    2014-05-01

    Biological nitrogen fixation (BNF) by cyanobacteria dwelling in forest floor moss layers is an important determinant of boreal black spruce forest productivity. Recent studies have suggested that these BNF rates may increase with increasing atmospheric CO2 and increasing temperature, as predicted by current weather models. This potential increase in BNF may be offset, however, by increasing atmospheric deposition of nitrogen, or by increasing demands for phosphorus (i.e. driving nodular ATP content) and for micronutrients such as Mo, Va and Fe (i.e. co-factors of nitrogenase enzyme). In order to study the relative and interactive effects of these factors controlling in situ BNF rates in boreal forest floor moss layers, a new Open Top Chamber (OTC) was developed in summer of 2013. The chambers measure 1.60 cm dia. × 60 cm height, and are equipped with an automated CO2 delivery system designed to maintain atmospheric daytime CO2 concentrations at 800 ppm, as well as buried heating coils that increase soil temperature by 4 ° C for 3 weeks in springtime. These 2 experimental factors are crossed in a full factorial (2 × 2) design that is replicated in 4 complete blocks. Each of the 16 OTCs is divided into 4 compartments, each of which are assigned 1 of 4 sub-plot factors. These include chronic additions of either atmospheric nitrogen, phosphorus, micronutrients or a non-amended control. Staring in summer 2014, a series of measurements will be made to assess the effects of treatments on BNF rates, cyanobacterial colonization and soil nitrogen cycling. Our poster will describe in detail the design and operation of the OTCs, as well as their construction and maintenance costs.

  1. Modification of surface layers of copper under the action of the volumetric discharge initiated by an avalanche electron beam in nitrogen and CO2 at atmospheric pressure

    Science.gov (United States)

    Shulepov, M. A.; Akhmadeev, Yu. Kh.; Tarasenko, V. F.; Kolubaeva, Yu. A.; Krysina, O. V.; Kostyrya, I. D.

    2011-05-01

    The results of experimental investigations of the action of the volumetric discharge initiated by an avalanche electron beam on the surface of copper specimens are presented. The volumetric (diffuse) discharge in nitrogen and CO2 at atmospheric pressure was initiated by applying high voltage pulses of nanosecond duration to a tubular foil cathode. It has been found that the treatment of a copper surface by this type of discharge increases the hardness of the surface layer due to oxidation.

  2. Effects of atmospheric nitrogen oxides on crops. I. Analysis of nitrogen dioxide absorption and utilization by means of /sup 15/N method

    Energy Technology Data Exchange (ETDEWEB)

    Tsuneo, M.; Koji, S.; Tsumugu, T.; Tadakatsu, Y.

    1979-01-01

    This study was made with the intention of obtaining the fundamental knowledge of the behavior of nitrogen dioxide (NO/sub 2/) fumigated against crops in the process of absorption, translocation and assimilation. Sunflower, tomato and corn plants were grown respectively in water culture solutions with graded nitrogen concentration and were fumigated to NO/sub 2/. Concerning the absorption and assimilation of NO/sub 2/ by the crops, analysis were made using /sup 15/N method. The results tested were as follows: Nitrogen dioxides (NO/sub 2/) is mainly absorbed into crops through their leaves and mostly remains there. The conclusion from this fact is that the nitrogen derived from NO/sub 2/ hardly translocates in crops. The NO/sub 2/ absorbed through leaves is almost assimilated to protein. The absorption rate of NO/sub 2/ has no correlation to the nitrogen concentration in water culture solutions. The rates are constant according to the species of crops and the rates of sunflower and tomato plants are great, the rate of corn plants is slow, however. The absorption of NO/sub 2/ is controlled by the dry weight of crops. Crops absorb and utilize NO/sub 2/, whereas their growth is suppressed when they are fumigated to 0.3 ppM NO/sub 2/. 10 references, 1 figure, 4 tables.

  3. Transmission and fluorescence X-ray absorption spectroscopy cell/flow reactor for powder samples under vacuum or in reactive atmospheres

    KAUST Repository

    Hoffman, A. S.

    2016-07-26

    X-ray absorption spectroscopy is an element-specific technique for probing the local atomic-scale environment around an absorber atom. It is widely used to investigate the structures of liquids and solids, being especially valuable for characterization of solid-supported catalysts. Reported cell designs are limited in capabilities—to fluorescence or transmission and to static or flowing atmospheres, or to vacuum. Our goal was to design a robust and widely applicable cell for catalyst characterizations under all these conditions—to allow tracking of changes during genesis and during operation, both under vacuum and in reactive atmospheres. Herein, we report the design of such a cell and a demonstration of its operation both with a sample under dynamic vacuum and in the presence of gases flowing at temperatures up to 300 °C, showing data obtained with both fluorescence and transmission detection. The cell allows more flexibility in catalyst characterization than any reported.

  4. Atmospheric reactive nitrogen concentrations at ten sites with contrasting land use in an arid region of central Asia

    Directory of Open Access Journals (Sweden)

    K. H. Li

    2012-10-01

    Full Text Available Atmospheric concentrations of reactive nitrogen (Nr species from 2009 to 2011 are reported for ten sites in Xinjiang, China, an arid region of central Asia. Concentrations of NH3, NO2, particulate ammonium and nitrate (pNH4+ and pNO3 showed large spatial and seasonal variation and averaged 7.71, 9.68, 1.81 and 1.13 μg N m−3, and PM10 concentrations averaged 249.2 μg m−3 across all sites. Lower NH3 concentrations and higher NO2, pNH4+ and pNO3 concentrations were found in winter, reflecting serious air pollution due to domestic heating in winter and other anthropogenic sources such as increased emissions from motor traffic and industry. The increasing order of total concentrations of Nr species was alpine grassland; desert, desert-oasis ecotone; desert in an oasis; farmland; suburban and urban ecosystems. Lower ratios of secondary particles (NH4+ and NO3 were found in the desert and desert-oasis ecotone, while urban and suburban areas had higher ratios, which implied that anthropogenic activities have greatly influenced local air quality and must be controlled.

  5. Source apportionment of atmospheric ammonia before, during, and after the 2014 APEC summit in Beijing using stable nitrogen isotope signatures

    Directory of Open Access Journals (Sweden)

    Y. Chang

    2016-09-01

    Full Text Available Stable nitrogen isotope composition (δ15N offers new opportunities to address the long-standing and ongoing controversy regarding the origins of ambient ammonia (NH3, a vital precursor of PM2.5 (particulate matters with aerodynamic diameter equal or less than 2.5 µm inorganic components, in the urban atmosphere. In this study, the δ15N values of NH3 samples collected from various sources were constrained using a novel and robust chemical method coupled with standard elemental analysis procedures. Independent of the wide variation in mass concentrations (ranging from 33 (vehicle to over 6000 (human excreta µg m−3, different NH3 sources have generally different δ15N values (ranging from −52.0 to −9.6 ‰. Significantly high δ15N values are seen as a characteristic feature of all vehicle-derived NH3 samples (−14.2 ± 2.8 ‰, which can be distinguished from other sources emitted at environmental temperature (−29.1 ± 1.7, −37.8 ± 3.6, and −50.0 ± 1.8 ‰ for livestock, waste, and fertilizer, respectively. The isotope δ15N signatures for a range of NH3 emission sources were used to evaluate the contributions of the different sources within measured ambient NH3 in Beijing, using an isotope mixing model (IsoSource. The method was used to quantify the sources of ambient NH3 before, during and after the 2014 Asia-Pacific Economic Cooperation (APEC summit, when a set of stringent air quality control measures were implemented. Results show that the average NH3 concentrations (the overall contributions of traffic, waste, livestock, and fertilizer during the three periods were 9.1 (20.3, 28.3, 23.6, and 27.7 %, 7.3 (8.8, 24.9, 14.3, and 52.0 %, and 12.7 (29.4, 23.6, 31.7, and 15.4 % µg m−3, respectively, representing a 20.0 % decrease first and then a 74.5 % increase in overall NH3 mass concentrations. During (after the summit, the contributions of traffic, waste, livestock, and fertilizer

  6. Source apportionment of atmospheric ammonia before, during, and after the 2014 APEC summit in Beijing using stable nitrogen isotope signatures

    Science.gov (United States)

    Chang, Yunhua; Liu, Xuejun; Deng, Congrui; Dore, Anthony J.; Zhuang, Guoshun

    2016-09-01

    Stable nitrogen isotope composition (δ15N) offers new opportunities to address the long-standing and ongoing controversy regarding the origins of ambient ammonia (NH3), a vital precursor of PM2.5 (particulate matters with aerodynamic diameter equal or less than 2.5 µm) inorganic components, in the urban atmosphere. In this study, the δ15N values of NH3 samples collected from various sources were constrained using a novel and robust chemical method coupled with standard elemental analysis procedures. Independent of the wide variation in mass concentrations (ranging from 33 (vehicle) to over 6000 (human excreta) µg m-3), different NH3 sources have generally different δ15N values (ranging from -52.0 to -9.6 ‰). Significantly high δ15N values are seen as a characteristic feature of all vehicle-derived NH3 samples (-14.2 ± 2.8 ‰), which can be distinguished from other sources emitted at environmental temperature (-29.1 ± 1.7, -37.8 ± 3.6, and -50.0 ± 1.8 ‰ for livestock, waste, and fertilizer, respectively). The isotope δ15N signatures for a range of NH3 emission sources were used to evaluate the contributions of the different sources within measured ambient NH3 in Beijing, using an isotope mixing model (IsoSource). The method was used to quantify the sources of ambient NH3 before, during and after the 2014 Asia-Pacific Economic Cooperation (APEC) summit, when a set of stringent air quality control measures were implemented. Results show that the average NH3 concentrations (the overall contributions of traffic, waste, livestock, and fertilizer) during the three periods were 9.1 (20.3, 28.3, 23.6, and 27.7 %), 7.3 (8.8, 24.9, 14.3, and 52.0 %), and 12.7 (29.4, 23.6, 31.7, and 15.4 %) µg m-3, respectively, representing a 20.0 % decrease first and then a 74.5 % increase in overall NH3 mass concentrations. During (after) the summit, the contributions of traffic, waste, livestock, and fertilizer decreased (increased) by 56.7 (234.2), 12.0 (-5.0), 39.4 (120

  7. Element- and charge-state-resolved ion energies in the cathodic arc plasma from composite AlCr cathodes in argon, nitrogen and oxygen atmospheres.

    Science.gov (United States)

    Franz, Robert; Polcik, Peter; Anders, André

    2015-06-25

    The energy distribution functions of ions in the cathodic arc plasma using composite AlCr cathodes were measured as a function of the background gas pressure in the range 0.5 to 3.5 Pa for different cathode compositions and gas atmospheres. The most abundant aluminium ions were Al+ regardless of the background gas species, whereas Cr2+ ions were dominating in Ar and N2 and Cr+ in O2 atmospheres. The energy distributions of the aluminium and chromium ions typically consisted of a high-energy fraction due to acceleration in the expanding plasma plume from the cathode spot and thermalised ions that were subjected to collisions in the plasma cloud. The fraction of the latter increased with increasing background gas pressure. Atomic nitrogen and oxygen ions showed similar energy distributions as the aluminium and chromium ions, whereas the argon and molecular nitrogen and oxygen ions were formed at greater distance from the cathode spot and thus less subject to accelerating gradients. In addition to the positively charged metal and gas ions, negatively charged oxygen and oxygen-containing ions were observed in O2 atmosphere. The obtained results are intended to provide a comprehensive overview of the ion energies and charge states in the arc plasma of AlCr composite cathodes in different gas atmospheres as such plasmas are frequently used to deposit thin films and coatings.

  8. The Influence of CO2 Admixtures on the Product Composition in a Nitrogen-Methane Atmospheric Glow Discharge Used as a Prebiotic Atmosphere Mimic.

    Science.gov (United States)

    Mazankova, V; Torokova, L; Krcma, F; Mason, N J; Matejcik, S

    2016-11-01

    This work extends our previous experimental studies of the chemistry of Titan's atmosphere by atmospheric glow discharge. The Titan's atmosphere seems to be similarly to early Earth atmospheric composition. The exploration of Titan atmosphere was initiated by the exciting results of the Cassini-Huygens mission and obtained results increased the interest about prebiotic atmospheres. Present work is devoted to the role of CO2 in the prebiotic atmosphere chemistry. Most of the laboratory studies of such atmosphere were focused on the chemistry of N2 + CH4 mixtures. The present work is devoted to the study of the oxygenated volatile species in prebiotic atmosphere, specifically CO2 reactivity. CO2 was introduced to the standard N2 + CH4 mixture at different mixing ratio up to 5 % CH4 and 3 % CO2. The reaction products were characterized by FTIR spectroscopy. This work shows that CO2 modifies the composition of the gas phase with the detection of oxygenated compounds: CO and others oxides. There is a strong influence of CO2 on increasing concentration other products as cyanide (HCN) and ammonia (NH3).

  9. Chlorophyll Fluorescence and Gas Exchanges in 'Abbé Fétel'and 'Conference' Pears Stored in Atmosphere Cynamically Controlled with the Aid of Fluorescence Sensors

    NARCIS (Netherlands)

    Eccher Zerbini, P.C.; Grassi, M.

    2010-01-01

    A new technology for monitoring the physiological status of fruit during storage (HarvestWatch™ system with FIRM™ sensors, Satlantic, Canada) was used to detect anaerobic stress in pears by the increase in fluorescence response (Falpha). Two pear cultivars were studied: ‘Conference’, a long-term

  10. Overstory vegetation influence nitrogen and dissolved organic carbon flux from the atmosphere to the forest floor: Boreal Plain, Canada

    Science.gov (United States)

    David E. Pelster; Randall K. Kolka; Ellie E. Prepas

    2009-01-01

    Nitrate, ammonium, total dissolved nitrogen (TDN), dissolved organic nitrogen (DON) and dissolved organic carbon (DOC) concentrations and flux were measured for one year in bulk deposition and throughfall from three stand types (upland deciduous, upland conifer and wetland conifer) on the Boreal Plain, Canada. Annual (November 2006 to October 2007 water year) flux...

  11. Application of a Chemiluminescence Detector for the Measurement of Total Oxides of Nitrogen and Ammonia in the Atmosphere

    Science.gov (United States)

    Hodgeson, J. A.; Bell, J. P.; Rehme, K. A.; Krost, K. J.; Stevens, R. K.

    1971-01-01

    By means of the thermal conversion of nitrogen dioxide to the nitric oxide, the chemiluminescent nitric oxide monitor, based on the nitric oxide plus ozone reaction, may be used for monitoring nitrogen dioxide plus nitric oxide (NO(x)). Under conditions previously described, ammonia is also converted to nitric oxide and therefore interferes. A metal surface, gold wool or stainless steel, operated at two different temperatures has been used to convert only nitrogen dioxide or nitrogen dioxide plus ammonia. Quantitative conversion of nitrogen dioxide to nitric oxide has been obtained at temperatures as low as 200 C. Conversion of ammonia is effected at temperatures of 300 C or higher. By the addition of a converter the basic nitric oxide monitor may be used for measuring NO(x) or NO(x) plus ammonia. As an alternate mode, for a fixed high temperature, a specific scrubber is described for removing NH3 without affecting NO2 concentrations.

  12. Anthropogenic emissions of oxidized sulfur and nitrogen into the atmosphere of the former Soviet Union in 1985 and 1990

    Energy Technology Data Exchange (ETDEWEB)

    Ryaboshapko, A.G.; Brukhanov, P.A.; Gromov, S.A.; Proshina, Yu.V; Afinogenova, O.G. [Institute of Global Climate and Ecology, Moscow (Russian Federation)

    1996-09-01

    Anthropogenic emissions of oxidized sulfur and nitrogen over the former Soviet Union for 1985 and 1990 were calculated on the basis of a combination of `bottom-up` and `top-down` approaches. Sulfur dioxide emissions from combustion of hard coal, brown coal, oil products, natural gas, shale oil, peat, wood as well as from metallurgy, sulfuric acid production, and cement production were estimated. Nitrogen oxides emissions were considered separately for large power plants, small power plants, industrial boilers, residential combustion units, and for transport. The sulfur and nitrogen emissions were spatially distributed over the former Soviet Union with 1 x 1 degree resolution. Data on 721 point sources of sulfur dioxide emissions and on the 242 largest power stations as nitrogen oxides sources were used. The area sources of both sulfur dioxide and nitrogen oxides were distributed according to the population density separately for about 150 administrative units of the former Soviet Union. 63 refs., 19 tabs.

  13. Fluorescence detection using optical waveguide collection device with high efficiency on assembly of nitrogen vacancy centers in diamond

    Science.gov (United States)

    Zhang, Shaowen; Ma, Zongmin; Qin, Li; Fu, Yueping; Shi, Yunbo; Liu, Jun; Li, Yan Jun

    2018-01-01

    In this letter, we propose a fluorescence waveguide excitation and collection (FWEC) method that allows for an excess of 45% collection efficiency of pump photons into optically detected magnetic resonance. The FWEC system used can collect fluorescence 96 times higher than the confocal system under spin manipulation with a microwave. Furthermore, the signal-to-noise ratio (SNR) of the FWEC system is improved 9 times compared with that of the confocal system. In addition, the increase in contrast observed using the FWEC system shows that the integration of the system is much improved with 3D printing technology. Thus, this research has a great potential application in subsequent magnetic detection and quantum optics.

  14. Using Different Regression Methods to Estimate Leaf Nitrogen Content in Rice by Fusing Hyperspectral LiDAR Data and Laser-Induced Chlorophyll Fluorescence Data

    Directory of Open Access Journals (Sweden)

    Lin Du

    2016-06-01

    Full Text Available Nitrogen is an essential nutrient element in crop photosynthesis and yield improvement. Thus, it is urgent and important to accurately estimate the leaf nitrogen contents (LNC of crops for precision nitrogen management. Based on the correlation between LNC and reflectance spectra, the hyperspectral LiDAR (HSL system can determine three-dimensional structural parameters and biochemical changes of crops. Thereby, HSL technology has been widely used to monitor the LNC of crops at leaf and canopy levels. In addition, the laser-induced fluorescence (LIF of chlorophyll, related to the histological structure and physiological conditions of green plants, can also be utilized to detect nutrient stress in crops. In this study, four regression algorithms, support vector machines (SVMs, partial least squares (PLS and two artificial neural networks (ANNs, back propagation NNs (BP-NNs and radial basic function NNs (RBF-NNs, were selected to estimate rice LNC in booting and heading stages based on reflectance and LIF spectra. These four regression algorithms were used for 36 input variables, including the reflectance spectral variables on 32 wavelengths and four peaks of the LIF spectra. A feature weight algorithm was proposed to select different band combinations for the LNC retrieval models. The determination coefficient (R2 and the root mean square error (RMSE of the retrieval models were utilized to compare their abilities of estimating the rice LNC. The experimental results demonstrate that (I these four regression methods are useful for estimating rice LNC in the order of RBF-NNs > SVMs > BP-NNs > PLS; (II The LIF data in two forms, including peaks and indices, display potential in rice LNC retrieval, especially when using the PLS regression (PLSR model for the relationship of rice LNC with spectral variables. The feature weighting algorithm is an effective and necessary method to determine appropriate band combinations for rice LNC estimation.

  15. Changes in susceptibility of beech (Fagus sylvatica) seedlings towards Phytophthora citricola under the influence of elevated atmospheric CO{sub 2} and nitrogen fertilization

    Energy Technology Data Exchange (ETDEWEB)

    Fleischmann, F., E-mail: fleischmann@wzw.tum.d [Phytopathology of Woody Plants, Technische Universitaet Muenchen, Am Hochanger 13, 85354 Freising (Germany); Raidl, S. [Department Biology I and GeoBioCenterLMU, Systematic Mycology, Ludwig Maximilians Universitaet Muenchen, Menzinger Strasse 67, 80638 Muenchen (Germany); Osswald, W.F. [Phytopathology of Woody Plants, Technische Universitaet Muenchen, Am Hochanger 13, 85354 Freising (Germany)

    2010-04-15

    The growth-differentiation balance hypothesis (GDBH) predicts changes in susceptibility of plants against herbivores with changing resource availability. In the presented study we tested the validity of the GDBH for trees infected with a root pathogen. For this purpose Fagus sylvatica seedlings grown under different atmospheric CO{sub 2}- and soil nitrogen regimes were infected with the root pathogen Phytophthora citricola. High nitrogen supply increased total biomass of beech regardless of the CO{sub 2}-treatment, whereas elevated CO{sub 2} enhanced biomass only in the high nitrogen treatment. The responses of beech under the different growing regimes to the Phytophthora root infection were not in line with the predictions of the GDBH. Enhanced susceptibility of beech against P. citricola was found in seedlings grown under elevated CO{sub 2} and low nitrogen supply. Fifteen months after inoculation these plants were characterized by enhanced water use efficiency, by altered root-shoot ratios, and by enhanced specific root tip densities. - Susceptibility of Fagus sylvatica to the root pathogen Phytophthora citricola increased under elevated CO{sub 2}

  16. EnviroAtlas - Atmospheric Nitrogen and Sulfur Deposition by 12-digit HUC for the Conterminous United States (2011)

    Data.gov (United States)

    U.S. Environmental Protection Agency — This EnviroAtlas dataset includes annual nitrogen and sulfur deposition within each 12-digit HUC subwatershed for the year 2011. Values are provided for total...

  17. Comparison of argon-based and nitrogen-based modified atmosphere packaging on bacterial growth and product quality of chicken breast fillets.

    Science.gov (United States)

    Herbert, Ulrike; Rossaint, Sonja; Khanna, Meik-Ankush; Kreyenschmidt, Judith

    2013-05-01

    Poultry fillets were packaged under 6 different gas atmospheres (A: 15% Ar, 60% O2, 25% CO2; B: 15% N2, 60% O2, 25% CO2; C: 25% Ar, 45% O2, 30% CO2; D: 25% N2, 45% O2, 30% CO2; E: 82% Ar; 18% CO2; F: 82% N2, 18% CO2) and stored at 4°C. During storage, the growth of typical spoilage organisms (Brochothrix thermosphacta, Pseudomonas spp., Enterobacteriaceae, and Lactobacilli spp.) and total viable count were analyzed and modeled using the Gompertz function. Sensory analyses of the poultry samples were carried out by trained sensory panelists for color, odor, texture, drip loss, and general appearance. No significant difference in microbiological growth parameters was observed for fresh poultry stored under an argon-enriched atmosphere in comparison with nitrogen, except the B. thermosphacta stored under 82% argon. The sensory evaluation showed a significant effect of an argon-enriched atmosphere, particularly on color of meat stored under 15% argon (P < 0.05). In contrast, 25 and 82% argon concentrations in place of nitrogen showed no beneficial effect on sensory parameters.

  18. Changes in fluorescence spectra of bioaerosols exposed to ozone in a laboratory reaction chamber to simulate atmospheric aging.

    Science.gov (United States)

    Santarpia, Joshua L; Pan, Yong-Le; Hill, Steven C; Baker, Neal; Cottrell, Brian; McKee, Laura; Ratnesar-Shumate, Shanna; Pinnick, Ronald G

    2012-12-31

    A laboratory system for exposing aerosol particles to ozone and rapidly measuring the subsequent changes in their single-particle fluorescence is reported. The system consists of a rotating drum chamber and a single-particle fluorescence spectrometer (SPFS) utilizing excitation at 263 nm. Measurements made with this system show preliminary results on the ultra-violet laser-induced-fluorescence (UV-LIF) spectra of single aerosolized particles of Yersinia rohdei, and of MS2 (bacteriophage) exposed to ozone. When bioparticles are exposed in the chamber the fluorescence emission peak around 330 nm: i) decreases in intensity relative to that of the 400-550 nm band; and ii) shifts slightly toward shorter-wavelengths (consistent with further drying of the particles). In these experiments, changes were observed at exposures below the US Environmental Protection Agency (EPA) limits for ozone.

  19. Multi-model Mean Nitrogen and Sulfur Deposition from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP): Evaluation Historical and Projected Changes

    Science.gov (United States)

    Lamarque, J.-F.; Dentener, F.; McConnell, J.; Ro, C.-U.; Shaw, M.; Vet, R.; Bergmann, D.; Cameron-Smith, P.; Doherty, R.; Faluvegi, G.; hide

    2013-01-01

    We present multi-model global datasets of nitrogen and sulfate deposition covering time periods from 1850 to 2100, calculated within the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). The computed deposition fluxes are compared to surface wet deposition and ice-core measurements. We use a new dataset of wet deposition for 2000-2002 based on critical assessment of the quality of existing regional network data. We show that for present-day (year 2000 ACCMIP time-slice), the ACCMIP results perform similarly to previously published multi-model assessments. For this time slice, we find a multi-model mean deposition of 50 Tg(N) yr1 from nitrogen oxide emissions, 60 Tg(N) yr1 from ammonia emissions, and 83 Tg(S) yr1 from sulfur emissions. The analysis of changes between 1980 and 2000 indicates significant differences between model and measurements over the United States but less so over Europe. This difference points towards misrepresentation of 1980 NH3 emissions over North America. Based on ice-core records, the 1850 deposition fluxes agree well with Greenland ice cores but the change between 1850 and 2000 seems to be overestimated in the Northern Hemisphere for both nitrogen and sulfur species. Using the Representative Concentration Pathways to define the projected climate and atmospheric chemistry related emissions and concentrations, we find large regional nitrogen deposition increases in 2100 in Latin America, Africa and parts of Asia under some of the scenarios considered. Increases in South Asia are especially large, and are seen in all scenarios, with 2100 values more than double 2000 in some scenarios and reaching 1300 mg(N) m2 yr1 averaged over regional to continental scale regions in RCP 2.6 and 8.5, 3050 larger than the values in any region currently (2000). The new ACCMIP deposition dataset provides novel, consistent and evaluated global gridded deposition fields for use in a wide range of climate and ecological studies.

  20. The contribution to nitrogen deposition and ozone formation in South Norway from atmospheric emissions related to the petroleum activity in the North Sea

    Energy Technology Data Exchange (ETDEWEB)

    Solberg, S.; Walker, S.-E.; Knudsen, S.; Lazaridis, M.; Beine, H.J.; Semb, A

    1999-03-01

    A photochemical plume model has been developed and refined. The model is designed to simulate the advection and photochemistry for several simultaneous point sources as well as the atmospheric mixing. the model has been used to calculate nitrogen deposition and ozone formation due to offshore emissions in the North Sea. Based on meteorological data for 1992 the calculations give a total contribution of 60-80 mg (N)/m{sub 2} at most in South Norway. Emission from British and Norwegian sector is calculated to contribute less than 5% each to the AOT40 index for ozone. (author)

  1. Absolute atomic oxygen and nitrogen densities in radio-frequency driven atmospheric pressure cold plasmas: Synchrotron vacuum ultra-violet high-resolution Fourier-transform absorption measurements

    Energy Technology Data Exchange (ETDEWEB)

    Niemi, K.; O' Connell, D.; Gans, T. [York Plasma Institute, Department of Physics, University of York, York YO10 5DD (United Kingdom); Oliveira, N. de; Joyeux, D.; Nahon, L. [Synchrotron Soleil, l' Orme des Merisiers, St. Aubin BP 48, 91192 Gif sur Yvette Cedex (France); Booth, J. P. [Laboratoire de Physique des Plasmas-CNRS, Ecole Polytechnique, 91128 Palaiseau (France)

    2013-07-15

    Reactive atomic species play a key role in emerging cold atmospheric pressure plasma applications, in particular, in plasma medicine. Absolute densities of atomic oxygen and atomic nitrogen were measured in a radio-frequency driven non-equilibrium plasma operated at atmospheric pressure using vacuum ultra-violet (VUV) absorption spectroscopy. The experiment was conducted on the DESIRS synchrotron beamline using a unique VUV Fourier-transform spectrometer. Measurements were carried out in plasmas operated in helium with air-like N{sub 2}/O{sub 2} (4:1) admixtures. A maximum in the O-atom concentration of (9.1 {+-} 0.7) Multiplication-Sign 10{sup 20} m{sup -3} was found at admixtures of 0.35 vol. %, while the N-atom concentration exhibits a maximum of (5.7 {+-} 0.4) Multiplication-Sign 10{sup 19} m{sup -3} at 0.1 vol. %.

  2. The effect of nitrogen in sintered atmosphere of the ferritic stainless steels AISI 430L P/M; Efecto del nitrogeno en la atmosfera de sinterizacion del acero inoxiable ferritico AISI 430L P/M

    Energy Technology Data Exchange (ETDEWEB)

    Corpas, F. A.; Ruiz-Roman, J. M.; Codina, S.; Iglesias, F. J.

    2005-07-01

    In this paper, we have studied the nitrogen effects different sintering atmospheres (nitrogen-hydrogen, and dissociate ammonia) on ferritic stainless steels (430L), fabricated by powder metallurgy process. We have carried out a study of the physical (density, porosity and dimensional variation) and mechanical properties (hardness, tensile strength, and lengthening) of the ferritic stainless steels sintered in the afore-mentioned atmospheres, as well as of their behaviour in pitting corrosion. We have studied, also the microstructure of the steels, which depends on the atmosphere used for sintering. (Author) 13 refs.

  3. Estimates of the atmospheric deposition of sulfur and nitrogen species: Clean Air Status and Trends Network, 1990-2000

    Energy Technology Data Exchange (ETDEWEB)

    Baumgardner, R.E. Jr.; Lavery, T.F.; Rogers, C.M; Isil, S.S. [US Environmental Protection Agency, Research Triangle Park, NC (United States)

    2002-06-15

    The Clean Air Status and Trends Network (CASTNet) was established by the US EPA in response to the requirements of the 1990 Clean Air Act Amendment to assess and report on geographic patterns and long-term, temporal trends in ambient air pollution and acid deposition in order to gauge the effectiveness of current and future mandated emission reductions. This paper presents an analysis of the spatial patterns of deposition of sulfur and nitrogen pollutants for the period 1990-2000. Estimates of deposition are provided for two 4-yr periods: 1990-1993 and 1997-2000 selected to contrast deposition before and after the large decrease in SO{sub 2} emissions that occurred in 1995. An analysis of the deposition estimates showed a significant decline in sulfur deposition and no change in nitrogen deposition. The highest rates of sulfur deposition were observed in the Ohio River Valley and downwind states. This region also observed the largest decline in sulfur deposition. The highest rates of nitrogen deposition were observed in the Midwest from Illinois to southern New York State. Sulfur and nitrogen deposition fluxes were significantly higher in the eastern United States as compared to the western sites. Dry deposition contributed approximately 38% of total sulfur deposition and 30% of total nitrogen deposition in the eastern United States. Percentages are similar for the two 4-yr periods. Wet sulfate and dry SO{sub 2} depositions were the largest contributors to sulfur deposition. Wet nitrate, wet ammonium, and dry HNO{sub 3} deposition were the largest contributors to nitrogen deposition. 40 refs., 14 figs., 4 tabs.

  4. Chlorophyll fluorescence as a predictive method for detection of browning disorders in 'Conference' pears and 'Jonagold' apples during controlled atmosphere storage

    Directory of Open Access Journals (Sweden)

    Saquet Adriano Arriel

    2002-01-01

    Full Text Available The chlorophyll fluorescence technique was evaluated as a possible predictive and nondestructive method to detect low-O2 and/or high-CO2 injuries in 'Conference' pears and 'Jonagold' apples stored in controlled atmosphere (CA. The fruits were kept at 0°C in air, 1% CO2 + 2% O2 or 3% CO2 + 1% O2 during five months. Fluorescence parameters of minimal fluorescence (Fo, maximal fluorescence (Fm, and potential quantum yield - (Fm-Fo:Fm, also denoted as Fv:Fm- as well as the incidence of browning disorders were evaluated at several times during storage. No incidence of browning disorders was observed in 'Jonagold' apples, however, they showed a decrease in Fv:Fm during storage time with no differences between the CA-conditions. Air-stored apples showed a higher decrease in Fv:Fm. On the other hand, 'Conference' pears kept in 3% CO2 + 1% O2 developed a lot of browning injuries such as core flush, flesh browning and cavities. Under this CA-condition, a pronounced decrease in the quotient Fv:Fm was observed already in the first 15 days of storage prior to the development of browning, and this behaviour remained during the whole storage period. The air-stored pears showed a similar behaviour as of the air-stored apples with a pronounced decrease in the Fv:Fm at the end of the storage period. The present results indicate that chlorophyll fluorescence is a promising technique to detect browning injuries in 'Conference' pears prior to their development.

  5. Estimation of carbon sequestration in China’s forests induced by atmospheric wet nitrogen deposition using the principles of ecological stoichiometry

    Science.gov (United States)

    Zhu, Jianxing; He, Nianpeng; Zhang, Jiahui; Wang, Qiufeng; Zhao, Ning; Jia, Yanlong; Ge, Jianping; Yu, Guirui

    2017-11-01

    The worldwide development of industry and agriculture has generated noticeable increases in atmospheric nitrogen (N) deposition, significantly altering the global N cycle. These changes might affect the global carbon (C) cycle by enhancing forest C sequestration. Here, we used a series of datasets from eight typical forests along the north–south transect of eastern China (NSTEC). These datasets contained information on community structure, C and N concentrations in the soil and the organs (leaf, branch, stem, and fine-root) of 877 plant species, and atmospheric wet N deposition. Using the biomass weighting method, we scaled up the C:N ratios from the organ level to the ecosystem level, and evaluated the C sequestration rate (CSRN) in response to wet N deposition and N use efficiency (NUE) in China’s forests based on the principles of ecological stoichiometry. Our results showed that atmospheric wet N deposition had a modest impact on forest C storage. Specifically, mean CSRN was estimated as 231 kg C ha‑1 yr‑1 (range: 32.7–507.1 kg C ha‑1 yr‑1), accounting for 2.1% of NPP and 4.6% of NEP at the ecosystem level. The NUEeco of atmospheric N deposition ranged from 9.6‑27.7 kg C kg‑1 N, and increased with increasing latitude from subtropical to cold-temperate forests in China (P forest C sequestration based on the principles of ecological stoichiometry.

  6. Chapters in the industrial history of plasma arcs: The precursors (1800-1900); fixation of atmospheric nitrogen (1898-1920)

    Science.gov (United States)

    Bailleux, C.

    1981-12-01

    Early experiments involving plasma arc discharges are recalled, including Humphry Davy's electric egg, and Birkeland's disastrous attempt to build an electric cannon. The development of arc furnaces is traced, and the search for new sources of nitrogen at the turn of the century is described.

  7. Methane oxidation in soil profiles of Dutch and Finnish coniferous forests with different soil texture and atmospheric nitrogen deposition

    NARCIS (Netherlands)

    Saari, A.; Martikainen, P.J.; Ferm, A.; Ruuskanen, J.; De Boer, W.; Troelstra, S.R.; Laanbroek, H.J.

    1997-01-01

    We studied methane oxidation capacity in soil profiles of Dutch and Finnish coniferous forests. The Finnish sites (n = 9) had nitrogen depositions from 3 to 36 kg N ha(-1) a(-1). The deposition of N on the Dutch sites (n = 13) was higher ranging from 50 to 92 kg N ha(-1) a(-1). The Dutch sites had

  8. Attributes for MRB_E2RF1 Catchments by Major River Basins in the Conterminous United States: Average Atmospheric (Wet) Deposition of Inorganic Nitrogen, 2002

    Science.gov (United States)

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This tabular data set represents the average atmospheric (wet) deposition, in kilograms per square kilometer, of inorganic nitrogen for the year 2002 compiled for every catchment for MRB_E2RF1 of Major River Basins (MRBs, Crawford and others, 2006). The source data set for wet deposition was from the USGS's raster data set atmospheric (wet) deposition of inorganic nitrogen for 2002 (Gronberg, 2005). The MRB_E2RF1 catchments are based on a modified version of the U.S. Environmental Protection Agency's (USEPA) ERF1_2 and include enhancements to support national and regional-scale surface-water quality modeling (Nolan and others, 2002; Brakebill and others, 2011). Data were compiled for every catchment of MRB_E2RF1 catchments for the conterminous United States covering New England and Mid-Atlantic (MRB1), South Atlantic-Gulf and Tennessee (MRB2), the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy (MRB3), the Missouri (MRB4), the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf (MRB5), the Rio Grande, Colorado, and the Great basin (MRB6), the Pacific Northwest (MRB7) river basins, and California (MRB8).

  9. Fast, highly selective and sensitive anionic metal-organic framework with nitrogen-rich sites fluorescent chemosensor for nitro explosives detection.

    Science.gov (United States)

    Wang, Xu-Sheng; Li, Lan; Yuan, Da-Qiang; Huang, Yuan-Biao; Cao, Rong

    2018-02-15

    Developing a highly efficient fluorescent sensor for detection of trace amounts of nitro explosives remains a great challenge. Porous metal-organic frameworks (MOFs) are one class of promising fluorescent sensors towards small molecules. Herein, we constructed an anionic Zn-based MOF FJI-C8 based on π-conjugated aromatic ligand H6TDPAT (2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine) containing nitrogen-rich sites. On account of the high density of uncoordinated N atoms, the high overlap between the emission spectrum of the anionic MOF FJI-C8 and the UV-vis absorption spectrum of the representative nitro explosive 2,4-dinitrophenol (2,4-DNP), and the porosity of the MOF, FJI-C8 is demonstrated to be an excellent chemosensor for 2,4-DNP with fast response time (less than 30s), high selectivity (Ksv=5.11×104M-1 for 2,4-DNP), extra sensitivity (LOD=0.002866mM for 2,4-DNP), low usage amount (0.04mg/mL), good stability and quantitative detection features. To the best of our knowledge, this is the first example for highly selective detection of 2,4-DNP. More importantly, theoretical calculation and control experiments unveiled that the energy transfer is the main mechanism for highly detection of 2,4-DNP. This work will pave the way for designing highly efficient luminescent chemosensors. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. The Seasonal Cycle of Satellite Chlorophyll Fluorescence Observations and its Relationship to Vegetation Phenology and Ecosystem Atmosphere Carbon Exchange

    Science.gov (United States)

    Joiner, J.; Yoshida, Y.; Vasilkov, A. P.; Schaefer, K.; Jung, M.; Guanter, L.; Zhang, Y; Garrity, S.; Middleton, E. M.; Huemmrich, K. F.; hide

    2014-01-01

    Mapping of terrestrial chlorophyll uorescence from space has shown potentialfor providing global measurements related to gross primary productivity(GPP). In particular, space-based fluorescence may provide information onthe length of the carbon uptake period that can be of use for global carboncycle modeling. Here, we examine the seasonal cycle of photosynthesis asestimated from satellite fluorescence retrievals at wavelengths surroundingthe 740nm emission feature. These retrievals are from the Global OzoneMonitoring Experiment 2 (GOME-2) flying on the MetOp A satellite. Wecompare the fluorescence seasonal cycle with that of GPP as estimated froma diverse set of North American tower gas exchange measurements. Because the GOME-2 has a large ground footprint (40 x 80km2) as compared with that of the flux towers and requires averaging to reduce random errors, we additionally compare with seasonal cycles of upscaled GPP in the satellite averaging area surrounding the tower locations estimated from the Max Planck Institute for Biogeochemistry (MPI-BGC) machine learning algorithm. We also examine the seasonality of absorbed photosynthetically-active radiation(APAR) derived with reflectances from the MODerate-resolution Imaging Spectroradiometer (MODIS). Finally, we examine seasonal cycles of GPP as produced from an ensemble of vegetation models. Several of the data-driven models rely on satellite reflectance-based vegetation parameters to derive estimates of APAR that are used to compute GPP. For forested sites(particularly deciduous broadleaf and mixed forests), the GOME-2 fluorescence captures the spring onset and autumn shutoff of photosynthesis as delineated by the tower-based GPP estimates. In contrast, the reflectance-based indicators and many of the models tend to overestimate the length of the photosynthetically-active period for these and other biomes as has been noted previously in the literature. Satellite fluorescence measurements therefore show potential for

  11. Methodology to assess and map the potential development of forest ecosystems exposed to climate change and atmospheric nitrogen deposition: A pilot study in Germany.

    Science.gov (United States)

    Schröder, Winfried; Nickel, Stefan; Jenssen, Martin; Riediger, Jan

    2015-07-15

    A methodology for mapping ecosystems and their potential development under climate change and atmospheric nitrogen deposition was developed using examples from Germany. The methodology integrated data on vegetation, soil, climate change and atmospheric nitrogen deposition. These data were used to classify ecosystem types regarding six ecological functions and interrelated structures. Respective data covering 1961-1990 were used for reference. The assessment of functional and structural integrity relies on comparing a current or future state with an ecosystem type-specific reference. While current functions and structures of ecosystems were quantified by measurements, potential future developments were projected by geochemical soil modelling and data from a regional climate change model. The ecosystem types referenced the potential natural vegetation and were mapped using data on current tree species coverage and land use. In this manner, current ecosystem types were derived, which were related to data on elevation, soil texture, and climate for the years 1961-1990. These relations were quantified by Classification and Regression Trees, which were used to map the spatial patterns of ecosystem type clusters for 1961-1990. The climate data for these years were subsequently replaced by the results of a regional climate model for 1991-2010, 2011-2040, and 2041-2070. For each of these periods, one map of ecosystem type clusters was produced and evaluated with regard to the development of areal coverage of ecosystem type clusters over time. This evaluation of the structural aspects of ecological integrity at the national level was added by projecting potential future values of indicators for ecological functions at the site level by using the Very Simple Dynamic soil modelling technique based on climate data and two scenarios of nitrogen deposition as input. The results were compared to the reference and enabled an evaluation of site-specific ecosystem changes over time

  12. Carbon-Nitrogen-Oxygen Line Radiation and the X-ray Bowen Fluorescence Mechanism in Optically Thick, Highly Ionized Media

    Science.gov (United States)

    Sako, Masao

    2003-01-01

    Radiative transfer effects due to overlapping X-ray lines in a high-temperature, optically thick, highly ionized medium are investigated. One particular example, in which the O VIII Lyalpha doublet (2(sup 2) P(sub 1/2,3/2)-1(sup 2) S(sub 1/2) coincides in frequency with the N VII Lyzeta lines (7(sup 2) P(sub 1/2,3/2)-1(sup 2) S(sub 1/2) is studied in detail to illustrate the effects on the properties of the emergent line spectrum. We solve the radiative transfer equation to study the energy transport of resonance-line radiation in a static, infinite, plane-parallel geometry, which is used to compute the destruction/escape probabilities for each of the lines for various total optical thicknesses of the medium, as well as destruction probabilities by sources of underlying photoelectric opacity. It is found that a large fraction of the O vIII Lyalpha line radiation can be destroyed by N VII, which can result in a reversal of the O VIII Lyalpha/N VII Lyalpha line intensity ratio similar to what may be seen under nonsolar abundances. Photoelectric absorption by ionized carbon and nitrogen can also subsequently increase the emission-line intensities of these ions. We show that line ratios, which are directly proportional to the abundance ratios in optically thin plasmas, are not good indicators of the true CNO abundances. Conversely, global spectral modeling that assumes optically thin conditions may yield incorrect abundance estimates when compared with observations, especially if the optical depth is large. Other potentially important overlapping lines and continua in the X-ray band are also identified, and their possible relevance to recent high-resolution spectroscopic observations with Chandra and XMM-Newton are briefly discussed.

  13. Spectrophotometry near the atmospheric cutoff of the strongest Bowen resonance fluorescence lines of O III in two planetary nebulae

    Science.gov (United States)

    O'Dell, C. R.; Opal, Chet B.

    1989-01-01

    Spectrophotometric results are presented for the stronger, well-resolved Bowen O III resonance fluorescence emission lines in the planetary nebulae 7027 and NGC 7662 down to and including the intrinsically strong line at 3133 A. These data are combined with results from the IUE atlas of spectra and similar results for the longer wavelength lines by Likkel and Aller (1986) to give the first full coverage of the Bowen lines. Good agreement is found with fluorescence theory for the primary cascade lines, except for the Likkel and Aller results. The efficiency of conversion of the exciting He II Ly-alpha into O III lines is determined, and values comparable to other planetary nebulae are found.

  14. Hydride generation atomic fluorescence spectrometric determination of As, Bi, Sb, Se(IV) and Te(IV) in aqua regia extracts from atmospheric particulate matter using multivariate optimization

    Energy Technology Data Exchange (ETDEWEB)

    Moscoso-Perez, Carmen [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Moreda-Pineiro, Jorge [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain)]. E-mail: jmoreda@udc.es; Lopez-Mahia, Purificacion [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Muniategui-Lorenzo, Soledad [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Fernandez-Fernandez, Esther [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain); Prada-Rodriguez, Dario [Department of Analytical Chemistry, Faculty of Sciences, University of A Coruna, Campus da Zapateira s/n, E-15071 A Coruna (Spain)

    2004-11-22

    A highly sensitive and simple method, based on hydride generation and atomic fluorescence detection, has been developed for the determination of As, Bi, Sb, Se(IV) and Te(IV) in aqua regia extracts from atmospheric particulate matter samples. Atmospheric particulates matter was collected on glass fiber filters using a medium volume sampler (PM1 particulate matter). Two-level factorial designs have been used to optimise the hydride generation atomic fluorescence spectrometry (HG-AFS) procedure. The effects of several parameters affecting the hydride generation efficiency (hydrochloric acid, sodium tetrahydroborate and potassium iodide concentrations and flow rates) have been evaluated using a Plackett-Burman experimental design. In addition, parameters affecting the hydride measurement (delay, analysis and memory times) have been also investigated. The significant parameters obtained (sodium tetrahydroborate concentration, sodium tetrahydroborate flow rate and analysis time for As; hydrochloric acid concentration and sodium tetrahydroborate flow rate for Se(IV); and sodium tetrahydroborate concentration and sodium tetrahydroborate flow rate for Te(IV)) have been optimized by using 2{sup n} + star central composite design. Hydrochloric acid concentration and sodium tetrahydroborate flow rate were the significant parameters obtained for Sb and Bi determination, respectively. Using a univariate approach these parameters were optimized. The accuracy of methods have been verified by using several certified reference materials: SRM 1648 (urban particulate matter) and SRM 1649a (urban dust). Detection limits in the range of 6 x 10{sup -3} to 0.2 ng m{sup -3} have been achieved. The developed methods were applied to several atmospheric particulate matter samples corresponding to A Coruna city (NW Spain)

  15. COMPARISON OF FEMTOSECOND AND NANOSECOND TWO PHOTON ABSORPTION LASER INDUCED FLUORESCENCE (TALIF) OF ATOMIC OXYGEN IN ATMOSPHERIC PRESSURE PLASMAS

    Science.gov (United States)

    2016-08-01

    Division (AFRL/RQQE) Combustion Branch, Turbine Engine Division (AFRL/RQTC) Jacob B. Schmidt and Sukesh Roy Spectral Energies LLC Brian Sands ...quenching coefficient, kqi. The effective quenching coefficient is measured by directly monitoring the fluorescence decay in both the plasma jet and...gas added directly to the unpowered helium jet for signal calibration [Van Gessel et al. 2013]. In this method, effective branching ratios aXe were

  16. Increasing the speed of computational fluid dynamics procedure for minimization the nitrogen oxide polution from the premixed atmospheric gas burner

    Directory of Open Access Journals (Sweden)

    Fotev Vasko G.

    2017-01-01

    Full Text Available This article presents innovative method for increasing the speed of procedure which includes complex computational fluid dynamic calculations for finding the distance between flame openings of atmospheric gas burner that lead to minimal NO pollution. The method is based on standard features included in commercial computational fluid dynamic software and shortens computer working time roughly seven times in this particular case.

  17. [Methodology of the description of atmospheric air pollution by nitrogen dioxide by land use regression method in Ekaterinburg].

    Science.gov (United States)

    Antropov, K M; Varaksin, A N

    2013-01-01

    This paper provides the description of Land Use Regression (LUR) modeling and the result of its application in the study of nitrogen dioxide air pollution in Ekaterinburg. The paper describes the difficulties of the modeling for air pollution caused by motor vehicles exhaust, and the ways to address these challenges. To create LUR model of the NO2 air pollution in Ekaterinburg, concentrations of NO2 were measured, data on factors affecting air pollution were collected, a statistical analysis of the data were held. A statistical model of NO2 air pollution (coefficient of determination R2 = 0.70) and a map of pollution were created.

  18. Potential of chlorophyll fluorescence and VIS/NIR spectroscopy measurement use for the detection of nitrogen content and disease infection of apple leaves

    Directory of Open Access Journals (Sweden)

    Václava Spáčilová

    2011-01-01

    Full Text Available A possibility of using spectral methods for determining a nutritional status and detecting pathogens in apple-tree cvs. ’Jonagold’ and ’Idared’ was verified in an orchard and pot experiments in 2007–2010. Treatments differed in the fertilizer or fungicide dose. Leaf samples were collected from the experimental variants to determine nitrogen content and to measure spectral reflectance (spectrophotometer Avantes USB 2000 and chlorophyll fluorescence imaging (FluorCam. Results of the measurements were correlated to leaf analyses for nitrogen content in dry matter. At the same time, a health status (the occurrence of fungal pathogens Venturia inaequalis and Podosphaera leucotricha was assessed and changes of photochemical efficiency of PSII of infected leaves were evaluated. The parameters providing the best description of differences in the photosynthetic activity of leaves depending on treatments (parameter Fv/Fm and parameter GENTY, known as ΦPSII – effective quantum yield of PSII were selected. The values of correlation coefficients of Fv/Fm and ΦPSII depending on fertilization treatments were as follows: Fv/Fm: r = −0.4735, p<0.000089, α = 0.05; ΦPSII: r = 0.755; p < 0.00038, α = 0.05. Data obtained from measuring with a spectrophotometer was used for the calculation to normalized difference vegetation indices NDVI; a significant relationship was found for the index GNDVI (r = 0.4691, p < 0,0002, α = 0.05. The significant difference between healthy leaves and leaves infected by the pathogens V. inaequalis and P. leucotricha was confirmed using the spectrophotometer, and the largest differences in reflectances were found in wavelengths around 400 nm. The values of indices GNDVI, RNDVI and NDVI 450 obtained from measuring reflectance of leaves with symptoms of V. inaequalis and P. leucotricha infections were significantly lower compared to the indices of healthy leaves. The values of indices NDVI were as follows: GNDVI 0

  19. Atmospheric dry deposition of inorganic and organic nitrogen to the Bay of Bengal: Impact of continental outflow

    Digital Repository Service at National Institute of Oceanography (India)

    Srinivas, B.; Sarin, M.M.; Sarma, V.V.S.S.

    -AES. The detailed description for the measurements of trace metals and carbonaceous species has been described in earlier publications (Rengarajan et al., 2007). 3. Results and Discussions 6 3.1. Air mass back trajectory analysis Air mass back... trajectories (AMBTs) have been used to trace the possible source regions of aerosols at the sampling site along with the cruise track (Fig. 1a). Seven-day air mass back trajectories are computed from the National Oceanic and Atmospheric Administration (NOAA...

  20. Atmospheric pressure glow discharge generated in nitrogen-methane gas mixture: PTR-MS analyzes of the exhaust gas

    Science.gov (United States)

    Torokova, Lucie; Mazankova, Vera; Krcma, Frantisek; Mason, Nigel J.; Matejcik, Stefan

    2015-07-01

    This paper reports the results of an extensive study of with the in situ mass spectrometry analysis of gaseous phase species produced by an atmospheric plasma glow discharge in N2-CH4 gas mixtures (with methane concentrations ranging from 1% to 4%). The products are studied using proton-transfer-reaction mass spectrometry (PTR-MS). HCN and CH3CN are identified as the main gaseous products. Hydrazine, methanimine, methyldiazene, ethylamine, cyclohexadiene, pyrazineacetylene, ethylene, propyne and propene are identified as minor compounds. All the detected compounds and their relative abundances are determined with respect to the experimental conditions (gas composition and applied power). The same molecules were observed by the Cassini-Huygens probe in Titan's atmosphere (which has same N2-CH4 gas mixtures). Such, experiments show that the formation of such complex organics in atmospheres containing C, N and H, like that of Titan, could be a source of prebiotic molecules. Contribution to the topical issue "The 14th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XIV)", edited by Nicolas Gherardi, Ronny Brandenburg and Lars Stollenwark

  1. Discussion of "Atmospheric deposition as an important nitrogen load to a typical agro-ecosystem in the Huang-Huai-Hai Plain" by Huang et al. (2016)

    Science.gov (United States)

    Pan, Yuepeng; Xu, Wen; Wentworth, Gregory R.; Tian, Shili

    2017-03-01

    In a recent publication of Atmospheric Environment, Huang et al. (2016) reported nitrogen (N) deposition estimates using the water surrogate surface method. This method may be suitable to evaluate the atmospheric N input to a body of water, wetland or paddy fields rather than dry crop land without sustained waterlogged conditions. Such a method may also result in the potential underestimation of both dry and wet N deposition due to the release of ammonia (NH3) from water evaporation and/or N loss from biological activities, and hence bias the relative contribution of dry deposition to total deposition. Besides the uncertainties regarding the magnitude and pathways of N deposition, the statement by Huang et al. (2016) that "nitrate was the dominant species in N deposition even in cropland" is also questionable. We suggest that reduced species dominate the N deposition in Huang-Huai-Hai Plain (i.e., North China Plain) even in urban and industrial regions due to the abundance of NH3.

  2. Spatially valid data of atmospheric deposition of heavy metals and nitrogen derived by moss surveys for pollution risk assessments of ecosystems.

    Science.gov (United States)

    Schröder, Winfried; Nickel, Stefan; Schönrock, Simon; Meyer, Michaela; Wosniok, Werner; Harmens, Harry; Frontasyeva, Marina V; Alber, Renate; Aleksiayenak, Julia; Barandovski, Lambe; Carballeira, Alejo; Danielsson, Helena; de Temmermann, Ludwig; Godzik, Barbara; Jeran, Zvonka; Karlsson, Gunilla Pihl; Lazo, Pranvera; Leblond, Sebastien; Lindroos, Antti-Jussi; Liiv, Siiri; Magnússon, Sigurður H; Mankovska, Blanka; Martínez-Abaigar, Javier; Piispanen, Juha; Poikolainen, Jarmo; Popescu, Ion V; Qarri, Flora; Santamaria, Jesus Miguel; Skudnik, Mitja; Špirić, Zdravko; Stafilov, Trajce; Steinnes, Eiliv; Stihi, Claudia; Thöni, Lotti; Uggerud, Hilde Thelle; Zechmeister, Harald G

    2016-06-01

    For analysing element input into ecosystems and associated risks due to atmospheric deposition, element concentrations in moss provide complementary and time-integrated data at high spatial resolution every 5 years since 1990. The paper reviews (1) minimum sample sizes needed for reliable, statistical estimation of mean values at four different spatial scales (European and national level as well as landscape-specific level covering Europe and single countries); (2) trends of heavy metal (HM) and nitrogen (N) concentrations in moss in Europe (1990-2010); (3) correlations between concentrations of HM in moss and soil specimens collected across Norway (1990-2010); and (4) canopy drip-induced site-specific variation of N concentration in moss sampled in seven European countries (1990-2013). While the minimum sample sizes on the European and national level were achieved without exception, for some ecological land classes and elements, the coverage with sampling sites should be improved. The decline in emission and subsequent atmospheric deposition of HM across Europe has resulted in decreasing HM concentrations in moss between 1990 and 2010. In contrast, hardly any changes were observed for N in moss between 2005, when N was included into the survey for the first time, and 2010. In Norway, both, the moss and the soil survey data sets, were correlated, indicating a decrease of HM concentrations in moss and soil. At the site level, the average N deposition inside of forests was almost three times higher than the average N deposition outside of forests.

  3. Total Peroxy Nitrates (ΣPNs in the atmosphere: the Thermal Dissociation-Laser Induced Fluorescence (TD-LIF technique and comparisons to speciated PAN measurements

    Directory of Open Access Journals (Sweden)

    B. W. LaFranchi

    2010-05-01

    Full Text Available Peroxyacetyl nitrate (PAN and its chemical analogues are increasingly being quantified in the ambient atmosphere by thermal dissociation (TD followed by detection of either the peroxyacyl radical or the NO2 product. Here we present details of the technique developed at University of California, Berkeley which detects the sum of all peroxynitrates (ΣPNs via laser-induced fluorescence (LIF of the NO2 product. We review the various deployments and compare the Berkeley ΣPNs measurements with the sums of PAN and its homologue species detected individually by other instruments. The observed TD-LIF ΣPNs usually agree to within 10% with the summed individual species, thus arguing against the presence of significant concentrations of unmeasured PAN-type compounds in the atmosphere, as suggested by some photochemical mechanisms. Examples of poorer agreement are attributed to a sampling inlet design that is shown to be inappropriate for high NOx conditions. Interferences to the TD-LIF measurements are described along with strategies to minimize their effects.

  4. Influence of atmospheric [CO2] on growth, carbon allocation and cost of plant tissues on leaf nitrogen concentration maintenance in nodulated Medicago sativa

    Science.gov (United States)

    Pereyra, Gabriela; Hartmann, Henrik; Ziegler, Waldemar; Michalzik, Beate; Gonzalez-Meler, Miquel; Trumbore, Susan

    2015-04-01

    Plant carbon (C) allocation and plant metabolic processes (i.e. photosynthesis and respiration) can be affected by changes in C availability, for example from changing atmospheric [CO2]. In nodulated plants, C availability may also influence nitrogen (N) fixation by bacteriods. But C allocation and N fixation are often studied independently and hence do not allow elucidating interactive effects. We investigated how different atmospheric [CO2] (Pleistocene: 170 ppm, ambient: 400 ppm and projected future: 700 ppm) influence plant growth, allocation to nodules, and the ratio of photosynthesis-to-respiration (R:A) as an indicator of C cost in Medicago sativa inoculated with Ensifer meliloti. M. sativa grew c. 38% more nodules at 400 ppm and 700 ppm than at 170 ppm. However, ratios of above- and belowground plant biomass to nodule biomass were constant over time and independent of atmospheric [CO2]. Total non-structural carbohydrate concentrations were not significantly different between plants grown at 400 and 700 ppm, but were four to five-fold higher than in 170 ppm plants. Leaf level N concentration was similar across treatments, but N-based photosynthetic rates were 82% and 93% higher in leaves of plants grown at 400 and 700 ppm, respectively, than plants grown at 170 ppm. In addition, leaf R:A was greater (48% or 55%) in plants grown at 170 ppm than plants grown at 400 and 700 ppm. Similarly, the greatest proportion of assimilated CO2 released by root respiration occurred in rhizobial plants growing at 170 ppm. Our results suggest that C limitation in nodulated Medicago sativa plants did not influence C allocation to nodule biomass but caused a proportionally greater allocation of C to belowground respiration, most likely to bacteriods. This suggests that N tissue concentration was maintained at low [CO2] by revving up bacteriod metabolism and at the expense of non-structural carbohydrate reserves.

  5. Development and Study of Hard-Facing Materials on the Base of Heat-Resisting High-Hardness Steels for Plasma-Jet Hard- Facing in Shielding-Doping Nitrogen Atmosphere

    Science.gov (United States)

    Malushin, N. N.; Kovalev, A. P.; Valuev, D. V.; Shats, E. A.; Borovikov, I. F.

    2016-08-01

    The authors develop hard-facing materials on the base of heat-resisting highhardness steels for plasma-jet hard-facing in nitrogen atmosphere for manufacturing parts of mining and metallurgic equipment which significantly simplify the production process and effect a saving when producing bimetallic parts and tools.

  6. Effect of Heat Treatment Under Nitrogen Atmosphere on Sprayed Fluorine Doped In2O3 Thin Films

    Science.gov (United States)

    Beji, Nasreddine; Ajili, Mejda; Turki, Najoua Kamoun

    2016-07-01

    Fluorine-doped indium oxide thin films (In2O3:F) were prepared at 500°C for different fluorine concentrations (0 at.%, 2 at.%, 6 at.% and 10 at.%) using the chemical spray pyrolysis technique. Structure and surface morphology of these films were characterized by x-ray diffraction (XRD) and atomic force microscopy (AFM). XRD analysis revealed that fluorine doped In2O3 thin films exhibit a centered cubic structure with the (400) preferential orientation. The change of the preferential reflection plane from (222) to (400) was found after doping. The doping optimum concentration of thin film crystal structure is obtained witha fluorine ratio equal to 2 at.%. The crystallinity improvement of In2O3:F (2 at.%) film is detected after annealing at 200°C, 300°C, and 400°C in nitrogen gas for 45 min. Transmission and reflection spectra measurements were performed over the wavelength range of 250-2500 nm. The band gap energy increase from 3.10 eV to 3.45 eV was detected after treatment at 400°C. In parallel, the electrical resistivity, deduced from Hall effect measurements, decreases from 428.90 × 10-4 Ω cm to 6.58 × 10-4 Ω cm.

  7. Observations of atmosphere-biosphere exchange of total and speciated peroxynitrates: nitrogen fluxes and biogenic sources of peroxynitrates

    Directory of Open Access Journals (Sweden)

    K.-E. Min

    2012-10-01

    Full Text Available Peroxynitrates are responsible for global scale transport of reactive nitrogen. Recent laboratory observations suggest that they may also play an important role in delivery of nutrients to plant canopies. We measured eddy covariance fluxes of total peroxynitrates (ΣPNs and three individual peroxynitrates (APNs ≡ PAN + PPN + MPAN over a ponderosa pine forest during the Biosphere Effects on AeRosols and Photochemistry EXperiment 2009 (BEARPEX 2009. Concentrations of these species were also measured at multiple heights above and within the canopy. While the above-canopy daytime concentrations are nearly identical for ΣPNs and APNs, we observed the downward flux of ΣPNs to be 30–60% slower than the flux of APNs. The vertical concentration gradients of ΣPNs and APNs vary with time of day and exhibit different temperature dependencies. These differences can be explained by the production of peroxynitrates other than PAN, PPN, and MPAN within the canopy (presumably as a consequence of biogenic VOC emissions and upward fluxes of these PN species. The impact of this implied peroxynitrate flux on the interpretation of NOx fluxes and ecosystem N exchange is discussed.

  8. Observations of atmosphere-biosphere exchange of total and speciated peroxynitrates: nitrogen fluxes and biogenic sources of peroxynitrates

    Science.gov (United States)

    Min, K.-E.; Pusede, S. E.; Browne, E. C.; LaFranchi, B. W.; Wooldridge, P. J.; Wolfe, G. M.; Harrold, S. A.; Thornton, J. A.; Cohen, R. C.

    2012-10-01

    Peroxynitrates are responsible for global scale transport of reactive nitrogen. Recent laboratory observations suggest that they may also play an important role in delivery of nutrients to plant canopies. We measured eddy covariance fluxes of total peroxynitrates (ΣPNs) and three individual peroxynitrates (APNs ≡ PAN + PPN + MPAN) over a ponderosa pine forest during the Biosphere Effects on AeRosols and Photochemistry EXperiment 2009 (BEARPEX 2009). Concentrations of these species were also measured at multiple heights above and within the canopy. While the above-canopy daytime concentrations are nearly identical for ΣPNs and APNs, we observed the downward flux of ΣPNs to be 30-60% slower than the flux of APNs. The vertical concentration gradients of ΣPNs and APNs vary with time of day and exhibit different temperature dependencies. These differences can be explained by the production of peroxynitrates other than PAN, PPN, and MPAN within the canopy (presumably as a consequence of biogenic VOC emissions) and upward fluxes of these PN species. The impact of this implied peroxynitrate flux on the interpretation of NOx fluxes and ecosystem N exchange is discussed.

  9. Determination of water vapor and aerosol densities in the tropospheric atmosphere from nitrogen and water vapor raman signals

    CERN Document Server

    Kim, D H; Lee, J M; Yeon, K H; Choi, S C

    1998-01-01

    A Raman lidar system has been developed for the measurement of the water-vapor mixing ratio and the aerosol backscatter and extinction coefficients. To suppress the elastic scattering from the XeCl excimer laser, an acetone edge filter and narrow-band interference filters are used. By using independently calculated backscatter and extinction coefficients, we calculate the lidar ratios (extinction coefficient divided by the backscatter coefficient). The obtained ratios between 30 and 50 sr explain the special characteristics of the aerosol existing in the atmosphere. These ratios are also used as important parameters in the lidar inversion program. We have also obtained the water-vapor mixing ratio and find that big differences exist between the ratios inside the boundary layer and those of other regions.

  10. Comparison of atmospheric concentrations of sulphur and nitrogen compounds, chloride and base cations at Ahtari and Hyytiala, Finland

    Energy Technology Data Exchange (ETDEWEB)

    Ruoho-Airola, T. [Finnish Meteorological Institute, Helsinki (Finland)

    2012-11-01

    Seven-year (2003-2009) time series of atmospheric SO{sub 2}, SO{sub 4}{sup 2-}, NO{sub 3}-, NH{sub 4}{sup +} and Cl{sup -} concentrations as well as four-year time series of atmospheric Na{sup +}, K{sup +}, Ca{sup 2+} and Mg{sup 2+} concentrations from Ahtari and Hyytiala background stations in southern Finland, located within 85 km of each other were compared. At Ahtari the air sampler was located in a clearing within a young forest, while at Hyytiala it was within dense forest stands. Pearson's correlations between the time series were very strong (r{sub P} {>=} 0.9) for SO{sub 2}, SO{sub 4}{sup 2-}, NO{sub 3}{sup -}, NH{sub 4}{sup +}, Cl{sup -} and Ca{sup 2+}, strong (r{sub P} > 0.8) for Na{sup +} and Mg{sup 2+} and week (r{sub P} = 0.65) for K{sup +}. The concentrations recorded at Hyytiala were on average 0.8-1.0 times those at Ahtari, although for K{sup +} and Ca{sup 2+} the ratios were higher. The GLS-ARMA method used takes into account the seasonal behaviour and serial correlation in the air quality time series, which revealed similar seasonal and temporal behaviour for S and N compounds and Cl- at both stations. As a result of the dense seasonalization of the time series, the part of the data heavily influenced by local agricultural sources could be identified. This enables elimination of the minimal part of the data affected and the use of the remaining data for further studies on a more regional level. (orig.)

  11. Reactions of Azine Anions with Nitrogen and Oxygen Atoms: Implications for Titan's Upper Atmosphere and Interstellar Chemistry.

    Science.gov (United States)

    Wang, Zhe-Chen; Cole, Callie A; Demarais, Nicholas J; Snow, Theodore P; Bierbaum, Veronica M

    2015-08-26

    Azines are important in many extraterrestrial environments, from the atmosphere of Titan to the interstellar medium. They have been implicated as possible carriers of the diffuse interstellar bands in astronomy, indicating their persistence in interstellar space. Most importantly, they constitute the basic building blocks of DNA and RNA, so their chemical reactivity in these environments has significant astrobiological implications. In addition, N and O atoms are widely observed in the ISM and in the ionospheres of planets and moons. However, the chemical reactions of molecular anions with abundant interstellar and atmospheric atomic species are largely unexplored. In this paper, gas-phase reactions of deprotonated anions of benzene, pyridine, pyridazine, pyrimidine, pyrazine, and s-triazine with N and O atoms are studied both experimentally and computationally. In all cases, the major reaction channel is associative electron detachment; these reactions are particularly important since they control the balance between negative ions and free electron densities. The reactions of the azine anions with N atoms exhibit larger rate constants than reactions of corresponding chain anions. The reactions of azine anions with O atoms are even more rapid, with complex product patterns for different reactants. The mechanisms are studied theoretically by employing density functional theory; spin conversion is found to be important in determining some product distributions. The rich gas-phase chemistry observed in this work provides a better understanding of ion-atom reactions and their contributions to ionospheric chemistry as well as the chemical processing that occurs in the boundary layers between diffuse and dense interstellar clouds.

  12. One-pot green synthesis of high quantum yield oxygen-doped, nitrogen-rich, photoluminescent polymer carbon nanoribbons as an effective fluorescent sensing platform for sensitive and selective detection of silver(I) and mercury(II) ions.

    Science.gov (United States)

    Wang, Zhong-Xia; Ding, Shou-Nian

    2014-08-05

    This work reports on a facile, economical, and green preparative strategy toward water-soluble, fluorescent oxygen-doped, nitrogen-rich, photoluminescent polymer carbon nanoribbons (ONPCRs) with a quantum yield of approximately 25.61% by the hydrothermal process using uric acid as a carbon-nitrogen source for the first time. The as-prepared fluorescent ONPCRs showed paddy leaf-like structure with 80-160 nm length and highly efficient fluorescent quenching ability in the presence of mercury(II) (Hg(2+)) or silver (Ag(+)) ions due to the formed nonfluorescent metal complexes via robust Hg(2+)-O or Ag(+)-N interaction with the O and N of fluorescent ONPCRs, which allowed the analysis of Hg(2+) and Ag(+) ions in a very simple method. By employing this sensor, excellent linear relationships existed between the quenching degree of the ONPCRs and the concentrations of Hg(2+) and Ag(+) ions in the range of 2.0 nM to 60 μM and 5.0 nM to 80 μM, respectively. By using ethylenediaminetetraacetate and ammonia as the masking agent of Hg(2+) and Ag(+) ions, respectively, Hg(2+) or Ag(+) ions were exclusively detected in coexistence with Ag(+) or Hg(2+) ions with high sensitivity, and the detection limits as low as 0.68 and 1.73 nM (3σ) were achieved, respectively, which also provided a reusable detection method for Hg(2+) and Ag(+) ions. Therefore, the easily synthesized fluorescent ONPCRs may have great potential applications in the detection of Hg(2+) and Ag(+) ions for biological assay and environmental protection.

  13. Application of the 15N tracer method to study the effect of pyrolysis temperature and atmosphere on the distribution of biochar nitrogen in the biomass-biochar-plant system.

    Science.gov (United States)

    Tan, Zhongxin; Ye, Zhixiong; Zhang, Limei; Huang, Qiaoyun

    2017-12-01

    Biochar nitrogen is key to improving soil fertility, but the distribution of biochar nitrogen in the biomass-biochar-plant system is still unclear. To provide clarity, the 15N tracer method was utilised to study the distribution of biochar nitrogen in the biochar both before and after its addition to the soil. The results can be summarised as follows. 1) The retention rate of 15N in biochar decreases from 45.23% to 20.09% with increasing pyrolysis temperature from 400 to 800°C in a CO2 atmosphere. 2) The retention rate of 15N in biochar prepared in a CO2 atmosphere is higher than that prepared in a N2 atmosphere when the pyrolysis temperature is below 600°C. 3) Not only can biochar N slowly facilitate the adsorption of N by plants but the addition of biochar to the soil can also promote the supply of soil nitrogen to the plant; in contrast, the direct return of wheat straw biomass to the soil inhibits the absorption of soil N by plants. 4) In addition, the distribution of nitrogen was clarified; that is, when biochar was prepared by the pyrolysis of wheat straw at 400°C in a CO2 atmosphere, the biochar retained 45.23% N, and after the addition of this biochar to the soil, 39.99% of N was conserved in the biochar residue, 4.55% was released into the soil, and 0.69% was contained in the wheat after growth for 31days. Therefore, this study very clearly shows the distribution of nitrogen in the biomass-biochar-plant system. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Photolysis imprint in the nitrate stable isotope signal in snow and atmosphere of East Antarctica and implications for reactive nitrogen cycling

    Directory of Open Access Journals (Sweden)

    J. M. F. Martins

    2009-11-01

    Full Text Available The nitrogen15N and triple oxygen (δ17O and δ18O isotopic composition of nitrate (NO3 was measured year-round in the atmosphere and snow pits at Dome C, Antarctica (DC, 75.1° S, 123.3° E, and in surface snow on a transect between DC and the coast. Comparison to the isotopic signal in atmospheric NO3 shows that snow NO3 is significantly enriched in δ15N by >200‰ and depleted in δ18O by <40‰. Post-depositional fractionation in Δ17O(NO3 is small, potentially allowing reconstruction of past shifts in tropospheric oxidation pathways from ice cores. Assuming a Rayleigh-type process we find fractionation constants ε of −60±15‰, 8±2‰ and 1±1‰, for δ15N, δ18O and Δ17O, respectively. A photolysis model yields an upper limit for the photolytic fractionation constant 15ε of δ15N, consistent with lab and field measurements, and demonstrates a high sensitivity of 15ε to the incident actinic flux spectrum. The photolytic 15ε is process-specific and therefore applies to any snow covered location. Previously published 15ε values are not representative for conditions at the Earth surface, but apply only to the UV lamp used in the reported experiment (Blunier et al., 2005; Jacobi et al., 2006. Depletion of oxygen stable isotopes is attributed to photolysis followed by isotopic exchange with water and hydroxyl radicals. Conversely, 15N enrichment of the NO3 fraction in the snow implies 15N depletion of emissions. Indeed, δ15N in atmospheric NO3 shows a strong decrease from background levels (4±7‰ to −35‰ in spring followed by recovery during summer, consistent with significant snowpack

  15. Synthesis of recent advances in critical loads research on impacts from atmospheric nitrogen deposition on terrestrial plant communities.

    Science.gov (United States)

    Clark, C.; Horn, K. J.; Thomas, R. Q.; Simkin, S.; Pardo, L. H.; Blett, T.; Lawrence, G. B.; Belyazid, S.; Phelan, J.

    2015-12-01

    Nitrogen (N) deposition is one of the primary threats to plant biodiversity world-wide after habitat destruction and climate change. As a primary limiting nutrient and contributor to soil acidification, N inputs have the capacity to alter ecosystems through several mechanisms. Up until now, there was very little detailed information on the impacts from this stressor at the species level, or how climate and edaphic factors could alter ecosystem sensitivity. Here we summarize and synthesize four major efforts, funded by EPA, USGS, USFS, and the NPS, which greatly advance our understanding of this stressor. These include (1) a national analysis of sensitivity to N deposition for 114 tree species, (2) a national analysis of impacts from N deposition on herbaceous species and how climate and soil factors modify that sensitivity, (3) a regional dynamic modeling study of impacts and recovery from N and S deposition for a dominant northeastern forest type under a range of future climate and deposition scenarios, and (4) a large assessment of impacts to streams, soils, and vegetation along the 2000+ mile stretch of the Appalachian Trail. Here we show many responses to this stressor for all taxonomic groups, with some species decreasing, some increasing, and some unaffected by N deposition. However, dozens of tree and herb species are negatively affected and are of particular concern for conservation purposes, with vulnerability being greatly affected by regional climate and local edaphic factors. Dynamic modeling suggests that, at least in some northeastern forests, recovery across a broad range of climate change and management scenarios is unlikely by 2100. The study along the Appalachian Trail, a beloved national recreation trail, echoes these findings, with stream, soils, and vegetation impacted across large percentages of sites, and only moderate capacity for recovery by 2100. In total, this work highlights several recent advances in the area of critical loads research

  16. Intercomparison of OH Radical Measurements by Long-Path Absorption and Laser Induced Fluorescence in the Atmosphere Simulation Chamber SAPHIR

    Science.gov (United States)

    Dorn, H.-P.; Brauers, T.; Greif, J.; Häseler, R.; Hofzumahaus, A.; Holland, F.; Rupp, L.

    2003-04-01

    A striking advantage of the SAPHIR chamber is the availability of two spectroscopic detection instruments for OH radicals: Laser-Induced Fluorescence Spectroscopy (LIF) and Long-Path Differential Optical Laser Absorption Spectroscopy (DOAS). Both instruments have already been compared in 1994 during the field measurement campaign POPCORN. They agreed well with a correlation coefficient of r=0.90 and a weighted linear fit with a slope of 1.09 +- 0.12. However, OH measurements in the simulation chamber differ significantly from measurements in ambient air. While DOAS measures OH as an integral value along the central longitudinal axis of SAPHIR, LIF samples the air locally and close (2 cm) to the floor of the chamber. Thus, the LIF measurements might be possibly affected by local concentration gradients caused by insufficient mixing of the chamber air or by deposition to the wall. On the other hand, if turbulent mixing of the chamber air is weak and high concentrations of ozone are used in experiments, the DOAS instrument might be subject to artificial formation of OH radicals in the air volume which is illuminated by the detection laser. This interference results from laser induced photolysis of ozone and the subsequent reaction of water vapor with the excited oxygen atoms formed. Thus it is of decisive importance to compare OH measurements from both instruments in order to investigate potential disturbing effects due to the specific sampling properties of both instruments within SAPHIR. We report on OH measurements accomplished simultaneously with both instruments using different trace gas compositions and experimental conditions.

  17. Letter to the editor: Critical assessments of the current state of scientific knowledge, terminology, and research needs concerning the ecological effects of elevated atmospheric nitrogen deposition in China

    Science.gov (United States)

    Pan, Yuepeng; Liu, Yongwen; Wentworth, Gregory R.; Zhang, Lin; Zhao, Yuanhong; Li, Yi; Liu, Xuejun; Du, Enzai; Fang, Yunting; Xiao, Hongwei; Ma, Hongyuan; Wang, Yuesi

    2017-03-01

    In a publication in Atmospheric Environment (http://dx.doi.org/10.1016/j.atmosenv.2015.10.081), Gu et al. (2015) estimated that "the total nitrogen (N) deposition in 2010 was 2.32 g N m-2 yr-1" in China. This value is comparable with previous estimations based on a synthesized dataset of wet/bulk inorganic N deposition observations, which underestimates the total N deposition since their algorithm (equations (2) and (3) in their paper) does not account for dry deposition of NH3, HNO3, NOx and wet/dry deposition of HONO and organic nitrogen (e.g. amines, amides, PAN). Indeed, Gu et al. (2015) mixed the terminology of wet/bulk deposition and total deposition. Another flawed assumption by Gu et al. (2015) is that all inorganic N in precipitation estimated by their algorithm originates from fertilizer and coal combustion. This is incorrect and almost certainly causes biases in the spatial and temporal distribution of estimated wet/bulk inorganic N deposition (Fig. 5 in their paper), further considering the fact that they neglected important N sources like livestock and they did not consider the nonlinearity between various sources and deposition. Besides the input data on N deposition, the model validation (Sect. 2.3.2) described in their paper also requires clarification because the detailed validation information about the time series of observational dataset versus modeling results was not given. As a result of these combined uncertainties in their estimation of N deposition and the lack of detail for model-measurement comparison, their estimates of the impacts of N deposition on carbon storage in Chinese forests may need further improvement. We suggest the clarification of the terminology regarding N deposition, especially for wet deposition, bulk deposition, gaseous and particulate dry deposition or total deposition since the accurate distinction between these terms is crucial to investigating and estimating the effects of N deposition on ecosystems.

  18. Atmospheric deposition of reactive nitrogen oxides and ozone in a temperate deciduous forest and a subarctic woodland: 1. Measurements and mechanisms

    Science.gov (United States)

    Munger, J. William; Wofsy, Steven C.; Bakwin, Peter S.; Fan, Song-Miao; Goulden, Michael L.; Daube, Bruce C.; Goldstein, Allen H.; Moore, Kathleen E.; Fitzjarrald, David R.

    1996-05-01

    We present 5 years of NOy and O3 eddy flux and concentration measurements and NOx concentration measurements at Harvard Forest (1990-1994), a mixed deciduous forest in central Massachusetts, and 2 months of data for a spruce woodland near Schefferville, Quebec, during the NASA ABLE3B/Northern Wetlands Study (1990). Mean midday values of net dry NOy flux from atmosphere to canopy were 3.4 and 3.2 μmole m-2 hr-1 at Harvard Forest in summer and winter, respectively, and 0.5 μmole m-2hr-1 at Schefferville during summer. Nighttime values were 1.3, 2.0, and 0.15 μmole m-2 hr-1, respectively. For 1990-1994, the net annual dry deposition of nitrogen oxides was 17.9 mmole m-2 yr-1 (2.49 kgN ha-1 y-1). Oxidized species such as HNO3 dominated N deposition, with minor contributions from direct deposition of NO2. Emissions of NO from the forest soil were negligible compared to deposition. Comparison of NOy deposition at Harvard Forest and Schefferville and analysis of the dependence on meteorological parameters show that anthropogenic sources dominate the nitrogen oxide inputs over much of North America. Heterogeneous reactions account for >90% of the conversion of NO2 to HNO3 in winter, leading to rates for dry deposition of NOy similar to fluxes in summer despite 10-fold decrease in OH concentrations. In summer, formation of HNO3 by heterogeneous reactions (mainly at night) could provide 25-45% of the NO2 oxidation.

  19. Spatial patterns of atmospheric deposition of nitrogen and sulfur using ion-exchange resin collectors in Rocky Mountain National Park, USA

    Science.gov (United States)

    Clow, David W.; Roop, Heidi; Nanus, Leora; Fenn, Mark; Sexstone, Graham A.

    2015-01-01

    Lakes and streams in Class 1 wilderness areas in the western United States (U.S.) are at risk from atmospheric deposition of nitrogen (N) and sulfur (S), and protection of these resources is mandated under the Federal Clean Air Act and amendments. Assessment of critical loads, which are the maximum exposure to pollution an area can receive without adverse effects on sensitive ecosystems, requires accurate deposition estimates. However, deposition is difficult and expensive to measure in high-elevation wilderness, and spatial patterns in N and S deposition in these areas remain poorly quantified. In this study, ion-exchange resin (IER) collectors were used to measure dissolved inorganic N (DIN) and S deposition during June 2006–September 2007 at approximately 20 alpine/subalpine sites spanning the Continental Divide in Rocky Mountain National Park. Results indicated good agreement between deposition estimated from IER collectors and commonly used wet + dry methods during summer, but poor agreement during winter. Snowpack sampling was found to be a more accurate way of quantifying DIN and S deposition during winter. Summer DIN deposition was significantly greater on the east side of the park than on the west side (25–50%; p ≤ 0.03), consistent with transport of pollutants to the park from urban and agricultural areas to the east. Sources of atmospheric nitrate (NO3−) were examined using N isotopes. The average δ15N of NO3− from IER collectors was 3.5‰ higher during winter than during summer (p combustion and vehicular sources of atmospheric NO3−. There were no significant differences in δ15N of NO3− between east and west sides of the park during summer or winter (p = 0.83), indicating that the two areas may have similar sources of atmospheric NO3−. Results from this study indicate that a combination of IER collectors and snowpack sampling can be used to characterize spatial variability in DIN and S deposition in high-elevation wilderness

  20. Distribution of atmospheric reactive nitrogen at two sites of different socio- economic characteristics in IndoGangetic Plain(IGP) region, India.

    Science.gov (United States)

    Singh, S.; Sharma, A.; Kulshrestha, U. C.

    2015-12-01

    In India, most of the human population lives in rural areas. People depends on agriculture products to meet the demand of food supply. In order to get higher yield of agriculture and food product, increased practice of fertilizer application has added extra burden of nutrients especially, the reactive nitrogen (Nr) species viz NH3 and NOx. Growing energy demands has resulted in increased emissions of NOx from coal combustion in thermal power plant and the petroleum combustion in transport sector. In addition, biomass burning in traditional cooking and heating has become significant source of NH3 and NOx in Indian region. Significance of the study lies in the fact that increasing Nr emissions have adverse impact on human health, plant, soil and water bodies directly and to see the effect, knowledge of emission and deposition for Nr at different sites. Hence, the selection of the sites for present study was done very carefully. Delhi city and Mai village were selected to represent typical characteristics of high and low socioeconomic region respectively. Delhi is the capital of India, known for higher income group urban cluster where rural site having agricultural dominance has its importance in Indian scenario because still in India our primary source of income is agriculture. Atmospheric abundance of two major gaseous inorganic (Nr) species i.e NH3 and NO2 has been measured for one year, on monthly basis. Average concentrations of NH3 at urban and rural site have been recorded as 40.4 ±16.8 and 51.57 ±22.8 μg/m3 respectively. The average concentrations of NO2 have been recorded as 24.4 ±13.5 and 18.8 ± 12.6 μg/m3 at urban & rural site respectively. Study, also presents seasonal and diurnal variations of gaseous reactive nitrogen species at urban & rural sites to observe the contribution of different the sources of atmospheric Nr. Dynamics of Nr at both sites will be discussed in details at the conference.

  1. Evaluation of heavy metals in atmospheric emissions from automotive industry by total reflection X-ray fluorescence with synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Moreira, Silvana; Weber Neto, Jose, E-mail: silvana@fec.unicamp.b [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Civil, Arquitetura e Urbanismo. Dept. de Saneamento e Ambiente; Vives, Ana Elisa Sirito de, E-mail: aesvives@unimep.b [Universidade Metodista de Piracicaba (UNIMEP), Santa Barbara D' Oeste, SP (Brazil). Faculdade de Engenharia, Arquitetura e Urbanismo

    2009-07-01

    This study had as goal to determine heavy metals and other elements (Ba, Br, Ca, Pb, Cl, Cr, Sr, Fe, Mn, Ni, K, Si, Ti and Zn) in atmospheric pollutants generated by an automotive industry located in the city of Engenheiro Coelho, state of Sao Paulo, Brazil. The sampling and sample preparation procedures were based on methods established by the Company of Sanitation and Technology (CETESB L9.234) and also by the Environmental Protection Agency (EPA - Method 29). The analysis was performed at XRF Beamline (D09B-XRF) in the Synchrotron Light Source Laboratory (Campinas/SP). A white beam of synchrotron radiation was used for sample and standard excitation which were irradiated by 100 seconds. For X-ray lines detection, a Ge (HP) detector with 150 eV of resolution at 5.9 keV was employed. For zinc, iron, barium, calcium and potassium, the values obtained were in the range of 30 mg/Nm{sup 3} and, for other elements, the concentrations were approximately 1 mg/Nm{sup 3}. The sum of As, Be, Co, Cr, Cu, Mn, Ni, Pb, Sb, Se, Sn, Te and Zn concentration was compared with the limits established by CONAMA 264/1999 and SEMA 041/2002 resolutions (7.0 mg/Nm{sup 3}) and it was observed that, for all samples, sums are higher than the permissive value mainly due to the high concentration of zinc. Detection limits for SR-TXRF technique were 0.10 mug/Nm{sup 3} for Pb and 0.02 mug/Nm{sup 3} for Zn. (author)

  2. Spatial patterns of atmospheric deposition of nitrogen and sulfur using ion-exchange resin collectors in Rocky Mountain National Park, USA

    Science.gov (United States)

    Clow, David W.; Roop, Heidi A.; Nanus, Leora; Fenn, Mark E.; Sexstone, Graham A.

    2015-01-01

    Lakes and streams in Class 1 wilderness areas in the western United States (U.S.) are at risk from atmospheric deposition of nitrogen (N) and sulfur (S), and protection of these resources is mandated under the Federal Clean Air Act and amendments. Assessment of critical loads, which are the maximum exposure to pollution an area can receive without adverse effects on sensitive ecosystems, requires accurate deposition estimates. However, deposition is difficult and expensive to measure in high-elevation wilderness, and spatial patterns in N and S deposition in these areas remain poorly quantified. In this study, ion-exchange resin (IER) collectors were used to measure dissolved inorganic N (DIN) and S deposition during June 2006-September 2007 at approximately 20 alpine/subalpine sites spanning the Continental Divide in Rocky Mountain National Park. Results indicated good agreement between deposition estimated from IER collectors and commonly used wet + dry methods during summer, but poor agreement during winter. Snowpack sampling was found to be a more accurate way of quantifying DIN and S deposition during winter. Summer DIN deposition was significantly greater on the east side of the park than on the west side (25-50%; p ≤ 0.03), consistent with transport of pollutants to the park from urban and agricultural areas to the east. Sources of atmospheric nitrate (NO3-) were examined using N isotopes. The average δ15N of NO3- from IER collectors was 3.5‰ higher during winter than during summer (p policy makers to better protect sensitive natural resources in Class 1 Wilderness areas.

  3. On the use of UV photo-oxidation for the determination of total nitrogen in rainwater and water-extracted atmospheric aerosol

    Science.gov (United States)

    Mace, Kimberly A.; Duce, Robert A.

    Three methods are currently in use for the determination of total N within rainwater and water-extracted aerosols—UV photo-oxidation, persulfate digestion, and high-temperature combustion. Among these methods, UV photo-oxidation has received scrutiny for its reported inability to digest "refractory" organic N compounds. In this manuscript we utilized inorganic and organic nitrogen standards to carefully assess the ability of a specific UV digestor, the Metrohm 705 UV digestor, to correctly digest organic N within dilute solutions (such as rainwater and atmospheric aerosol). We also discuss the negative aspects of the three methods listed above, comment on the photochemical reactions and chemical products produced by exposure to UV light, and make suggestions concerning the proper use of UV digestion technique when determining total N. Our tests indicate that at a digestion time of 2 h and a temperature of 85°C the system is satisfactory for determining the total amount of organic N within dilute solutions. The upper concentration limit using this UV system was found to be 50 μM N of organic N. Diluted samples were found to carry a larger burden of analytical error due to the combined effects of UV blanks (that can range from 0.1-0.6 μM N) and the uncertainty associated with the chromatographic ion analysis (for nitrate, nitrite, and ammonium). This error can often lead to negative values when reporting organic N. We suggest that negative values for organic N be included within the mean and standard deviation of organic N measurements rather than excluding them by rounding negative values to zero. Only by including all analytical error within measurements will true concentrations of organic N within rainwater and atmospheric aerosols and its relevance to total N budgets be known.

  4. Deposition of nitrogen into the North Sea

    DEFF Research Database (Denmark)

    Leeuw, G. de; Skjøth, C.A.; Hertel, O.

    2003-01-01

    The flux of nitrogen species from the atmosphere into the ocean, with emphasis on coastal waters, was addressed during the ANICE project (Atmospheric Nitrogen Inputs into the Coastal Ecosystem). ANICE focused on quantifying the deposition of atmospheric inputs of inorganic nitrogen compounds (HNO3...

  5. Development of gas chromatography-flame ionization detection system with a single column and liquid nitrogen-free for measuring atmospheric C2-C12 hydrocarbons.

    Science.gov (United States)

    Liu, Chengtang; Mu, Yujing; Zhang, Chenglong; Zhang, Zhibo; Zhang, Yuanyuan; Liu, Junfeng; Sheng, Jiujiang; Quan, Jiannong

    2016-01-04

    A liquid nitrogen-free GC-FID system equipped with a single column has been developed for measuring atmospheric C2-C12 hydrocarbons. The system is consisted of a cooling unit, a sampling unit and a separation unit. The cooling unit is used to meet the temperature needs of the sampling unit and the separation unit. The sampling unit includes a dehydration tube and an enrichment tube. No breakthrough of the hydrocarbons was detected when the temperature of the enrichment tube was kept at -90 °C and sampling volume was 400 mL. The separation unit is a small round oven attached on the cooling column. A single capillary column (OV-1, 30 m × 0.32 mm I.D.) was used to separate the hydrocarbons. An optimal program temperature (-60 ∼ 170 °C) of the oven was achieved to efficiently separate C2-C12 hydrocarbons. There were good linear correlations (R(2)=0.993-0.999) between the signals of the hydrocarbons and the enrichment amount of hydrocarbons, and the relative standard deviation (RSD) was less than 5%, and the method detection limits (MDLs) for the hydrocarbons were in the range of 0.02-0.10 ppbv for sampling volume of 400 mL. Field measurements were also conducted and more than 50 hydrocarbons from C2 to C12 were detected in Beijing city. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Impact of simulated atmospheric nitrogen deposition on nutrient cycling and carbon sink via mycorrhizal fungi in two nutrient-poor peatlands

    Science.gov (United States)

    Larmola, Tuula; Kiheri, Heikki; Bubier, Jill L.; van Dijk, Netty; Dise, Nancy; Fritze, Hannu; Hobbie, Erik A.; Juutinen, Sari; Laiho, Raija; Moore, Tim R.; Pennanen, Taina

    2017-04-01

    Peatlands store one third of the global soil carbon (C) pool. Long-term fertilization experiments in nutrient-poor peatlands showed that simulated atmospheric nitrogen (N) deposition does not enhance ecosystem C uptake but reduces C sink potential. Recent studies have shown that a significant proportion of C input to soil in low-fertility forests entered the soil through mycorrhizal fungi, rather than as plant litter. Is atmospheric N deposition diminishing peatland C sink potential due to the suppression of ericoid mycorrhizal fungi? We studied how nutrient addition influences plant biomass allocation and the extent to which plants rely on mycorrhizal N uptake at two of the longest-running nutrient addition experiments on peatlands, Whim Bog, United Kingdom, and Mer Bleue Bog, Canada. We determined the peak growing season aboveground biomass production and coverage of vascular plants using the point intercept method. We also analyzed isotopic δ15N patterns and nutrient contents in leaves of dominant ericoid mycorrhizal shrubs as well as the non-mycorrhizal sedge Eriophorum vaginatum under different nutrient addition treatments. The treatments receive an additional load of 1.6-6.4 N g m-2 y-1 either as ammonium (NH4) nitrate (NO3) or NH4NO3 and with or without phosphorus (P) and potassium (K), alongside unfertilized controls. After 11-16 years of nutrient addition, the vegetation structure had changed remarkably. Ten of the eleven nutrient addition treatments showed an increase of up to 60% in total vascular plant abundance. Only three (NH4Cl, NH4ClPK, NaNO3PK) of the nutrient addition treatments showed a concurrent decrease of down to 50% in the relative proportion of ericoid mycorrhizal shrubs to total vascular plant abundance. The response to nutrient load may be explained by the water table depth, the form of N added and whether N was added with PK. Shrubs were strong competitors at the dry Mer Bleue bog while sedges gained in abundance at the wetter Whim bog

  7. Absolute atomic oxygen density measurements for nanosecond-pulsed atmospheric-pressure plasma jets using two-photon absorption laser-induced fluorescence spectroscopy

    Science.gov (United States)

    Jiang, C.; Carter, C.

    2014-12-01

    Nanosecond-pulsed plasma jets that are generated under ambient air conditions and free from confinement of electrodes have become of great interest in recent years due to their promising applications in medicine and dentistry. Reactive oxygen species that are generated by nanosecond-pulsed, room-temperature non-equilibrium He-O2 plasma jets among others are believed to play an important role during the bactericidal or sterilization processes. We report here absolute measurements of atomic oxygen density in a 1 mm-diameter He/(1%)O2 plasma jet at atmospheric pressure using two-photon absorption laser-induced fluorescence spectroscopy. Oxygen number density on the order of 1013 cm-3 was obtained in a 150 ns, 6 kV single-pulsed plasma jet for an axial distance up to 5 mm above the device nozzle. Temporally resolved O density measurements showed that there are two maxima, separated in time by 60-70 µs, and a total pulse duration of 260-300 µs. Electrostatic modeling indicated that there are high-electric-field regions near the nozzle exit that may be responsible for the observed temporal behavior of the O production. Both the field-distribution-based estimation of the time interval for the O number density profile and a pulse-energy-dependence study confirmed that electric-field-dependent, direct and indirect electron-induced processes play important roles for O production.

  8. Stable Carbon and Nitrogen isotopic characterization of bulk atmospheric particles over Indian coastal site (Goa) during monsoon, post-monsoon and winter periods of 2011-12

    Science.gov (United States)

    Yadav, K.; Agnihotri, R.; Sarma, V. V.; Karapurkar, S. G.; Poosarla, P. K.; Kumar, M. D.

    2012-12-01

    Atmospheric carbonaceous aerosols are known for their influential nature on regional biogeochemical cycles of biogenic elements e.g. carbon (C) and nitrogen (N) as well as to radiation budgets. As they may have multiple primary sources of natural and anthropogenic origin, their detailed chemical and isotopic characterization can greatly help in identifying source and secondary processes they undergo. Using high volume air sampler, bulk aerosols were collected on tissue quartz filters from the roof of National Institute of Oceanography Goa (15.46o N, 73.8oE; at 55.8 MASL height) on almost weekly intervals for the monsoon, post- monsoon, and full winter period of 2011-12. Nearly 60 aerosol samples were analyzed for their carbon (TC) and nitrogen TN mass concentrations together with their isotopic values (δ13C, δ15N). Overall, δ13C of TC varied in a narrow range (average: -22.8±2.7‰) compared to δ15N of TN, showing a wider range (average: 12.7±5.1‰) during this sampling campaign. δ15N of bulk aerosols were found to be significantly lower (average: 3.0±0.5‰ ; n=7) during monsoon period as compared to those for post monsoon (average: 12.3±3.8‰ ; n=6) and winter period (average: 14.2±3.8‰; n=47). In contrast, δ13C of TC were found to be similar during monsoon, post-monsoon and winter periods (average: -23.8±2.3‰, -23.6±1.9‰, -23.1±1.8‰, respectively). TSP mass concentrations together with their TC and TN contents also showed clear differences; highest values during winter and late winter as compared to monsoon and post monsoon periods. Lower δ15N values of Goa aerosols during monsoon are similar to those during pre monsoon period (Agnihotri et al., 2011) and thereby attributable to incorporation of isotopically depleted nitrogenous compounds originating from adjacent Arabian Sea. δ13C of TC values, on an average, represent an intermediate value of carbonaceous material originating from continental and marine sources (-26‰ and -21

  9. One-step fabrication of nitrogen-doped fluorescent nanoparticles from non-conjugated natural products and their temperature-sensing and bioimaging applications

    Directory of Open Access Journals (Sweden)

    Xiaoling Zeng

    2015-03-01

    Full Text Available A facile solvothermal method was used to prepare N-doped fluorescent nanoparticles (NFNPs at gram scale from tartaric acid/citric acid/ethylenediamine using oleic acid as the reaction medium. The quantum yield of the obtained fluorescent nanoparticles could reach 48.7%. The NFNPs were characterized by multiple analytical techniques. By combining with the circular dichroism (CD spectra, the structure and the origin of photoluminescence of the NFNPs were discussed. The fluorescent intensity of the obtained NFNPs had remarkable stability, and exhibited a reversible temperature-dependent enhancement/quenching. The products with low cytotoxicity could be introduced into the target cells for in vitro bioimaging.

  10. One year of urban background fluorescent aerosol measurements

    Science.gov (United States)

    Pope, Francis

    2016-04-01

    Online aerosol fluorescence is a popular methodology for detecting bioaerosols in the atmosphere. In recent years there has been considerable effort into refining the technique to be able to distinguish between different bioaerosol classes such as pollen, spores and bacteria. A near continuous record of aerosol fluorescence measurements has been recorded at an urban background observation site in Birmingham, UK for the year 2015. Fluorescence measurements were performed using the Biral aerosol fluorescence spectrometer (AFS) which measures both UV and visible fluorescence resulting from the excitation of aerosol particles at 280 nm. Speciation of the fluorescent particles into different bioaerosol class is possible with the AFS but the lack of particle sizing makes the task difficult compared to other techniques. In addition to the fluorescence measurements, further campaign mode measurements were also generated for size segregated total particle numbers, ozone, nitrogen oxides and other chemical species. These measurements allow for the influence of road traffic on the concentration of fluorescent particle to be determined. This presentation will provide an in depth look into how bioaerosol concentrations and speciation (pollen, spores and bacteria) change throughout the year. These changes will be linked to local and regional meteorology and climate. In particular, the consequences of the unusually warm UK winter upon bioaerosol concentrations will be highlighted.

  11. Simultaneous Quantification of Active Carbon- and Nitrogen-Fixing Communities and Estimation of Fixation Rates Using Fluorescence In Situ Hybridization and Flow Cytometry

    OpenAIRE

    Allison S. McInnes; Shepard, Alicia K.; Raes, Eric J.; Waite, Anya M.; Quigg, Antonietta

    2014-01-01

    Understanding the interconnectivity of oceanic carbon and nitrogen cycles, specifically carbon and nitrogen fixation, is essential in elucidating the fate and distribution of carbon in the ocean. Traditional techniques measure either organism abundance or biochemical rates. As such, measurements are performed on separate samples and on different time scales. Here, we developed a method to simultaneously quantify organisms while estimating rates of fixation across time and space for b...

  12. Monitoring atmospheric nitrogen pollution in Guiyang (SW China) by contrasting use of Cinnamomum Camphora leaves, branch bark and bark as biomonitors.

    Science.gov (United States)

    Xu, Yu; Xiao, Huayun; Guan, Hui; Long, Chaojun

    2018-02-01

    Moss (as a reference material) and camphor (Cinnamomum Camphora) leaf, branch bark and bark samples were systematically collected across an urban-rural gradient in Guiyang (SW China) to determine the efficacy of using these bio-indicators to evaluate nitrogen (N) pollution. The tissue N concentrations (0.13%-2.70%) and δ15N values (-7.5‰ to +9.3‰) of all of these bio-indicators exhibited large spatial variations, as they recorded higher values in urban areas that quickly decreased with distance from the city center; moreover, both soil N concentrations and soil δ15N values were found no significant differences within each 6 km from the urban to the rural area. This not only suggests that the different N uptake strategies and variety of N responses of these bio-indicators can be reflected by their different susceptibilities to variations in N deposition but also reveals that they are able to indicate that urban N deposition is mostly from traffic and industry (NOx-N), whereas rural N deposition is mainly from agriculture (NHx-N). Compared to previously collected urban moss and camphor leaf samples, the significantly increased δ15N values in current urban moss and camphor leaf samples further indicate a greater contribution of NOx-N than NHx-N to urban N deposition. The feasibility of using the N concentrations and δ15N values of branch bark and bark as biomarkers of N deposition thus was further confirmed through the comparative use of these bio-indicators. It can be concluded that vascular plant leaves, branch bark and bark can be used as useful biomonitoring tools for evaluating atmospheric N pollution. For further study, quantitative criteria for the practical use of these bio-indicators in response to N deposition should be developed and the differences in the δ15N values of different plant parts should also be considered, particularly in urban environments that are severely disrupted by atmospheric pollution. Copyright © 2017 Elsevier Ltd. All

  13. Impact of nitrogen fertilization on soil-Atmosphere greenhouse gas exchanges in eucalypt plantations with different soil characteristics in southern China.

    Science.gov (United States)

    Zhang, Kai; Zheng, Hua; Chen, Falin; Li, Ruida; Yang, Miao; Ouyang, Zhiyun; Lan, Jun; Xiang, Xuewu

    2017-01-01

    Nitrogen (N) fertilization is necessary to sustain productivity in eucalypt plantations, but it can increase the risk of greenhouse gas emissions. However, the response of soil greenhouse gas emissions to N fertilization might be influenced by soil characteristics, which is of great significance for accurately assessing greenhouse gas budgets and scientific fertilization in plantations. We conducted a two-year N fertilization experiment (control [CK], low N [LN], middle N [MN] and high N [HN] fertilization) in two eucalypt plantations with different soil characteristics (higher and lower soil organic carbon sites [HSOC and LSOC]) in Guangxi, China, and assessed soil-atmosphere greenhouse gas exchanges. The annual mean fluxes of soil CO2, CH4, and N2O were separately 153-266 mg m-2 h-1, -55 --40 μg m-2 h-1, and 11-95 μg m-2 h-1, with CO2 and N2O emissions showing significant seasonal variations. N fertilization significantly increased soil CO2 and N2O emissions and decreased CH4 uptake at both sites. There were significant interactions of N fertilization and SOC level on soil CO2 and N2O emissions. At the LSOC site, the annual mean flux of soil CO2 emission was only significantly higher than the CK treatment in the HN treatment, but, at the HSOC site, the annual mean flux of soil CO2 emission was significantly higher for both the LN (or MN) and HN treatments in comparison to the CK treatment. Under the CK and LN treatments, the annual mean flux of N2O emission was not significantly different between HSOC and LSOC sites, but under the HN treatment, it was significantly higher in the HSOC site than in the LSOC site. Correlation analysis showed that changes in soil CO2 and N2O emissions were significantly related to soil dissolved organic carbon, ammonia, nitrate and pH. Our results suggested significant interactions of N fertilization and soil characteristics existed in soil-atmosphere greenhouse gas exchanges, which should be considered in assessing greenhouse gas

  14. Attributes for NHDPlus catchments (version 1.1) for the conterminous United States: normalized atmospheric deposition for 2002, Total Inorganic Nitrogen

    Science.gov (United States)

    Wieczorek, Michael; LaMotte, Andrew E.

    2010-01-01

    This data set represents the average normalized atmospheric (wet) deposition, in kilograms, of Total Inorganic Nitrogen for the year 2002 compiled for every catchment of NHDPlus for the conterminous United States. Estimates of Total Inorganic Nitrogen deposition are based on National Atmospheric Deposition Program (NADP) measurements (B. Larsen, U.S. Geological Survey, written commun., 2007). De-trending methods applied to the year 2002 are described in Alexander and others, 2001. NADP site selection met the following criteria: stations must have records from 1995 to 2002 and have a minimum of 30 observations. The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River

  15. Surface modification of biphasic calcium phosphate scaffolds by non-thermal atmospheric pressure nitrogen and air plasma treatment for improving osteoblast attachment and proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yu-Ri [Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Research Center for Orofacial Hard Tissue Regeneration, College of Dentistry, Yonsei University, Seoul 120-752 (Korea, Republic of); Kwon, Jae-Sung [Research Center for Orofacial Hard Tissue Regeneration, College of Dentistry, Yonsei University, Seoul 120-752 (Korea, Republic of); Song, Doo-Hoon [Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Research Center for Orofacial Hard Tissue Regeneration, College of Dentistry, Yonsei University, Seoul 120-752 (Korea, Republic of); Choi, Eun Ha [Plasma Bioscience Research Center Kwangwoon University, Seoul 139-701, 447-1 Wokgye-Dong, Nowon-Gu, Seoul (Korea, Republic of); Lee, Yong-Keun [Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Kim, Kyoung-Nam [Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Research Center for Orofacial Hard Tissue Regeneration, College of Dentistry, Yonsei University, Seoul 120-752 (Korea, Republic of); Kim, Kwang-Mahn, E-mail: kmkim@yuhs.ac [Department and Research Institute of Dental Biomaterials and Bioengineering, College of Dentistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Research Center for Orofacial Hard Tissue Regeneration, College of Dentistry, Yonsei University, Seoul 120-752 (Korea, Republic of)

    2013-11-29

    Surface modifications induced by non-thermal plasma have been used extensively in biomedical applications. The attachment and proliferation of osteoblast cells are important in bone tissue engineering using scaffolds. Hence the effect of non-thermal plasma on hydroxyapatite/β-tri-calcium phosphate (HA/β-TCP) scaffolds in terms of improving osteoblast attachment and proliferation was investigated. Experimental groups were treated with non-thermal plasma for 10 min and 20 min and a control group was not treated with non-thermal plasma. For surface chemistry analysis, X-ray photoelectron spectroscopy (XPS) analysis was carried out. The hydrophilicity was determined from contact angle measurement on the surface. Atomic force microscopy analysis (AFM) was used to test the change in surface roughness and cell attachment and proliferation were evaluated using MC3T3-E1 osteoblast cells. XPS spectra revealed a decreased amount of carbon on the surface of the plasma-treated sample. The contact angle was also decreased following plasma treatment, indicating improved hydrophilicity of plasma-treated surfaces compared to the untreated disc. A significant increase in MC3T3E-1 cell attachment and proliferation was noted on plasma-treated samples as compared to untreated specimens. The results suggest that non-thermal atmospheric pressure nitrogen and air plasma treatments provide beneficial surface characteristics on HA/β-TCP scaffolds. - Highlights: ► Non-thermal plasma increased OH- and decreased C on biphasic scaffold. ► Non-thermal plasma had no effect on surface roughness. ► Non-thermal plasma resulted in hydrophilic surface. ► Non-thermal plasma resulted in better cell attachment and proliferation. ► Non-thermal plasma treatment on biphasic scaffold is useful for tissue engineering.

  16. Flux of OH and O radicals onto a surface by an atmospheric-pressure helium plasma jet measured by laser-induced fluorescence

    Science.gov (United States)

    Yonemori, Seiya; Ono, Ryo

    2014-03-01

    The atmospheric-pressure helium plasma jet is of emerging interest as a cutting-edge biomedical device for cancer treatment, wound healing and sterilization. Reactive oxygen species such as OH and O radicals are considered to be major factors in the application of biological plasma. In this study, density distribution, temporal behaviour and flux of OH and O radicals on a surface are measured using laser-induced fluorescence. A helium plasma jet is generated by applying pulsed high voltage of 8 kV with 10 kHz using a quartz tube with an inner diameter of 4 mm. To evaluate the relation between the surface condition and active species production, three surfaces are used: dry, wet and rat skin. When the helium flow rate is 1.5 l min-1, radial distribution of OH density on the rat skin surface shows a maximum density of 1.2 × 1013 cm-3 at the centre of the plasma-mediated area, while O atom density shows a maximum of 1.0 × 1015 cm-3 at 2.0 mm radius from the centre of the plasma-mediated area. Their densities in the effluent of the plasma jet are almost constant during the intervals of the discharge pulses because their lifetimes are longer than the pulse interval. Their density distribution depends on the helium flow rate and the surface humidity. With these results, OH and O production mechanisms in the plasma jet and their flux onto the surface are discussed.

  17. Can mushrooms fix atmospheric nitrogen?

    Indian Academy of Sciences (India)

    Unknown

    developed on an agar slab floating on the broth, which allows proper contact of the microbes with acetylene that is important in evaluating nitrogenase activity using the acetylene reduction assay (ARA) (Somasegaran and Hoben. 1994). Petridishes (10 cm in diameter) were used for this. To produce biofilm cultures, a 2 × 2 ...

  18. Glutamine Synthetases GLN1;2 and GLN2 in Relation to Arabidopsis Growth Response to Elevated Atmospheric Carbon Dioxide and Varying Nitrogen Forms

    DEFF Research Database (Denmark)

    Vurrakula, Swathi

    content while diluting nitrogen concentrations. Such a reduction in nitrogen concentration will affect plant response to stress and seed/grain yield. Glutamine synthetase (GS) is the central nitrogen-assimilatory enzyme, performing primary and secondary nitrogen assimilation, in response to environmental...... in nitrate assimilation. This was the case as the gln2 mutant biomass was highly reduced with an increased supply of nitrate in solo. Nitrate assimilation was impaired in the mutant in parallel with reduced NR activity and activation state (%), leading to reduced glutamine content while glycine accumulated...

  19. Study of cell-differentiation and assembly of photosynthetic proteins during greening of etiolated Zea mays leaves using confocal fluorescence microspectroscopy at liquid-nitrogen temperature.

    Science.gov (United States)

    Shibata, Yutaka; Katoh, Wataru; Tahara, Yukari

    2013-04-01

    Fluorescence microspectroscopy observations were used to study the processes of cell differentiation and assemblies of photosynthesis proteins in Zea mays leaves under the greening process. The observations were done at 78K by setting the sample in a cryostat to avoid any undesired progress of the greening process during the measurements. The lateral and axial spatial resolutions of the system were 0.64μm and 4.4μm, respectively. The study revealed the spatial distributions of protochlorophyllide (PChld) in both the 632-nm-emitting and 655-nm-emitting forms within etiolated Zea mays leaves. The sizes of the fluorescence spots attributed to the former were larger than those of the latter, validating the assignment of the former and latter to the prothylakoid and prolamellar bodies, respectively. In vivo microspectroscopy observations of mature Zea mays leaves confirmed the different photosystem II (PS I)/photosystem I (PS II) ratio between the bundle sheath (BS) and mesophyll (MS) cells, which is specific for C4-plants. The BS cells in Zea mays leaves 1h after the initiation of the greening process tended to show fluorescence spectra at shorter wavelength side (at around 679nm) than the MS cells (at around 682nm). The 679-nm-emitting chlorophyll-a form observed mainly in the BS cells was attributed to putative precursor complexes to PS I. The BS cells under 3-h greening showed higher relative intensities of the PS I fluorescence band at around 735nm, suggesting the reduced PS II amount in the BS cells in this greening stage. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. The nitrogen cycle.

    Science.gov (United States)

    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Improvements to the Characterization of Organic Nitrogen Chemistry

    Science.gov (United States)

    Excess atmospheric nitrogen deposition can cause significant harmful effects to ecosystems. Organic nitrogen deposition can be an important contributor to the total nitrogen budget, contributing 10-30%, however there are large uncertainties in the chemistry and deposition of thes...

  2. Enhanced-quantum yield sulfur/nitrogen co-doped fluorescent carbon nanodots produced from biomass Enteromorpha prolifera: synthesis, posttreatment, applications and mechanism study.

    Science.gov (United States)

    Xu, Yuanhong; Li, Dan; Liu, Mengli; Niu, Fushuang; Liu, Jingquan; Wang, Erkang

    2017-07-03

    Enteromorpha prolifera (E. prolifera), one of the main algae genera for green tide, significantly influences both the coastal ecological environment and seawater quality. How to effectively utilize this waste as reproducible raw resource with credible application mechanism are urgent environmental issues to be solved. Herein, E. prolifera was converted to attractive fluorescent carbon nanodots (CNDs) by one-pot green hydrothermal process. The purity and quantum yields for the as-prepared CNDs can be enhanced upon the post-treatment of ethanol sedimentation. The CNDs can be well dispersed in aqueous medium with uniform spherical morphology, narrow size distribution and average size of 2.75 ± 0.12 nm. The ease synthesis and relatively high quantum yields of the CNDs make E. prolifera inexpensive benefit to the human and nature, such as applications in efficient cell imaging and fiber staining. Furthermore, it was discovered that the fluorescence intensity of the CNDs can be selectively quenched upon Fe3+ addition, which can be used for specific sensitive assay and removal of Fe3+ in aqueous medium. More importantly, it was reasonably proposed that the quenching was resulted from the synergistic effects of CNDs aggregation and Fe3+-CNDs charge-transfer transitions due to the coordination interactions between Fe3+ and the oxygenous groups on the CNDs.

  3. Nitrogen cycling in ombrotrophic peat bogs in the Czech Republic: Is microbial N-fixation occurring at atmospheric depositions of reactive N higher than 10 kg/ha/yr?

    Science.gov (United States)

    Novak, Martin; Jackova, Ivana; Cejkova, Bohuslava; Buzek, Frantisek; Curik, Jan; Stepanova, Marketa; Prechova, Eva; Veselovsky, Frantisek; Komarek, Arnost

    2017-04-01

    Biogeochemical cycling of carbon (C) and nitrogen (N) in peat bogs are coupled. Whereas at low pollution levels, reactive nitrogen (Nr, mainly nitrate- and ammonium-N) inputs may positively affect C storage, high Nr deposition may have a detrimental effect on C storage. We have previously reported N isotope systematics at two ombrotrophic peat bogs in the Czech Republic, receiving medium levels of Nr of about 10 kg/ha/yr via atmospheric deposition. Nitrogen of living Sphagnum was systematically heavier than N of the atmospheric input (p Sphagnum from negative values of atmospheric deposition to the zero value of N2. In 2016, we conducted a laboratory study in which living Sphagnum from sites receiving annually slightly over 10 kg Nr/ha/yr via atmospheric deposition was incubated in an atmosphere enriched in 15N-N2. At the end of the incubation, we detected a 1 to 3 per mil increase in del15N of Sphagnum. Rinsing Sphagnum capitula in deionized water prior to the 15N-N2 incubation has led to a slight further increase in del15N of Sphagnum. Also in 2016, we monitored del15N of atmospheric deposition at three medium Nr-polluted peat bogs. Open-area precipitation had the following mean del 15N values: Uhlirska -6.1 per mil (NH4) and -6.2 per mil (NO3); Brumiste -1.7 per mil (NH4) and -3.4 per mil (NO3); Male Mechove Jezirko -3.3 per mil (NH4) and -3.9 per mil (NO3). At all sites, atmospheric Nr deposition was made up by NO3-N and NH4-N in a roughly 1.1 ratio. We found that N of winter-time deposition became isotopically extremely light (less than -10.0 per mil). During the growing season, del15N of total atmospheric input was higher, closer to 0.0 per mil, but still slightly lower than del15N of living Sphagnum. These data thus confirm a N isotope discrepancy between the N isotope signature of deposition and Sphagnum. In the paper, we will also discuss a mass balance discrepancy in long-term atmospheric N input and N storage at the Czech sites, determined for replicated

  4. A multi-isotope approach for assessing industrial contributions to atmospheric nitrogen deposition in the Athabasca oil sands region in Alberta, Canada

    Science.gov (United States)

    Bernadette C. Proemse; Bernhard Mayer; Mark E. Fenn; Christopher S. Ross

    2013-01-01

    Industrial nitrogen (N) emissions in the Athabasca oil sands region (AOSR), Alberta, Canada, affect nitrate (NO3) and ammonium (NH4) deposition rates in close vicinity of industrial emitters. NO3-N and NH4-N open field and throughfall deposition rates were determined at various...

  5. Alternative futures of dissolved inorganic nitrogen export from the Mississippi River Basin: influence of crop management, atmospheric deposition, and population growth

    Science.gov (United States)

    Nitrogen (N) export from the Mississippi River Basin contributes to seasonal hypoxia in the Gulf of Mexico (GOM). We explored monthly dissolved inorganic N (DIN) export to the GOM for a historical year (2002) and two future scenarios (year 2022) by linking macroeonomic energy, ag...

  6. The leaking soil nitrogen cycle and rising atmospheric N2O: Is there anything we can do to cap the well?

    Science.gov (United States)

    Nutrient management refers to the addition and management of synthetic or organic fertilizers to soils primarily for purposes of increasing the supply of nutrients and efficiency of crop nutrient uptake in order to improve yields while minimizing environmental impact. Nitrogen (N) is generally the m...

  7. The Effect of Percentage of Nitrogen in Plasma Gas on Nitrogen ...

    African Journals Online (AJOL)

    The effect of percentage of nitrogen in plasma gas on nitrogen solution from an arc plasma into liquid iron has been investigated by melting iron in an atmosphere of nitrogen and argon using an arc plasma. Results show that both the rate of nitrogen absorption and the steady-state (plateau) solubility are increased as the ...

  8. Molecular nitrogen yields from fuel nitrogen in backmixed combustion

    Energy Technology Data Exchange (ETDEWEB)

    Corlett, R.C.; Monteith, L.E.; Malte, P.C.

    1977-01-01

    The major species disposition of nitrogen from pyridine, added to a propane-argon-oxygen stream burned in a jet-stirred reactor, was investigated. Fuel/oxidant equivalence ratio ranged from 0.9 to 1.5, residence time from 10-50 ms, and temperature from 1500-1900/sup 0/K. Nitrogen mass fraction relative to propane plus pyridine was normally 0.01, in a few cases 0.02. Molecular nitrogen (measured by gas chromatograph) included with nitrogen oxides (chemiluminescent analyzer) and ammonia and hydrogen cyanide (wet chemistry) indicate for each reactor setting a complete nitrogen balance consistent with an estimated random error of approximately 10%. Examination of accumulated results for over 20 best quality cases suggest no systematic imbalance. The results are consistent with data from comparison runs using atmospheric air oxidant (hence no molecular nitrogen measurement) with fuel nitrogen provided in the form of pyridine again, and also as ammonia and nitric oxide.

  9. Measurements of Atmospheric NH3, NOy/NOx, and NO2 and Deposition of Total Nitrogen at the Beaufort, NC CASTNET Site (BFT142)

    Science.gov (United States)

    The Clean Air Status and Trends Network (CASTNET) is a long-term environmental monitoring program that measures trends in ambient air quality and atmospheric dry pollutant deposition across the United States. CASTNET has been operating since 1987 and currently consists of 89 moni...

  10. Inactivation of chemical and heat-resistant spores of Bacillus and Geobacillus by nitrogen cold atmospheric plasma and comparison to thermal and chemical based methods

    NARCIS (Netherlands)

    Bokhorst-van de Veen, van H.; Xie, H.; Esveld, D.C.; Abee, T.; Mastwijk, H.C.; Nierop Groot, M.N.

    2015-01-01

    Bacterial spores are resistant to severe conditions and form a challenge to eradicate from food or food packaging material. Cold atmospheric plasma (CAP) treatment is receiving more attention as potential sterilization method at relatively mild conditions but the exact mechanism of inactivation is

  11. Are climate warming and enhanced atmospheric deposition of sulfur and nitrogen threatening tufa landscapes in Jiuzhaigou National Nature Reserve, Sichuan, China?

    Science.gov (United States)

    Qiao, Xue; Du, Jie; Lugli, Stefano; Ren, Jinhai; Xiao, Weiyang; Chen, Pan; Tang, Ya

    2016-08-15

    Massive deposition of calcium carbonate in ambient temperature waters (tufa) can form magnificent tufa landscapes, many of which are designated as protected areas. However, tufa landscapes in many areas are threatened by both local anthropogenic activities and climate change. This study, for the first time, posed the question whether the tufa landscape degradation (characterized by tufa degradation and increased biomass of green algae) in Jiuzhaigou National Nature Reserve of China is partially caused by regional air pollution and climate warming. The results indicate that wet deposition (including rain and snow) polluted by anthropogenic SO2, NOx, and NH3 emissions dissolves exposed tufa and may considerably reduce tufa deposition rate and even cause tufa dissolution within shallow waters. These effects of wet deposition on tufa enhanced as pH of wet deposition decreased from 8.01 to 5.06. Annual Volume Weighted Mean concentration of reactive nitrogen (including NH4(+) and NO3(-)) in wet deposition (26.1μmolL(-1)) was 1.8 times of the corresponding value of runoff (14.8μmolL(-1)) and exceeded China's national standard of total nitrogen in runoff for nature reserves (14.3μmolL(-1)), indicating a direct nitrogen fertilization effect of wet deposition on green algae. As water temperature is the major limiting factor of algal growth in Jiuzhaigou and temperature in the top layer (0-5cm) of runoff (depthnatural processes also influence tufa landscape evolution. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Spatial and Temporal Variability of Ground and Satellite Column Measurements of NO2 and O3 over the Atlantic Ocean During the Deposition of Atmospheric Nitrogen to Coastal Ecosystems Experiment

    Science.gov (United States)

    Martins, Douglas K.; Najjar, Raymond G.; Tzortziou, Maria; Abuhassan, Nader; Thompson, Anne M.; Kollonige, Debra E.

    2016-01-01

    In situ measurements of O3 and nitrogen oxides (NO + NO2=NOx) and remote sensing measurements of total column NO2 and O3 were collected on a ship in the North Atlantic Ocean as part of the Deposition of Atmospheric Nitrogen to Coastal Ecosystems (DANCE) campaign in July August 2014,100 km east of the mid-Atlantic United States. Relatively clean conditions for both surface in situ mixing ratio and total column O3 and NO2 measurements were observed throughout the campaign. Increased surface and column NO2 and O3 amounts were observed when a terrestrial air mass was advected over the study region. Relative to ship-based total column measurements using a Pandora over the entire study, satellite measurements overestimated total column NO2 under these relatively clean atmospheric conditions over offshore waters by an average of 16. Differences are most likely due to proximity, or lack thereof, to surface emissions; spatial averaging due to the field of view of the satellite instrument; and the lack of sensitivity of satellite measurements to the surface concentrations of pollutants. Total column O3 measurements from the shipboard Pandora showed good correlation with the satellite measurements(r 0.96), but satellite measurements were 3 systematically higher than the ship measurements, in agreement with previous studies. Derived values of boundary layer height using the surface in situ and total column measurements of NO2 are much lower than modeled and satellite-retrieved boundary layer heights, which highlight the differences in the vertical distribution between terrestrial and marine environments.

  13. Quantification of β-carotene, retinol, retinyl acetate and retinyl palmitate in enriched fruit juices using dispersive liquid-liquid microextraction coupled to liquid chromatography with fluorescence detection and atmospheric pressure chemical ionization-mass spectrometry.

    Science.gov (United States)

    Viñas, Pilar; Bravo-Bravo, María; López-García, Ignacio; Hernández-Córdoba, Manuel

    2013-02-01

    A detailed optimization of dispersive liquid-liquid microextraction (DLLME) was carried out for developing liquid chromatographic (HPLC) techniques, using both fluorescence and atmospheric pressure chemical ionization mass spectrometric (APCI-MS) detection, for the simultaneous analysis of preforms of vitamin A: retinol (R), retinyl acetate (RA), retinyl palmitate (RP) and β-carotene (β-C). The HPLC analyses were carried out using a mobile phase composed of methanol and water, with gradient elution. The APCI-MS and fluorescence spectra permitted the correct identification of compounds in the analyzed samples. Parameters affecting DLLME were optimized using 2 mL of methanol (disperser solvent) containing 150 μL carbon tetrachloride (extraction solvent). The precision ranged from 6% to 8% (RSD) and the limits of detection were between 0.03 and 1.4 ng mL(-1), depending on the compound. The enrichment factor values were in the 21-44 range. Juice samples were analyzed without saponification and no matrix effect was found when using fluorescence detection, so calibration was possible with aqueous standards. However, a matrix effect appeared with APCI-MS, in which case it was necessary to apply matrix-matched calibration. There was great variability in the forms of vitamin A present in the juices, the most abundant ester being retinyl acetate (0.04 to 3.4 μg mL(-1)), followed by the amount of retinol (0.01 to 0.16 μg mL(-1)), while retinyl palmitate was not detected, except in the milk-containing juice, in which RP was the main form. The representative carotenoid β-carotene was present in the orange, peach, mango and multifruit juices in high amounts. The method was validated using two certified reference materials. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Biosphere-atmosphere exchange of reactive nitrogen and greenhouse gases at the NitroEurope core flux measurement sites: Measurement strategy and first data sets

    DEFF Research Database (Denmark)

    Skiba, U.; Drewer, J.; Tang, Y.S.

    2009-01-01

    The NitroEurope project aims to improve understanding of the nitrogen (N) cycle at the continental scale and quantify the major fluxes of reactive N by a combination of reactive N measurements and modelling activities. As part of the overall measurement strategy, a network of 13 flux ‘super sites...... by a network of low-cost flux measurements (Level-2, 9 sites) and a network to infer reactive N fluxes at 58 sites (Level-1), for comparison with carbon (C) flux measurements. Measurements at the Level-3 sites include high resolution N2O, NO (also CH4, CO2) fluxes, wet and dry N deposition, leaching of N and C...

  15. Reply to "Critical assessment of the current state of scientific knowledge, terminology, and research needs concerning the ecological effects of elevated atmospheric nitrogen deposition in China"

    Science.gov (United States)

    Gu, Fengxue; Zhang, Yuandong; Huang, Mei; Tao, Bo; Yan, Huimin; Guo, Rui; Li, Jie

    2017-03-01

    In their assessment, Pan et al. (2016) criticize that our estimation of 2.32 g N m-2 yr-1 in 2010 underestimates the total nitrogen (N) deposition amounts by a factor around two by comparing with the estimation of Xu et al. (2015). Our paper entitled "Nitrogen deposition and its effect on carbon storage in Chinese forests during 1981-2010" aims to evaluate the influence of elevated N deposition in China on carbon storage in forest ecosystems by using a process-based model. As limited by observed N deposition dataset availability, we developed a simple algorithm to evaluate the temporal and spatial variations in N deposition based on the relationships among N deposition, precipitation, N fertilizer use, and fuel consumption with reference to the method of Lin et al. (2000). Our results show that the rate of N deposition increased by 0.058 g N m-2 yr-1 between 1981 and 2010. The N deposition rate in 2010 was 2.32 g N m-2 yr-1, and it showed a large spatial variation from 0 to 0.25 g N m-2 yr-1 on the northwestern Qinghai-Tibet Plateau to over 4.5 g N m-2 yr-1 in the southeastern China. We really underestimated the total N deposition in China because we were lack of dry deposition observation dataset in our research. However, we think Pan et al. (2016) overestimated the difference between our estimation and that in Xu et al. (2015). It should be encouraged to discuss the past and current status of N deposition in China based on both observation and simulation. All comments, assessments and suggestions contribute to promote the scientific understanding of N deposition and its influence on ecosystems.

  16. Indicators: Nitrogen

    Science.gov (United States)

    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).

  17. Fixação do nitrogênio do ar pelas bactérias que vivem em simbiose com as raízes da centrosema Fixation of the atmospheric nitrogen by bacteria which live symbiotically on centrosema

    Directory of Open Access Journals (Sweden)

    J. Casado Montojos

    1963-01-01

    Full Text Available Continuando a série de trabalhos sôbre a quantidade de nitrogênio atmosférico fixada por bactérias que vivem em simbiose com raízes de leguminosas, são relatados os resultados encontrados em centrosema (Centrosema pubescens Benth. Foram utilizados vasos de Mitscherlich, com terra-roxa-misturada. A colheita das plantas foi efetuada por ocasião do florescimento. A parte aérea foi pesada para cálculo da quantidade de massa verde produzida, e, em seguida, juntamente com as raízes, sêca a 60°C até pêso constante. Determinaram-se os teores de nitrogênio na parte aérea e subterrânea das plantas, assim como da terra dos vasos. Os resultados mostraram elevada capacidade de fixação simbiótica de nitrogênio pela centrosema correspondente a cêrca de 204 quilogramas de nitrogênio por hectare.Following a series of research work with the purpose of verifying the amount of atmospheric nitrogen fixed by symbiotic bacteria, the authors report in this paper the results on their research with the leguminous plant Centrosema pubescens Benth. This experiment was conducted in Mitscherlich pots containing terra-roxa-misturada obtained from a 20 cm deep layer of soil taken from the Central Experiment Station "Theodureto de Camargo", in Campinas. The plants were cut in the blooming period, as this is the proper season for turning over green manure crops. The aerial portion of the plants was weighed so as to determine the total production of green matter and then it was dried together with the roots at 60°C. Thus, nitrogen of the total plant was determined and the same analysis was done at the end of the experiment for the soil removed from the pots. According to the results of this experiment, it was found that 204 kilograms of nitrogen per hectare were fixed, showing therefore that centrosema has a high capacity of symbiotic nitrogen fixation.

  18. Fluorescence spectroscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2016-01-01

    Fluorescence spectroscopy is a powerful experimental tool used by scientists from many disciplines. During the last decades there have been important developments on distinct fluorescence methods, particularly those related to the study of biological phenomena. This chapter discusses...... the foundations of the fluorescence phenomenon, introduces some general methodologies and provides selected examples on applications focused to disentangle structural and dynamical aspects of biological processes....

  19. Numerical and experimental investigation of light emissions of a planar nitrogen atmospheric-pressure dielectric barrier discharge due to addition of ammonia considering oxygen impurity

    Science.gov (United States)

    Li, F.-L.; Hung, C.-T.; Lin, K.-M.; Wei, T.-C.; Wu, J.-S.

    2013-12-01

    In this paper, the mechanisms of light emissions, including NO-γ, NO-β and N2-SPS, produced in a N2/NH3 atmospheric-pressure dielectric barrier discharge considering realistic oxygen impurity (30 ppm) are investigated numerically and experimentally. Self-consistent, one-dimensional fluid modeling is used to numerically simulate the discharge process with 48 species and 235 reaction channels. An optical emission spectrometer (OES) is used to measure the relative intensities of the light emission. The simulations of the light emission intensities for the above-mentioned OES lines generally reproduce the trends observed in the experiments caused by changes in the NH3 concentration. All of the predicted intensities of NO-γ, NO-β and N2-SPS decrease with increasing amount of NH3 caused by various reaction mechanisms. The former is due to the loss of N2(A) and NO(A) by the reaction of NH3 with N2(A) and NO(A), respectively. The decrease in NO-β is due to the depletion of N and O because of NH3, and the decrease in N2-SPS is due to electron attachment to NH3 and a weaker metastable-metastable associative ionization of N2. All of the simulated results demonstrate that the discharges are typically Townsend-like because the ions outnumber the electrons and the electric field across the gap is distorted only slightly by the charged particles during the breakdown. Finally, a reduced chemical kinetics model for a planar atmospheric-pressure N2/O2/NH3 dielectric barrier discharge is proposed and validated by benchmarking against the above complete chemical kinetics. This results in a reduced chemical kinetics consisting of 33 species and 87 reactions with a very limited loss of accuracy of discharge properties, while it is 2.1 times faster in computational time as compared with the complete version.

  20. Effects of atmospheric CO2 concentration, irradiance, and soil nitrogen availability on leaf photosynthetic traits of Polygonum sachalinense around natural CO2 springs in northern Japan.

    Science.gov (United States)

    Osada, Noriyuki; Onoda, Yusuke; Hikosaka, Kouki

    2010-09-01

    Long-term exposure to elevated CO2 concentration will affect the traits of wild plants in association with other environmental factors. We investigated multiple effects of atmospheric CO2 concentration, irradiance, and soil N availability on the leaf photosynthetic traits of a herbaceous species, Polygonum sachalinense, growing around natural CO2 springs in northern Japan. Atmospheric CO2 concentration and its interaction with irradiance and soil N availability affected several leaf traits. Leaf mass per unit area increased and N per mass decreased with increasing CO2 and irradiance. Leaf N per area increased with increasing soil N availability at higher CO2 concentrations. The photosynthetic rate under growth CO2 conditions increased with increasing irradiance and CO2, and with increasing soil N at higher CO2 concentrations. The maximal velocity of ribulose 1,5-bisphosphate carboxylation (V (cmax)) was affected by the interaction of CO2 and soil N, suggesting that down-regulation of photosynthesis at elevated CO2 was more evident at lower soil N availability. The ratio of the maximum rate of electron transport to V (cmax) (J (max)/V (cmax)) increased with increasing CO2, suggesting that the plants used N efficiently for photosynthesis at high CO2 concentrations by changes in N partitioning. To what extent elevated CO2 influenced plant traits depended on other environmental factors. As wild plants are subject to a wide range of light and nutrient availability, our results highlight the importance of these environmental factors when the effects of elevated CO2 on plants are evaluated.

  1. [Influence of elevated atmospheric CO2 concentration on photosynthesis and leaf nitrogen partition in process of photosynthetic carbon cycle in Musa paradisiaca].

    Science.gov (United States)

    Sun, G; Zhao, P; Zeng, X; Peng, S

    2001-06-01

    The photosynthetic rate (Pn) in leaves of Musa paradisiaca grown under elevated CO2 concentration (700 +/- 56 microliters.L-1) for one week was 5.14 +/- 0.32 mumol.m-2.s-1, 22.1% higher than that under ambient CO2 concentration, while under elevated CO2 concentration for 8 week, the Pn decreased by 18.1%. It can be inferred that the photosynthetic acclimation to elevated CO2 concentration and the Pn inhibition occurred in leaves of M. paradisiaca. The respiration rate in light (Rd) was lower in leaves under higher CO2 concentration, compared with that under ambient CO2 concentration. If the respiration in light was not included, the difference in CO2 compensation point for the leaves of both plants was not significant. Under higher CO2 concentration for 8 weeks, the maximum carboxylation rate(Vcmax) and electron transportation rate (J) in leaves decreased respectively by 30.5% and 14.8%, compared with that under ambient CO2 concentration. The calculated apparent quantum yield (alpha) in leaves under elevated CO2 concentration according to the initial slope of Pn/PAR was reduced to 0.014 +/- 0.010 molCO2.mol-1 quanta, compared with the value of 0.025 +/- 0.005 molCO2.mol-1 quanta in the control. The efficiency of light energy conversion also decreased from 0.203 to 0.136 electrons.quanta-1 in plants under elevated CO2 concentration. A lower partitioning coefficient for leaf nitrogen in Rubisco, bioenergetics and thylakoid light-harvesting components was observed in plants under higher CO2 concentration. The results indicated that the multi-process of photosynthesis was suppressed significantly by a long-term (8 weeks) higher CO2 concentration incubation.

  2. Nitrogen gas flushing can be bactericidal: The temperature-dependent destiny of Bacillus weihenstephanensis KBAB4 under a pure N2 atmosphere

    Directory of Open Access Journals (Sweden)

    Patricia eMunsch-Alatossava

    2014-11-01

    Full Text Available Tremendous food spoilage on one side and increased concern about the incidence of food-borne pathogens on the other side urge the development of additional steps to ensure food safety and quality. In previous studies, nitrogen (N2 gas flushing treatments of raw and pasteurized milk at cold chain-temperatures inhibited bacterial spoilage and highlighted different susceptibilities to the N2 treatment with the exclusion of certain bacterial types. Gram-negative Pseudomonas and Gram-positive Bacillus are the most common spoilage bacteria in raw and pasteurised milk, respectively. Here, we investigated the effects of pure N2 gas flushing on representative strains of these genera grown in mono- or co-cultures at 15°C and 25°C. Bacillus weihenstephanensis, which is a frequent inhabitant of fluid dairy products, is represented by the genome-sequenced KBAB4 strain. Among Pseudomonas, P. tolaasii LMG 2342T and strain C1, a raw milk psychrotroph, were selected. The N2 gas flushing treatment revealed: 1 temperature-dependent responses; 2 inhibition of the growth of both pseudomonads; 3 emergence of small colony variants for B. weihenstephanensis strain KBAB4 at 15°C induced by the N2 treatment or when grown in co-culture with Pseudomonas strains; 4 N2 gas flushing modulates (suppressed or stimulated bacterial antagonistic reactions in co-cultures; 5 most importantly, SEM and TEM analyses revealed that at 25°C the majority of the KBAB4 cells were killed by pure N2 gas flushing. This observation constitutes the first evidence that N2 gas flushing has bactericidal effects.

  3. Mineral commodity profiles: nitrogen

    Science.gov (United States)

    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 Global Nitrogen Cycle

    Science.gov (United States)

    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

  5. The Global Nitrogen Story

    Science.gov (United States)

    Galloway, J. N.

    2001-05-01

    In the absence of human activities, biotic nitrogen fixation is the primary source of reactive N to the environment. Over the last few decades, human activity has surpassed natural terrestrial nitrogen fixation rates by energy production (fossil fuel combustion) and food production (Haber-Bosch based fertilizer production and crop cultivation). An amount equivalent to over half of the anthropogenic N fixed each year is emitted to the atmosphere or discharged to rivers, for dispersion to environmental systems. An unknown amount of this anthropogenic N is accumulating in the environment resulting in a enhanced greenhouse effect, acid deposition, photochemical smog, stratospheric ozone depletion and eutrophication of fresh and marine waters. This paper will assess the state of knowledge on the global N cycle and present a context in which to place the impacts of humans on nitrogen cycling at regional scales.

  6. Terrestrial nitrogen cycles: Some unanswered questions

    Science.gov (United States)

    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.

  7. Gas assisted method synthesis nitrogen-doped carbon quantum dots and Hg (II) sensing.

    Science.gov (United States)

    Li, Yamei; Wang, Nan; He, Zhanhang

    2017-06-01

    Nitrogen-doped fluorescent carbon quantum dots (CQDs) was prepared by gas-assisted method using cellulose as precursors under ammonia atmosphere, which not only exhibited excellent photoluminescent properties, but also showed highly selective and sensitive detection of mercury ion. The nitrogen-doped CQDs displayed excitation wavelength dependent fluorescent behavior with outstanding dispersibility. Moreover, they exhibited high tolerance to various external conditions, such as storage time, pH value, and ionic strength. The rapid detection of Hg (II) by one-step operation within 1 min and the good linear correlation between I0/I and Hg (II) concentration in the range of 10-100 nM made the nitrogen-doped CQDs a promising nanoprobe for Hg (II) detection. The detection limit of the nitrogen-doped CQDs is about 7.7 nM. Such a nanoprobe has been successfully applied for the analysis of Hg (II) in natural water samples, demonstrating excellent practical feasibility.

  8. Recent studies of the ocean nitrogen cycle

    Science.gov (United States)

    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.

  9. Novel Instrument to Measure Aerosol Fluorescence, Absorption, and Scattering Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Picarro, Inc proposes to develop the first cavity ringdown spectroscopy (CRDS) system to measure fluorescence, absorption, and scattering properties of atmospheric...

  10. Recent Progress in Fluorescent Imaging Probes

    Science.gov (United States)

    Pak, Yen Leng; Swamy, K. M. K.; Yoon, Juyoung

    2015-01-01

    Due to the simplicity and low detection limit, especially the bioimaging ability for cells, fluorescence probes serve as unique detection methods. With the aid of molecular recognition and specific organic reactions, research on fluorescent imaging probes has blossomed during the last decade. Especially, reaction based fluorescent probes have been proven to be highly selective for specific analytes. This review highlights our recent progress on fluorescent imaging probes for biologically important species, such as biothiols, reactive oxygen species, reactive nitrogen species, metal ions including Zn2+, Hg2+, Cu2+ and Au3+, and anions including cyanide and adenosine triphosphate (ATP). PMID:26402684

  11. Staging atmospheres

    DEFF Research Database (Denmark)

    Bille, Mikkel; Bjerregaard, Peter; Sørensen, Tim Flohr

    2015-01-01

    The article introduces the special issue on staging atmospheres by surveying the philosophical, political and anthropological literature on atmosphere, and explores the relationship between atmosphere, material culture, subjectivity and affect. Atmosphere seems to occupy one of the classic...

  12. Organic nitrate chemistry and its implications for nitrogen budgets in an isoprene- and monoterpene-rich atmosphere: constraints from aircraft (SEAC4RS) and ground-based (SOAS) observations in the Southeast US

    Science.gov (United States)

    Fisher, Jenny A.; Jacob, Daniel J.; Travis, Katherine R.; Kim, Patrick S.; Marais, Eloise A.; Miller, Christopher Chan; Yu, Karen; Zhu, Lei; Yantosca, Robert M.; Sulprizio, Melissa P.; Mao, Jingqiu; Wennberg, Paul O.; Crounse, John D.; Teng, Alex P.; Nguyen, Tran B.; St. Clair, Jason M.; Cohen, Ronald C.; Romer, Paul; Nault, Benjamin A.; Wooldridge, Paul J.; Jimenez, Jose L.; Campuzano-Jost, Pedro; Day, Douglas A.; Hu, Weiwei; Shepson, Paul B.; Xiong, Fulizi; Blake, Donald R.; Goldstein, Allen H.; Misztal, Pawel K.; Hanisco, Thomas F.; Wolfe, Glenn M.; Ryerson, Thomas B.; Wisthaler, Armin; Mikoviny, Tomas

    2016-05-01

    Formation of organic nitrates (RONO2) during oxidation of biogenic volatile organic compounds (BVOCs: isoprene, monoterpenes) is a significant loss pathway for atmospheric nitrogen oxide radicals (NOx), but the chemistry of RONO2 formation and degradation remains uncertain. Here we implement a new BVOC oxidation mechanism (including updated isoprene chemistry, new monoterpene chemistry, and particle uptake of RONO2) in the GEOS-Chem global chemical transport model with ~ 25 x 25 km2 resolution over North America. We evaluate the model using aircraft (SEAC4RS) and ground-based (SOAS) observations of NOx, BVOCs, and RONO2 from the Southeast US in summer 2013. The updated simulation successfully reproduces the concentrations of individual gas- and particle-phase RONO2 species measured during the campaigns. Gas-phase isoprene nitrates account for 25-50 % of observed RONO2 in surface air, and we find that another 10 % is contributed by gas-phase monoterpene nitrates. Observations in the free troposphere show an important contribution from long-lived nitrates derived from anthropogenic VOCs. During both campaigns, at least 10 % of observed boundary layer RONO2 were in the particle phase. We find that aerosol uptake followed by hydrolysis to HNO3 accounts for 60 % of simulated gas-phase RONO2 loss in the boundary layer. Other losses are 20 % by photolysis to recycle NOx and 15 % by dry deposition. RONO2 production accounts for 20 % of the net regional NOx sink in the Southeast US in summer, limited by the spatial segregation between BVOC and NOx emissions. This segregation implies that RONO2 production will remain a minor sink for NOx in the Southeast US in the future even as NOx emissions continue to decline.

  13. Organic nitrate chemistry and its implications for nitrogen budgets in an isoprene- and monoterpene-rich atmosphere: constraints from aircraft (SEAC4RS and ground-based (SOAS observations in the Southeast US

    Directory of Open Access Journals (Sweden)

    J. A. Fisher

    2016-05-01

    Full Text Available Formation of organic nitrates (RONO2 during oxidation of biogenic volatile organic compounds (BVOCs: isoprene, monoterpenes is a significant loss pathway for atmospheric nitrogen oxide radicals (NOx, but the chemistry of RONO2 formation and degradation remains uncertain. Here we implement a new BVOC oxidation mechanism (including updated isoprene chemistry, new monoterpene chemistry, and particle uptake of RONO2 in the GEOS-Chem global chemical transport model with  ∼  25  ×  25 km2 resolution over North America. We evaluate the model using aircraft (SEAC4RS and ground-based (SOAS observations of NOx, BVOCs, and RONO2 from the Southeast US in summer 2013. The updated simulation successfully reproduces the concentrations of individual gas- and particle-phase RONO2 species measured during the campaigns. Gas-phase isoprene nitrates account for 25–50 % of observed RONO2 in surface air, and we find that another 10 % is contributed by gas-phase monoterpene nitrates. Observations in the free troposphere show an important contribution from long-lived nitrates derived from anthropogenic VOCs. During both campaigns, at least 10 % of observed boundary layer RONO2 were in the particle phase. We find that aerosol uptake followed by hydrolysis to HNO3 accounts for 60 % of simulated gas-phase RONO2 loss in the boundary layer. Other losses are 20 % by photolysis to recycle NOx and 15 % by dry deposition. RONO2 production accounts for 20 % of the net regional NOx sink in the Southeast US in summer, limited by the spatial segregation between BVOC and NOx emissions. This segregation implies that RONO2 production will remain a minor sink for NOx in the Southeast US in the future even as NOx emissions continue to decline.

  14. Fluorescence microscopy.

    Science.gov (United States)

    Sanderson, Michael J; Smith, Ian; Parker, Ian; Bootman, Martin D

    2014-10-01

    Fluorescence microscopy is a major tool with which to monitor cell physiology. Although the concepts of fluorescence and its optical separation using filters remain similar, microscope design varies with the aim of increasing image contrast and spatial resolution. The basics of wide-field microscopy are outlined to emphasize the selection, advantages, and correct use of laser scanning confocal microscopy, two-photon microscopy, scanning disk confocal microscopy, total internal reflection, and super-resolution microscopy. In addition, the principles of how these microscopes form images are reviewed to appreciate their capabilities, limitations, and constraints for operation. © 2014 Cold Spring Harbor Laboratory Press.

  15. Fluorescence calibration method for single-particle aerosol fluorescence instruments

    Science.gov (United States)

    Shipley Robinson, Ellis; Gao, Ru-Shan; Schwarz, Joshua P.; Fahey, David W.; Perring, Anne E.

    2017-05-01

    Real-time, single-particle fluorescence instruments used to detect atmospheric bioaerosol particles are increasingly common, yet no standard fluorescence calibration method exists for this technique. This gap limits the utility of these instruments as quantitative tools and complicates comparisons between different measurement campaigns. To address this need, we have developed a method to produce size-selected particles with a known mass of fluorophore, which we use to calibrate the fluorescence detection of a Wideband Integrated Bioaerosol Sensor (WIBS-4A). We use mixed tryptophan-ammonium sulfate particles to calibrate one detector (FL1; excitation = 280 nm, emission = 310-400 nm) and pure quinine particles to calibrate the other (FL2; excitation = 280 nm, emission = 420-650 nm). The relationship between fluorescence and mass for the mixed tryptophan-ammonium sulfate particles is linear, while that for the pure quinine particles is nonlinear, likely indicating that not all of the quinine mass contributes to the observed fluorescence. Nonetheless, both materials produce a repeatable response between observed fluorescence and particle mass. This procedure allows users to set the detector gains to achieve a known absolute response, calculate the limits of detection for a given instrument, improve the repeatability of the instrumental setup, and facilitate intercomparisons between different instruments. We recommend calibration of single-particle fluorescence instruments using these methods.

  16. Ultrafast ammonia-driven, microwave-assisted synthesis of nitrogen-doped graphene quantum dots and their optical properties

    OpenAIRE

    Zheng Binjie; Chen Yuanfu; Li Pingjian; Wang Zegao; Cao Bingqiang; Qi Fei; Liu Jinbo; Qiu Zhiwen; Zhang Wanli

    2016-01-01

    For the first time, a facile, ultrafast, ammonia-driven microwave-assisted synthesis of high-quality nitrogen-doped graphene quantum dots (NGQDs) at room temperature and atmospheric pressure is presented. This one-step method is very cheap, environment friendly, and suitable for large-scale production. The as-synthesized NGQDs consisting of one to three graphene monolayers exhibit highly crystalline quality with an average size of 5.3 nm. A new fluorescence (FL) emission peak at 390 nm is obs...

  17. Using a biochemical C4 photosynthesis model and combined gas exchange and chlorophyll fluorescence measurements to estimate bundle-sheath conductance of maize leaves differing in age and nitrogen content

    NARCIS (Netherlands)

    Yin, X.; Sun, Z.; Struik, P.C.; Putten, van der P.E.L.; Ieperen, van W.; Harbinson, J.

    2011-01-01

    Bundle-sheath conductance (gbs) affects CO2 leakiness, and, therefore, the efficiency of the CO2-concentrating mechanism (CCM) in C4 photosynthesis. Whether and how gbs varies with leaf age and nitrogen status is virtually unknown. We used a C4-photosynthesis model to estimate gbs, based on combined

  18. Nitrogen on Mars: Insights from Curiosity

    Science.gov (United States)

    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.

  19. Organic Nitrate Chemistry and Its Implications for Nitrogen Budgets in an Isoprene- and Monoterpene-Rich Atmosphere: Constraints From Aircraft (SEAC4RS) and Ground-Based (SOAS) Observations in the Southeast US

    Science.gov (United States)

    Fisher, Jenny; Jacob, D. J.; Travis, K. R.; Kim, P. S.; Marais, E. A.; Miller, C. Chan; Yu, K.; Zhu, L.; Yantosca, R. M.; Sulprizio, M. P.; hide

    2016-01-01

    Formation of organic nitrates (RONO2) during oxidation of biogenic volatile organic compounds (BVOCs: isoprene, monoterpenes) is a significant loss pathway for atmospheric nitrogen oxide radicals (NOx), but the chemistry of RONO2 formation and degradation remains uncertain. Here we implement a new BVOC oxidation mechanism (including updated isoprene chemistry, new monoterpene chemistry, and particle uptake of RONO2) in the GEOS-Chem global chemical transport model with approximately 25 times 25 km(exp 2) resolution over North America. We evaluate the model using aircraft (SEAC4RS) and ground-based (SOAS) observations of NOx, BVOCs, and RONO2 from the Southeast US in summer 2013. The updated simulation successfully reproduces the concentrations of individual gas- and particle-phase RONO2 species measured during the campaigns. Gas-phase isoprene nitrates account for 2550 of observed RONO2 in surface air, and we find that another 10 is contributed by gas-phase monoterpene nitrates. Observations in the free troposphere show an important contribution from long-lived nitrates derived from anthropogenic VOCs. During both campaigns, at least 10 of observed boundary layer RONO2 were in the particle phase. We find that aerosol uptake followed by hydrolysis to HNO3 accounts for 60 of simulated gas-phase RONO2 loss in the boundary layer. Other losses are 20 by photolysis to recycle NOx and 15 by dry deposition. RONO2 production accounts for 20 of the net regional NOx sink in the Southeast US in summer, limited by the spatial segregation between BVOC and NOx emissions. This segregation implies that RONO2 production will remain a minor sink for NOx in the Southeast US in the future even as NOx emissions continue to decline. XXXX We have used airborne and ground-based observations from two summer 2013 campaigns in the Southeast US (SEAC4RS, SOAS) to better understand the chemistry and impacts of alkyl and multi-functional organic nitrates (RONO2). We used the observations, along

  20. Nitrogen tank

    CERN Multimedia

    2006-01-01

    Wanted The technical file about the pressure vessel RP-270 It concerns the Nitrogen tank, 60m3, 22 bars, built in 1979, and installed at Point-2 for the former L3 experiment. If you are in possession of this file, or have any files about an equivalent tank (probably between registered No. RP-260 and -272), please contact Marc Tavlet, the ALICE Glimos.

  1. Hydrothermal treatment of grass: a low-cost, green route to nitrogen-doped, carbon-rich, photoluminescent polymer nanodots as an effective fluorescent sensing platform for label-free detection of Cu(II) ions.

    Science.gov (United States)

    Liu, Sen; Tian, Jingqi; Wang, Lei; Zhang, Yingwei; Qin, Xiaoyun; Luo, Yonglan; Asiri, Abdullah M; Al-Youbi, Abdulrahman O; Sun, Xuping

    2012-04-17

    Increasing reaction temperature produces photoluminescent polymer nanodots (PPNDs) with decreased particle size and increased quantum yield. Such PPNDs are used as an effective fluorescent sensing platform for label-free sensitive and selective detection of Cu(II) ions with a detection limit as low as 1 nM. This method is successfully applied to determine Cu(2+) in real water samples. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. A fluorescence resonance energy transfer (FRET) based "Turn-On" nanofluorescence sensor using a nitrogen-doped carbon dot-hexagonal cobalt oxyhydroxide nanosheet architecture and application to α-glucosidase inhibitor screening.

    Science.gov (United States)

    Li, Guoliang; Kong, Weiheng; Zhao, Mei; Lu, Shuaimin; Gong, Peiwei; Chen, Guang; Xia, Lian; Wang, Hua; You, Jinmao; Wu, Yongning

    2016-05-15

    The medicines targeted at α-glucosidase played an important role in anti-diabetes and anti-HIV therapy. Unfortunately, the method based on fluorescent assay strategy for α-glucosidase inhibitor screening remains poorly investigated. In this study, a novel "Turn On" fluorescence sensor platform has been developed for trace α-glucosidase inhibitor screening from natural medicines. Firstly, carbon dots were prepared by one-pot synthesis and used as the signal output. Combining with the carbon dots, cobalt oxyhydroxide (CoOOH) nanoflakes were employed to build the fluorescence resonance energy transfer (FRET) based sensor platform. Secondly, L-ascorbic acid-2-O-α-D-glucopyranosyl (AAG) was innovatively introduced as α-glucosidase substrate. With hydrolysis of AAG by α-glucosidase, ascorbic acids (AA) were released that can rapidly reduce CoOOH nanoflakes to Co(2+), and then FRET was stopped accompanying with the fluorescence recovery of CDs. The sensor platform was ultrasensitive to AA with a detection limit of 5 nM, ensuring the sensitive monitoring of enzyme activity. Acarbose was used as the inhibitor model and its inhibition rate is proportional to the logarithm of concentration in range of 10(-9)-10(-3)M with the correlation coefficient of R(2)=0.996, and an ultralow limit of detection of ~1×10(-9)M was obtained. The inhibiting ability of seven compounds isolated from natural medicines was also evaluated. The constructed sensor platform was proven to be sensitive and selective as well as cost-effective, facile and reliable, making it promising as a candidate for trace α-glucosidase inhibitor screening. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Effects of increased atmospheric CO{sub 2} concentrations on transpiration of a wheat field in consideration of water and nitrogen limitation; Die Wirkung von erhoehten atmosphaerischen CO{sub 2}-Konzentrationen auf die Transpiration eines Weizenbestandes unter Beruecksichtigung von Wasser- und Stickstofflimitierung

    Energy Technology Data Exchange (ETDEWEB)

    Grossman-Clarke, S.

    2000-09-01

    Primary responses of C{sub 3}-plants to elevated atmospheric CO{sub 2} concentrations are an increase in the net assimilation rate, leading to greater biomass, and an associated decrease in the transpiration rate per unit leaf area due to CO{sub 2}-induced stomatal closure. The question has therefore arisen: does canopy transpiration increase because of the greater biomass, or decrease because of the stomatal closure? The direct impact of an elevated atmospheric CO{sub 2} concentration of 550 {mu}mol mol{sup -1} on the seasonal course of canopy transpiration of a spring wheat crop was investigated by means of the simulation model DEMETER for production under unlimited water and nutrient supply, production under limited water but unlimited nutrient supply and the production under unlimited water but limited nitrogen supply. Independent data of the free-air carbon dioxide enrichment wheat experiments in Arizona, USA (1993-96) were used to test if the model is able to make reasonable predictions of water use and productivity of the spring wheat crop using only parameters derived from the literature. A model integrating leaf photosynthesis, stomatal conductance and energy fluxes between the plant and the atmosphere was scaled to a canopy level in order to be used in the wheat crop growth model. Temporal changes of the model parameters were considered by describing them as dependent on the changing leaf nitrogen content. Comparison of the simulation and experimental results showed that the applicability of the model approach was limited after anthesis by asynchronous changes in mesophyll and stomatal conductance. Therefore a new model approach was developed describing the interaction between assimilation rate and stomatal conductance during grain filling. The simulation results revealed only small differences in the cumulative sum of canopy transpiration and soil evaporation between elevated CO{sub 2} and control conditions. For potential growth conditions the model

  4. Middle Atmosphere Program. Handbook for MAP. Volume 13: Ground-based Techniques

    Science.gov (United States)

    Vincent, R. A. (Editor)

    1984-01-01

    Topics of activities in the middle Atmosphere program covered include: lidar systems of aerosol studies; mesosphere temperature; upper atmosphere temperatures and winds; D region electron densities; nitrogen oxides; atmospheric composition and structure; and optical sounding of ozone.

  5. QTL analysis of symbiotic nitrogen fixation in a black bean RIL population

    Science.gov (United States)

    Dry bean (Phaseolus vulgaris L) acquires nitrogen (N) from the atmosphere through symbiotic nitrogen fixation (SNF) but it has a low efficiency to fix nitrogen. The objective of this study is to map the genes controlling nitrogen fixation in common bean. A mapping population consisting of 122 recomb...

  6. Nitrogen mineralization and nitrification in a mixed-conifer forest in southern California : controlling factors, fluxes, and nitrogen fertilization response at a high and low nitrogen deposition site

    Energy Technology Data Exchange (ETDEWEB)

    Fenn, M.E.; Poth, M.A.; Terry, J.D.; Blubaugh, T.J. [United States Dept. of Agriculture, Riverside, CA (United States). Forest Service, Pacific Southwest Research Station

    2005-06-01

    Human activities and anthropogenic emissions have disturbed the global nitrogen (N) cycle to the point that atmospheric deposition of inorganic nitrogen has increased nearly threefold above preindustrial levels. These increased levels have the potential to cause excessive nitrogen enrichment of aquatic and terrestrial ecosystems. Increased nitrogen levels stimulate nitrogen mineralization and nitrification, thereby contributing to mobilization of nitrogen and nitrogen saturation conditions. In this study, net fluxes of nitrogen mineralization and nitrification were measured in situ on a monthly basis for 3 years in the San Bernardino Mountains in California. The objective was to quantify the rates of net nitrogen mineralization and nitrification in the humus layer and mineral soil under field conditions in fertilized and unfertilized plots at a nitrogen deposition forest site that is highly N saturated as well as a low nitrogen deposition site to determine whether relative nitrification patterns in field assays are similar to laboratory study results. The main factors affecting nitrogen cycling rates in the mineral soil and the forest floor were determined. The study also tested the hypothesis that slow release nitrogen fertilization over 3 years at a low nitrogen site results in net nitrification rates that approach those of high nitrogen sites. The study revealed the relative nitrification rates under different tree canopies. The key factor for predicting the rate of net nitrification is the rate of net nitrogen mineralization. A high nitrogen fertilization had no substantial impact on net nitrification. It was concluded that at low-deposition sites, increased nitrification occurs in the short term due to added nitrogen. However, the accumulation of nitrogen enriched litter and soil organic matter along with chronic throughfall nitrogen deposition causes sustained elevated net nitrification. 67 refs., 7 tabs., 7 figs.

  7. Atmospheric pollution; Pollution atmospherique

    Energy Technology Data Exchange (ETDEWEB)

    Lambrozo, J.; Guillossou, G. [EDF-Gas de France, Service des Etudes Medicales, 75 - Paris (France)

    2008-10-15

    The atmosphere is the reservoir of numerous pollutants (nitrogen oxides, sulfur oxides, carbon oxides, particulates, volatile organic compounds, polycyclic aromatic hydrocarbons) from natural origin or anthropogenic origin ( industry, transport, agriculture, district heating). With epidemiologic studies the atmospheric pollution is associated with an increase of respiratory and cardiovascular diseases. At the european level, the technological progress, the legislation have allowed a reduction of pollutant emissions, however these efforts have to be continued because the sanitary impact of atmospheric pollution must not be underestimated, even if the risks appear less important that these ones in relation with tobacco, inside pollution or others factors of cardiovascular risks. Indeed, on these last factors an individual action is possible for the exposure to air pollution people have no control. (N.C.)

  8. The nitrogen cycle on Mars

    Science.gov (United States)

    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.

  9. Ultrafast ammonia-driven, microwave-assisted synthesis of nitrogen-doped graphene quantum dots and their optical properties

    Science.gov (United States)

    Zheng, Binjie; Chen, Yuanfu; Li, Pingjian; Wang, Zegao; Cao, Bingqiang; Qi, Fei; Liu, Jinbo; Qiu, Zhiwen; Zhang, Wanli

    2017-01-01

    For the first time, a facile, ultrafast, ammonia-driven microwave-assisted synthesis of high-quality nitrogen-doped graphene quantum dots (NGQDs) at room temperature and atmospheric pressure is presented. This one-step method is very cheap, environment friendly, and suitable for large-scale production. The as-synthesized NGQDs consisting of one to three graphene monolayers exhibit highly crystalline quality with an average size of 5.3 nm. A new fluorescence (FL) emission peak at 390 nm is observed, which might be attributed to the doped nitrogen atoms into the GQDs. An interesting red-shift is observed by comparing the FL excitation spectra to the UV-visible absorption spectra. Based on the optical properties, the detailed Jablonski diagram representing the energy level structure of NGQDs is derived.

  10. Ultrafast ammonia-driven, microwave-assisted synthesis of nitrogen-doped graphene quantum dots and their optical properties

    Directory of Open Access Journals (Sweden)

    Zheng Binjie

    2016-06-01

    Full Text Available For the first time, a facile, ultrafast, ammonia-driven microwave-assisted synthesis of high-quality nitrogen-doped graphene quantum dots (NGQDs at room temperature and atmospheric pressure is presented. This one-step method is very cheap, environment friendly, and suitable for large-scale production. The as-synthesized NGQDs consisting of one to three graphene monolayers exhibit highly crystalline quality with an average size of 5.3 nm. A new fluorescence (FL emission peak at 390 nm is observed, which might be attributed to the doped nitrogen atoms into the GQDs. An interesting red-shift is observed by comparing the FL excitation spectra to the UV-visible absorption spectra. Based on the optical properties, the detailed Jablonski diagram representing the energy level structure of NGQDs is derived.

  11. Nitrogen-fixing bacteria in Mediterranean seagrass (Posidonia oceanica) roots

    KAUST Repository

    Garcias Bonet, Neus

    2016-03-09

    Biological nitrogen fixation by diazotrophic bacteria in seagrass rhizosphere and leaf epiphytic community is an important source of nitrogen required for plant growth. However, the presence of endophytic diazotrophs remains unclear in seagrass tissues. Here, we assess the presence, diversity and taxonomy of nitrogen-fixing bacteria within surface-sterilized roots of Posidonia oceanica. Moreover, we analyze the nitrogen isotopic signature of seagrass tissues in order to notice atmospheric nitrogen fixation. We detected nitrogen-fixing bacteria by nifH gene amplification in 13 out of the 78 roots sampled, corresponding to 9 locations out of 26 meadows. We detected two different types of bacterial nifH sequences associated with P. oceanica roots, which were closely related to sequences previously isolated from the rhizosphere of a salt marsh cord grass and a putative anaerobe. Nitrogen content of seagrass tissues showed low isotopic signatures in all the sampled meadows, pointing out the atmospheric origin of the assimilated nitrogen by seagrasses. However, this was not related with the presence of endophytic nitrogen fixers, suggesting the nitrogen fixation occurring in rhizosphere and in the epiphytic community could be an important source of nitrogen for P. oceanica. The low diversity of nitrogen-fixing bacteria reported here suggests species-specific relationships between diazotrophs and P. oceanica, revealing possible symbiotic interactions that could play a major role in nitrogen acquisition by seagrasses in oligotrophic environments where they form lush meadows.

  12. Nitrogen Deposition: A Component of Global Change Analyses

    Energy Technology Data Exchange (ETDEWEB)

    Norby, Richard J.

    1997-12-31

    The global cycles of carbon and nitrogen are being perturbed by human activities that increase the transfer from large pools of nonreactive forms of the elements to reactive forms that are essential to the functioning of the terrestrial biosphere. The cycles are closely linked at all scales, and global change analyses must consider carbon and nitrogen cycles together. The increasing amount of nitrogen originating from fossil fuel combustion and deposited to terrestrial ecosystems as nitrogen oxides could increase the capacity of ecosystems to sequester carbon thereby removing some of the excess carbon dioxide from the atmosphere and slowing the development of greenhouse warming. Several global and ecosystem models have calculated the amount of carbon sequestration that can be attributed to nitrogen deposition based on assumptions about the allocation of nitrogen among ecosystem components with different carbon-nitrogen ratios. They support the premise that nitrogen deposition is responsible for a an increasing terrestrial carbon sink since industrialization began, but there are large uncertainties related to the continued capacity of ecosystems to retain exogenous nitrogen. Whether terrestrial ecosystems continue to sequester additional carbon will depend in part on their response to increasing atmospheric carbon dioxide concentrations, which is widely thought to be constrained by limited nitrogen availability. Ecosystem models generally support the conclusion that the responses of ecosystems to increasing concentrations of carbon dioxide will be larger, and the range of possible responses will be wider, in ecosystems with increased nitrogen inputs originating as atmospheric deposition.

  13. Preparation of nitrogen-doped carbon tubes

    Science.gov (United States)

    Chung, Hoon Taek; Zelenay, Piotr

    2015-12-22

    A method for synthesizing nitrogen-doped carbon tubes involves preparing a solution of cyanamide and a suitable transition metal-containing salt in a solvent, evaporating the solvent to form a solid, and pyrolyzing the solid under an inert atmosphere under conditions suitable for the production of nitrogen-doped carbon tubes from the solid. Pyrolyzing for a shorter period of time followed by rapid cooling resulted in a tubes with a narrower average diameter.

  14. Seasonal Nitrogen Cycles on Pluto

    Science.gov (United States)

    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.

  15. Nitrogen oxides

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, T.; Horiike, E.; Murakami, M.; Hosoya, T.; Miyanishi, T.; Amamiya, S.

    1975-08-01

    This invention relates to the removal of nitrogen oxides with an aqueous alkaline solution. Waste gas was introduced to an absorbing tower at a flow rate of 0.7--1.0 m/s while sodium hydroxide solution was pumped to the top of the tower at 10--15 l/m/sup 3/ gas. The liquid was sprayed into the waste gas and the resulting gas was led to a second absorbing tower and then a decomposition tower where the remaining NO/sub x/ was removed by sodium sulfide solution or Na/sub 2/S and NaOH mixed solution. With two absorbing towers and one decomposition tower, NO/sub x/ concentration was reduced from 2500 ppM to as low as 36 ppM, or 99 percent removal. With three absorbing towers, the rate of removal was below 80 percent.

  16. Effect of binding and conformation on fluorescence quenching in new 2',7'-dichlorofluorescein derivatives.

    Science.gov (United States)

    Sparano, Brian A; Shahi, Shatrughan P; Koide, Kazunori

    2004-06-10

    [structure: see text] Symmetrical and unsymmetrical 2',7'-dichlorofluorescein (DCF) derivatives have been synthesized by means of Mannich reactions and an aromatic Claisen rearrangement. NMR and fluorescence spectroscopic studies reveal the correlation between the conformations, the photoinduced electron transfer mechanism, and fluorescent intensities of these DCF derivatives. Two quenching nitrogen atoms cooperatively and reversibly suppress the fluorescence of the chromophore.

  17. Atmospheric Dispositifs

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2015-01-01

    Through the coupling of dispositif with atmosphere this paper engages in a discussion of the atmospherics as both a form of knowledge and a material practice. In doing so the objective is to provide an inventory of tools and methodologies deployed in the construction of atmosphere understood......, the conceptual foundations and protocols for the production of atmosphere in architecture might be found beneath the surface of contemporary debates. In this context, the notion of atmospheric dispositif – illustrated through an oeuvre of the German architect Werner Ruhnau and its theoretical and historical...

  18. Introduction to fluorescence microscopy.

    Science.gov (United States)

    Ghiran, Ionita C

    2011-01-01

    This chapter is an overview of basic principles of fluorescence microscopy, including a brief history on the invention of this type of microscopy. The chapter highlights important points related to properties of fluorochromes, resolution in fluorescence microscopy, phase contrast and fluorescence, fluorescence filters, construction of a fluorescence microscope, and tips on the correct use of this equipment.

  19. Understanding Nitrogen Fixation

    Energy Technology Data Exchange (ETDEWEB)

    Paul J. Chirik

    2012-05-25

    The purpose of our program is to explore fundamental chemistry relevant to the discovery of energy efficient methods for the conversion of atmospheric nitrogen (N{sub 2}) into more value-added nitrogen-containing organic molecules. Such transformations are key for domestic energy security and the reduction of fossil fuel dependencies. With DOE support, we have synthesized families of zirconium and hafnium dinitrogen complexes with elongated and activated N-N bonds that exhibit rich N{sub 2} functionalization chemistry. Having elucidated new methods for N-H bond formation from dihydrogen, C-H bonds and Broensted acids, we have since turned our attention to N-C bond construction. These reactions are particularly important for the synthesis of amines, heterocycles and hydrazines with a range of applications in the fine and commodity chemicals industries and as fuels. One recent highlight was the discovery of a new N{sub 2} cleavage reaction upon addition of carbon monoxide which resulted in the synthesis of an important fertilizer, oxamide, from the diatomics with the two strongest bonds in chemistry. Nitrogen-carbon bonds form the backbone of many important organic molecules, especially those used in the fertilizer and pharamaceutical industries. During the past year, we have continued our work in the synthesis of hydrazines of various substitution patterns, many of which are important precursors for heterocycles. In most instances, the direct functionalization of N{sub 2} offers a more efficient synthetic route than traditional organic methods. In addition, we have also discovered a unique CO-induced N{sub 2} bond cleavage reaction that simultaneously cleaves the N-N bond of the metal dinitrogen compound and assembles new C-C bond and two new N-C bonds. Treatment of the CO-functionalized core with weak Broensted acids liberated oxamide, H{sub 2}NC(O)C(O)NH{sub 2}, an important slow release fertilizer that is of interest to replace urea in many applications. The

  20. High-Throughput Accurate Single-Cell Screening of Euglena gracilis with Fluorescence-Assisted Optofluidic Time-Stretch Microscopy.

    Science.gov (United States)

    Guo, Baoshan; Lei, Cheng; Ito, Takuro; Jiang, Yiyue; Ozeki, Yasuyuki; Goda, Keisuke

    2016-01-01

    The development of reliable, sustainable, and economical sources of alternative fuels is an important, but challenging goal for the world. As an alternative to liquid fossil fuels, algal biofuel is expected to play a key role in alleviating global warming since algae absorb atmospheric CO2 via photosynthesis. Among various algae for fuel production, Euglena gracilis is an attractive microalgal species as it is known to produce wax ester (good for biodiesel and aviation fuel) within lipid droplets. To date, while there exist many techniques for inducing microalgal cells to produce and accumulate lipid with high efficiency, few analytical methods are available for characterizing a population of such lipid-accumulated microalgae including E. gracilis with high throughout, high accuracy, and single-cell resolution simultaneously. Here we demonstrate high-throughput, high-accuracy, single-cell screening of E. gracilis with fluorescence-assisted optofluidic time-stretch microscopy-a method that combines the strengths of microfluidic cell focusing, optical time-stretch microscopy, and fluorescence detection used in conventional flow cytometry. Specifically, our fluorescence-assisted optofluidic time-stretch microscope consists of an optical time-stretch microscope and a fluorescence analyzer on top of a hydrodynamically focusing microfluidic device and can detect fluorescence from every E. gracilis cell in a population and simultaneously obtain its image with a high throughput of 10,000 cells/s. With the multi-dimensional information acquired by the system, we classify nitrogen-sufficient (ordinary) and nitrogen-deficient (lipid-accumulated) E. gracilis cells with a low false positive rate of 1.0%. This method holds promise for evaluating cultivation techniques and selective breeding for microalgae-based biofuel production.

  1. High-Throughput Accurate Single-Cell Screening of Euglena gracilis with Fluorescence-Assisted Optofluidic Time-Stretch Microscopy.

    Directory of Open Access Journals (Sweden)

    Baoshan Guo

    Full Text Available The development of reliable, sustainable, and economical sources of alternative fuels is an important, but challenging goal for the world. As an alternative to liquid fossil fuels, algal biofuel is expected to play a key role in alleviating global warming since algae absorb atmospheric CO2 via photosynthesis. Among various algae for fuel production, Euglena gracilis is an attractive microalgal species as it is known to produce wax ester (good for biodiesel and aviation fuel within lipid droplets. To date, while there exist many techniques for inducing microalgal cells to produce and accumulate lipid with high efficiency, few analytical methods are available for characterizing a population of such lipid-accumulated microalgae including E. gracilis with high throughout, high accuracy, and single-cell resolution simultaneously. Here we demonstrate high-throughput, high-accuracy, single-cell screening of E. gracilis with fluorescence-assisted optofluidic time-stretch microscopy-a method that combines the strengths of microfluidic cell focusing, optical time-stretch microscopy, and fluorescence detection used in conventional flow cytometry. Specifically, our fluorescence-assisted optofluidic time-stretch microscope consists of an optical time-stretch microscope and a fluorescence analyzer on top of a hydrodynamically focusing microfluidic device and can detect fluorescence from every E. gracilis cell in a population and simultaneously obtain its image with a high throughput of 10,000 cells/s. With the multi-dimensional information acquired by the system, we classify nitrogen-sufficient (ordinary and nitrogen-deficient (lipid-accumulated E. gracilis cells with a low false positive rate of 1.0%. This method holds promise for evaluating cultivation techniques and selective breeding for microalgae-based biofuel production.

  2. Application of thermal-dissociation laser induced fluorescence (TD-LIF to measurement of HNO3, Σalkyl nitrates, Σperoxy nitrates, and NO2 fluxes using eddy covariance

    Directory of Open Access Journals (Sweden)

    D. K. Farmer

    2006-01-01

    Full Text Available Nitrogen exchange between the atmosphere and biosphere directly influences atmospheric composition. While much is known about mechanisms of NO and N2O emissions, instrumentation for the study of mechanisms contributing to exchange of other major nitrogen species is quite limited. Here we describe the application of a new technique, thermal dissociation-laser induced fluorescence (TD-LIF, to eddy covariance measurements of the fluxes of NO2, total peroxy acyl and peroxy nitrates, total alkyl and multifunctional alkyl nitrates, and nitric acid. The technique offers the potential for investigating mechanisms of exchange of these species at the canopy scale over timescales from days to years. Examples of flux measurements at a ponderosa pine plantation in the mid-elevation Sierra Nevada Mountains in California are reported and used to evaluate instrument performance.

  3. Fluorescence detection: SPIE volume 743

    Energy Technology Data Exchange (ETDEWEB)

    Menzel, E.R.

    1987-01-01

    This book contains proceedings arranged into four sessions. They are: Fluorescence spectroscopic techniques; Fluorescence in analysis and materials characterization; Fluorescence in medicine and biochemistry; and Fluorescence in criminalistics.

  4. Effects of atmospheric fallouts of sulfur and nitrogen on soils and fresh waters in France; Effets des depots atmospheriques de soufre et d'azote sur les sols et les eaux douces en France

    Energy Technology Data Exchange (ETDEWEB)

    Le Gall, A.Ch.

    2004-11-15

    The sulfur oxides, nitrogen oxides, the ammonia and the chlorine emitted in the environment by human activities contribute to the soils and waters acidity. After a presentation of the acidification and the eutrophication, the author describes and qualifies the mechanisms. In a second part she discusses the mathematical models of the acidification and the eutrophication, the biological criteria and the uncertainties. The last part presents the french situation and general recommendations on land restoration. (A.L.B.)

  5. Atmospheric gas phase reactions

    Science.gov (United States)

    Platt, Ulrich

    This chapter introduces the underlying physicochemical principles and the relevance of atmospheric gas phase reactions. In particular, reaction orders, the concept of elementary reactions, definition of and factors determining reaction rates (kinetic theory of chemical reactions), and photochemical reactions are discussed. Sample applications of the pertinent reaction pathways in tropospheric chemistry are presented, particularly reactions involving free radicals (OH, NO3, halogen oxides) and their roles in the self-cleaning of the troposphere. The cycles of nitrogen and sulfur species as well as the principles of tropospheric ozone formation are introduced. Finally, the processes governing the stratospheric ozone layer (Chapman Cycle and extensions) are discussed.

  6. Articulating Atmospheres

    DEFF Research Database (Denmark)

    Kinch, Sofie

    2011-01-01

    This paper presents an architectural approach to designing computational interfaces by articulating the notion of atmosphere in the field of interaction design. It draws upon the concept of kinesthetic interaction and a philosophical notion on atmosphere emphasizing the importance of bodily exper......” implications and qualities of the approach are identified through concrete examples of a design case, which also investigates the qualities and implications of addressing atmospheres both as design concern and user experience.......This paper presents an architectural approach to designing computational interfaces by articulating the notion of atmosphere in the field of interaction design. It draws upon the concept of kinesthetic interaction and a philosophical notion on atmosphere emphasizing the importance of bodily...... experience in space, presented as middle ground experience. In the field of HCI, middle ground experiences complete the unarticulated spectrum between designing for foreground of attention or background awareness. When “Articulating Atmospheres through Middle Ground Experiences in Interaction Design...

  7. Atmospheric electricity

    CERN Document Server

    Chalmers, J Alan

    1957-01-01

    Atmospheric Electricity brings together numerous studies on various aspects of atmospheric electricity. This book is composed of 13 chapters that cover the main problems in the field, including the maintenance of the negative charge on the earth and the origin of the charges in thunderstorms. After a brief overview of the historical developments of atmospheric electricity, this book goes on dealing with the general principles, results, methods, and the MKS system of the field. The succeeding chapters are devoted to some aspects of electricity in the atmosphere, such as the occurrence and d

  8. Atmospheric Neutrinos

    Directory of Open Access Journals (Sweden)

    Takaaki Kajita

    2012-01-01

    Full Text Available Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron-neutrinos and muon-neutrinos are produced mainly by the decay chain of charged pions to muons to electrons. Atmospheric neutrino experiments observed zenith angle and energy-dependent deficit of muon-neutrino events. It was found that neutrino oscillations between muon-neutrinos and tau-neutrinos explain these data well. This paper discusses atmospheric neutrino experiments and the neutrino oscillation studies with these neutrinos.

  9. Modelling land surface fluxes of CO2 in response to climate change and nitrogen deposition

    DEFF Research Database (Denmark)

    Hansen, Kristina; Ambelas Skjøth, Carsten; Geels, Camilla

    Climate change, land use variations, and impacts of atmospheric nitrogen (N) deposition represent uncertainties for the prediction of future greenhouse gas exchange between land surfaces and the atmosphere as the mechanisms describing nutritional effects are not well developed in climate...

  10. Measurements of the OH radical in forested environments by laser-induced fluorescence

    Science.gov (United States)

    Bottorff, B.; Lew, M.; Stevens, P. S.

    2016-12-01

    The hydroxyl radical (OH) is one of the most important oxidants in the atmosphere. The OH radical initiates the oxidation of volatile organic compounds (VOCs) which in the presence of nitrogen oxides (NOx) can lead to the production of ozone and secondary organic aerosols. Recent studies have shown discrepancies between measured and modeled OH concentrations, especially in forested, low-NOx environments. Therefore, additional measurements of OH radical concentrations in these environments are needed to provide a better understanding of the impact of BVOC emissions on the chemistry of the troposphere. In this study, measurements of OH were made using the Laser-Induced Fluorescence-Fluorescence Assay by Gas Ecpansion (LIF-FAGE) technique during two field campaigns: the Indiana Radical Reactivity and Ozone Production Intercomparison (IRRONIC) in Bloomington, Indiana during July 2015 and the Program for Research on Oxidants Photochemistry and Transport - Atmospheric Measurements of Oxidants in Summer (PROPHET-AMOS) in Pellston, Michigan during July 2016. Both campaigns were conducted in forested environments characterized by high isoprene emissions and low NOx mixing ratios. Ambient OH measurements from both campaigns, including measurements of unknown interferences, will be discussed and compared to modeled predictions.

  11. The geobiological nitrogen cycle: From microbes to the mantle.

    Science.gov (United States)

    Zerkle, A L; Mikhail, S

    2017-05-01

    Nitrogen forms an integral part of the main building blocks of life, including DNA, RNA, and proteins. N2 is the dominant gas in Earth's atmosphere, and nitrogen is stored in all of Earth's geological reservoirs, including the crust, the mantle, and the core. As such, nitrogen geochemistry is fundamental to the evolution of planet Earth and the life it supports. Despite the importance of nitrogen in the Earth system, large gaps remain in our knowledge of how the surface and deep nitrogen cycles have evolved over geologic time. Here, we discuss the current understanding (or lack thereof) for how the unique interaction of biological innovation, geodynamics, and mantle petrology has acted to regulate Earth's nitrogen cycle over geologic timescales. In particular, we explore how temporal variations in the external (biosphere and atmosphere) and internal (crust and mantle) nitrogen cycles could have regulated atmospheric pN2 . We consider three potential scenarios for the evolution of the geobiological nitrogen cycle over Earth's history: two in which atmospheric pN2 has changed unidirectionally (increased or decreased) over geologic time and one in which pN2 could have taken a dramatic deflection following the Great Oxidation Event. It is impossible to discriminate between these scenarios with the currently available models and datasets. However, we are optimistic that this problem can be solved, following a sustained, open-minded, and multidisciplinary effort between surface and deep Earth communities. © 2017 The Authors Geobiology Published by John Wiley & Sons Ltd.

  12. Eco-physiological responses and symbiotic nitrogen fixation ...

    African Journals Online (AJOL)

    Nitrogen nutrition of Hedysarum carnosum, a pastoral legume common in Tunisian central and southern rangelands, largely depends on atmospheric nitrogen fixation. Yet, this process is greatly affected by environmental factors such as salinity. This study aimed to characterize the tolerance limits and the physiological ...

  13. Fluorescence, Aqua MODIS, NPP, 0.125 degrees, West US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures chlorophyll fluorescence, which gives insight into the physiology of phytoplankton in the ocean. When phytoplankton are under stress, the rate at...

  14. Fluorescence, Aqua MODIS, NPP, 0.125 degrees, East US

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — MODIS measures chlorophyll fluorescence, which gives insight into the physiology of phytoplankton in the ocean. When phytoplankton are under stress, the rate at...

  15. Urban atmospheres.

    Science.gov (United States)

    Gandy, Matthew

    2017-07-01

    What is an urban atmosphere? How can we differentiate an 'atmosphere' from other facets of urban consciousness and experience? This essay explores some of the wider cultural, political, and philosophical connotations of atmospheres as a focal point for critical reflections on space and subjectivity. The idea of an 'affective atmosphere' as a distinctive kind of mood or shared corporeal phenomenon is considered in relation to recent developments in phenomenology, extended conceptions of agency, and new understandings of materialism. The essay draws in particular on the changing characteristics of air and light to reflect on different forms of sensory experience and their wider cultural and political connotations. The argument highlights some of the tensions and anomalies that permeate contemporary understandings of urban atmospheres.

  16. Global reactive nitrogen deposition from lightning NOx

    NARCIS (Netherlands)

    Shepon, A.; Gildor, H.; Labrador, L.J.; Butler, T.; Ganzeveld, L.N.; Lawrence, M.G.

    2007-01-01

    We present results of the deposition of nitrogen compounds formed from lightning (LNO x ) using the global chemical transport Model of Atmospheric Transport and Chemistry¿Max Planck Institute for Chemistry version. The model indicates an approximately equal deposition of LNO x in both terrestrial

  17. Biological nitrogen fixation, forms and regulating factors

    NARCIS (Netherlands)

    Giller, K.E.; Mapfumo, P.

    2002-01-01

    Nitrogen fixation is the basis of the global N cycle. Therefore it is not surprising that the ability to fix atmospheric N2 evolved in the "primeval soup" and is deeply rooted in the evolutionary tree of life. Despite this, nitrogenase remains an enzyme exclusive to prokaryotes; no eukaryote has

  18. Vegetation stress from soil moisture and chlorophyll fluorescence: synergy between SMAP and FLEX approaches

    Science.gov (United States)

    Moreno, Jose; Moran, Susan

    2014-05-01

    Vegetation stress detection continues being a focal objective for remote sensing techniques. It has implications not only for practical applications such as irrigation optimization or precision agriculture, but also for global climate models, providing data to better link water and carbon exchanges between the surface and the atmospheric and improved parameterization of the role of terrestrial vegetation in the coupling of water and carbon cycles. Traditional approaches to map vegetation stress using remote sensing techniques have been based on measurements of soil moisture status, canopy (radiometric) temperature and, to a lesser extent, canopy water content, but new techniques such as the dynamics of vegetation fluorescence emission, are also now available. Within the context of the preparatory activities for the SMAP and FLEX missions, a number of initiatives have been put in place to combine modelling activities and field experiments in order to look for alternative and more efficient ways of detecting vegetation stress, with emphasis on synergistic remote sensing approaches. The potential of solar-induced vegetation fluorescence as an early indicator of stress has been widely demonstrated, for different type of stress conditions: light amount (excess illumination) and conditions (direct/diffuse), temperature extremes (low and high), soil water availability (soil moisture), soil nutrients (nitrogen), atmospheric water vapour and atmospheric CO2 concentration. The effects caused by different stress conditions are sometimes difficult to be decoupled, also because different causes are often combined, but in general they then to change the overall fluorescence emission (modulating amplitude) or changing the relative contributions of photosystems PSI and PSII or the relative fluorescence re-absorption effects caused by modifications in the structure of pigment bed responsible for light absorption, in particular for acclimation for persistent stress conditions. While

  19. VUV photochemistry simulation of planetary upper atmosphere using synchrotron radiation.

    Science.gov (United States)

    Carrasco, Nathalie; Giuliani, Alexandre; Correia, Jean Jacques; Cernogora, Guy

    2013-07-01

    The coupling of a gas reactor, named APSIS, with a vacuum-ultraviolet (VUV) beamline at the SOLEIL synchrotron radiation facility, for a photochemistry study of gas mixtures, is reported. The reactor may be irradiated windowless with gas pressures up to hundreds of millibar, and thus allows the effect of energetic photons below 100 nm wavelength to be studied on possibly dense media. This set-up is perfectly suited to atmospheric photochemistry investigations, as illustrated by a preliminary report of a simulation of the upper atmospheric photochemistry of Titan, the largest satellite of Saturn. Titan's atmosphere is mainly composed of molecular nitrogen and methane. Solar VUV irradiation with wavelengths no longer than 100 nm on the top of the atmosphere enables the dissociation and ionization of nitrogen, involving a nitrogen chemistry specific to nitrogen-rich upper atmospheres.

  20. High-resolution methods for fluorescence retrieval from space

    NARCIS (Netherlands)

    Mazzoni, M.; Falorni, P.; Verhoef, W.

    2010-01-01

    The retrieval from space of a very weak fluorescence signal was studied in the O2A and O2B oxygen atmospheric absorption bands. The accuracy of the method was tested for the retrieval of the chlorophyll fluorescence and reflectance terms contributing to the sensor signal. The radiance at the top of

  1. Comparative thermogravimetric analyses of co-combustion of textile dyeing sludge and sugarcane bagasse in carbon dioxide/oxygen and nitrogen/oxygen atmospheres: Thermal conversion characteristics, kinetics, and thermodynamics.

    Science.gov (United States)

    Xie, Wenhao; Wen, Shaoting; Liu, Jingyong; Xie, Wuming; Kuo, Jiahong; Lu, Xingwen; Sun, Shuiyu; Chang, Kenlin; Buyukada, Musa; Evrendilek, Fatih

    2018-02-03

    Thermodynamic and kinetic parameters of co-combustion of textile dyeing sludge (TDS) and sugarcane bagasse (SB) were studied using thermogravimetric analysis in CO 2 /O 2 and N 2 /O 2 atmospheres. Our results showed that the comprehensive combustion characteristic index (CCI) of the blends was improved by 1.71-4.32 times. With the increased O 2 concentration, co-combustion peak temperature decreased from 329.7 to 318.2 °C, with an increase in its maximum weight loss rate from 10.04 to 14.99%/min and its CCI by 1.31 times (β = 20 °C·min -1 ). To evaluate the co-combustion characteristics, thermodynamic and kinetic parameters (entropy, Gibbs free energy and enthalpy changes, and apparent activation energy) were obtained in the five atmospheres. The lowest apparent activation energy of the TB64 blend was obtained in oxy-fuel atmosphere (CO 2 /O 2  = 7/3). Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Nitrogen from mountain to fiord. Annual report 1995; Nitrogen fra fjell til fjord. Aarsrapport 1995

    Energy Technology Data Exchange (ETDEWEB)

    Kaste, Oe.; Berge, D.; Fjeld, E.; Hoeyaas, T.R.; Mulder, J.; Stuanes, A.O. [Norges Landbrukshoegskole, Aas (Norway); Toerseth, K. [Norsk Inst. for Luftforskning, Kjeller (Norway)

    1996-06-01

    This is the annual report of a programme which aims to increase the knowledge of absorption, transfer, retention and run-off of nitrogen and to improve the prognoses of future effects of changes in the nitrogen cycle upon soil, forest, fresh water and fiords. The work was concentrated on two river systems in the southern part of Norway. It was found that nitrogen supplied by atmospherical precipitation is the most important source for one of the river systems while agricultural activities dominate for the other. 25 refs., 24 figs., 22 tabs.

  3. Atmospheric Infancy

    DEFF Research Database (Denmark)

    Roald, Tone; Pedersen, Ida Egmose; Levin, Kasper

    2017-01-01

    In this article we establish intersubjective meaning-making in infancy as atmospheric. Through qualitative descriptions of five mother–infant dyads in a video-recorded, experimental setting when the infant is 4, 7, 10, and 13 months, we discovered atmospheric appearances with a developmental...... pattern of atmospheric variations. These appearances, we argue, are contextual and intersubjective monologues. The monologues are similar to what Daniel Stern describes with his concept of “vitality affects,” but they arise as a unified force that envelops the mother and child. As such, we present a new...

  4. Fundamentals of fluorescence and fluorescence microscopy.

    Science.gov (United States)

    Wolf, David E

    2013-01-01

    This chapter discusses the fundamental physics of fluorescence. The application of fluorescence to microscopy represents an important transition in the development of microscopy, particularly as it applies to biology. It enables quantitating the amounts of specific molecules within a cell, determining whether molecules are complexing on a molecular level, measuring changes in ionic concentrations within cells and organelles, and measuring molecular dynamics. This chapter also discusses the issues important to quantitative measurement of fluorescence and focuses on four of quantitative measurements of fluorescence--boxcar-gated detection, streak cameras, photon correlation, and phase modulation. Although quantitative measurement presents many pitfalls to the beginner, it also presents significant opportunities to one skilled in the art. This chapter also examines how fluorescence is measured in the steady state and time domain and how fluorescence is applied in the modern epifluorescence microscope. Copyright © 2007 Elsevier Inc. All rights reserved.

  5. Synthetic biology approaches to engineering the nitrogen symbiosis in cereals.

    Science.gov (United States)

    Rogers, Christian; Oldroyd, Giles E D

    2014-05-01

    Nitrogen is abundant in the earth's atmosphere but, unlike carbon, cannot be directly assimilated by plants. The limitation this places on plant productivity has been circumvented in contemporary agriculture through the production and application of chemical fertilizers. The chemical reduction of nitrogen for this purpose consumes large amounts of energy and the reactive nitrogen released into the environment as a result of fertilizer application leads to greenhouse gas emissions, as well as widespread eutrophication of aquatic ecosystems. The environmental impacts are intensified by injudicious use of fertilizers in many parts of the world. Simultaneously, limitations in the production and supply of chemical fertilizers in other regions are leading to low agricultural productivity and malnutrition. Nitrogen can be directly fixed from the atmosphere by some bacteria and Archaea, which possess the enzyme nitrogenase. Some plant species, most notably legumes, have evolved close symbiotic associations with nitrogen-fixing bacteria. Engineering cereal crops with the capability to fix their own nitrogen could one day address the problems created by the over- and under-use of nitrogen fertilizers in agriculture. This could be achieved either by expression of a functional nitrogenase enzyme in the cells of the cereal crop or through transferring the capability to form a symbiotic association with nitrogen-fixing bacteria. While potentially transformative, these biotechnological approaches are challenging; however, with recent advances in synthetic biology they are viable long-term goals. This review discusses the possibility of these biotechnological solutions to the nitrogen problem, focusing on engineering the nitrogen symbiosis in cereals.

  6. Nitrogen fixation in Red Sea seagrass meadows

    KAUST Repository

    Abdallah, Malak

    2017-05-01

    Seagrasses are key coastal ecosystems, providing many ecosystem services. Seagrasses increase biodiversity as they provide habitat for a large set of organisms. In addition, their structure provides hiding places to avoid predation. Seagrasses can grow in shallow marine coastal areas, but several factors regulate their growth and distribution. Seagrasses can uptake different kinds of organic and inorganic nutrients through their leaves and roots. Nitrogen and phosphorous are the most important nutrients for seagrass growth. Biological nitrogen fixation is the conversion of atmospheric nitrogen into ammonia by diazotrophic bacteria. This process provides a significant source of nitrogen for seagrass growth. The nitrogen fixation is controlled by the nif genes which are found in diazotrophs. The main goal of the project is to measure nitrogen fixation rates on seagrass sediments, in order to compare among various seagrass species from the Red Sea. Moreover, we will compare the fixing rates of the Vegetated areas with the bare sediments. This project will help to ascertain the role of nitrogen fixing bacteria in the development of seagrass meadows.

  7. Effects of enhanced atmospheric ammonia on physiological characteristics of maize(Zea mays L.).

    Science.gov (United States)

    Chen, Xiaoli; Li, Shiqing

    2013-09-01

    Elevated atmospheric NH₃ may affect photosynthesis rates and biomass production of crops and the effect may be responsible for the soil nitrogen (N) levels. Plants were exposed to 0 and 1000 nL L⁻¹ with and without N (+N and - N) in open-top chambers (OTCs) to investigate effects of atmospheric NH₃ on photosynthetic and chlorophyll fluorescence parameters of maize plants. At two N levels, NH₃ exposure at 1000 nL L⁻¹ led to an increase in plant height, biomass production, net photosynthetic rates (P(n)) and stomatal conductance (g(s)) compared to ambient NH₃. Exposure to 1000 nL L⁻¹ NH₃ resulted in a significantly higher photochemical quenching (q(p)) and non-photochemical quenching (q(np)), while minimal fluorescence (F(o)), maximum fluorescence (F(m)) and maximum photochemical efficiency (F(v)/F(m)) were not affected. For shoots, N concentrations for - N-1000 and + N-1000 treatments were 49-50% and 26-30% higher, respectively, than those of - N-0 and + N-0 treatments. No visible damage was observed and plants growing on low soil N took up more leaf-derived N than those fertilised at higher N level. Therefore, atmospheric NH₃ can be considered as a quick fertiliser for crops and should be estimated in a further study with soil N fertilisers in order to reduce the dosage. © 2013 Society of Chemical Industry.

  8. Atmospheric-pressure plasma technology

    Science.gov (United States)

    Kogelschatz, U.

    2004-12-01

    Major industrial plasma processes operating close to atmospheric pressure are discussed. Applications of thermal plasmas include electric arc furnaces and plasma torches for generation of powders, for spraying refractory materials, for cutting and welding and for destruction of hazardous waste. Other applications include miniature circuit breakers and electrical discharge machining. Non-equilibrium cold plasmas at atmospheric pressure are obtained in corona discharges used in electrostatic precipitators and in dielectric-barrier discharges used for generation of ozone, for pollution control and for surface treatment. More recent applications include UV excimer lamps, mercury-free fluorescent lamps and flat plasma displays.

  9. Reviews in fluorescence 2010

    CERN Document Server

    Geddes, Chris D

    2011-01-01

    ""Reviews in Fluorescence 2010"", the seventh volume of the book serial from Springer, serves as a comprehensive collection of current trends and emerging hot topics in the field of fluorescence and closely related disciplines. It summarizes the year's progress in fluorescence and its applications, with authoritative analytical reviews specialized enough to be attractive to professional researchers, yet also appealing to the wider audience of scientists in related disciplines of fluorescence. ""Reviews in Fluorescence"" offers an essential reference material for any lab working in the fluoresc

  10. Principles of fluorescence techniques

    CERN Document Server

    2016-01-01

    Fluorescence techniques are being used and applied increasingly in academics and industry. The Principles of Fluorescence Techniques course will outline the basic concepts of fluorescence techniques and the successful utilization of the currently available commercial instrumentation. The course is designed for students who utilize fluorescence techniques and instrumentation and for researchers and industrial scientists who wish to deepen their knowledge of fluorescence applications. Key scientists in the field will deliver theoretical lectures. The lectures will be complemented by the direct utilization of steady-state and lifetime fluorescence instrumentation and confocal microscopy for FLIM and FRET applications provided by leading companies.

  11. Assessment of Nitrogen deposition effects and empirical critical loads of Nitrogen for ecoregions of the United States

    Science.gov (United States)

    L.H. Pardo; M.J. Robin-Abbott; C.T., eds. Driscoll

    2011-01-01

    This report synthesizes current research relating atmospheric nitrogen (N) deposition to effects on terrestrial and aquatic ecosystems in the United States and to identify empirical critical loads for atmospheric N deposition. The report evaluates the following receptors: freshwater diatoms, mycorrhizal fungi and other soil microbes, lichens, herbaceous plants, shrubs...

  12. Atmospheric neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Kajita, Takaaki [Research Center for Cosmic Neutrinos, Institute for Cosmic Ray Research, University of Tokyo, Kashiwa-no-ha 5-1-5, Kashiwa, Chiba 277-8582 (Japan)

    2004-12-01

    Neutrino oscillation was discovered through the study of atmospheric neutrinos. Atmospheric neutrinos are produced as decay products in hadronic showers resulting from collisions of cosmic rays with nuclei in the atmosphere. Electron neutrinos and muon neutrinos are produced mainly by the decay chain of charged pions to muons and electrons. Depending on the energy of the neutrinos, atmospheric neutrinos are observed as fully contained events, partially contained events and upward-going muon events. The energy range covered by these events is from a few hundred MeV to >1 TeV. Data from various experiments showed zenith angle- and energy-dependent deficit of {nu}{sub {mu}} events, while {nu}{sub e} events did not show any such effect. It was also shown that the {nu}{sub {mu}} survival probability obeys the sinusoidal function as predicted by neutrino oscillations. Two-flavour {nu}{sub {mu}} {r_reversible} {nu}{sub {tau}} oscillations, with sin{sup 2} 2{theta} > 0.90 and {delta}m{sup 2} in the region of 1.9 x 10{sup -3} to 3.0 x 10{sup -3} eV{sup 2}, explain all these data. Various detailed studies using high statistics atmospheric neutrino data excluded the alternative hypotheses that were proposed to explain the {nu}{sub {mu}} deficit.

  13. Recent Nitrogen Deposition In Poland Monitored With The Moss Pleurozium Schreberi

    Directory of Open Access Journals (Sweden)

    Kapusta Paweł

    2014-07-01

    Full Text Available In this study, atmospheric deposition of nitrogen was determined for Poland by moss biomonitoring. Nitrogen content was measured in the moss Pleurozium schreberi (Willd. ex Brid. Mitt. sampled in 2010 from 320 sites evenly distributed throughout the country. Mosses (green parts contained an average 1.56% nitrogen. The result places Poland among the European countries most polluted by airborne nitrogen. The highest nitrogen concentrations were found in mosses from the central and southern parts of the country, and the lowest in samples from some eastern and northern regions. Multiple regression showed that this variability was due mostly to nitrogen emissions from agricultural and industrial areas (moss nitrogen was positively associated with the consumption of mineral nitrogen fertilizers and the magnitude of particulate pollution. Some details of the spatial variability of the nitrogen data indicate that local and regional point sources of pollution (e.g., chemical plants played an important role in shaping the nitrogen deposition pattern

  14. Rapid cycling of reactive nitrogen in the marine boundary layer.

    Science.gov (United States)

    Ye, Chunxiang; Zhou, Xianliang; Pu, Dennis; Stutz, Jochen; Festa, James; Spolaor, Max; Tsai, Catalina; Cantrell, Christopher; Mauldin, Roy L; Campos, Teresa; Weinheimer, Andrew; Hornbrook, Rebecca S; Apel, Eric C; Guenther, Alex; Kaser, Lisa; Yuan, Bin; Karl, Thomas; Haggerty, Julie; Hall, Samuel; Ullmann, Kirk; Smith, James N; Ortega, John; Knote, Christoph

    2016-04-28

    Nitrogen oxides are essential for the formation of secondary atmospheric aerosols and of atmospheric oxidants such as ozone and the hydroxyl radical, which controls the self-cleansing capacity of the atmosphere. Nitric acid, a major oxidation product of nitrogen oxides, has traditionally been considered to be a permanent sink of nitrogen oxides. However, model studies predict higher ratios of nitric acid to nitrogen oxides in the troposphere than are observed. A 'renoxification' process that recycles nitric acid into nitrogen oxides has been proposed to reconcile observations with model studies, but the mechanisms responsible for this process remain uncertain. Here we present data from an aircraft measurement campaign over the North Atlantic Ocean and find evidence for rapid recycling of nitric acid to nitrous acid and nitrogen oxides in the clean marine boundary layer via particulate nitrate photolysis. Laboratory experiments further demonstrate the photolysis of particulate nitrate collected on filters at a rate more than two orders of magnitude greater than that of gaseous nitric acid, with nitrous acid as the main product. Box model calculations based on the Master Chemical Mechanism suggest that particulate nitrate photolysis mainly sustains the observed levels of nitrous acid and nitrogen oxides at midday under typical marine boundary layer conditions. Given that oceans account for more than 70 per cent of Earth's surface, we propose that particulate nitrate photolysis could be a substantial tropospheric nitrogen oxide source. Recycling of nitrogen oxides in remote oceanic regions with minimal direct nitrogen oxide emissions could increase the formation of tropospheric oxidants and secondary atmospheric aerosols on a global scale.

  15. Atmospheric thermodynamics

    CERN Document Server

    Iribarne, J V

    1973-01-01

    The thermodynamics of the atmosphere is the subject of several chapters in most textbooks on dynamic meteorology, but there is no work in English to give the subject a specific and more extensive treatment. In writing the present textbook, we have tried to fill this rather remarkable gap in the literature related to atmospheric sciences. Our aim has been to provide students of meteorology with a book that can playa role similar to the textbooks on chemical thermodynamics for the chemists. This implies a previous knowledge of general thermodynamics, such as students acquire in general physics courses; therefore, although the basic principles are reviewed (in the first four chapters), they are only briefly discussed, and emphasis is laid on those topics that will be useful in later chapters, through their application to atmospheric problems. No attempt has been made to introduce the thermodynamics of irreversible processes; on the other hand, consideration of heterogeneous and open homogeneous systems permits a...

  16. Fluorescent Lamp Replacement Study

    Science.gov (United States)

    2017-07-01

    C -1 D FLUORESCENT LAMP SPECIFICATION SHEETS . . . . . . . . . . . . . . . . . . . . . . . . . . D -1 E LED WAVES’ LED ...friendly products, advances in efficiency, and lower production costs for lamps . The conversion of fluorescent bulbs to LED technology has many benefits...repeatedly turned on and off. (5) LEDs can be used in existing fluorescent lighting fixtures using LED retrofit kits or replacement lamps . (6

  17. Electrostatic Precipitation in Nearly Pure Gaseous Nitrogen

    Science.gov (United States)

    Buhler, Charles; Calle, Carlos; Clements, Sid; Cox, Bobby; Ritz, Mindy

    2008-01-01

    Electrostatic precipitation was performed in a nearly pure gaseous nitrogen system as a possible remedy for black dust contaminant from high pressure 6000 psi lines at the NASA Kennedy Space Center. The results of a prototype electrostatic precipitator that was built and tested using nitrogen gas at standard atmospheric pressures is presented. High voltage pulsed waveforms are generated using a rotating spark gap system at 30 Hz. A unique dust delivery system utilizing the Venturi effect was devised that supplies a given amount of dust per unit time for testing purposes.

  18. Modelling the carbon and nitrogen cycles

    Directory of Open Access Journals (Sweden)

    Costas A Varotsos

    2014-04-01

    Full Text Available The issues of air pollution are inextricably linked to the mechanisms underlying the physicochemical functioning of the biosphere which together with the atmosphere, the cryosphere, the lithosphere, and the hydrosphere constitute the climate system. We herewith present a review of the achievements and unresolved problems concerning the modeling of the biochemical cycles of basic chemicals of the climate system, such as carbon and nitrogen. Although the achievements in this area can roughly describe the carbon and nitrogen cycles, serious problems still remain associated with the accuracy and precision of the processes and assessments employed in the relevant modeling.

  19. Effects of nitrogen deposition and empirical nitrogen critical loads for ecoregions of the United States

    Science.gov (United States)

    Linda H. Pardo; Mark E. Fenn; Christine L. Goodale; Linda H. Geiser; Charles T. Driscoll; Edith B. Allen; Jill S. Baron; Roland Bobbink; William D. Bowman; Christopher M. Clark; Bridget Emmett; Frank S. Gilliam; Tara L. Greaver; Sharon J. Hall; Erik A. Lilleskov; Lingli Liu; Jason A. Lynch; Knute J. Nadelhoffer; Steven S. Perakis; Molly J. Robin-Abbott; John L. Stoddard; Kathleen C. Weathers; Robin L. Dennis

    2011-01-01

    Human activity in the last century has led to a significant increase in nitrogen (N) emissions and atmospheric deposition. This N deposition has reached a level that has caused or is likely to cause alterations to the structure and function of many ecosystems across the United States. One approach for quantifying the deposition of pollution that would be harmful to...

  20. The marine nitrogen cycle: recent discoveries, uncertainties and the potential relevance of climate change

    OpenAIRE

    Voss, M.; Hermann W Bange; Dippner, J. W.; J. J. Middelburg; Montoya, J. P.; Ward, B

    2013-01-01

    The ocean's nitrogen cycle is driven by complex microbial transformations, including nitrogen fixation, assimilation, nitrification, anammox and denitrification. Dinitrogen is the most abundant form of nitrogen in sea water but only accessible by nitrogen-fixing microbes. Denitrification and nitrification are both regulated by oxygen concentrations and potentially produce nitrous oxide (N2O), a climate-relevant atmospheric trace gas. The world's oceans, including the coastal areas and upwelli...

  1. Highly luminescent N-doped carbon quantum dots as an effective multifunctional fluorescence sensing platform.

    Science.gov (United States)

    Qian, Zhaosheng; Ma, Juanjuan; Shan, Xiaoyue; Feng, Hui; Shao, Linxiang; Chen, Jianrong

    2014-02-17

    The doping of carbon quantum dots with nitrogen provides a promising direction to improve fluorescence performance and broaden their applications in sensing systems. Herein we report a one-pot solvothermal synthesis of N-doped carbon quantum dots (NCQDs) and the synthesis of a series of NCQDs with different nitrogen contents. The as-prepared NCQDs were compared with carbon quantum dots (CQDs); the introduction of nitrogen atoms largely increased the quantum yield of NCQDs and highest emission efficiency is up to 36.3 %. The fluorescence enhancement may originate from more polyaromatic structures induced by incorporated nitrogen atoms and protonation of nitrogen atoms on dots. It was found that NCQDs can act as a multifunctional fluorescence sensing platform because they can be used to detect pH values, Ag(I), and Fe(III) in aqueous solution. The fluorescence intensity of NCQDs is inversely proportional to pH values across a broad range from 5.0 to 13.5, which indicates that NCQDs can be devised as an effective pH indicator. Selective detection of Ag(I) and Fe(III) was achieved based on their distinctive fluorescence influence because Ag(I) can significantly enhance the fluorescence whereas Fe(III) can greatly quench the fluorescence. The quantitative determination of Ag(I) can be accomplished with NCQDs by using the linear relationship between fluorescence intensity of NCQDs and concentration of Ag(I). The sensitive detection of H2O2 was developed by taking advantage of the distinct quenching ability of Fe(III) and Fe(II) toward the fluorescence of NCQDs. Cellular toxicity test showed NCQDs still retain low toxicity to cells despite the introduction of a great deal of nitrogen atoms. Moreover, bioimaging experiments demonstrated that NCQDs have stronger resistance to photobleaching than CQDs and more excellent fluorescence labeling performance. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Alarming atmospheres

    DEFF Research Database (Denmark)

    Højlund, Marie; Kinch, Sofie

    2014-01-01

    Nurses working in the Neuro-Intensive Care Unit at Aarhus University Hospital lack the tools to prepare children for the alarming atmosphere they will enter when visiting a hospitalised relative. The complex soundscape dominated by alarms and sounds from equipment is mentioned as the main stressor...

  3. Atmospheric humidity

    Science.gov (United States)

    Water vapor plays a critical role in earth's atmosphere. It helps to maintain a habitable surface temperature through absorption of outgoing longwave radiation, and it transfers trmendous amounts of energy from the tropics toward the poles by absorbing latent heat during evaporation and subsequently...

  4. Greenhouse effect due to atmospheric nitrous oxide

    Science.gov (United States)

    Yung, Y. L.; Wang, W. C.; Lacis, A. A.

    1976-01-01

    The greenhouse effect due to nitrous oxide in the present atmosphere is about 0.8 K. Increase in atmospheric N2O due to perturbation of the nitrogen cycle by man may lead to an increase in surface temperature as large as 0.5 K by 2025, or 1.0 K by 2100. Other climatic effects of N2O are briefly discussed.

  5. Chronic nitrogen deposition influences the chemical dynamics ...

    Science.gov (United States)

    Atmospheric nitrogen deposition induces a forest carbon sink across broad parts of the Northern Hemisphere; this carbon sink may partly result from slower litter decomposition. Although microbial responses to experimental nitrogen deposition have been well-studied, evidence linking these microbial responses to changes in the degradation of specific compounds in decaying litter is sparse. We used wet chemistry and Fourier transform infrared spectroscopy (FTIR) methodologies to study the effects of chronic simulated nitrogen deposition on leaf litter and fine root chemistry during a three-year decomposition experiment at four northern hardwood forests in the north-central USA. Leaf litter and fine roots were highly different in initial chemistry such as concentrations of acid-insoluble fraction (AIF, or Klason lignin) and condensed tannins (CTs). These initial differences persisted over the course of decomposition. Results from gravimetrically-defined AIF and lignin/carbohydrate reference IR peak ratios both provide evidence that lignin in fine roots was selectively preserved under simulated nitrogen deposition. Lignin/carbohydrate peak ratios were strongly correlated with AIF, suggesting that AIF is a good predictor of lignin. Because AIF is abundant in fine roots, slower AIF degradation was the major driver of the slower fine root decomposition under nitrogen enrichment, explaining 73.9 % of the additional root mass retention. Nitrogen enrichment also slowed the

  6. Mapping background values of atmospheric nitrogen total depositions in Germany based on EMEP deposition modelling and the European Moss Survey 2005; Kartierung der Hintergrundwerte atmosphaerischer Stickstoff-Gesamtdepositionen in Deutschland anhand von Daten des EMEP-Messnetzes und des ICP Vegetation Moos-Monitoring 2005

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Winfried; Holy, Marcel; Pesch, Roland [University of Vechta, Chair of Landscape Ecology, P.O.B. 1553, Vechta (Germany); Harmens, Harry [Environment Centre Wales, Centre for Ecology and Hydrology, Bangor, Gwynedd (United Kingdom); Fagerli, Hilde [Norwegian Meteorological Institute, Meteorological Synthesizing Centre-West of EMEP, P.O. Box 43-Blindern, Oslo (Norway)

    2011-12-15

    In order to map exceedances of critical atmospheric deposition loads for nitrogen (N) surface data on the atmospheric deposition of N compounds to terrestrial ecosystems are needed. Across Europe such information is provided by the international European Monitoring and Evaluation Programme (EMEP) in a resolution of 50 km by 50 km, relying on both emission data and measurement data on atmospheric depositions. The objective of the article at hand is on the improvement of the spatial resolution of the EMEP maps by combining them with data on the N concentration in mosses provided by the International Cooperative Programme on Effects of Air Pollution on Natural Vegetation and Crops (ICP Vegetation) of the United Nations Economic Commission for Europe (UNECE) Long-range Transboundary Air Pollution (LTRAP). Methods The map on atmospheric depositions of total N as modelled by EMEP was intersected with geostatistical surface estimations on the N concentration in mosses at a resolution of 5 km by 5 km. The medians of the N estimations in mosses were then calculated for each 50 km by 50 km grid cell. Both medians of moss estimations and corresponding modelled deposition values were ln-transformed and their relationship investigated and modelled by linear regression analysis. The regression equations were applied on the moss kriging estimates of the N concentration in mosses. The respective residuals were projected onto the centres of the EMEP grid cells and were mapped using variogram analysis and kriging procedures. Finally, the residual and the regression map were summed up to the map of total N deposition in terrestrial ecosystems throughout Europe. The regression analysis of the estimated N concentrations in mosses and the modelled EMEP depositions resulted in clear linear regression patterns with coefficients of determination of r{sup 2}=0.62 and Pearson correlations of r{sub p}=0.79 and Spearman correlations of r{sub s}=0.70, respectively. Regarding the German

  7. Measurements of the UV Nocturnal Atmospheric Background in the 300-400 nm Wavelength Band with the Experiment BaBy during a Transmediterranean Balloon Flight

    Science.gov (United States)

    Giarrusso, S.; Gugliotta, G.; Agnetta, G.; Assis, P.; Biondo, B.; Catalano, O.; Celi, F.; Cusumano, G.; D'Ali Staiti, G.; Raffaele, R.Di.; Espirito-Santo, M.C.; Gabriele, M.; Rosa, G.La; Maccarone, M.C.; Mangano, A.; Mineo, T.; Pimenta, M.; Russo, F.; Sacco, B.; Santangelo, A.; Scarsi, P.; Tome, B.

    2003-07-01

    We present new results of U V no cturnal atmospheric background measured with the balloon borne experiment BaBy that performed a trans-Mediterranean flight on July 11 2002. The experiment looked downwards from about 40 km of altitude the dark no cturnal atmosphere over the sea in a moonless night. It is composed of 8 filtered and collimated fast PMTs detecting the U V light in the 300-400 nm wavelength band and in the 3 narrow bands centered at the emission lines of the atmospheric Nitrogen molecules. Both single photon counting and charge integration methods are used in pairs of PMTs with the same filter. The background measured over the sea is about 300 photons m-2 sr-1 ns-1 in the 300-400 nm wavelength band. Introduction The Backround Bypass, BaBy, experiment is a scientific support activity to the evaluation of the sensitivity of EUSO [3], devoted to the observation of the Extreme Energy Cosmic Rays from space by detecting U V fluorescence light. One of the fundamental information in EUSO design is the U V no cturnal atmospheric background level whose main sources are: light pollution from cities, planes and ships, naturally occurring bioluminescence, lightning flashes, reflected moonlight and starlight, auroral flashes, low energy cosmic ray air showers and atmospheric chemical reactions. Since 1998, no cturnal atmospheric U V background measurements, in the wavelength interval (300-400 nm) relevant for EUSO, have been performed by

  8. How important are air-sea nitrogen exchanges?.

    Science.gov (United States)

    Jickells, Tim

    2017-04-01

    We have recently reported an assessment of the magnitude and impact of atmospheric nitrogen (excluding N2 gas) deposition on the oceans (Jickells et al. Global Biogeochemical Cycles in press). The nitrogen budgets we present show a substantial component of the gross nitrogen deposition to the oceans being contributed from recycled marine emissions of organic nitrogen and ammonia. This recycling means that the net deposition of nitrogen to the oceans is 25% less than gross deposition, with 40% of gross deposition of ammonia/ammonium and organic nitrogen from recycled marine sources (Kanakidou et al., Global Biogeochemical Cycles, 2012). There is no doubt that these recycling fluxes occur. However, their relative importance, compared to atmospheric inputs from land based emissions, is uncertain. In the case of ammonia, the recycling mechanism is believed to be via direct emissions of ammonia from seawater. Thermodynamic calculations suggest that such ammonia emissions should occur predominantly at low latitudes. In the case of organic nitrogen, the emission mechanism is likely to be via organic nitrogen associated with sea-spray production, because volatile organic nitrogen concentrations in seawater are too low to sustain any significant flux. There is some indirect evidence both in support of, and in contradiction of, these large recycling fluxes for both organic nitrogen and ammonia. This reveals a major uncertainty in our understanding of the marine nitrogen cycle, one of the key biogeochemical cycles regulating the Earth system. In this contribution I will illustrate the scale of this uncertainty in the nitrogen cycle, consider the evidence in support of quantitatively large scale recycling, and consider methods by which these uncertainties can be reduced.

  9. U(IV) fluorescence spectroscopy. A new speciation tool

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, Susanne; Brendler, Vinzenz [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes; Steudtner, Robin [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Inst. of Resource Ecology

    2017-06-01

    We combined absorption and fluorescence spectroscopy to study the speciation of U(IV) in solution in concentrations down to 10{sup -6} M uranium. With our time-resolved laser-induced fluorescence setup we could determine the fluorescence decay time of U(IV) in perchloric as well as in chloric acid with 2.6 ± 0.3 ns at room temperature and 148.4 ± 6.5 ns at liquid nitrogen temperature. For the U(IV) sulfate system, we observed a bathochromic shift and a peak shape modification in the fluorescence spectra with increasing sulfate concentration in solution. Thus, the potential of U(IV) fluorescence for speciation analysis could be proven.

  10. Atmospheric materiality

    DEFF Research Database (Denmark)

    Wieczorek, Izabela

    2016-01-01

    A disjunction between the material and the immaterial has been at the heart of the architectural debate for decades. In this dialectic tension, the notion of atmosphere which increasingly claims attention in architectural discourse seems to be parallactic, leading to the re-evaluation of perceptual...... experience and, consequently, to the conceptual and methodological shifts in the production of space, and hence in the way we think about materiality. In this context, architectural space is understood as a contingent construction – a space of engagement that appears to us as a result of continuous...... and complex interferences revealed through our perception; ‘the atmospheric’ is explored as a spatial and affective quality as well as a sensory background, and materiality as a powerful and almost magical agency in shaping of atmosphere. Challenging existing dichotomies and unraveling intrinsic...

  11. Biotic Nitrogen Enrichment Regulates Calcium Sources to Forests

    Science.gov (United States)

    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

  12. Advanced carbon dots via plasma-induced surface functionalization for fluorescent and bio-medical applications.

    Science.gov (United States)

    Park, So Young; Lee, Che Yoon; An, Ha-Rim; Kim, Hyeran; Lee, Young-Chul; Park, Edmond Changkyun; Chun, Hang-Suk; Yang, Hee Young; Choi, Sae-Hae; Kim, Hee Sik; Kang, Kyoung Suk; Park, Hyun Gyu; Kim, Jong-Pil; Choi, Yunju; Lee, Jouhahn; Lee, Hyun Uk

    2017-07-06

    Multifunctional carbon-based nanodots (C-dots) are synthesized using atmospheric plasma treatments involving reactive gases (oxygen and nitrogen). Surface design was achieved through one-step plasma treatment of C-dots (AC-paints) from polyethylene glycol used as a precursor. These AC-paints show high fluorescence, low cytotoxicity and excellent cellular imaging capability. They exhibit bright fluorescence with a quantum yield twice of traditional C-dots. The cytotoxicity of AC-paints was tested on BEAS2B, THLE2, A549 and hep3B cell lines. The in vivo experiments further demonstrated the biocompatibility of AC-paints using zebrafish as a model, and imaging tests demonstrated that the AC-paints can be used as bio-labels (at a concentration of 1 mg mL(-1)). AC-paints can effectively inhibit the growth of Escherichia coli (E. coli) and Acinetobacter baumannii (A. baumannii). Such remarkable performance of the AC-paints has important applications in the biomedical field and environmental systems.

  13. [Transformation of Nitrogen Nutrients in the Urban Sewage Pipe Network].

    Science.gov (United States)

    Jin, Peng-kang; Jiao, Ding; Ren, Wu-ang

    2015-10-01

    The paper focuses on the changes of nitrogen compounds in the Pipe network. A 1.2km long urban sewage simulation network with artificial water distribution was selected as the research subject. Then we analyzed and evaluated the change characteristics of nitrogen nutrients along the pipe. The results proved that ammonium chloride as the nitrogen source matrix, which was necessary for microorganisms in the Pipe to survive and proliferate. Free amino acids, combined amino acids and nucleic acid produced by metabolism were the major nitrogenous organic compounds. Among which, amino acids accounted for dissolved organic nitrogen (DON) in the majority. The characterization results of three-dimensional fluorescence spectroscopy and size exclusion chromatography showed that the characteristic fluorescence peak of organic matter in waste water was increased, and the protein ( tyrosine, tryptophan)--based fluorescence intensity gradually increased along the pipe. It was also found that small molecules of nutrients in the water were converted to complex organic molecules under the assimilation of microorganisms.

  14. Modelling the ecosystem effects of nitrogen deposition: Model of Ecosystem Retention and Loss of Inorganic Nitrogen (MERLIN

    Directory of Open Access Journals (Sweden)

    B. J. Cosby

    1997-01-01

    Full Text Available A catchment-scale mass-balance model of linked carbon and nitrogen cycling in ecosystems has been developed for simulating leaching losses of inorganic nitrogen. The model (MERLIN considers linked biotic and abiotic processes affecting the cycling and storage of nitrogen. The model is aggregated in space and time and contains compartments intended to be observable and/or interpretable at the plot or catchment scale. The structure of the model includes the inorganic soil, a plant compartment and two soil organic compartments. Fluxes in and out of the ecosystem and between compartments are regulated by atmospheric deposition, hydrological discharge, plant uptake, litter production, wood production, microbial immobilization, mineralization, nitrification, and denitrification. Nitrogen fluxes are controlled by carbon productivity, the C:N ratios of organic compartments and inorganic nitrogen in soil solution. Inputs required are: 1 temporal sequences of carbon fluxes and pools- 2 time series of hydrological discharge through the soils, 3 historical and current external sources of inorganic nitrogen; 4 current amounts of nitrogen in the plant and soil organic compartments; 5 constants specifying the nitrogen uptake and immobilization characteristics of the plant and soil organic compartments; and 6 soil characteristics such as depth, porosity, bulk density, and anion/cation exchange constants. Outputs include: 1 concentrations and fluxes of NO3 and NH4 in soil solution and runoff; 2 total nitrogen contents of the organic and inorganic compartments; 3 C:N ratios of the aggregated plant and soil organic compartments; and 4 rates of nitrogen uptake and immobilization and nitrogen mineralization. The behaviour of the model is assessed for a combination of land-use change and nitrogen deposition scenarios in a series of speculative simulations. The results of the simulations are in broad agreement with observed and hypothesized behaviour of nitrogen

  15. The atmospheric degradation of methyl isocyanate (CH3NCO), a toxic substance

    Science.gov (United States)

    Papanastasiou, D. K.; Bernard, F.; Burkholder, J. B.

    2016-12-01

    Alkyl isocyanates (R-NCO), as well as isocyanic acid (HNCO), are toxic substances that are emitted into the atmosphere during incomplete combustion of biomass and also formed as products in the atmospheric photooxidation of nitrogen-containing organic species. For example, methyl isocyanate (MIC, CH3NCO) is formed in the atmospheric photochemical transformation of methylisothiocyanate (CH3NCS), a widely used soil fumigant, as well as in the atmospheric photooxidation of amides, such as N-methylformamide. MIC is of particular interest to society because of the possible exposure to this toxic trace compound (recommended exposure limit is 0.02 ppm) in the aftermath of fumigation. Although, there are limited observations of atmospheric MIC (mostly nearby agricultural/fumigation activities) the possibility of emission from combustion processes, such as wildfires, warrants future study. The atmospheric lifetime and fate (gas phase and heterogeneous chemistry) of CH3NCO are presently not well characterized with only a single study of the OH + CH3NCO reaction rate coefficient available in the literature. Additional results from fundamental laboratory studies regarding the major atmospheric degradation pathways of MIC are needed for input to air quality, health, and environmental impact studies. In this study, the reaction of CH3NCO with OH radicals was investigated using pulsed laser photolysis coupled with laser induced fluorescence detection of the OH radical. The rate coefficients, k(OH+CH3NCO), were determined over a range of temperature (295-375 K) and pressure (40-100 Torr, He). The present results are in significant disagreement with the recently published relative rate study. A relative rate kinetic method was also used in this study for comparison and the problems associated with these measurements will be discussed. The atmospheric lifetime of MIC with respect to its gas-phase reaction with OH radicals is estimated to be 85 days, which implies the possibility for

  16. The nitrogen cycle

    National Research Council Canada - National Science Library

    Stein, Lisa Y; Klotz, Martin G

    2016-01-01

    .... 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...

  17. Fluorescence Live Cell Imaging

    OpenAIRE

    Ettinger, Andreas; Wittmann, Torsten

    2014-01-01

    Fluorescence microscopy of live cells has become an integral part of modern cell biology. Fluorescent protein (FP) tags, live cell dyes, and other methods to fluorescently label proteins of interest provide a range of tools to investigate virtually any cellular process under the microscope. The two main experimental challenges in collecting meaningful live cell microscopy data are to minimize photodamage while retaining a useful signal-to-noise ratio and to provide a suitable environment for ...

  18. Nitrogen Fixation by Members of the Tribe Klebsielleae

    Science.gov (United States)

    Mahl, M. C.; Wilson, P. W.; Fife, M. A.; Ewing, W. H.

    1965-01-01

    Mahl, M. C. (University of Wisconsin, Madison), P. W. Wilson, M. A. Fife, and W. H. Ewing. Nitrogen fixation by members of the tribe Klebsielleae. J. Bacteriol. 89:1482–1487. 1965.—Strains of species of the tribe Klebsielleae were tested for nitrogen fixation by inoculating actively growing cultures into side-arm flasks containing a medium with a growth-limiting quantity of combined nitrogen (25 μg of nitrogen per ml as ammonium sulfate). The flasks were evacuated, filled with pure N2, sealed, and placed on a shaker at 30 C. Growth was followed by optical-density measurements; maximal growth was obtained in 9 to 10 hr. Yeast extract was then added as a source of amino acids to shorten the induction time for the nitrogen-fixing enzymes. Fixation was determined either by estimating total nitrogen with a semimicro Kjeldahl technique or by exposing 20- to 22-hr-old samples to an atmosphere of N215 and helium for 5 hr and then analyzing the digested sample for N15 in a mass spectrometer. None of the 22 strains of the two Enterobacter (formerly Aerobacter) species fixed nitrogen; neither did any of eight strains of Serratia species that were tested. Of 31 strains of Klebsiella pneumoniae, 13 incorporated atmospheric nitrogen. Net nitrogen fixed ranged from 17 to 65 μg/ml. It is concluded that these facultative anaerobic, gram-negative, nitrogen-fixing rods should be placed in the genus Klebsiella pneumoniae. The nitrogen-fixing organism tentatively classified as Achromobacter N-4 should also be changed to K. pneumoniae strain N-4, because it has been found to be an anaerogenic strain of K. pneumoniae. PMID:14291584

  19. [Simulation of polluted atmospheres for animal experimentation: toxic gases].

    Science.gov (United States)

    Godin, J; Boudène, C

    1976-09-20

    A process for the generation of standardized polluted atmospheres usable for animal exposure is described. It is based on the diffusion of compressed gases across a silicone membrane. This device has been tested with four gases of particular importance in the field of atmospheric pollution (sulfur dioxide, nitrogen oxide, carbon monoxide and ammoniac).

  20. Effect of the major components of industrial air pollution on nonsymbiotic nitrogen-fixation activity in soil

    Energy Technology Data Exchange (ETDEWEB)

    Islamov, S.S.; Chunderova, A.I.

    1976-01-01

    Industrial pollution of atmosphere inhibits the activity of non-symbiotic nitrogen fixation in soils. The inhibiting effect of polluted air can be explained by the presence of carbon monoxide and nitrogen dioxide in it. Sulfur dioxide does not depress the nitrogenase complex of aerobic and anaerobic nitrogen fixing microorganisms.

  1. Climate change impacts of US reactive nitrogen.

    Science.gov (United States)

    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.

  2. Toward nitrogen neutral biofuel production.

    Science.gov (United States)

    Huo, Yi-Xin; Wernick, David G; Liao, James C

    2012-06-01

    Environmental concerns and an increasing global energy demand have spurred scientific research and political action to deliver large-scale production of liquid biofuels. Current biofuel processes and developing approaches have focused on closing the carbon cycle by biological fixation of atmospheric carbon dioxide and conversion of biomass to fuels. To date, these processes have relied on fertilizer produced by the energy-intensive Haber-Bosch process, and have not addressed the global nitrogen cycle and its environmental implications. Recent developments to convert protein to fuel and ammonia may begin to address these problems. In this scheme, recycling ammonia to either plant or algal feedstocks reduces the demand for synthetic fertilizer supplementation. Further development of this technology will realize its advantages of high carbon fixation rates, inexpensive and simple feedstock processing, in addition to reduced fertilizer requirements. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Update: Biological Nitrogen Fixation.

    Science.gov (United States)

    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,…

  4. Nitrogen trading tool

    Science.gov (United States)

    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...

  5. Soybean Nitrogen Fixing Attributes

    African Journals Online (AJOL)

    reproductive unit and nitrogen fixing attributes (Carruthers er. al., 2000). In combination with various lupin and forages, these authors showed that soybean grain yield was decreased by most treatments. In order to limit over population and pollution risks, low nitrogen fertilizer agricultural systems are likely to be advocated.

  6. Nitrogen use efficiency (NUE)

    NARCIS (Netherlands)

    Oenema, O.

    2015-01-01

    There is a need for communications about resource use efficiency and for measures to increase the use efficiency of nutrients in relation to food production. This holds especially for nitrogen. Nitrogen (N) is essential for life and a main nutrient element. It is needed in relatively large

  7. National Status and Trends, Benthic Surveillance Project Fluorescent Aromatic Compounds (FAC) Data, 1984-1991, National Centers for Coastal Ocean Science

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The National Status and Trends (NSandT) Benthic Surveillance Fluorescent Aromatic Compounds (FAC) file reports the trace concentrations of Fluorescent Aromatic...

  8. Experiments with Fluorescent Lamps

    Science.gov (United States)

    Kraftmakher, Yaakov

    2010-10-01

    The experiments described below show the irradiance and illuminance spectra of two fluorescent lamps in relation to their color temperatures, and the efficacy in comparison to that of an incandescent lamp. Spectra of "warm white" and "cool daylight" fluorescent lamps are demonstrated.

  9. LEDs for fluorescence microscopy

    NARCIS (Netherlands)

    Young, I.T.; Garini, Y.; Dietrich, H.R.C.; Van Oel, W.; Liqui Lung, G.

    2004-01-01

    Traditional light sources for fluorescence microscopy have been mercury lamps, xenon lamps, and lasers. These sources have been essential in the development of fluorescence microscopy but each can have serious disadvantages: lack of near monochromaticity, heat generation, cost, lifetime of the light

  10. Membranes and Fluorescence microscopy

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2009-01-01

    Fluorescence spectroscopy-based techniques using conventional fluorimeters have been extensively applied since the late 1960s to study different aspects of membrane-related phenomena, i.e., mainly relating to lipid-lipid and lipid-protein (peptide) interactions. Even though fluorescence...

  11. Injection Seeded Laser for Formaldehyde Differential Fluorescence Lidar

    Science.gov (United States)

    Schwemmer, G.; Yakshin, M.; Prasad, C.; Hanisco, T.; Mylapore, A. R.; Hwang, I. H.; Lee, S.

    2016-01-01

    We describe the design and development of an injection seeded Nd:YVO4 laser for use in a differential fluorescence lidar for measuring atmospheric formaldehyde profiles. A high repetition rate Q-switched laser is modified to accept injection seed input to spectrally narrow and tune the output. The third harmonic output is used to excite formaldehyde (HCHO) fluorescence when tuned to a HCHO absorption line. Spectral confirmation is made with the use of a photoacoustic cell and grating spectrometer.

  12. The evolution and future of Earth's nitrogen cycle.

    Science.gov (United States)

    Canfield, Donald E; Glazer, Alexander N; Falkowski, Paul G

    2010-10-08

    Atmospheric reactions and slow geological processes controlled Earth's earliest nitrogen cycle, and by ~2.7 billion years ago, a linked suite of microbial processes evolved to form the modern nitrogen cycle with robust natural feedbacks and controls. Over the past century, however, the development of new agricultural practices to satisfy a growing global demand for food has drastically disrupted the nitrogen cycle. This has led to extensive eutrophication of fresh waters and coastal zones as well as increased inventories of the potent greenhouse gas nitrous oxide (N(2)O). Microbial processes will ultimately restore balance to the nitrogen cycle, but the damage done by humans to the nitrogen economy of the planet will persist for decades, possibly centuries, if active intervention and careful management strategies are not initiated.

  13. Assessment of nitrogen flows into the Cuban landscape

    OpenAIRE

    Baisre, J. A.

    2006-01-01

    The alteration of the nitrogen (N) cycle by human activities is widespread and has often resulted in increased flows of nitrogen to the marine environment. In this paper we have attempted to know the changes of N fluxes in Cuba by quantifying the N inputs to the landscape from (1) fertilizer applications, (2) atmospheric deposition, (3) biological nitrogen fixation and (4) net import of food and feeds. N-inputs to the country progressively increased until the end of the 20th century, reaching...

  14. Deriving chlorophyll fluorescence emissions of vegetation canopies from high resolution field reflectance spectra

    Science.gov (United States)

    Middleton, Elizabeth M.; Corp, Lawrence A.; Daughtry, Craig S.; Entcheva Campbell, Petya K.; Butcher, L. Maryn

    2005-11-01

    Fluorescence of foliage in the laboratory has proven more rigorous than reflectance for correlation to plant physiology. Especially useful are emissions produced from two stable red and far-red chlorophyll fluorescence (ChlF) peaks centered at 685 nm and 735 nm. Methods have been developed elsewhere to extract steady state solar induced fluorescence (SIF) from apparent reflectance of vegetation canopies/landscapes using the Fraunhofer Line Depth (FLD) principal. Our study utilized these methods in conjunction with field-acquired high spectral resolution canopy reflectance spectra obtained in 2004 and 2005 over corn crops and small tree plots of three deciduous species (red maple, tulip poplar, sweet gum). Leaf level measurements were also made of foliage which included ChlF, photosynthesis, and leaf constituents (photosynthetic pigment, carbon (C), and nitrogen (N) contents). As part of ongoing experiments, measurements were made on N application plots within corn (280, 140, 70, and 0 kg N/ha) and tree (0, 37.5, 75, 112.5, 150 kg N /ha) sites at the USDA/Agriculture Research Service in Beltsville, MD. SIF intensities for ChlF were derived directly from canopy reflectance spectra in specific narrow- band regions associated with atmospheric oxygen absorption features centered at 688 and 760 nm. The red/far-red SIF ratio (SIFratio) derived from these field reflectance spectra successfully discriminated foliar pigment ratios altered by N application rates in both corn crops. This ratio was also positively correlated to the C/N ratio at leaf and canopy levels, for the available corn data (e.g., 2004). No consistent N treatment or species differences in SIF were detected in the tree foliage, but additional 2005 data are forthcoming. This study has relevance to future passive satellite remote sensing approaches to monitoring C dynamics from space.

  15. Multicolor, Fluorescent Supercapacitor Fiber.

    Science.gov (United States)

    Liao, Meng; Sun, Hao; Zhang, Jing; Wu, Jingxia; Xie, Songlin; Fu, Xuemei; Sun, Xuemei; Wang, Bingjie; Peng, Huisheng

    2017-10-05

    Fiber-shaped supercapacitors have attracted broad attentions from both academic and industrial communities due to the demonstrated potentials as next-generation power modules. However, it is important while remains challenging to develop dark-environment identifiable supercapacitor fibers for enhancement on operation convenience and security in nighttime applications. Herein, a novel family of colorful fluorescent supercapacitor fibers has been produced from aligned multi-walled carbon nanotube sheets. Fluorescent dye particles are introduced and stably anchored on the surfaces of aligned multi-walled carbon nanotubes to prepare hybrid fiber electrodes with a broad range of colors from red to purple. The fluorescent component in the dye introduces fluorescent indication capability to the fiber, which is particularly promising for flexible and wearable devices applied in dark environment. In addition, the colorful fluorescent supercapacitor fibers also maintain high electrochemical performance under cyclic bending and charge-discharge processes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. MEAD Marine Effects of Atmospheric Deposition

    Science.gov (United States)

    Jickells, T.; Spokes, L.

    2003-04-01

    The coastal seas are one of the most valuable resources on the planet but they are threatened by human activity. We rely on the coastal area for mineral resources, waste disposal, fisheries and recreation. In Europe, high population densities and high levels of industrial activity mean that the pressures arising from these activities are particularly acute. One of the main problems concerning coastal seas is the rapid increase in the amounts of nitrogen-based pollutants entering the water. They come from many sources, the most important ones being traffic, industry and agriculture. These pollutants can be used by algae as nutrients. The increasing concentrations of these nutrients have led to excessive growth of algae, some of which are harmful. When algae die and decay, oxygen in the water is used up and the resulting lower levels of oxygen may lead to fish kills. Human activity has probably doubled the amount of chemically and biologically reactive nitrogen present globally. In Europe the increases have been greater than this, leading to real concern over the health of coastal waters. Rivers have, until recently, been thought to be the most important source of reactive nitrogen to the coastal seas but we now know that inputs from the atmosphere are large and can equal, or exceed, those from the rivers. Our initial hypothesis was that atmospheric inputs are important and potentially different in their effect on coastal ecosystems to riverine inputs and hence require different management strategies. However, we had almost no information on the direct effects of atmospheric deposition on marine ecosystems, though clearly such a large external nitrogen input should lead to enhanced phytoplankton growth The aim of this European Union funded MEAD project has been to determine how inputs of nitrogen from the atmosphere affect the chemistry and biology of coastal waters. To try to answer this, we have conducted field experiments in the Kattegat, an area where we know

  17. Method to minimize ozone effect on Cy5 fluorescent intensity in DNA microarrays.

    Science.gov (United States)

    Kim, Youngjun; Seo, Hyun Hee; Jeong, Mi Seon; Lee, Ki Heon; Lee, In Ho; So, Kyeong A; Kim, Mi Kyung; Lee, Yoo-Kyung; Kim, Seon Ah; Kim, Tae Jin

    2017-12-01

    Cyanine 5 (Cy5) is an established fluorescent dye in microarray analysis. It is degraded rapidly when exposed to atmospheric ozone during post-hybridization washes, which leads to loss of fluorescent intensity. To minimize this undesirable effect, we coated microarray slides with sodium dodecyl sulfate (SDS) solution at post-hybridization washes. The fluorescent intensities on coated slides were more stable than those on uncoated slide. We also performed the microarrays with SDS solution for a year to check the solution's effectiveness along with seasonal changes of atmospheric ozone level. Consistent results in microarray analysis were obtained using Cy5 dye under atmospheric ozone. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. High nitrogen availability reduces polyphenol content in Sphagnum peat.

    Science.gov (United States)

    Bragazza, Luca; Freeman, Chris

    2007-05-15

    Peat mosses of the genus Sphagnum constitute the bulk of living and dead biomass in bogs. These plants contain peculiar polyphenols which hamper litter peat decomposition through their inhibitory activity on microbial breakdown. In the light of the increasing availability of biologically active nitrogen in natural ecosystems, litter derived from Sphagnum mosses is an ideal substrate to test the potential effects of increased atmospheric nitrogen deposition on polyphenol content in litter peat. To this aim, we measured total nitrogen and soluble polyphenol concentration in Sphagnum litter peat collected in 11 European bogs under a chronic gradient of atmospheric nitrogen deposition. Our results demonstrate that increasing nitrogen concentration in Sphagnum litter, as a consequence of increased exogenous nitrogen availability, is accompanied by a decreasing concentration of polyphenols. This inverse relationship is consistent with reports that in Sphagnum mosses, polyphenol and protein biosynthesis compete for the same precursor. Our observation of modified Sphagnum litter chemistry under chronic nitrogen eutrophication has implications in the context of the global carbon balance, because a lower content of decay-inhibiting polyphenols would accelerate litter peat decomposition.

  19. Atmospheric Background Measurement in the 300-400 nm Band with a Balloon Borne Experiment During a Nocturnal Flight

    Science.gov (United States)

    La Rosa, Giovanni; Agnetta, Gaetano; Biondo, Benedetto; Catalano, Osvaldo; Celi, Filippo; Di Raffaele, Renato; Giarrusso, Salvatore; Mangano, Angelo; Russo, Francesco; Linsley, John; Lo Bue, Angelo

    2001-03-01

    The balloon borne experiment, named BABY (BAckground BYpass) belongs to a wider program, AIRWATCH-OWL, intended for the observation of high energy Cosmic Rays from space, detecting the faint UV fluorescence light emitted by the atmospheric Nitrogen as final result of a complex hadronic cascade. In this framework, one of the fundamental information concern the knowledge of the background level. This is one of the main parameters that contribute to the sensitivity of any kind of instrument. The apparatus used for the BABY experiment was designed and completely built at the IFCAI-CNR in Palermo. The instrument is composed by two filtered and collimated photomultipliers (PMT) that detect the UV light in the 300-400 nm wavelength. We report a brief description of the design of the detector and the results coming from a preliminary analysis of the data taken during a nocturnal over-sea observation.

  20. Identification and Quantification of Nitrogen in a Reservoir, Jiaodong Peninsula, China.

    Science.gov (United States)

    Zheng, Meng; Sheng, Yanqing; Sun, Ruichuan; Tian, Chongguo; Zhang, Haibo; Ning, Jicai; Sun, Qiyao; Li, Zhaoran; Bottrell, Simon H; Mortimer, Robert J G

    2017-04-01

      Identification of nitrogen (N) sources is important in water quality control and management. Nitrogen pollution can lead to eutrophication of waterbodies and high concentrations of nitrate in drinking water can pose potential health problems. The 15N isotope and nitrogen fluxes budget approach is useful for determining the source of to surface waters. In this study, mass balance and 15N isotope approaches and nitrogen flux budgets were applied to identify total nitrogen (TN) sources and nitrogen transformation processes in the Menlou Reservoir (MR), Jiaodong Peninsula, China. The different fractions of nitrogen and their 15N isotope signatures were analyzed in the reservoir water, river water, groundwater, soil, and atmospheric precipitation. The results indicate that surface runoff pollution (e.g., fertilizer and animal manure) is the main source of in MR. High concentrations of TN in MR are caused by low nitrogen self-purification (denitrification) rate, low sediment adsorption capacity, and the influx of rich groundwater.

  1. An overview of remote sensing of chlorophyll fluorescence

    Science.gov (United States)

    Xing, Xiao-Gang; Zhao, Dong-Zhi; Liu, Yu-Guang; Yang, Jian-Hong; Xiu, Peng; Wang, Lin

    2007-03-01

    Besides empirical algorithms with the blue-green ratio, the algorithms based on fluorescence are also important and valid methods for retrieving chlorophyll-a concentration in the ocean waters, especially for Case II waters and the sea with algal blooming. This study reviews the history of initial cognitions, investigations and detailed approaches towards chlorophyll fluorescence, and then introduces the biological mechanism of fluorescence remote sensing and main spectral characteristics such as the positive correlation between fluorescence and chlorophyll concentration, the red shift phenomena. Meanwhile, there exist many influence factors that increase complexity of fluorescence remote sensing, such as fluorescence quantum yield, physiological status of various algae, substances with related optical property in the ocean, atmospheric absorption etc. Based on these cognitions, scientists have found two ways to calculate the amount of fluorescence detected by ocean color sensors: fluorescence line height and reflectance ratio. These two ways are currently the foundation for retrieval of chlorophyl l - a concentration in the ocean. As the in-situ measurements and synchronous satellite data are continuously being accumulated, the fluorescence remote sensing of chlorophyll-a concentration in Case II waters should be recognized more thoroughly and new algorithms could be expected.

  2. Gas exchange and chlorophyll a fluorescence parameters of ornamental bromeliads

    Directory of Open Access Journals (Sweden)

    Karina Gonçalves da Silva

    2017-10-01

    Full Text Available Gas exchange and chlorophyll a fluorescence are widely used in physiological and ecological studies; however, few studies have used these techniques with ornamental plants. This study tested the potential contribution of gas exchange and chlorophyll a fluorescence to evaluate the water and nutrients uptake by the tank and root system of epiphyte bromeliad Guzmania lingulata. For this purpose, we conducted an experiment with different water regime and another with different concentrations of nitrogen. The experiments were: 1 - Watering: Control (application of water into Tank and Root, Tank (watering into Tank, Root (watering Root and Drought (water suspension during the 90 days of experimentation and 2 - Nitrogen: Plants fertilized with Hoagland and Arnon nutrient solution exclusively into Tank or Root with nitrogen concentrations of control and 2.62 or 5.34 mM N applied as urea. The Fv /Fm ratio allowed comparing the treatments between experiments, demonstrating that Root and Tank both have the capacity to maintain G. lingulata photosynthetic activity and growth, while Drought treatment (water suspension was the limiting factor for energy conversion efficiency of PSII. However, gas exchange was more permissive as a parameter for comparing treatments in the nitrogen experiment, providing important information about the general aspects of the photosynthetic process in the watering experiment. Both gas exchange and chlorophyll a fluorescence can support the evaluation of G. lingulata physiological status and can be useful tools in ornamental horticultural studies.

  3. The position of gas turbine power plants w