Download or read book Isotopic Characterisation of Atmospheric Nitrous Oxide by Fourier Transform Infrared Spectroscopy written by Federico Turatti and published by . This book was released on 2001 with total page 908 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Development of a Spectroscopic Technique for Continuous Online Monitoring of Oxygen and Site specific Nitrogen Isotopic Composition of Atmospheric Nitrous Oxide written by Eliza Harris and published by . This book was released on 2014 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrous oxide is an important greenhouse gas and ozone-depleting-substance. Its sources are diffuse and poorly characterized, complicating efforts to understand anthropogenic impacts and develop mitigation policies. Online, spectroscopic analysis of N2O isotopic composition can provide continuous measurements at high time resolution, giving new insight into N2O sources, sinks, and chemistry. We present a new preconcentration unit, "Stheno II," coupled to a tunable infrared laser direct absorption spectroscopy (TILDAS) instrument, to measure ambient-level variations in 18O and site-specific 15N N2O isotopic composition at remote sites with a temporal resolution of
Download or read book Determination by Isotope Ratio Mass Spectrometry of the Absolute Isotope Amount Fractions of Oxygen and Nitrogen in Nitrous Oxide written by and published by . This book was released on 2007 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: The significant interest related to atmospheric Nitrous oxide as a greenhouse gas and as a tool to regulate the Ozone concentration is well-known and requires to define a precise budget in the atmosphere for this gas. Therefore, the isotopic measurements are proposed to become the necessary additional instrument to better quantify this budget. The lack of a real comparability tool for the disparate Nitrous oxide isotopic measurement done required to start the work related to the development of a Reference material for Nitrogen and Oxygen in this gas. A measurement procedure for the complete isotope characterization of atmospheric Nitrous oxide sample has been developed and applied to establish a first Reference material for this gas. The whole work has been based on the peculiar instrumental capabilities of "Avogadro" MAT 271IRMS. Additional hardware and software improvement has been done for this mass spectrometer to apply the proposed method.
Download or read book Oxygen Isotopic Studies of Atmospheric Nitrous Oxide written by Steven Scott Cliff and published by . This book was released on 1998 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stable Isotope Investigations of Atmospheric Nitrous Oxide written by Jan Kaiser and published by . This book was released on 2003 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stable Isotope Investigations of Atmospheric Nitrous Oxide written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: AbstractThe analysis of isotope ratios is of increasing importance to study the sources and sinks of atmospheric trace gases and to investigate their chemical reaction pathways. Nitrous oxide (N2O) has four mono-substituted rare isotopic species: 14N15N16O, 15N14N16O, 14N217O and 14N218O. Mass-spectrometric measurement techniques have been developed during the work described here which enable a complete characterisation of abundance variations of these species. The hitherto most comprehensive account of these variations in the troposphere and stratosphere is given and interpreted in detail with reference to a suite of laboratory experiments. The laboratory experiments represent a major part of this thesis and focus on the isotopic fractionation of N2O in its stratospheric sink reactions, i.e. ultraviolet photolysis and reaction with electronically excited oxygen atoms, O(1D). These processes are of dominant influence for the isotopic composition of atmospheric N2O. Parameters of potential importance such as temperature and pressure variations as well as wavelength changes in case of UV photolysis were considered. Photolysis at stratospherically relevant wavelengths> 190 nm invariably showed enrichments in 15N at both nitrogen atoms of the residual N2O as well as in 17O and 18O. Enrichments were significantly larger for the central N atom than for the terminal N (with intermediate values for 18O) and increased towards longer wavelengths and colder temperatures. For the first time, isotopic depletions were noted for 18O and 15N at the terminal nitrogen site in N2O photolysis at 185 nm. In contrast, the second important N2O sink, reaction with O(1D), causes comparatively smaller isotopic enrichments in stratospheric N2O. However, its position-dependent fractionation pattern is directly opposite to the one in photolysis corresponding to larger enrichments at the terminal N atom. Hence, both sink processes leave distinct isotope signatures in stratospheric N2O. Further N.
Download or read book The Isotopic Signature of Nitrous Oxide Emitted from Agricultural Soils Measured by FTIR Spectroscopy written by Stephen Parkes and published by . This book was released on 2008 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Isotopic Analysis of Nitrogen in Ammonia by Fourier Transform Infrared Spectroscopy written by Mohamed Ali Abuzwida and published by . This book was released on 1982 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Enrichment of 15N and 18O in Stratospheric Nitrous Oxide written by Thomas A. Rahn and published by . This book was released on 1998 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Abundance of Atmospheric Nitrous Oxide as Derived from Infrared Spectroscopic Measurements written by Edward Foote Gardner and published by . This book was released on with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Infrared Spectroscopy Investigations Into the Mechanism of Nitrite to nitric Oxide Conversion by Nafion written by Gerardo Castillo Valdes and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrous acid (HONO) is a photochemical source of hydroxyl radical (OH) and nitric oxide (NO) that plays an important role in controlling the atmosphere's oxidative capacity. Measurements of nitrous acid in both field and laboratory settings are important for modeling atmospheric chemistry and studying the mechanisms responsible for its environmental fate. Recently, it was shown that the reaction of HONO on Nafion surfaces produces NO, providing a means to quantify HONO at trace levels using commercially available chemiluminescence NO analyzers. However, the mechanism for this catalytic reaction remains unknown. In this work, we investigate the reaction of nitrite (the conjugate base of HONO) on Nafion surfaces with the goal of obtaining mechanistic insights into the key intermediates responsible for the reduction of nitrite/HONO to NO. Chemiluminescence analysis was used to show that the main gas phase products evolved from the reaction of nitrite with Nafion are HONO, nitrogen dioxide (NO2), and NO. We used Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy to search for evidence of intermediate chemical species responsible for nitrite-to-NO conversion. Although we were unable to identify such intermediates using these methods, our study indicates that nitrite-to-NO conversion does not proceed to completion as is the case for HONO-to-NO conversion in the analogous gas phase system. Results demonstrate that double protonation of nitrite to form nitrosonium (NO+) is a prerequisite for complete conversion to NO on Nafion surfaces.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1990 with total page 852 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Estimating Regional Nitrous Oxide Emissions Using Isotopic Ratio Observations and a Bayesian Inverse Framework written by Michael James McClellan and published by . This book was released on 2018 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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. Global atmospheric concentrations of N2O, produced by natural and anthropogenic processes, continue to rise due to increases in emissions linked to human activity. The understanding of the impact of this gas is incomplete as there remain significant uncertainties in its global budget. The experiment described in this thesis, in which a global chemical transport model (MOZART-4), a fine-scale regional Lagrangian model (NAME), and new high-frequency atmospheric observations are combined, shows that uncertainty in N2O emissions estimates can be reduced in areas with continuous monitoring of N2O mole fraction and site-specific isotopic ratios. Due to unique heavy-atom (15N and 18O) isotopic substitutions made by different N2O sources, the measurement of N2O isotopic ratios in ambient air can help identify the distribution and magnitude of distinct sources. The new Stheno-TILDAS continuous wave laser spectroscopy instrument developed at MIT, recently installed at the Mace Head Atmospheric Research Station in western Ireland, can produce high-frequency timelines of atmospheric N2O isotopic ratios that can be compared to contemporaneous trends in correlative trace gas mole fractions and NAME-based statistical distributions of the origin of air sampled at the station. This combination leads to apportionment of the relative contribution from five major N2O sectors in the European region (agriculture, oceans, natural soils, industry, and biomass burning) plus well-mixed air transported from long distances to the atmospheric N2O measured at Mace Head. Bayesian inverse modeling methods that compare N2O mole fraction and isotopic ratio observations at Mace Head and at Diibendorf, Switzerland to simulated conditions produced using NAME and MOZART-4 lead to an optimized set of source-specific N2O emissions estimates in the NAME Europe domain. Notably, this inverse modeling experiment leads to a significant decrease in uncertainty in summertime emissions for the four largest sectors in Europe, and shows that industrial and agricultural N2O emissions in Europe are underestimated in inventories such as EDGAR v4.3.2. This experiment sets up future work that will be able to help constrain global estimates of N2O emissions once additional isotopic observations are made in other global locations and integrated into the NAME-MOZART inverse modeling framework described in this thesis.
Download or read book American Doctoral Dissertations written by and published by . This book was released on 2002 with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nitrous Oxide N2O Isotopic Composition in the Troposphere written by Katherine Ellison Potter and published by . This book was released on 2011 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nitrous oxide (N2O) is a significant greenhouse gas and main contributor to stratospheric ozone destruction. Surface measurements of N2O mole fractions have been used to attribute source and sink strengths, but large uncertainties remain. Stable isotopic ratios of N2O (here considered 14N15N16O, 15N14N16O, 14N14N18O, relative to the abundant 14N14N16O) linked to source and sink isotopic signatures can provide additional constraints on emissions and counter-balancing stratospheric sink. However, the isotopic composition in the troposphere has been regarded and measured as a fixed value, limited by insufficient measurement precision and few data. This thesis provides the foundation for high-frequency, high-precision measurements and utilization of N2O tropospheric isotopic composition. This is achieved through the development of a new measuring capability with sufficient precision to detect the subtle signals of N2O isotopic composition in tropospheric air and uniquely fully-automated and high-frequency capable. This instrument was applied to produce the first set of tropospheric air observations gathered at a remote research station covering a full annual cycle, paired with air origin information, and providing a valuable assessment of tropospheric composition and its potential utility. The first regional model of tropospheric N2O isotopic composition was developed for further assessment of expected variability and utility of isotopic composition data. The optimized fully-automated, liquid-cryogen-free pre-concentration device coupled to continuous flow IRMS resulted in 15N site-specific precisions markedly improved over other systems of 0.11 and 0.14 0/00 (1[sigma]) for [delta]15N[alpha] and [delta]15Nbulk, respectively, and among the best bulk composition precisions of 0.05 and 0.10 0/00 for [delta]15Nbulk and [delta]18O, respectively. The high-precision, non-continuous flask observations of N2O 15N site-specific composition (January 2010 to January 2011; Mace Head Atmospheric Research Station, Ireland) detected statistically significant signals on short-term and annual timescales, and when analyzed with air history information showed consistencies with source-receptor relationships. No seasonal cycle could be detected in the low-frequency observations, but regional model scenarios of the stratospheric seasonal signal resulted in amplitudes at the cusp of current measurement capabilities. This thesis illustrated detectable variations in tropospheric N2O isotopic composition which can potentially reduce uncertainty in the N2O budget with high-frequency, high-precision observations, now feasible by the instrumentation developed here.
Download or read book Application of Fourier Transform Infrared Spectrometry to Studies of Gas phase Kinetics written by Ti Jo Tsay and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
