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Measurements And Model Predictions Of Hydroxyl Radical Peroxy Radicals And Nitrous Acid
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Book Synopsis Measurements and Model Predictions of Hydroxyl Radical, Peroxy Radicals, and Nitrous Acid by : Emily Kathleen Reidy
Download or read book Measurements and Model Predictions of Hydroxyl Radical, Peroxy Radicals, and Nitrous Acid written by Emily Kathleen Reidy and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The hydroxyl radical (OH) is the dominant oxidant in the atmosphere, controlling the lifetimes of volatile organic compounds (VOCs) and contributing to the formation of ozone (O3) and secondary organic aerosols (SOA). The oxidation of VOCs by OH propagates a radical cycle between OH, the hydroperoxy radical (HO2), and organic peroxy radical (RO2). Due to its importance in the atmosphere, there is a substantial body of literature investigating ROX (≡ OH + HO2 + RO2) chemistry in the outdoor environment, but few measurements occurring indoors, where people spend the majority of their time. This work includes the first measurements of OH and HO2 in a residential environment during use of a gas stove. Emissions from the gas stove quickly create a complex indoor atmosphere with unexpectedly high concentrations of OH and HO2, suggesting missing radical sources in indoor spaces.In more pristine regions, there has been significant disagreement between measurements and modeled concentrations of ROX. While progress has been made in improving OH agreement in deciduous forests, HO2 and RO2 model disagreement persists. Measurements of radicals spanning three forested campaigns are compared through a chemical coordinate analysis and suggest that newly proposed radical loss pathways still cannot account for the discrepancies between model and measurements.Finally, measurements of radical species and their major precursors in a coniferous forest emphasize the importance of nitrous acid (HONO) on ROX concentrations. HONO photolyzes to form OH and NO, producing a substantial amount of total ROX. HONO concentrations are particularly difficult to model, as there are numerous sources of varying importance in different environments. While common chemical mechanisms only include gas-phase reactions of HONO, heterogeneous reactions were added in order to characterize sources of HONO in the remote, forested environment. Overall, this work discusses missing sources and sinks of radicals and their major precursor, HONO, in indoor spaces, deciduous, and coniferous forests, addressing gaps in our understanding of radical chemistry that impact the formation of secondary air pollution.
Book Synopsis Nitrous Acid, Hydroxyl Radicals, and Peroxy Radicals by : Brandon Bottorff
Download or read book Nitrous Acid, Hydroxyl Radicals, and Peroxy Radicals written by Brandon Bottorff and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The hydroxyl radical (OH) and peroxy radicals (HO2 and RO2) are key species that drive the oxidation of trace gases and control the fate of several tropospheric pollutants. Reactions of these radical species with volatile organic compounds (VOCs) and nitrogen oxides (NO + NO2 = NOx) establish a fast radical-propagation cycle that can lead to a net production of harmful secondary pollutants such as ozone (O3) and secondary organic aerosols (SOA). Attempts to develop accurate control strategies for these pollutants require an in-depth understanding of radical chemistry, however recent measurements of radical concentrations have shown discrepancies with predictive models.This work will describe measurements of radicals made by the Indiana University Laser- Induced Fluorescence-Fluorescence Assay by Gas Expansion (LIF-FAGE) instrument that has been described previously, and will also detail the development and initial measurements made by a Laser-photofragmentation/Laser-induced fluorescence (LP/LIF) instrument capable of nearsimultaneous detection of OH and nitrous acid (HONO), an important radical precursor. In particular, this work will detail measurements of OH, and HO2 made by the LIF-FAGE instrument in a forested environment in northern Michigan as part of the 2016 Program for Research on Oxidants, Photochemistry, and Transport (PROPHET) field campaign. An extensive set of supporting measurements, including photolysis rates and mixing ratios of NOx, VOCs, and other trace gases was used to constrain a zero dimensional box to assess our current understanding of atmospheric chemistry in remote environments characterized by high VOC mixing ratios and low mixing ratios of NOx.In addition, the development and initial field deployment of the LP/LIF instrument will be detailed. This will include a discussion on a novel calibration method based on determining the photofragmentation efficiency (PE) of HONO by the 355-nm photolysis laser, and also includes initial measurements of HONO and OH in both a forested and urban setting. Lastly, HONO mixing ratios in the indoor environment will be analyzed through measurements made as part of the House Observations of Microbial and Environmental Chemistry (HOMEChem) field campaign. HONO behavior during a variety of common household activities will be assessed and measurements from the LP/LIF instrument are compared to simultaneous measurements from a chemical ionization mass spectrometry (CIMS) instrument. The agreement between the two instruments gives confidence in both measurement techniques and also suggests that HONO concentrations can be well mixed in indoor environments.
Book Synopsis Hydroxyl Radical Chemistry Below a Forest Canopy by : Amanda E. Heino
Download or read book Hydroxyl Radical Chemistry Below a Forest Canopy written by Amanda E. Heino and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydroxyl (OH) and peroxy (RO2, HO2) radicals dictate the fate of most trace gases in the troposphere due to their high reactivity. Reactions of OH with volatile organic compounds (VOCs) in the presence of nitrogen oxides (NO, NO2, together referred to as NOx) can lead to the production of ozone (O3) and secondary organic aerosols. Current models have overestimated ozone production over forests, bringing into question our understanding of radical chemistry in these environments. It has been suggested that the overestimation of ozone concentrations over forests is due to canopy shading and turbulence that leads to low radical production below the forest canopy resulting in a net loss of ozone within the forest canopy. During the summer of 2022, OH, HO2, and RO2 (together referred to as HOx) radical measurements were conducted below the forest canopy in a deciduous forest at the University of Michigan Biological Station (UMBS) Program for Research on Oxidants: PHotochemistry, Emissions, and Transport (PROPHET) site. Supporting measurements of photolysis rates, HONO, VOCs, and NOx were used to constrain a zero-dimensional box model to predict the radical concentrations.
Download or read book Interim Assessment written by and published by . This book was released on 1987 with total page 986 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Interim Assessment, the Causes and Effects of Acidic Deposition: Atmospheric processes by :
Download or read book Interim Assessment, the Causes and Effects of Acidic Deposition: Atmospheric processes written by and published by . This book was released on 1988 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Interim Assessment: Atmospheric processes by : National Acid Precipitation Assessment Program (U.S.)
Download or read book Interim Assessment: Atmospheric processes written by National Acid Precipitation Assessment Program (U.S.) and published by . This book was released on 1987 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Interim Assessment, the Causes and Effects of Acidic Deposition by :
Download or read book Interim Assessment, the Causes and Effects of Acidic Deposition written by and published by . This book was released on 1988 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Airborne Measurement and Interpretation of Peroxy Radical Concentrations with a Focus on the Oxidation Mechanisms in the Asian Free Troposphere by : Midhun George
Download or read book Airborne Measurement and Interpretation of Peroxy Radical Concentrations with a Focus on the Oxidation Mechanisms in the Asian Free Troposphere written by Midhun George and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydroperoxyl (HO2) and organic peroxy (RO2, where R stands for any organic group) radicals are highly reactive molecules produced in the oxidation of many compounds in the troposphere. They participate in the catalytic cycle producing or destroying ozone (O3) in the troposphere. Thus, HO2 and RO2 measurements provide unique information about the chemical processing of an air mass. Over the last decades, the understanding of the role of HO2 and RO2 in the chemical processes in the planetary boundary layer (PBL) has improved through ground-based in-situ measurements. However, the number of unequivocal measurements of peroxy radicals in the free troposphere is still quite limited. Measurements from airborne platforms offer a unique opportunity to measure HO2 and RO2 together with other relevant trace gases to test and improve the understanding of their chemistry in the free troposphere. During this doctoral study, an extensive set of airborne RO2* (RO2* = HO2 + ∑RO2, where RO2 represents the organic peroxy radicals reacting with NO to produce NO2) measurements in the PBL and free troposphere was acquired, analysed and interpreted. The RO2* measurements were made using the Peroxy Radical Chemical Enhancement and Absorption Spectrometer (PeRCEAS) developed at the Institut für Umweltphysik (IUP) of the University of Bremen. PeRCEAS has successfully deployed onboard the High Altitude LOng range research aircraft (HALO) in three research campaigns: the Oxidation Mechanism Observations (OMO) Asia and the Effect of Megacities on the transport and transformation of pollutants on the Regional to Global scales (EMeRGe) field missions in Europe and Asia. The PeRCEAS instrument was characterised and calibrated under atmospherically representative conditions in the laboratory to assure data quality, reproducibility, accuracy and to define optimal operating conditions for the airborne measurements. PeRCEAS successfully measured RO2* in 33 HALO flights. RO2* mixing ratios of up to 120 pmole mole-1 were measured in air masses having different origins, chemical compositions and physical conditions in Europe and Asia. The RO2* measurements, the simultaneous measurements of other relevant trace gases, aerosol concentration, photolysis frequencies and other meteorological parameters were synergistically analysed to identify the chemical processes controlling the amount of RO2*. From the analysis, it was found that RO2* is primarily produced following the photolysis of ozone (O3), formaldehyde (HCHO), glyoxal (CHOCHO), and nitrous acid (HONO) in the air masses investigated. The estimate for the contribution of O3 photolysis to RO2* production rate is > 40 % in the PBL and 40% in the free troposphere. This reduction is explained by the decrease in the water vapour concentration ([H2O]) as a function of altitude. Subsequently, the RO2* mixing ratios in the air masses measured during the EMeRGe in Asia and Europe campaigns were calculated assuming a photostationary steady-state (PSS) for RO2*. The RO2* production from precursor photolysis, the loss through HO2 - HO2, RO2 - RO2 and HO2 - RO2 reactions, the hydroxyl radical (OH) and organic oxy-radicals (RO) loss during the radical interconversion, and HO2 uptake on aerosol were considered for the calculation of RO2*. The calculations were constrained by the simultaneous measurements of photolysis frequencies, trace gas concentrations and aerosol particle number concentrations onboard HALO. Case studies confirmed the validity of the PSS assumption for air masses having different chemical compositions under different physical conditions. The RO2* calculated are generally in excellent agreement with the RO2* measurements. An experimental budget analysis was performed to estimate the main loss processes of RO2* by introducing the RO2* measurements in the PSS equation. Except for the measurements inside pollution plumes with NO 800 pmole mole-1 or aerosol particle number concentration > 800 particles cm-3, the HO2 - RO2 and HO2 - HO2 were the dominant RO2* loss process during both EMeRGe Asia and Europe. The RO2* losses through HO2 uptake on aerosol were higher in the pollution outflows measured in Asia than in Europe. This is attributed to the higher aerosol concentrations observed in the air masses probed during EMeRGe in Asia. The contribution from the HO2 uptake on aerosol increases up to 60 % for an assumed aerosol uptake coefficient of 0.24 inside pollution plumes in Asia, where the aerosol particle number concentration is > 1000 particles cm-3. In Europe, the OH - NOx reactions were the dominant RO2* loss process in the pollution outflow. This finding is explained by the EMeRGe in Europe measurements being typically closer to anthropogenic emissions sources than in Asia, except for the case study of Taipei and Manila.
Book Synopsis Differential Optical Absorption Spectroscopy by : Ulrich Platt
Download or read book Differential Optical Absorption Spectroscopy written by Ulrich Platt and published by Springer Science & Business Media. This book was released on 2008-05-30 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first part of this book reviews the basics of atmospheric chemistry, radiation transport, and optical spectroscopy before detailing the principles underlying DOAS. The second part describes the design and application of DOAS instruments as well as the evaluation and interpretation of spectra. The recent expansion of DOAS application to the imaging of trace gas distributions by ground, aircraft, and satellite-based instruments is also covered.
Book Synopsis Reactive Species Detection in Biology by : Frederick A. Villamena
Download or read book Reactive Species Detection in Biology written by Frederick A. Villamena and published by Elsevier. This book was released on 2016-10-23 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt: Reactive Species Detection in Biology: From Fluorescence to Electron Paramagnetic Resonance Spectroscopy discusses the reactive oxygen species that have been implicated in the pathogenesis of various diseases, presenting theories, chemistries, methodologies, and various applications for the detection of reactive species in biological systems, both in-vitro and in-vivo. Techniques covered include fluorescence, high performance chromatography, mass spectrometry, immunochemistry, and electron paramagnetic resonance spectroscopy. Probe design and development are also reviewed in order to advance new approaches in radical detection through synthesis, computations, or experimental applications. Reviews all current advances in radical detection Emphasizes chemical structures and reaction schemes fundamental to radical detection and identification Describes the uses, advantages, and disadvantages of various probe designs Examines new approaches to radical probe development
Book Synopsis Air Pollution Modeling and Its Application II by : C. De Wispelaere
Download or read book Air Pollution Modeling and Its Application II written by C. De Wispelaere and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 851 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1969 the North Atlantic Treaty Organization established the Committee on the Challenges of Hodern Society. Air Pollution was from the start one of the priority problems under study within the framework of the pilot studies undertaken by this Committee. The organization of a yearly symposium dealing with air pollution modeling and its application is one of the main activities within the pilot study in relation to air pollution. After being organized for five years by the United States and for five years by the Federal Republic of Germany, Belgium, repre sented by the Prime Minister's Office for Science Policy Programming, became responsible in 1980 for the organization of this symposium. This volume contains the papers presented at the 12th Interna tional Technical Meeting on Air Pollution Modeling and its Appli cation held at SRI International, Menlo Park, California in the USA from 25th to 28th August 1981. The meeting was jointly organized by the Prime Minister's Office for Science Policy Programming, Belgium and SRI International, USA. The conference was attended by 109 participants and 51 papers have been presented. The members of the selection committee of the 12th I.T.M. were A. Berger (Chair man, Belgium), W. Klug (Federal Republic of Germany), L.E. Niemeyer (United States of America), L. Santomauro (Italy), J. Tikvart (United States of America), M.L. Williams (United Kingdom), H. Van Dop (The Netherlands), C. De Wispelaere (Coordinator, Belgium).
Author :United States. Congress. House. Committee on Science, Space, and Technology. Subcommittee on Natural Resources, Agriculture Research, and Environment Publisher : ISBN 13 : Total Pages :264 pages Book Rating :4.3/5 (91 download)
Book Synopsis National Acid Precipitation Assessment Program by : United States. Congress. House. Committee on Science, Space, and Technology. Subcommittee on Natural Resources, Agriculture Research, and Environment
Download or read book National Acid Precipitation Assessment Program written by United States. Congress. House. Committee on Science, Space, and Technology. Subcommittee on Natural Resources, Agriculture Research, and Environment and published by . This book was released on 1988 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Chemistry of the Upper and Lower Atmosphere by : Barbara J. Finlayson-Pitts
Download or read book Chemistry of the Upper and Lower Atmosphere written by Barbara J. Finlayson-Pitts and published by Elsevier. This book was released on 1999-11-17 with total page 993 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here is the most comprehensive and up-to-date treatment of one of the hottest areas of chemical research. The treatment of fundamental kinetics and photochemistry will be highly useful to chemistry students and their instructors at the graduate level, as well as postdoctoral fellows entering this new, exciting, and well-funded field with a Ph.D. in a related discipline (e.g., analytical, organic, or physical chemistry, chemical physics, etc.). Chemistry of the Upper and Lower Atmosphere provides postgraduate researchers and teachers with a uniquely detailed, comprehensive, and authoritative resource. The text bridges the "gap" between the fundamental chemistry of the earth's atmosphere and "real world" examples of its application to the development of sound scientific risk assessments and associated risk management control strategies for both tropospheric and stratospheric pollutants. Serves as a graduate textbook and "must have" reference for all atmospheric scientists Provides more than 5000 references to the literature through the end of 1998 Presents tables of new actinic flux data for the troposphere and stratospher (0-40km) Summarizes kinetic and photochemical date for the troposphere and stratosphere Features problems at the end of most chapters to enhance the book's use in teaching Includes applications of the OZIPR box model with comprehensive chemistry for student use
Book Synopsis Selected Water Resources Abstracts by :
Download or read book Selected Water Resources Abstracts written by and published by . This book was released on 1991 with total page 884 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Organic Peroxy Radicals by : P. D. Lightfoot
Download or read book Organic Peroxy Radicals written by P. D. Lightfoot and published by . This book was released on 1992 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Air Pollution by Photochemical Oxidants by : Robert Guderian
Download or read book Air Pollution by Photochemical Oxidants written by Robert Guderian and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 355 pages. Available in PDF, EPUB and Kindle. Book excerpt: Photochemical oxidants are secondary air pollutants formed under the influence of sunlight by complex photochemical reactions in air which contains nitrogen oxides and reactive hydrocarbons as precursors. The most adverse components formed by photochemical reactions in polluted air are ozone (0 ) 3 and peroxyacetyl nitrate (PAN), among many other products such as aldehydes, ketones, organic and inorganic acids, nitrates, sulfates etc. An analysis and evaluation of the available knowledge has been used to characterize the relationships among emissions, ambient air concentrations, and effects, and to identify the important controlling influences on the formation and effects of photochemical oxidants. The biological activity of photochemical oxidants was first clearly manifested during the early 1940's, when vegetation injury was observed in the Los Angeles Basin in the United States. Since that time, as a consequence of the increasing emissions of photochemical oxidant precursors, the photochemical oxidants have become the most important air pollutants in North America. In other parts of the world, for example South and Central America, Asia, and Australia, photo chemical oxidants threaten vegetation, particularly the economic and ecological performance of plant life. According to my knowledge, the first observations of ozone and PAN injury to vegetation in Europe were made by Dr. Ellis F. Darley (Statewide Air Pollution Research Center, University of California, Riverside, California) during a study visit (1963/64) to the Federal Republic of Germany.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1988 with total page 692 pages. Available in PDF, EPUB and Kindle. Book excerpt:
