Download or read book Laboratory Studies of Reactions of Atmospheric Gases with Components of Mineral Dust Aerosol and Research in Chemical Education written by Jennifer Dianne Schuttlefield and published by . This book was released on 2008 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Heterogeneous and Multiphase Chemistry of Trace Atmospheric Gases with Mineral Dust and Other Metal Containing Particles written by Aruni Gankanda and published by . This book was released on 2016 with total page 152 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particulate matter in the atmosphere emitted from various natural and anthropogenic sources is important due to their effects on the chemical balance of the atmosphere, the Earth's climate, human health and biogeochemical cycles. Although there have been many studies performed to understand the above effects, there still remains substantial uncertainty associated with processes involved and thus it is difficult for current atmospheric chemistry and climate models to reconcile model results with field measurements. Therefore, it is important to have better agreement between models and observations as the accuracy of future atmospheric chemistry and climate predictions depends on it. In this research, a greater understanding of the role of mineral dust chemistry was pursued through focused laboratory studies in order to better understand fundamental processes involved. In particular, studies to further understand the photochemistry of adsorbed nitrate, an important inorganic ion associated with particulate matter exposed to gas-phase nitrogen oxides, were conducted using Al2O3, TiO2 and NaY zeolite to represent non-photoactive components, photoactive components and aluminosilicate respectively, present in mineral dust. These studies reveal that photochemistry of nitrate adsorbed on mineral dust is governed by wavelength of light, physicochemical properties of dust particles and adsorption mode of nitrate. Gas phase NO2, NO and N2O are the photolysis products of nitrate on oxide particles under dry conditions. In contrast, nitrate adsorbed on zeolite is converted mainly to adsorbed nitrite upon irradiation. This nitrite yield is decreased with increasing relative humidity. Gas phase N2O is the main photolysis product of nitrate adsorbed in zeolite in the presence of co-adsorbed ammonia. Water adsorbed on semiconducting TiO2 can be photochemically converted to hydroxyl radicals.

Download or read book Heterogeneous Chemistry of Atmospheric Mineral Dust Particles and Their Resulting Cloud nucleation Properties written by Ryan Christopher Sullivan and published by . This book was released on 2008 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mineral dust particles are a major component of tropospheric aerosol mass and affect regional and global atmospheric chemistry and climate. Dust particles experience heterogeneous reactions with atmospheric gases that alter the gas and particle-phase chemistry. These in turn influence the warm and cold cloud nucleation ability and optical properties of the dust particles. This dissertation investigates the atmospheric chemistry of mineral dust particles and their role in warm cloud nucleation through a combination of synergistic field measurements, laboratory experiments, and theoretical modeling. In-situ measurements made with a single-particle mass spectrometer during the ACE-Asia field campaign in 2001 provide the motivation for this work. The observed mixing state of the individual ambient particles with secondary organic and inorganic components is described in Chapter 2. A large Asian dust storm occurred during the campaign and produced dramatic changes in the aerosol's composition and mixing state. The effect of particle size and mineralogy on the atmospheric processing of individual dust particles is explored in Chapters 3 & 4. Sulfate was found to accumulate preferentially in submicron iron and aluminosilicate-rich dust particles, while nitrate and chloride were enriched in supermicron calcite-rich dust. The mineral dust (and sea salt particles) were also enriched in oxalic acid, the dominant component of water soluble organic carbon. Chapter 5 explores the roles of gas-phase photochemistry and partitioning of the diacids to the alkaline particles in producing this unique behavior. The effect of the dust's mixing state with secondary organic and inorganic components on the dust particles' solubility, hygroscopicity, and thus warm cloud nucleation properties is explored experimentally and theoretically in Chapter 6. Cloud condensation nucleation (CCN) activation curves revealed that while calcium nitrate and calcium chloride particles were very hygroscopic and CCN-active, due to the high solubility of these compounds, calcium sulfate and calcium oxalate were not. Particles composed of these two sparingly soluble compounds had apparent hygroscopicities similar to pure calcium carbonate. This implies that the commonly made assumption that all dust particles become more hygroscopic after atmospheric processing must be revisited. Calcium sulfate and oxalate represent two forms of aged mineral dust particles that remain non-hygroscopic and thus have poor CCN nucleation ability. The particle generation method (dry versus wet) was found to significantly affect the chemistry and hygroscopicity of the aerosolized particles. Finally, in Chapter 7 the timescale for the atmospheric conversion of insoluble calcite particles to soluble, CCN-active calcium nitrate particles was derived from aerosol flow tube experiments. The reaction rate is rapid was used to estimate the conversion of calcite particles to very hygroscopic particles can occur in just a few hours of exposure to tropospheric levels of nitric acid. This process will therefore be controlled by the availability of nitric acid and its precursors, as opposed to the available atmospheric reaction time.

Download or read book Chemical and Photochemical Reactions on Mineral Oxide Surfaces in Gaseous and Liquid Phases written by Gayan Randika S. Rubasinghege and published by . This book was released on 2011 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mineral dust aerosols emitted from the Earth crust during various natural and anthropogenic processes continuously alter the chemical balance of the atmosphere via heterogeneous processes and thus, impact on the global climate. Understanding of heterogeneous chemistry and photochemistry on mineral dust has become vital to accurately predict the effect of mineral dust loading on the Earth's atmosphere. Here, laboratory measurements are coupled with model studies to understand heterogeneous chemistry and photochemistry in the atmosphere with the specific focus on reactions on mineral oxide surfaces.

Download or read book Laboratory Studies of the Physicochemical Properties of Mixed Organic mineral Dust Atmospheric Aerosols written by Kelly M. Gierlus and published by . This book was released on 2011 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mineral dust aerosol generated from windblown soil can participate in climate forcing either directly through scattering or absorbing solar radiation or indirectly through acting as cloud condensation nuclei (CCN). In recent field studies organic material, such as oxalic acid and humic-like substances (HULIS), has been shown to be present in mineral dust aerosol. The presence of these internally mixed organic compounds can alter the physicochemical properties of the dust particles in the Earth's atmosphere. Thus, in this dissertation research the hygroscopic growth and CCN activity of model humic and fulvic acids and of calcite (CaCO3) particles coated with humic and fulvic acids has been measured. Furthermore, the CCN activity of calcite aerosol reacted with oxalic acid (H2C2O4) has been measured and compared to that of the humic and fulvic acids. The CCN measurements indicate that humic- or fulvic acid-coated calcite particles are significantly more CCN active than uncoated calcite particles, whereas reacted oxalate/calcite particles are not significantly more CCN active than the unreacted calcite particles, because the enhancement in CCN activity is reduced due to the reaction of calcite with oxalic acid to yield calcium oxalate. These results show that atmospheric processing of mineral dust through surface adsorption and/or heterogeneous reactions can alter hygroscopicity and CCN activity to an extent which depends on mineralogy and chemical speciation.

Download or read book Laboratory Studies of Upper Atmosphere Chemical Reactions written by FREDERICK. KAUFMAN and published by . This book was released on 1962 with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt: A LABORATORY RESE RCH PROGRAM IS DESCRIBED WHICH DEALS WITH MEASUREME T OF THE RA OF OXYGEN AND NITROGEN ATOM REACTIONS AND WHICH CLARIFIES THE ORIGIN AND MECHANISM OF ASSOCIATED AFTERGLOWS. O- and N-atoms are generated in microwave gas discharges ixed with other reactant or diluent gases, and pumped through a flow tube nd r s eady-state conditio s. The nature of the air afterglow, nitrogen afterglow, and blue nitric oxide afterglow are discussed, and new results are presente on the effect of five diluent gases on the rate of the light-producing process of the air afterglow. The efficiency of these diluents as third bodies in the recombination r ac ion O + O + YIELDS NO2 + M is also determined. New experiments on the i termolecular recombination of O with O2 to form ozone yield a lower rate constant than is currently quoted in the literature. Further work on this important reaction is outlined which will help explain the composition of the upper atmosphere. (Author).

Download or read book The Characterization of Atmospheric Aerosols written by and published by . This book was released on 1998 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project of the Los Alamos National Laboratory (LANL). The objective of this collaborative research project is the measurement and modeling of atmospheric aerosols and heterogeneous (gas/aerosol) chemical reactions. The two major accomplishments are single particle characterization of tropospheric particles and experimental investigation of simulated stratospheric particles and reactions thereon. Using aerosol time-of-flight mass spectrometry, real-time and composition measurements of single particles are performed on ambient aerosol samples. This technique allows particle size distributions for chemically distinct particle types to be described. The thermodynamics and chemical reactivity of polar stratospheric clouds are examined using vapor deposited thin ice films. Employing nonlinear optical methods, as well as other techniques, phase transitions on both water and acid ices are monitored as a function of temperature or the addition of gases.

Download or read book Investigation of Mineral Dust Aerosols Chemistry Intractions in the Marine Environments written by Gill-Ran Jeong and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Mineral dust aerosols play an important role in atmospheric chemistry through photolysis and heterogeneous uptake. Both mechanisms strongly depend on the size and composition of mineral dust. Because of the complex nature of dust, chemistry modeling commonly relies on simplified assumptions about the properties of dust particles relevant to physiochemical processes. The goal of this thesis is to investigate the impact of size-resolved composition of dust aerosols on atmospheric photochemistry. The relative importance of dust characteristics in photolysis and heterogeneous loss and the relative roles of the two mechanisms on atmospheric photochemistry are investigated. A new block of spectral aerosol optical properties was developed and incorporated into the tropospheric ultraviolet and visible radiation transfer code in order to calculate spectral actinic fluxes and photolysis rates, J-values. The Fuchs-Sutugin approximation was employed to compute mass transfer from gas to dust mineral species and heterogeneous loss rate, kloss, j. The J-values and kloss, j were incorporated into a one-dimensional photochemistry model to simulate the diurnal cycle of a vertical profile of photochemical species. Several cases of dust loading were considered in the clean and polluted marine environments. A size-resolved mineralogical composition was constructed by selecting a range of the mass fraction of the three main mineral species such as iron oxide-containing clay minerals, carbonate-containing species, and quartz.

Download or read book The Future of Atmospheric Chemistry Research written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2017-01-29 with total page 227 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our world is changing at an accelerating rate. The global human population has grown from 6.1 billion to 7.1 billion in the last 15 years and is projected to reach 11.2 billion by the end of the century. The distribution of humans across the globe has also shifted, with more than 50 percent of the global population now living in urban areas, compared to 29 percent in 1950. Along with these trends, increasing energy demands, expanding industrial activities, and intensification of agricultural activities worldwide have in turn led to changes in emissions that have altered the composition of the atmosphere. These changes have led to major challenges for society, including deleterious impacts on climate, human and ecosystem health. Climate change is one of the greatest environmental challenges facing society today. Air pollution is a major threat to human health, as one out of eight deaths globally is caused by air pollution. And, future food production and global food security are vulnerable to both global change and air pollution. Atmospheric chemistry research is a key part of understanding and responding to these challenges. The Future of Atmospheric Chemistry Research: Remembering Yesterday, Understanding Today, Anticipating Tomorrow summarizes the rationale and need for supporting a comprehensive U.S. research program in atmospheric chemistry; comments on the broad trends in laboratory, field, satellite, and modeling studies of atmospheric chemistry; determines the priority areas of research for advancing the basic science of atmospheric chemistry; and identifies the highest priority needs for improvements in the research infrastructure to address those priority research topics. This report describes the scientific advances over the past decade in six core areas of atmospheric chemistry: emissions, chemical transformation, oxidants, atmospheric dynamics and circulation, aerosol particles and clouds, and biogeochemical cycles and deposition. This material was developed for the NSF's Atmospheric Chemistry Program; however, the findings will be of interest to other agencies and programs that support atmospheric chemistry research.

Download or read book Charged Particle Reactions Involving Oxygen and Nitrogen in the E and F regions written by William Swider and published by . This book was released on 1973 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two-body ionospheric reactions involving oxygen and/or nitrogen are briefly reviewed with special emphasis on the temperature dependencies of these reactions and reactions involving excited ions. The temperature dependence of most reactions are fairly well known except for processes which can occur over a wide range of thermospheric temperatures, particularly O and/or O(+) reactions and dissociative recombination processes. Disagreements between laboratory and aeronomically deduced loss processes for O(+) ions are discussed. The absence of laboratory measurements of excited ion reactions at typical E- and F-region temperatures hinders twilight and auroral studies. The lack of knowledge concerning the state of excitation of reaction products impairs airglow and chemical aeronomy studies. The reaction between O(2(+) and NO may be an important source of electronically excited O2 molecules in auroras.

Download or read book The Heterogeneous Chemistry of Mineral Dust and Sea Salt and Their Components with Trace Atmospheric Gases written by Brenda Jean Krueger and published by . This book was released on 2005 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Understanding Atmospheric Mineral Dust Photochemistry written by Milena Ponczek and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Minerals that absorb light near UV/Vis present in dust aerosols interact with trace gases in the atmosphere and can initiate a new and potentially significant photo-induced heterogeneous chemistry, which is currently poorly documented. This thesis aims to address different issues of mineral dust reactivity towards organic compounds and, therefore, assesses the impact of these interactions on several aspects of atmospheric sciences. We investigated experimentally the physicochemical interaction of mineral aerosols (synthetic and natural), pure or coated with organic/inorganic materials with trace gases from several chemical families (alcohols, ketones, carboxylic acids, etc.), under simulated conditions close to the real environment (regarding to humidity, concentration in the gas phase, wavelength and intensity of irradiation, pressure and temperature). In a first approach, we studied the uptake of oxygenated organics onto different dust proxies such as SiO2, TiO2 and Arizona test dust (ATD) evaluating the effects of ambient conditions on the uptake kinetics and product generation. Then, we discussed the chemistry of 5 dicarboxylic acids (C4-C8) on ATD particles upon UV-A irradiation monitoring products in the gas phase as well as those whose stay adsorbed on the particulate phase. Lastly, we investigated the influence of nitrate anions on the uptake of acetone on ATD and SiO2 and in the photochemical product formation of glutaric acid on ATD. Overall, our results clearly show that photochemical processing of dust aerosols should be considered as a source of reactive compounds and as a key process affecting their action as ice nucleation and cloud condensation nuclei.

Download or read book Atmospheric Reaction Chemistry written by Hajime Akimoto and published by Springer. This book was released on 2018-04-25 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is aimed at graduate students and research scientists interested in gaining a deeper understanding of atmospheric chemistry, fundamental photochemistry, and gas phase and heterogeneous reaction kinetics. It also provides all necessary spectroscopic and kinetic data, which should be useful as reference sources for research scientists in atmospheric chemistry. As an application of reaction chemistry, it provides chapters on tropospheric and stratospheric reaction chemistry, covering tropospheric ozone and photochemical oxidant formation, stratospheric ozone depletion and sulfur chemistry related to acid deposition and the stratospheric aerosol layer. This book is intended not only for students of chemistry but also particularly for non-chemistry students who are studying meteorology, radiation physics, engineering, and ecology/biology and who wish to find a useful source on reaction chemistry.

Download or read book Chemical Reactions in the Lower and Upper Atmosphere written by Stanford Research Institute and published by . This book was released on 1961 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Assessment of Climate Change over the Indian Region written by R. Krishnan and published by Springer Nature. This book was released on 2020-06-12 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book discusses the impact of human-induced global climate change on the regional climate and monsoons of the Indian subcontinent, adjoining Indian Ocean and the Himalayas. It documents the regional climate change projections based on the climate models used in the IPCC Fifth Assessment Report (AR5) and climate change modeling studies using the IITM Earth System Model (ESM) and CORDEX South Asia datasets. The IPCC assessment reports, published every 6–7 years, constitute important reference materials for major policy decisions on climate change, adaptation, and mitigation. While the IPCC assessment reports largely provide a global perspective on climate change, the focus on regional climate change aspects is considerably limited. The effects of climate change over the Indian subcontinent involve complex physical processes on different space and time scales, especially given that the mean climate of this region is generally shaped by the Indian monsoon and the unique high-elevation geographical features such as the Himalayas, the Western Ghats, the Tibetan Plateau and the adjoining Indian Ocean, Arabian Sea, and Bay of Bengal. This book also presents policy relevant information based on robust scientific analysis and assessments of the observed and projected future climate change over the Indian region.

Download or read book Heterogeneous Reaction and Kinetics of Acetic Acid on Components of Mineral Dust Aerosol written by Whitney Anne Larish and published by . This book was released on 2014 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Chemistry Of Air Air Pollution written by S.A. Iqbal and published by Discovery Publishing House. This book was released on 2010 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: