Author: Kai Wang
Publisher:
ISBN:
Category : Mass spectrometry
Languages : en
Pages :

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Author: Yun Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Carlos Borrego
Publisher: Springer Science & Business Media
ISBN: 0387688544
Category : Science
Languages : en
Pages : 750

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In 1969 the North Atlantic Treaty Organisation (NATO) established the Committee on Challenges of Modern Society (CCMS). The subject of air pol- tion was from the start, one of the priority problems under study within the fra- work of various pilot studies undertaken by this committee. The organization of a periodic conference dealing with air pollution modeling and its application has become one of the main activities within the pilot study relating to air pollution. The first five international conferences were organized by the United States as the pilot country; the second five by the Federal Republic of Germany; the third five by Belgium; the next four by The Netherlands; and the next five by Denmark; and with this one, the last three by Portugal. th This volume contains the papers and posters presented at the 27 NATO/CCMS International Technical Meeting on Air Pollution Modeling and Its Application held in Banff, Canada, 24-29 October 2004. The key topics at this ITM included: Role of Atmospheric Models in Air Pollution Policy and Abatement Strategies; Integrated Regional Modeling; Effects of Climate Change on Air Quality; Aerosols as Atmospheric Contaminants; New Developments; and Model Assessment and Verification. 104 participants from North and South America, Europe, Africa and Asia attended th the 27 ITM. The conference was jointly organized by the University of Aveiro, Portugal (Pilot Country) and by The University of Calgary, Canada (Host Country). A total of 74 oral and 22 poster papers were presented during the conference.

Author: Felipe Daniel Lopez-Hilfiker
Publisher:
ISBN:
Category :
Languages : en
Pages : 178

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The guiding question to this research is: To what extent and by what mechanisms do biogenic volatile organic compounds contribute to atmospheric aerosol mass? To address this question we need to understand the chemistry that produces condensable vapors which when in the presence of particles may partition onto the aerosol surface depending on their chemical and physical properties. I developed an insitu gas and aerosol sampling system, the FIGAERO (Filter Inlet for Gases and AEROsol) to speciate gas and particle phase organics derived from photochemical reactions with biogenic volatile organic compounds under both field and laboratory conditions. By coupling the FIGAERO to a High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer (HR-TOF-CIMS) I am able to elucidate chemical pathways by identifying elemental compositions and in some cases functional groups present in the detected molecular ions. The coupling of the FIGAERO to the HR-TOF-CIMS also allows the estimation of effective vapor pressures of the aerosol components and this information can be used to improve vapor pressure models and test associated partitioning theories and parameterizations. The approach also provides hundreds of speciated chemical tracers that can be correlated with traditional environmental and chemical measurements (e.g AMS, NOx, SO2, SMPS, VOC) to help derive sources and sinks and to constrain the mechanisms responsible for the formation and growth of organic aerosol. Measurements obtained across a wide range of conditions and locations allowing connections and contrasts between different chemical systems, providing insights into generally controlling factors of secondary organic aerosol (SOA) and its properties.

Author: Courtney Leigh Herring
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Atmospheric aerosols impact human health, climate, and air pollution and arrive in the atmosphere by countless number of sources. One of the largest uncertainties in understanding these impacts is due to limitations in our understanding of the organic aerosol (OA) components. To understand this complex mixture of thousands of compounds accurate high-resolution chemical speciation is needed. An Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer (HR-ToF-AMS or HR-AMS) was deployed in two separate month-long studies to measure atmospheric particulate pollution. The first study, at the Lovelace Respiratory Research Institute (LRRI), focused on the measurement of gasoline and diesel engine exhaust under various loads and dilutions in controlled chamber experiments. HR-AMS data demonstrated clean signal associated with 53 polycyclic aromatic hydrocarbon (PAH) compounds. PAHs are of interest due to their carcinogenic implication and negative health effects especially when associated with submicron particles. From this work a novel methodology was developed for quantifying these compounds by their molecular ion signal (P-MIP). In the second study, conducted in Yakima, WA, ambient wintertime pollution was characterized and the OA components were deconvolved using positive matrix factorization (PMF). This investigation resulted in the identification of two new amine associated factors which were identified by mass spectra peaks from six dominant amine ions (C3H8N+, C2H6N2+, C4H 10N+, C3H8N2 +, C5H12N+, and C6H 14N+). Amine ions are of interest to atmospheric research because of their implications on climate and formation of new particles. The unifying implication from both studies was the utilization of the HR-AMS to identify atmospheric pollutants that continue to generate ongoing research interests (due to their impacts on climate, pollution, or human health) and are typically difficult to measure by the HR-AMS. Additionally, included in this dissertation are four examples of science/engineering related inquiry-based lessons that were developed to relate well with my own Master's research field and implemented into three high school science and math classrooms over the course of a two year NSF STEM Fellowship. Lastly, a two-year long case study following qualitative and quantitative data from 296 students one of these activities provides examples of the positive impact by these types of developed activities.

Author: Quentin Gerald James Malloy
Publisher:
ISBN:
Category : Aerosols
Languages : en
Pages : 414

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Author: Rachel Elizabeth Sellon
Publisher:
ISBN:
Category :
Languages : en
Pages : 274

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Atmospheric aerosols can affect visibility and the Earth's climate by scattering and absorbing light and they also can have adverse effects on human health. The organic portion of atmospheric aerosols is very complex and is a major fraction of fine particulate matter. High molecular weight (high-MW)/oligomeric organic compounds can make up a large part of this organic fraction and the composition, sources, and formation mechanisms for these compounds are not well understood. This knowledge and understanding is necessary to decrease the uncertainty in the climate affects of aerosols and to improve climate models. This dissertation investigates the composition and formation mechanisms for the high-MW/oligomeric fraction of secondary organic aerosols (SOA) collected in Bakersfield, CA and presents a comparative analysis of chamber and ambient SOA, from both Los Angeles (LA) and Bakersfield, to investigate sources at both locations. A novel sampling technique, nanospray-Desorption Electrospray Ionization (nano-DESI), was used with high resolution mass spectrometry (HR-MS) to determine the molecular formulas of the high molecular weight (HMW)/oligomeric fraction of SOA. Nano-DESI involves direct desorption from the sample surface and was used to limit reactions that can take place with extraction and storage in solvent. The samples were collected in Bakersfield and LA during CalNex 2010. Both Bakersfield and LA are out of compliance with EPA standards of ozone and particulate matter and provide opportunities to examine air masses affected by both anthropogenic and biogenic sources. This dissertation has provided the first evidence of observable changes in the composition of high-MW/oligomeric compounds throughout the day. Using positive mode nano-DESI, afternoon increases in the number of compounds that contain carbon, hydrogen and oxygen (CHO) were observed consistent with photochemistry/ozonolysis as a major source for these compounds. Compounds containing reduced nitrogen groups were dominant at night and had precursors consistent with imine formation products from the reaction of carbonyls and ammonia. In the negative mode, organonitrates (CHON) and nitroxy organosulfates (CHONS) had larger numbers of compounds in the night/morning samples consistent with nitrate radical formation reactions. A subset of the CHONS compounds and compounds containing sulfur (CHOS) had the same composition as known biogenic organosulfates and nitroxy organosulfates indicating contributions from both biogenic and anthropogenic sources to the SOA. This dissertation also provides the first analysis of the high-MW/oligomeric fraction in size resolved samples; the majority of the compounds were found in aerosol diameters between 0.18-1.0 micrometers and the CHON were bimodal with size. Finally, this dissertation presents the first comparative analysis of the overlap in the composition of this fraction of SOA between ambient and chamber samples. Samples collected in Pasadena, LA and Bakersfield were compared with samples collected in a smog chamber using diesel and isoprene sources. The results indicate that diesel had the highest overlap at both sites, Bakersfield samples were more oxidized, and LA showed evidence of a SOA plume arriving from downtown LA. The addition of ammonia to the diesel chamber experiment was necessary to form many of the 2N compounds found in Bakersfield. These results increase our understanding of the types of compounds found in urban environments and give evidence for the timescales of formation reactions in an ambient environment. They show that the majority of the high-MW oligomeric compounds are found in submicron size particles and that the composition of this fraction of SOA varies with aerosol size. Results from the chamber comparisons show that both diesel and isoprene are important sources for these compounds and also that there other sources are present. Future work that combines this type of analysis, in other ambient environments, with studies of the optical properties of aerosols could be used to help improve climate models and to start to close the gap in our understanding of the climate effects of atmospheric aerosols.

Author: Fred Warren McLafferty (Chemiker, USA)
Publisher:
ISBN: 9780805370485
Category : Mass spectrometry
Languages : en
Pages : 278

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Author: Manousos-Ioannis Manousakas
Publisher: MDPI
ISBN: 303650995X
Category : Science
Languages : en
Pages : 246

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Research related to ambient particulate matter (PM) remains very relevant today due to the adverse effects that PM have on human health. PM are pollutants with varying chemical compositions and may originate from multiple emission sources, which directly affects their toxicity. To formulate effective control and mitigation strategies, it is necessary to identify PM sources and to estimate their influence on ambient PM concentration, a process that is known as source apportionment (SA). Depending on the geographical location and characteristics of an area, many anthropogenic and natural sources may contribute to PM concentration levels, such as dust resuspension, sea salt, traffic, secondary aerosol formation, industrial emissions, ship emissions, biomass burning, power plant emissions, etc. Different methodological approaches have been used over the years to study the aforementioned topics, but some scientific challenges remain, mainly related to the following subjects: real-time chemical analysis and SA, uncertainty estimation of SA results, and analytical optimization for PM samples. Additionally, there are areas in the world for which the results regarding composition and sources of PM are still scarce. The objective of this collection was to include studies on all aspects of PM chemical characterization and source apportionment regarding the inorganic and/or organic fractions of PM.