Thesis (M. S.)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2006. / Dickinson, Robert, Committee Chair ; Fu, Rong, Committee Co-Chair ; Yu, Hongbin, Committee Member.

Atmospheric aerosols are a major contributor to the total energy balance of the Earth's atmosphere. The exact effect of these aerosols on global climate is not well understood, due to poorly-characterized compositional variation that takes place over a given aerosol's lifetime. Organic aerosol (OA) species are of particular interest, forming through a myriad of gas- and aerosol-phase mechanisms and contributing to aerosol light absorbance, cloud formation properties, and overall particle lifetime. As different organic species will affect physical properties in different ways, proper prediction of these compounds forming in the aerosol phase is necessary to estimate the net physical properties of aerosols, and subsequently their effects on overall global climate. Several previous models exist that attempt to predict organic components of aqueous-phase mass in aerosols, with varying degrees of scope of chemistry and range of applicability. Many of such simulations emphasize OA formation via oxidation of gas-phase organic species that results in low-volatility compounds that subsequently partition into aerosols. Other models focus on aqueous-phase processing of semi-volatile and non-volatile water-soluble organic compounds (WSOC's) under cloud water conditions. However, aqueous reactions that occur in atmospheric, deliquesced salt aerosols have recently also been found to be potentially important additional pathway for the creation of additional aerosol-phase organic mass, contributing different products due to the significantly higher inorganic concentrations present under these conditions. It is desirable to incorporate these reactions into analogous predictive simulations, allowing for the chemistry taking place in small, deliquesced salt atmospheric aerosols to be more accurately represented. In this work, we discuss a new photochemical box model known as GAMMA, the Gas-Aerosol Model for Mechanism Analysis. GAMMA couples gas-phase organic chemistry with highly detailed aqueous-phase chemistry, yielding speciated predictions for dozens of secondary organic aqueous aerosol-phase compounds under various atmospheric and laboratory initial conditions. From these studies, we find that isoprene-derived epoxides (IEPOX) and their substitution products are predicted to dominate aqueous-phase organic aerosol mass in conditions with low NOx in the atmosphere, representative of rural environments. The contribution of these epoxide species is expected to be high under acidic conditions, though our findings still estimate significant contribution to aqueous-phase organic mass under higher pH or under cloudwater conditions, when acidity is expected to be lower. Under high-NOx conditions typical of urban environments, glyoxal is seen to form the majority of evolved aqueous organic species, with organic acids comprising the bulk of the difference. We then implement a series of physical property modules, designed to predict changes in aerosol absorbance and surface tension due to bulk concentrations of evolved OA species. Preliminary results from these modules indicate that bulk solution effects of aqueous-phase carbonyl-containing volatile organic compounds (CVOCs) and organic acids are insufficient to significantly affect net aerosol surface tension under any condition tested, implying that observed deviations from pure inorganic aerosol surface tension will arise from surface-aerosol partitioning rather than bulk compositional effects. Light absorption of aqueous aerosols is seen to be driven by dark glyoxal chemistry in deliquesced salt aerosols and organic acids in cloud droplets, though additional information about the absorbance properties of IEPOX and its derivatives is required to accurately predict the net absorbance of aerosols where these species dominate OA mass. The predictions as described by GAMMA are comparable to field observations, and give further credence to the significance of epoxide formation as a source of aqueous-phase organic aerosol mass. These results also suggest the relative importance of specific organic compounds in the aqueous phase of both deliquesced salt aerosols and cloud droplets in the atmosphere, which gives direction to the study of compounds whose impact on aerosol physical properties will matter the most. In turn, new kinetic and physical information can be directly applied into the groundwork laid here, allowing GAMMA to provide a continuously better understanding of the effect of organic material on aqueous aerosols and their implicit effect on the environment.

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Oceanography." Includes bibliographical references (p. 116-133).

Thesis (Ph. D.)--University of Canterbury, 2009. / Typescript (photocopy). "May 2009." Includes bibliographical references (p. 10/1-10/9). Also available via the World Wide Web.

Not available / text

The total concentrations of particulate trace metals (Al. Cd, Co, Cu, Fe. Mn, Na. Ni. Pb, Zn) with analytical quality assurance, have been determined in atmospheric aerosols at two coastal sites, and during cruises in the Celtic Sea. Sampling at a site on the western English Channel covered 19 months and represents one of the most comprehensive time series of trace metals in atmospheric aerosols. Aerosol concentrations of Cd. Cu, Pb and Zn for the English Channel were lower than previously reported and Al. Co and Mn concentrations were similar to literature values. The elements were grouped according to behaviour such that Group 1 elements (Cd, Fe. Mn, Pb and Zn) displayed enhanced concentrations in autumn/winter 1994 and 1995. whereas Group 2 elements (Al, Co, Cu, Na and Ni) had enhanced concentrations during winter 1995 only. This was ascribed to source functions being dependant on wind direction with Group 1 elements being carried mainly by north easterly air masses, whereas Group 2 elements originated mainly with air masses from the south west. Dissolved trace metal (Al, Co, Cu, Ni, Pb) analyses were carried out on rain waters collected at the English Channel site. The rain water analyses showed that the soluble trace metal fraction was in the order Co = Cu > Ni >Pb > Na » Al and wet and dry depositional fluxes accounted for the differential behaviour and the solubility of aerosol trace metals on contact with sea water. Aerosol concentrations are also reported for the north western Mediterranean and the Celtic Sea. In the former location, the aerosol trace metal concentrations were lower than those reported in literature and in the Celtic Sea there was a gradient in the trace metal composition of the aerosol from land to open sea. The solid state speciation of Cd and Pb gave an increasingly matrix-bound fraction in the order north western Mediterranean < western English Channel < Celtic Sea and the Celtic Sea aerosols had the greatest sea water solubilities of all elements, except Ni. Concentrations of Cu, Ni and Pb in English Channel aerosols, rain waters and the fraction partitioning from aerosols on contact with sea water, together with sea water concentrations from the literature, were used to devise a trace metal flux model for the English Channel. The model showed that of the total trace metal fluxes into the English Channel, the atmospheric fluxes were in the order of importance Pb > Cu > Ni. The overall budgets revealed discrepancies in the mass balances, which were identified as sediment-water exchange for Ni and Pb and adsorption onto particles for Cu. These budget calculations provide a basis for the development of more advanced modelling concepts involving coupled atmosphere-ocean interactions.

Thesis (Ph.D.)--York University, 2006. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 188-201). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19810

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references. Also available in electronic version.

Thesis (Ph.D.)--York University, 2006. Graduate Programme in Earth and Space Science. / Typescript. Includes bibliographical references (leaves 271-296). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:NR19790

Thesis (Ph.D.) OGI School of Science & Engineering at OHSU, March 2008. / Includes bibliographical references (leaves 98 - 99).