The aims of this dissertation are to better understand the sources of aerosol particles reaching coastal Antarctica, and the processes that control aerosol deposition to the snow surface and inclusion into the ice. Daily collections of aerosol particles and surface snow samples were made from British Antarctic Survey base, Halley. Aerosol and snow sea salt were found to have maximum concentrations during the austral winter and non sea salt sulphate and methane sulphonic acid concentrations peaked during the summer, confirming previous work by other authors. These species were compared with local meterological events (such as wind speed and direction) to identify a source for particularly high concentration events. Winter sea salt was found to have a local source, consisting probably of concentrated brine pools on surfaces of freshly formed sea ice and needle-like structures, known as frost flowers, which form from the pools. The sea salt component of these high events was also found to be fractionated, with a deficit of sodium sulphate (mirabilite). Methane sulphonic acid and nonsea salt sulphate did not appear to have a local source. Instead, using back trajectories of air mass origins to identify a longer range aerosol source, high concentration events were associated with the air mass having passed over an area of open water several days before reaching Halley. The processes of aerosol deposition to the snow surface were then quantified. Dry, fog and wet deposition, sublimation, wind pumping, blowing and drifting snow were examined experimentally and theoretically. For this coastal Antarctic location, wet deposition was found to be highly dominant (80%). Dry deposition accounted for about 10% and drifting and blowing snow were found to be important in determining whether a snowfall event remained recorded in the accumulated snow record, and ultimately in any ice core. This thesis has suggested that for sea salt, methane sulphonic acid (MSA) and non sea salt sulphate, there may be an alternate way of interpreting concentrations of these species in coastal Antarctic ice cores. Rather than an indication of increased storminess and long range transport, high loadings of sea salt could actually give information on the extent of new, fresh sea ice and could therefore be used to infer the local temperature, sea ice extent and possible wind direction at the time of core formation. Elevated MSA and non sea salt sulphate concentrations in ice cores could also give us information on the extent of open water and not simply an increase in marine biogenic activity and DMS emissions.

This study uses airborne data from multiple field campaigns off the California coast to determine the extent to which a size distribution parameter and a cloud water chemical measurement can capture the effect of giant cloud condensation nuclei (GCCN), specifically sea salt, on marine stratocumulus cloud properties. The two GCCN proxy variables, near-surface particle number concentration for diameters >5 mu m and cloud water chloride concentration, are significantly correlated (95% confidence) with each other, and both exhibit expected relationships with other parameters (e.g., surface wind) that typically coincide with sea salt emissions. Factors influencing the relationship between these two GCCN proxy measurements include precipitation rate (R) and the standard deviation of the subcloud vertical velocity owing likely to scavenging effects and improved mixing/transport of sea salt to cloud base, respectively. When comparing 12 pairs of high and low chloride cloud cases (at fixed liquid water path and cloud drop number concentration), the average drop spectra for high chloride cases exhibit enhanced drop number at diameters exceeding 20 mu m, especially above 30 mu m. In addition, high chloride cases coincide with enhanced mean columnar R and negative values of precipitation susceptibility. The difference in drop effective radius between high and low chloride conditions decreases with height in cloud, suggesting that some GCCN-produced raindrops precipitate before reaching cloud tops. The sign of cloud responses (i.e., R) to perturbations in giant sea salt particle concentration, as evaluated from Modern Era Retrospective Analysis for Research and Applications version 2 reanalysis data, is consistent with the aircraft data.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 112-118).

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [133]-142).

Marine stratocumulus clouds often become decoupled from the vertical layer immediately above the ocean surface. This study contrasts cloud chemical composition between coupled and decoupled marine stratocumulus clouds for dissolved nonwater substances. Cloud water and droplet residual particle composition were measured in clouds off the California coast during three airborne experiments in July-August of separate years (Eastern Pacific Emitted Aerosol Cloud Experiment 2011, Nucleation in California Experiment 2013, and Biological and Oceanic Atmospheric Study 2015). Decoupled clouds exhibited significantly lower air-equivalent mass concentrations in both cloud water and droplet residual particles, consistent with reduced cloud droplet number concentration and subcloud aerosol (D-p>100nm) number concentration, owing to detachment from surface sources. Nonrefractory submicrometer aerosol measurements show that coupled clouds exhibit higher sulfate mass fractions in droplet residual particles, owing to more abundant precursor emissions from the ocean and ships. Consequently, decoupled clouds exhibited higher mass fractions of organics, nitrate, and ammonium in droplet residual particles, owing to effects of long-range transport from more distant sources. Sodium and chloride dominated in terms of air-equivalent concentration in cloud water for coupled clouds, and their mass fractions and concentrations exceeded those in decoupled clouds. Conversely, with the exception of sea-salt constituents (e.g., Cl, Na, Mg, and K), cloud water mass fractions of all species examined were higher in decoupled clouds relative to coupled clouds. Satellite and Navy Aerosol Analysis and Prediction System-based reanalysis data are compared with each other, and the airborne data to conclude that limitations in resolving boundary layer processes in a global model prevent it from accurately quantifying observed differences between coupled and decoupled cloud composition.

Fine and coarse particles were collected for eight weeks during the summer of 1991, at a coastal site (Yaquina Head) and a non-industrial site (Corvallis) in Western Oregon to characterize the aerosol composition and evaluate whether the sites are appropriate for sampling "background" marine air. Concentrations of up to 11 species (S0₄²⁻, NO₃⁻, Cl⁻, Na, Fe, Ni, Pb, Cr, Co, Sb, and CH₃SO₃H) for 95 samples were determined using four chemical analysis techniques. The influences of seasalt and soil dust were identified by analyzing concentrations of Na and Fe in the aerosol samples. Relative elemental composition in fine and coarse fractions indicated that the aerosol composition at Yaquina Head was greatly affected by seasalt. "Seasalt" enrichment factors (relative to Na) indicated that seasalt is the only source of Cl⁻ and SO₄²⁻ in coarse particles at Yaquina Head. In contrast, the seasalt influence was relatively weak at the Corvallis site. "Crustal" enrichment factors suggested that soil dust was not a major source of Na⁺, Cl⁻, or S0₄²⁻ at either site. A simple conceptual model that relies on meteorological conditions was used to identify sampling periods with long range transport from either marine or continental areas as well as local influences. This model suggested that during 61% of the experiment period the aerosols were advected from marine areas. At Yaquina Head, 52% of the sampling periods are associated with the "clean" background air (marine air with no local influences). Thus, Yaquina Head represents a useful location for collecting marine background air from the Pacific Ocean. The chemical composition of the marine background air collected at the Yaquina Head site is similar to that for other remote sites around the world. At Corvallis, "clean" marine background air can occasionally (21%) be collected even though Corvallis is located 64 km from the ocean. / Graduation date: 1993

Particulate nitrates play important roles in the atmosphere. They consist mainly of NH4NO3 and NaNO3, products from the reactions of gaseous HNO3 with gaseous NH3 and sea salt, respectively. The gas-to-particle phase conversion of nitrate changes its deposition characteristics and ultimately changes the transport and deposition rates of the locally produced species. Studies were conducted to develop background information on the particle concentrations and size distributions and the chemistry and kinetics behind the interactions. The predominant nitrate species in the Tampa Bay area was identified as coarse mode NaNO3. NH4NO3 was not detected as it has high volatility at ambient temperatures. Spatial distribution sampling determined a gradient of NaCl and NaNO3 with increased distance from the coastal shore and an increase in the gas-to-particle conversion of nitric acid along a predominant air mass trajectory. The EQUISOLV II thermodynamic equilibrium model was evaluated. It was determined that the model can be used to predict gas and size-distributed particulate matter concentrations. The model was also used to examine the gas-to-particle partitioning of nitric acid to nitrate by NaCl and CaCO3. Both sodium and calcium partitioned nitrate to the particle phase. The magnitude of the partitioning was directly dependent on the equilibrium coefficients. The fine mode percentage of the total nitrate was determined using two methods. The results were used to expand the current data set to account for the coarse mode nitrate, and they indicated that particle nitrate accounted for 9% of the total nitrogen deposition flux to Tampa Bay. The formation of particle nitrate was examined using a nitrate accumulation model. Results indicated that the equilibrium time for particles less than 10 um in diameter was significantly less than their atmospheric residence time, with fastest conversion occurring under the highest relative humidity conditions. This information is vital in the development of atmospheric nitrogen dry deposition estimates, which are used to assess water quality and nutrient loading. These data can be used to determine air-monitoring strategies and to develop models that account for the coarse particle nitrogen species.

Antarctic ice cores preserve the record of past aerosols, an important proxy of past atmospheric chemistry. Here we present the aerosol compositions of sulphate and chloride particles in the Talos Dome (TD) ice core from the Holocene and Last Glacial Period. We find that the main salt types of both periods are NaCl, Na2SO4 and CaSO4, indicating that TD ice contains relatively abundant sea salt (NaCl) from marine primary particles. By evaluating the molar ratio of NaCl to Na2SO4, we show that about half of the sea salt does not undergo sulphatisation during late Holocene. Compared to in inland Antarctica, the lower sulphatisation rate at TD is probably due to relatively little contact between sea salt and sulphuric acid. This low contact rate can be related to a reduced time of reaction for marine-sourced aerosol before reaching TD and/or to a reduced post-depositional effect from the higher accumulation rate at TD. Many sulphate and chloride salts are adhered to silicate minerals. The ratio of sulphate-adhered mineral to particle mass and the corresponding ratio of chloride-adhered mineral both increase with increasing dust concentration. Also, the TD ice appears to contain Ca(NO3)(2) or CaCO3 particles, thus differing from aerosol compositions in inland Antarctica, and indicating the proximity of peripheral regions to marine aerosols. / <p>AuthorCount:9;</p>

Two studies on potential approaches for processing low-salt, low-fat (LSLF) bologna were completed. In study 1, the effects of three factors, namely salt type (sea salt vs. regular NaCl), NaCl concentration (0.75%, 1.00%, 1.25% and 2.00%) and holding of stuffed batter before cooking (cooked immediately (CI) vs. delayed cooking (DC)), on the quality of LSLF bologna were investigated. There was no difference between salt type for most of the parameters measured. The holding factor significantly improved the water holding capacity (WHC) and texture of bologna samples containing 0.75% NaCl, as shown by lower (p<0.05) expressible moisture. However, holding factor did not affect WHC and instrumental texture of samples with 1.00%, 1.25% or 2.00% NaCl. A NaCl level by hold effect (p<0.05) was observed for texture profile analysis (TPA) in which there was significant improvement in the texture of samples containing 0.75% NaCl that were subjected to DC, but no effect at other NaCl levels. Panelists were able to detect the positive effect (p<0.05) of DC on the texture of samples with 0.75% or 1.00% NaCl. This study showed that DC is effective in improving the texture of bologna samples with extremely low NaCl (0.75%) content. The biggest challenge in this first study was the difficult sample handling experienced during slicing. Since bologna is commonly sold as thin slices, the bologna must be firm enough for ease of slicing. The second study focused on improving bologna firmness by the addition of microbial transglutaminase (MTG), known for its functionality as a protein cross-linker, and of flaxseed meal (FSM), known for its excellent water holding capacity. The physico-chemical and sensory characteristics of 12 treatment combinations (0, 0.15% and 0.30% MTG; 0, 0.5%, 1.0% and 1.5% FSM) were determined. In general, results showed that MTG significantly improved the textural quality of bologna, but resulted in a higher purge loss during storage of vacuum packaged slices. On the other hand, FSM significantly reduced the expressible moisture content and purge loss of the product. In terms of product colour, MTG had no effect but FSM when added to the formulation at level as low as 0.5%, affected the colour as determined by both instrumental and sensory evaluation. The overall results of the project indicated that texture in LSLF bologna is not a major issue, since processing conditions and combinations of ingredients can be manipulated to improve texture. The biggest challenge, however, is in the area of flavour – improving the flavour of low-salt processed meats warrants further research.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 236 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Particulate nitrates play important roles in the atmosphere. They consist mainly of NH4NO3 and NaNO3, products from the reactions of gaseous HNO3 with gaseous NH3 and sea salt, respectively. The gas-to-particle phase conversion of nitrate changes its deposition characteristics and ultimately changes the transport and deposition rates of the locally produced species. Studies were conducted to develop background information on the particle concentrations and size distributions and the chemistry and kinetics behind the interactions. The predominant nitrate species in the Tampa Bay area was identified as coarse mode NaNO3. NH4NO3 was not detected as it has high volatility at ambient temperatures. Spatial distribution sampling determined a gradient of NaCl and NaNO3 with increased distance from the coastal shore and an increase in the gas-to-particle conversion of nitric acid along a predominant air mass trajectory. / ABSTRACT: The EQUISOLV II thermodynamic equilibrium model was evaluated. It was determined that the model can be used to predict gas and size-distributed particulate matter concentrations. The model was also used to examine the gas-to-particle partitioning of nitric acid to nitrate by NaCl and CaCO3. Both sodium and calcium partitioned nitrate to the particle phase. The magnitude of the partitioning was directly dependent on the equilibrium coefficients. The fine mode percentage of the total nitrate was determined using two methods. The results were used to expand the current data set to account for the coarse mode nitrate, and they indicated that particle nitrate accounted for 9% of the total nitrogen deposition flux to Tampa Bay. The formation of particle nitrate was examined using a nitrate accumulation model. / ABSTRACT: Results indicated that the equilibrium time for particles less than 10 um in diameter was significantly less than their atmospheric residence time, with fastest conversion occurring under the highest relative humidity conditions. This information is vital in the development of atmospheric nitrogen dry deposition estimates, which are used to assess water quality and nutrient loading. These data can be used to determine air-monitoring strategies and to develop models that account for the coarse particle nitrogen species. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.