The data presented in this thesis highlights how sea water composition and biological activity can affect the morphology, composition, organic volume fraction, and hygroscopicity of individual sea spray aerosols (SSA). A variety of techniques were used to measure seawater and aerosol composition with the emphasis placed on spatial chemical composition obtained through Scanning Transmission X-ray Microscopy-Near Edge X-ray Absorption Fine Structure (STXM-NEXAFS). Through NEXAFS data, organic volume fractions were derived from Beer's Law, and spatially resolved chemical composition for individual particles were determined through application of singular value decomposition and principal component analysis. These methods were applied to two specific studies: a 30 day mesocosm study using a wave flume termed Investigation into Marine PArticle Chemistry and Transfer Science (IMPACTS) and a smaller scale collection of SSA generated from a miniature Marine Aerosol Reference Tank (mini-MART) with bacteria enriched sea water. For IMPACTS, two consecutive phytoplankton blooms were observed; however, organic enrichment in sea spray aerosols only occurred during one of the blooms. STXM-NEXAFS measurements revealed four distinct particle types: sea salt-organic particles with a distinct NaCl core and an organic carbon coating, homogenously mixed organic-inorganic particles, calcium-rich needle-like particles, and agglomerations of optically thick organic material with inorganic salts. Organic enrichment was correlated with aliphatic-rich organic species as detected by an intense Cls—•a(C-H)* exciton excitation. This enrichment was unique to particles collected in the aerodynamic size range 0.18-0.32 µm and corresponded with a depression in the hygroscopicity of small particles. This depression can significantly suppress the number of cloud condensation nuclei thus influencing cloud properties. Results of the mini-MART collection revealed that whole bacterial inclusions are ejected into SSA via jet drops. Bacterial inclusions are rich in protein and can be identified through Principal Component Analysis (PCA) on image stacks acquired at the carbon K edge. Vesicles were not identified in SSA but could be resolved in standard liquid cell samples in which they exhibited a strong phospholipid spectrum that could also be resolved spatially usually PCA coupled with k-means clustering. Bacterial inclusions in SSA may affect SSA physical properties by serving as ice nuclei.1,2,3
| Identifer | oai:union.ndltd.org:pacific.edu/oai:scholarlycommons.pacific.edu:uop_etds-5024 |
| Date | 01 January 2016 |
| Creators | Pham, Don Q. |
| Publisher | Scholarly Commons |
| Source Sets | University of the Pacific |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | University of the Pacific Theses and Dissertations |
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