Portland State University. Department of Environmental Science and Management
Erik J. Sánchez
Date of Award
Doctor of Philosophy (Ph.D.) in Environmental Sciences and Resources
Environmental Sciences and Resources
1 online resource (xiii, 223 pages)
Thin films -- Surfaces -- Analysis, Microbial ecology, Metallic films, Surface chemistry
The air-water interface is an important natural boundary layer that has been neglected as an area of environmental field research. This study establishes that comparative microscopy can be an effective environmental method, and establishes that the term metallic surface films, is a more accurate descriptor than iron oxide surface films. This research shows that surface films are complex, often with layered structure, serve as habitat for significant biota, and act as a point of mineralization to several transition metal elements including manganese, iron, copper, nickel and zinc. This study demonstrates that surface films form under several conditions and can have diverse morphology. Activity of biota, microbes, particularly diatoms, suggests that bacteria and cyanobacteria integrate into the film often in patches, represented by forms and casts. Analytical imaging is used to document and compare film morphology and structures, using scanning electron microscopy, photoemission electron microscopy and transmission electron microscopy with elemental analysis by energy dispersive spectroscopy to confirm the hypothesis. Instrument parameters and strengths are reviewed. Component layers of a copper/zinc film were used to confirm metallic layers and elemental distribution. Bacterial casts were used to confirm film interaction, and to show entrainment and enrichment of the film to incorporate autochthonous and allochthonous materials into the films themselves. Most samples were from Oregon selected sites, with some samples from Maryland and Barbados.
Smith, Randall William, "Investigations of the Air-Water Interface: A Structural Analysis of Metallic Surface Films and Aquatic Surface Films by Comparative Microscopy" (2015). Dissertations and Theses. Paper 2306.