Intrinsic to the many nano-enabled products are atomic-size multifunctional engineered nanomaterials, which upon release contaminate the environments, raising considerable health and safety concerns. This Ph.D. dissertation is designed to investigate (i) whether metals or oxide nanoparticles are more toxic than ions, and if MetPLATETM bioassay is applicable as a rapid nanotoxicity screening tool; (ii) how variable water chemistry (dissolved organic carbon (DOC), pH, and hardness) and organic compounds (cysteine, humic acid, and trolox) modulate colloidal stability, ion release, and aquatic toxicity of silver nanoparticles (AgNP); and (iii) the developmental responses of crop plants exposed to Ag- or ZnO- (zinc oxide) nanoparticles. Results suggest that the MetPLATEcan be considered a high-throughput screening tool for rapid nanotoxicity evaluation. Detectable changes in the colloidal diameter, surface charge, and plasmonic resonance revealed modulating effects of variable water chemistry and organic ligands on the particle stability, dissolution, and toxicity of AgNPs against Escherichia coli or Daphnia magna. Silver dissolution increased as a function of DOC concentrations but decreased with increasing hardness, pH, cysteine, or trolox levels. Notably, the dissociated Ag+ was inadequate to explain AgNP toxicity, and that the combined effect of AgNPs and dissolved Ag+ under each ligand treatment was lower than of AgNO3. Significant attenuation by trolox signifies an oxidative stress-mediated AgNP toxicity; its inability to attenuate AgNO3 toxicity, however, negates oxidative stress as Ag+ toxicity mechanism, and that cysteine could effectively quench free Ag+ to alleviate AgNO3 toxicity in D. magna. Surprisingly, DOC-AgNPs complex that apparently formed at higher DOC levels might have led daphnids filter-feed on aggregates, potentially elevating internal dose, and thus higher mortality. Maize root anatomy showed differential alterations upon exposure to AgNPs, ZnONPs, or their ions. Overall, various metal-based nanoparticles revealed lower toxicity than their ions against multiple organisms. This study showed that particle size, surface properties, and ion release kinetics of AgNPs modify following release into aquatic environment, suggesting potential implications to ecosystem health and functions, and that caution be applied when extending one species toxicity results to another because obvious differences in organism biology—supporting species sensitivity paradigm—can significantly alter nanoparticle or ionic toxicity.

This report focuses on using the Papathoma Tsunami Vulnerability Assessment Model (PTVA) to demonstrate the vulnerability of Cayucos to a 500-year tsunami, and using the results to inform specific planning recommendations. By modeling inundation with GIS and analyzing building attributes via the PTVA model, this study has gone beyond any previous vulnerability assessments of Cayucos. Findings include: delineation of the most vulnerable areas, estimates of numbers of lost civic buildings, commercial buildings and houses, as well as estimates of people displaced from tsunami damaged homes. The report goes on to discuss what mitigation measures are in place and what further specific steps could be taken to ensure the long term sustainability of the town and help reduce future tsunami losses. Cayucos is a small coastal town in San Luis Obispo County, California; popular with tourists and locals for its beach, pier, and downtown. Intense coastal development and low lying topography makes Cayucos among the most tsunami vulnerable communities in the county. Many civic and economically important buildings, as well as homes, are within the 500-year tsunami inundation area. In the absence of fully developed, and accessible assessment tools like FEMA’s HAZUS tsunami program; local planners have had only basic information to assess the community’s tsunami vulnerability. The Papathoma Tsunami Vulnerability Assessment Model (PTVA) is a method that uses available tsunami runup estimations and field data collection to produce a detailed assessment of individual building survivability and overall community vulnerability.

Landslides are a massive problem within the Appalachians causing large amounts of damage, and even loss of life. Urban development on the hill slope further destabilizes slope and accelerates failure. The objective of this project is to examine the slope stability condition at an urban community in eastern Tennessee and assess the relative risk in the area. The first step included a digital survey of the area by collecting all available soil, geology, elevation, watershed, slope, drainage condition, stream, and building footprint data. This data was collected from a multitude of sources including but not limited to the United States Geological Survey (USGS), Environmental Systems Research Institute (ESRI) and Tennessee State Government resources. After this a process of field verification was required to confirm the validity of acquired digital data. This field verification process included four separate trips that aimed to access the extent of damage, slope condition, bedrock geology, and soil information. The data collected from the previous digital survey and field verification trips were used to prepare a landslide hazard prediction map using Weighted Overlay method in ArcGIS Pro software. To validate the accuracy of the hazard map, an unmanned aircraft system (UAS) drone survey will be completed in April 2023. A final Slope Stability Hazard Map will be produced for the urban community and the report will be shared with the community members. The result indicated that both the soil and geology reports were spatially inaccurate as the entirety of urban development was constructed on Sevier Shale Formation, whereas Knox Formation appears on the map. The slope and hill shade information were correct including the identification of a road that was uncompleted that undercut a steep slope. After our first survey the maps were combined and weighted in a “Weighted Overlay map” with slope, curvature, and stream data to make a map that showed likely areas of risk. The study area contains multiple areas with high slope instability risk. These areas are steep slopes as high as 51° and weathered shale with a lack of vegetation that has been undercut by a roadway that was unfinished. Other areas of high concern with clear evidence of slope sliding are present with the movement of supportive foundation beams. Signs of cracking and sliding have been spotted within the road leading to some of the housing complexes. This information will then be compared to a UAS drone survey to create a final Slope Stability Hazard Map. The urban community can plant vegetation, divert storm water, keep the slope dry, and reduce overburden pressure on the slopes to reduce further movement. Costly engineering structures like slope anchors, soil nails, and retaining walls are possible solutions and could help to support the steep and overburdened slopes.

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