Thesis
Evaluation of Extracellular Genetic Material Sorption to Microplastics and Environmental Porous Media
Washington State University
Master of Science (MS), Washington State University
2023
DOI:
https://doi.org/10.7273/000005207
Abstract
The spread of antibiotic resistance genes (ARGs) and silencing RNAs (siRNAs) in the environment has increased for several decades and represents a growing threat to public health and the environment. While significant research has assessed the biological factors driving ARGs and siRNAs, few studies have evaluated how emerging contaminants like microplastics (MPs) can accelerate their spread. MPs are ubiquitous in wastewater treatment plants and can adsorb diverse compounds, which may be transported to aquatic environments in treated effluents and to soils in biosolids. Understanding how ARGs and siRNAs are carried on MPs requires characterizing MPs’ diversity and abundance in sewage sludge and treated effluents. The main purpose of this research is to determine MP adsorption capacity for extracellular ARGs and siRNAs using adsorption isotherms and the identification of sorbent physicochemical properties. The adsorption isotherm assays were evaluated on biosolids, soils, and MPs with DNA and RNA as adsorbate material. The data were analyzed by the Langmuir and Freundlich adsorption isotherms and the best-fitting model was selected with the highest R2 obtained from the linearization. For this study, the best fitting model was the Freundlich which was applied to calculate the adsorption capacity between the adsorbent material (e.g., biosolids, soils, and MPs) and the adsorbate material (e.g., DNA and RNA). The higher adsorption of DNA and RNA into the adsorbent porous media was statically significant (P < .001) showing a higher adsorption capacity in biosolids > soils > MPs. The adsorption mechanisms for the porous media studied in this research are the hydrophobic interactions, van der Waals, electrostatic interactions, H-bonding, and π-π interactions. MPs’ adsorption capacity may be attributed to the small particle size ranging from 143.8 nm to 600 nm and the presence of numerous pore sites, observed throughout a Scanning Electron Microscope, which increased their surface area allowing them to adsorb more genetic material from the environment.
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Details
- Title
- Evaluation of Extracellular Genetic Material Sorption to Microplastics and Environmental Porous Media
- Creators
- Ana Isabel Granja Villacis
- Contributors
- Courtney Gardner (Advisor)Indranil Chowdhury (Committee Member)Amanda Hohner (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Civil and Environmental Engineering, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 133
- Identifiers
- 99901019231701842
- Language
- English
- Resource Type
- Thesis