- Title
- Characterisation and fate of microplastics in soils and their toxicity to the earthworms
- Creator
- Sobhani, Zahra
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2022
- Description
- Research Doctorate - Doctor of Philosophy (PhD)
- Description
- Small-sized particles such as microplastics are increasingly distributed in the environment. Microplastics are introduced into the terrestrial environment through irrigation of agricultural lands using wastewater or sludge as soil amendment. Microplastics have the potential to alter the geochemistry of the terrestrial environment and adversely affect the soil biota. The fate and toxicity of micro and nano-sized plastics are governed by their physicochemical properties such as concentration, size, shape, aging and polymer type, etc. Characterisation of microplastics in soil is a challenge due to the complexity of environmental background and limitation of the analytical techniques. The first part of this study focuses on the Raman spectroscopy technique to map different microplastics of polystyrene (PS), polyethylene terephthalate (PET), polyethylene (PE), polyvinyl chloride (PVC), and polypropylene (PP). During this study the microplastics were mapped first individually and then simultaneously together. The results confirmed that the Raman mapping is an effective technique to identify and visualise microplastics down to 1 μm from soil/sand background. This method minimized the sample preparation and the interferences from water/organic matter/fluorescence background signals which are the challenges faced especially during the analysis of environmental samples. The Raman spectroscopy methodology improved to enhance the method efficiency for identification and visualisation of microplastics as well as nanoplastics. Polystyrene nanoplastics with a diameter of 600, 300, and 100 nm were mapped. The second part of this study focuses on the fate and toxicity of microplastics on earthworms. For this purpose, we characterised microplastic pollution in different agricultural and urban soils and examined these soils for the presence of microplastics associated additives such as phthalates. The potential of polyvinyl chloride microplastics as a vector for perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in earthworms (Eisenia fetida) is demonstrated. This study confirmed the PVC MP induced enhanced uptake of PFOS and PFOA in earthworms and a significant reduction in their reproduction. This study also illustrates the adverse effect of different types of microplastics (polystyrene, polyethylene, polyvinyl chloride, and polyethylene terephthalate) in the form of pure and commercial on the earthworm (Eisenia fetida). To understand their long-term exposure, the earthworms have been incubated in soils with different concentrations of microplastic for 2 consecutive generations. Their acute toxicity and genotoxicity were evaluated after 28 days and 180 days for the parents (F0) and the first filial generation (F1), respectively. The results of this study demonstrate the adverse effect of the polystyrene microplastic on earthworm survival, DNA damage, and reproduction. Chemical analysis of microplastic‐exposed soils confirmed the presence of different chemicals.
- Subject
- microplastics; soils; toxicity; earthworms
- Identifier
- http://hdl.handle.net/1959.13/1484435
- Identifier
- uon:51332
- Rights
- Copyright 2022 Zahra Sobhani
- Language
- eng
- Full Text
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| Thumbnail | File | Description | Size | Format | |||
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| View Details Download | ATTACHMENT01 | Thesis | 8 MB | Adobe Acrobat PDF | View Details Download | ||
| View Details Download | ATTACHMENT02 | Abstract | 937 KB | Adobe Acrobat PDF | View Details Download |