Microplastic pollution in the estuarine and river environment of the River Thames, UK

Microplastic pollution is ubiquitous globally and is considered a leading threat to ecosystems. As microplastic studies increase, key areas remain understudied, such as rivers, with new areas and sources of microplastics still being discovered. The overall aim of this thesis is to investigate the abundance of microplastics within the tidal river Thames, UK and identify potential sources of microplastics. In this thesis, I assess the current literature on microplastics, identify potential research gaps within current known knowledge, and show the range of laboratory methods used in studies worldwide to identify and quantify microplastic abundance within the environment. Through surface water samples collected along the river Thames from May 2019 -May 2021, I demonstrate that microplastics are present within the river Thames and vary between sites and samples, as well as identifying potential sources. I highlight how seasonality and rainfall impact microplastic abundance within this river system.
During this study, the Covid -19 pandemic occurred, proving a unique sampling opportunity. As a result, this thesis acknowledges that this pandemic may have impacted microplastic abundance and provides valuable information on the short-term impacts of the pandemic on microplastic within this time. Finally, I highlight the effects of the New Year fireworks displays on microplastic abundance within water samples collected from the river Thames at Westminster. This data is novel as it had not previously been noted or identified when this study was published. The data and results presented within this thesis provide valuable information on the abundance, possible sources and accumulation of microplastics along the river Thames that can be used as a baseline for future studies. This data and results can also be used by stakeholders such as the Environment Agency, Thames Water and non-profit organisations to inform possible decisions on the removal of microplastic pollution from the river.