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Thesis Format

Monograph

Degree

Master of Science

Program

Chemistry

Supervisor

Sumarah, Mark W

Affiliation

Agriculture and Agri-Food Canada

2nd Supervisor

Yeung, Ken

Abstract

Human impact on the environment can be seen in the wide variety of chemicals that are found in our water and soil. Common contaminants arise from insufficient treatment in wastewater treatment plants (WWTPs), and runoff from agriculture. Surface water samples collected in 2017-2020 at 40 different sites in six different watersheds were analyzed to determine if the commonly targeted emerging substances of concern (ESOCs) are present in Ontario and Quebec waterways. The diabetes medication metformin was analyzed more closely alongside its degradation product guanylurea as they have become targets of increasing interest due to their common occurrences and new toxicological data on organisms. Sediment samples at the same sampling sites were also collected. This work is to our knowledge the first long term analysis of metformin and guanylurea in Ontario and Quebec and offers potentially valuable insight into where metformin and guanylurea partition and accumulate in waterways.

Biosolid samples from Ontario WWTPs were also analyzed for the presence of ESOCs to determine if treatment used to remove micropollutants and bacteria is also able to remove common chemical contaminants. Two extraction methods were assessed to determine their efficacy in extracting a wide variety of compounds. The concentrations of extracted compounds were also compared between the untreated biosolid cake and treated fertilizer to determine if a thermal hydrolysis process (THP) could degrade ESOCs. This work serves to validate a widespread biosolid analysis method for use in further ecotoxicological studies.

Summary for Lay Audience

We use a wide variety of chemicals in everyday life, whether for medicine, agriculture, or recreational use. Once we have used these chemicals, very few of them degrade and get removed from the ecosystem. In fact, many of them can be found in surface water and soil around the world. Some of these compounds are relatively harmless, while others can be toxic to plants and animals. Even more worryingly, there are many compounds that we have not detected yet, or whose effects we do not know. This makes it a priority in environmental contamination studies to have ways to identify these compounds, and to figure out how much is there. In this work, we use methods to detect these compounds and determine how much is present at various sites in Canada. By doing this, we can ensure that chemicals that are present in high amounts can be regulated to manage their risk. Also, because our samples come from between 2017-2020, we can determine if the amount of chemicals have been increasing in the environment and figure out which compounds are most important to restrict.

To investigate environmental contamination, we examine water, sediment, and biosolids. The water and sediment samples come from rivers, lakes, and streams around Canada, and each site we look at has different things nearby. For example, a sample taken from a river going through a city should contain different compounds than a sample from a river going through farmland. We can identify those compounds in water and sediment to make sure there is nothing toxic or dangerous present. Biosolids are the solid waste produced by humans after it has been treated in a wastewater treatment plant. This waste can be cleaned up and used as fertilizer, but we need to make sure that any harmful chemicals that may have been in the human waste have been removed, otherwise it may impact the farmland it is applied to. These types of samples are all important to investigate to make sure that we are not damaging our environment in any way.

Creative Commons License

Creative Commons Attribution-Noncommercial 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

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