Analytical Methods for Understanding Sources and Fate Processes of Emerging Environmental Contaminants

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The presence of chemical pollutants in the environment is of great concern to many people today. Knowledge of how physical and chemical processes influence pollutant concentrations in the environment is necessary to accurately determine sources of pollutants and for controlling their potential risks to humans and ecosystems. Of particularly concern to the Canadian environment are petroleum carboxylic acids (often referred to as naphthenic acids). These compounds are naturally present in bitumen and may enter the environment through the erosion of exposed bitumen outcrops. However, oil sands process-affected water (OSPW) contains high concentrations of these chemicals, which have been identified as the main driver of chemical toxicity in OSPW. Their detection in surface waters raises concerns about potential human sources and adverse effects on ecosystems. Petroleum carboxylic acids exist as a complex mixture of chemicals, which makes identification of individual components difficult. This, in turn, hampers understanding of potential sources and risks posed by these chemicals.*** We will address this knowledge gap by first reducing the complexity of the mixture by separating components based on chemical properties. Small and less complex portions of the mixture will be collected individually and the petroleum carboxylic acids in each will be converted to hydrocarbons. This conversion will to permit analysis using common instrumentation available in most laboratories. Additionally, by converting the petroleum carboxylic acids to hydrocarbons, well-understood and widely used methods developed for petroleum analysis can be used to characterize and identify components of the mixture-knowledge that will significantly increase understanding of its chemical composition.*** The developed method will be applied to understand sources and fate of petroleum carboxylic acids to the environment. Chemical fingerprints of petroleum carboxylic acids in surface water from sites not impacted by mining operations will be compared to potentially impacted sites to delineate natural and human sources of these compounds. We will also apply this new method to understand how chemical processes, such as photolysis, alter the chemical composition and impact concentrations of petroleum carboxylic acids in the environment. *** This research program will contribute new and necessary knowledge to our understanding of the chemical composition of petroleum carboxylic acids and their sources to the environment. This knowledge will be of importance for future assessments of risks posed by oil sands mining operations and petroleum spills, and ultimately play a significant role in protecting and remediating our ecosystems. **