Overarching Research Interests

We study the fate of organic chemicals in the environment. Specifically, we are interested in transformation reactions of anthropogenic chemicals, how they can be precursors to other toxic contaminants, and how environmental reactions can enable long-range transport to remote regions. Our interests are driven by persistence, bioaccumulation potential and toxicity. Thus, some of the contaminants we are currently studying include per- and polyfluoroalkyl substances (PFAS), pesticides, pharmaceuticals, and plastic additives. Systems we are interested in include aquatic photochemistry, atmospheric chemistry (including indoors) and biotransformation, and we are interested in how climate change alters chemical usage patterns and transport.

Additionally, understanding reactivity in the environment can be used by synthetic chemists to design chemicals that retain functionality for the required applications, but are not transformed to harmful chemicals in the environment after their desired usage, which is how our work ties into Green Chemistry.

Environmental chemistry of PFAS

Per- and polyfluoroalkyl substances (PFAS) are a class of ubiquitous environmental contaminants that are concerning due to the persistence, bioaccumulation, and toxicity of some of their most studied analogues. We are interested in understudied sources of PFAS, including characterizing how chemical reactions can liberate small molecule PFAS from side-chain fluoropolymers used as surface protectants on textiles. We are also studying how fluoropolymers can be sources of small molecule PFAS from synthetic residuals or chemical ageing of the polymers. Overall, this allows us to better understand how humans and ecosystems are exposed to these harmful chemicals.

Funding: Environment and Climate Change Canada’s Chemical Management Plan and the University of Alberta Faculty of Science

Sources and fate of trifluoroacetic acid (TFA)

TFA is the smallest and most ubiquitous PFAS that has been detected in all compartments of the environment in rapidly increasing concentrations. Unlike most larger PFAS, TFA is rarely used directly – instead, it is formed in the environment as a transformation product of other fluorine-containing chemicals including refrigerants, anaesthetics, and fluoropolymers. While some chemical industry producers argue TFA has a large natural source based on the high unaccounted for environmental concentrations, there is no direct evidence this is true. Our research aims to understand the fate and transport of TFA, including identifying additional sources to close the gap of the TFA that is accounted for in the environment. An understudied source of TFA are agrochemicals and pharmaceuticals containing aromatic groups with CF3 substitutions (aryl-CF3).

Collaborators: Rylan Lundgren (UofA Chemistry)

Funding: Future Energy Systems (Canada First Research Excellence Fund) and NSERC Discovery Grant

TOC art from Insufficient evidence for the existence of natural trifluoroacetic acid: Joudan, De Silva, Young, ESPI, 2021.

Chemical contaminants in the Arctic

The Canadian Arctic receives contaminants from both long-range transport from lower latitudes and from local point sources. The region is impacted by climate change and changes in human activities including increased shipping. Through a series of collaborative projects, we are investigating the presence of contaminants in Nunavut, including in Frobisher Bay, Baker Lake, and the Canadian High Arctic Research Station (CHARS) in Cambridge Bay.         

Collaborators: Tamzin Blewett (UofA Biological Sciences), James Harynuk (UofA Chemistry), Ken Jeffries (University of Manitoba), Mark Hanson (University of Manitoba)

Funding: Fisheries and Oceans Canada (DFO)