A037-0009
The atmospheric deposition of Perfluoroalkyl Substances (PFAS ) in Canada across five (5) different latitudes.

Tuesday, 8 December 2020
Poster
Daniel Persaud1, Alison S Criscitiello2, Christine Spencer3, Kate A. Edwards4, Susan E Ziegler5, Amila O De Silva3, Trevor C VandenBoer1 and Cora Young1, (1)York University, Chemistry, Toronto, ON, Canada, (2)University of Alberta, Earth and Atmospheric Sciences, Edmonton, AB, Canada, (3)Environment and Climate Change Canada, Burlington, ON, Canada, (4)Natural Resources Canada, Canadian Forest Service, Ottawa, ON, Canada, (5)Memorial University, Earth Sciences, St John's, NF, Canada
Abstract:
Perfluoroalkyl substances (PFAS) are a class of extremely persistent and bioaccumulative compounds that are distributed ubiquitously in the environment. These compounds can be transported directly or formed from the oxidation of volatile precursor compounds, where they can be subsequently removed by different deposition processes. In the current study, precipitation samples were collected from four (4) locations across the Newfoundland and Labrador Boreal Ecosystem Latitudinal Transect (NL-BELT) in Canada. The sampling sites ranged from 47.9° N to 53.6° N, with samples collected on a monthly schedule from October 2013 to August 2016. Deposition was also obtained through a 16-metre ice core representing approximately five decades of deposition (1967-2016) from the Mt. Oxford icefield on northern Ellesmere Island, Nunavut, Canada at 84.2°N, 73.8° W.

Perfluorocarboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs) were detected consistently in precipitation and ice core samples. In the mid-latitude samples, the short-chain compound perfluorobutanoic acid (PFBA) was found to have the highest concentration range (<0.001 to 9.85 ng L-1) with a detection frequency of 82 %. Perfluorooctanoic acid (PFOA) was detected in 100 % of the samples with a mean concentration of 0.72 ng L-1. The other PFCAs (C6 – C11) were detected in <79% of samples. Perfluorooctane sulfonate (PFOS) was only detected in 45% of the samples with concentration ranging from <0.0003 to 0.121 ng L-1. Annual fluxes of PFCAs ranged from 0.34 to 8918 ng m-2 yr-1 whereas PFSAs ranged from 11.135 to 182.505 ng m-2 yr-1.

Generally, a trend of decreasing PFAS deposition with increasing latitude was observed. The average PFCA and PFSA fluxes obtained from the ice core concentrations were 30 ng m-2 yr-1 and 13 ng m-2 yr-1, respectively. Air mass back trajectory analysis for the NL-BELT sampling sites suggests input coming directly from the polluted North American continent. Using major ion and homologue correlations, we can elucidate sources leading to deposition in the five locations. In this presentation, the sources of PFAS to sites at different latitudes will be assessed with emphasis on the difference between sources to lower-latitudes and high-latitude regions.

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