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Environmental Processes
Fate and transport of perfluoroalkyl substances from snowpacks into a lake in the High Arctic of Canada John J. MacInnis, Igor Lehnherr, Derek C. G. Muir, Kyra Alexandra St. Pierre, Vincent L. St.Louis, Christine Spencer, and Amila O. De Silva Environ. Sci. Technol., Just Accepted Manuscript • DOI: 10.1021/acs.est.9b03372 • Publication Date (Web): 14 Aug 2019 Downloaded from pubs.acs.org on August 28, 2019
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Environmental Science & Technology
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Fate and transport of perfluoroalkyl substances from
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snowpacks into a lake in the High Arctic of Canada
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John J. MacInnis‡, Igor Lehnherr∆, Derek C.G. Muir†, Kyra A. St. Pierre§, Vincent L. St.
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Louis§, Christine Spencer† and Amila O. De Silva*†
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‡Department
of Chemistry, Memorial University, St. John’s, Newfoundland and Labrador
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∆Department
of Geography, University of Toronto, Mississauga, Ontario
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†Aquatic
Contaminants Research Division, Environment and Climate Change Canada
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Burlington, Ontario
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§Department
of Biological Sciences, University of Alberta, Edmonton, Alberta
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[email protected]; ORCID ID: 0000-0002-3273-6843
[email protected]; ORCID ID: 0000-0002-4618-7128
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[email protected]; ORCID ID: 0000-0001-6631-9776
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[email protected]; ORCID ID: 0000-0003-0981-920X
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[email protected]; ORCID ID: 0000-0001-5405-1522
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[email protected] 20
[email protected]; ORCID ID: 0000-0002-5126-8854
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Abstract. The delivery of perfluoroalkyl substances (PFAS) from snowpacks into Lake
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Hazen, located on Ellesmere Island (Nunavut, Canada, 82º N) indicates that annual
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atmospheric deposition is a major source of PFAS that undergoes complex cycling in the
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High Arctic. Perfluoroalkyl carboxylic acids (PFCA) in snowpacks display odd-even
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concentration ratios characteristic of long-range atmospheric transport and oxidation of
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volatile precursors. Major ion analysis in snowpacks suggests that sea spray, mineral
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dust, and combustion aerosol are all relevant to the fate of PFAS in the Lake Hazen
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watershed. Distinct drifts of light and dark snow (enriched with light absorbing particles,
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LAPs) facilitate the study of particle loads on the fate of PFAS in the snowpack. Total
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PFAS (ΣPFAS, ng m-2) loads are lower in snowpacks enriched with LAPs and are
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attributed to reductions in snowpack albedo combined with enhanced post-depositional
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melting. Elevated concentrations of PFCA are observed in the top 5 m of the water
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column during snowmelt periods compared to ice-covered or ice-free periods. PFAS
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concentrations in deep waters of the Lake Hazen water column were consistent between
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snowmelt, ice-free, and ice-covered periods which is ascribed to the delivery of dense
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and turbid glacier meltwaters mixing PFAS throughout the Lake Hazen water column.
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These observations highlight the underlying mechanisms in PFAS cycling in High Arctic
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Lakes particularly in the context of increased particle loads and melting.
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Introduction. Perfluoroalkyl substances (PFAS) are environmentally ubiquitous
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chemicals that have been manufactured since the 1950s1. PFAS are incorporated into
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coating layers of many commercial products such as textiles, furniture, and food-contact
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paper to impart oil, water, and stain repellency2. Due to concerns over environmental
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persistence and bioaccumulation, long-chain perfluoroalkyl acids (i.e. >C6, PFAA),
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including perfluoroalkyl carboxylic acids (PFCA) and perfluoroalkyl sulfonic acids
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(PFSA), are regulated in Canada and many other countries3–5.
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The discovery of PFAS in the High Arctic provides evidence of their long-range
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transport ability1,6–10. It is hypothesized, for example, that indirect sources of PFAS to the
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High Arctic include the long-range atmospheric transport of volatile precursors such as
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fluorotelomer alcohols (FTOH) and perfluoroalkane sulfonamido substances7,8, all of
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which undergo atmospheric oxidation in regions with low NOx: HO2 ratios such as the
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Arctic. Direct sources of PFAS to the High Arctic include the long-range atmospheric
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transport of PFAS on particles10–12.
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The measurement of PFAS in snow can provide insights into long-range
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atmospheric transport in the High Arctic of Canada6–9. In a recent study, PFAS are
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reported in a snow core from the summit of the Devon Ice Cap that encapsulate the
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period 1977-20158. The continuous annual accumulation of PFAS on the Devon Ice Cap
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is attributed to the long-range atmospheric transport and oxidation of volatile precursors
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such as FTOH, consistent with results from a 2006-2014 air monitoring campaign at
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Alert (Nunavut, Canada, 82º N). This demonstrates the continuous annual delivery of
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volatile precursors and particle-bound PFAA to the High Arctic of Canada10. The
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accumulation of atmospherically-supplied PFAS in snow is also observed on the
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Melville, Agassiz, and Meighen Ice Caps (Nunavut, Canada, 75-80º N) in 2005-20066,
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demonstrating that snow is a repository for PFAS in the High Arctic of Canada.
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Indeed, snowmelt is a source of PFAS to freshwater ecosystems13–15. For
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example, in the Krycklan watershed (northern Sweden, 64° N), 0.11-0.48 ng L-1
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perfluorohexanoic acid (PFHxA), 0.20-0.68 ng L-1 perfluoroheptanoic acid (PFHpA),
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0.12-0.81 ng L-1 perfluorooctanoic acid (PFOA), 0.09-0.79 ng L-1 perfluorononanoic acid
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(PFNA) and 0.03-0.45 ng L-1 perfluorodecanoic acid (PFDA) are in snowmelt (Table
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1)13. Similar observations are reported in an urban watershed in Highland Creek (Ontario,
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Canada, 44º N) where approximately one-fifth of the increasing riverine flux of PFAS in
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early spring is attributed to snowmelt14. More recently, Skaar et al. report high total
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concentrations of PFAS (ΣPFAS, mean 1.4 ng L-1, 0.1-4.1 ng L-1) in glacial- and
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snowmelt-impacted surface waters from Lake Linnévatnet (Svalbard, Norway, 78° N) in
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2014 and 2015, dominated by PFBA (mean 0.6 ng L-1,
