Extending the Monitoring of Perfluoroalkyl Substances in Arctic Air Reveals a High Abundance of Both Short Acids and Neutral Compounds

TL;DR

This study tracks perfluoroalkyl substances in Arctic air, finding high levels of short-chain compounds and new insights into their transport and trends.

Contribution

The study introduces a new method for analyzing PFAS in Arctic air and identifies previously overlooked short-chain and neutral compounds.

Findings

Short-chain PFASs like TFA, PFPrA, and PFBA were frequently detected at high concentrations in Arctic air.

HF2OH and HFIPA were confirmed as new PFAS compounds in Arctic air with detection frequencies over 75%.

Concentrations of PFBA, PFOA, and PFOS have increased since 2019, suggesting ongoing emissions despite regulatory actions.

Abstract

Interest in per-
and polyfluoroalkyl substances (PFASs) in the
remote atmosphere now extends to perfluoroalkyl carboxylic acids (PFCAs)
and perfluoroalkyl sulfonic acids (PFSAs) with short (n
C < 4), medium (3 < n
C < 13), and long (n
C > 12) alkyl
chains.
A liquid chromatography–mass spectrometry method for the combined
analysis of PFASs of variable chain length was applied to 204 high
volume active air samples collected at Alert, Nunavut (82° 30′
N 62° 20′ W) between March 2014 and October 2023. Short-chain
PFASs (scPFASs) were detected frequently (>75%) and at the highest
median concentrations (trifluoroacetic acid (TFA): 20 pg/m3, perfluoropropionic acid (PFPrA): 1.1 pg/m3, perfluorobutanoic
acid (PFBA): 3.7 pg/m3), while nC > 10 PFAS
were sparsely detected (detection frequency [DF] < 20%). Using
a suspect-screening approach, hexafluoro-2,2-propanediol (HF2OH) and
hexafluoroisopropanol (HFIPA) were confirmed in Arctic air at DF exceeding
75%. We find that concentrations of TFA and HF2OH were significantly
correlated with temperature and increased during snowmelt periods,
suggesting local emission or precursor release followed by degradation
processes. The modified OECD LRTP and Pov assessment tool supported
the potential of HFIPA and HF2OH to undergo long-range atmospheric
transport. Time trend analysis reveals that after a short period of
stable or declining levels in the mid-2010s, concentrations of PFBA,
PFOA, and PFOS in Arctic air are increasing again since 2019, which
may be a useful consideration when evaluating the effectiveness of
the Stockholm Convention’s listing of PFOA and PFOS.

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