Neutral polyfluoroalkyl substances in the global atmosphere

Area of Science:

• Environmental Chemistry
• Atmospheric Science
• Analytical Chemistry

Background:

• Neutral per- and polyfluoroalkyl substances (nPFAS) are key atmospheric precursors to perfluoroalkyl acids.
• Understanding nPFAS atmospheric concentrations is crucial due to their mobility and role as precursors.

Purpose of the Study:

• To assess the feasibility of XAD 2-resin based passive air samplers (XAD-PAS) for determining long-term average nPFAS air concentrations.
• To investigate the temporal and spatial distribution of nPFAS across six continents.

Main Methods:

• Deployment of XAD-PAS at 17-46 sites globally between 2006-2011 as part of the Global Atmospheric Passive Sampling (GAPS) study.
• Analysis of nPFAS concentrations, including fluorotelomer alcohols (FTOHs), fluorinated sulfonamides (FOSAs), and fluorinated sulfonamidoethanols (FOSEs).

Main Results:

• Higher nPFAS levels were observed in urban areas compared to rural and remote sites, correlating positively with population density.
• Fluorotelomer alcohols (FTOHs) were more abundant than FOSAs and FOSEs across all sites.
• FOSAs and FOSEs showed a decreasing trend over the study period, while FTOH concentrations initially declined then stabilized.

Conclusions:

• XAD-PAS is a feasible method for monitoring long-term average nPFAS concentrations in diverse climatic conditions.
• Global nPFAS distribution is influenced by proximity to urban centers and population density.
• While absolute nPFAS levels from XAD-PAS may differ from other methods, relative composition agreement suggests sampler representativeness.