To Örebro University

Per- and polyfluorinated substances (PFAS) are fluorinated, man-made chemicals that are found everywhere in the environment. Studies have shown that certain PFAS could have harmful effects on humans and animals. For this reason, research has been conducted to understand how PFAS spread in the environment. One way for PFAS to spread is through atmospheric transport. Through travelling in the atmosphere, PFAS have been found in remote locations. In this study, the levels and composition of PFAS were investigated in snow from high altitudes from Lake Waiau and Subaru telescope (United States), Mt Wolong (China) and Leh (India), as the main source of PFAS contamination is atmospheric transport and deposition. The snow samples were collected at the same location but 6 years apart (United States), at different locations but similar time points (United States, China and India), and at different depths (United States and India). A total of 25 PFAS were found in varying ranges in the samples. PFHpA, PFOA, PFNA and PFUnDA were found in all of the samples. The analysis of snow samples collected from different depths showed a general trend of higher PFAS concentrations in lower layers. The temporal analysis of PFAS concentrations showed an increase in one location (Subaru telescope) and a decrease in another (Lake Waiau). The spatial analysis of different locations (US, China and India) showed varying concentrations between locations, and similar compositions between locations close to each other (US samples). The total oxidizable precursor assay (TOPA) that was conducted to investigate precursors showed an increase in PFCAs after oxidation. Due to contamination issues in this study, it is not possible to say how much of the increase was from precursors or contamination. However, TOPA can still be a good indicator for the presence of unknown precursors, to have a better picture of total PFAS concentrations.