Horizontal and Vertical Distribution of Perfluoroalkyl Acids (PFAAs) in the Water Column of the Atlantic Ocean

Eleni K Savvidou; Bo Sha; Matthew E Salter; Ian T Cousins; Jana H Johansson

doi:10.1021/acs.estlett.3c00119

Horizontal and Vertical Distribution of Perfluoroalkyl Acids (PFAAs) in the Water Column of the Atlantic Ocean

Environ Sci Technol Lett. 2023 Apr 12;10(5):418-424. doi: 10.1021/acs.estlett.3c00119. eCollection 2023 May 9.

Authors

Eleni K Savvidou¹, Bo Sha¹, Matthew E Salter^{1

2}, Ian T Cousins¹, Jana H Johansson³

Affiliations

¹ Department of Environmental Science, Stockholm University, 106 91 Stockholm, Sweden.
² Bolin Centre for Climate Research, Stockholm University, 106 91 Stockholm, Sweden.
³ Department of Thematic Studies - Environmental Change, Linköping University, 581 83 Linköping, Sweden.

Abstract

Perfluoroalkyl acids (PFAAs) are widely distributed in the oceans which are their largest global reservoir, but knowledge is limited about their vertical distribution and fate. This study measured the concentrations of PFAAs (perfluoroalkyl carboxylic acids (PFCAs) with 6 to 11 carbons and perfluoroalkanesulfonic acids (PFSAs) with 6 and 8 carbons) in the surface and deep ocean. Seawater depth profiles from the surface to a 5000 m depth at 28 sampling stations were collected in the Atlantic Ocean from ∼50° N to ∼50° S. The results demonstrated PFAA input from the Mediterranean Sea and the English Channel. Elevated PFAA concentrations were observed at the eastern edge of the Northern Atlantic Subtropical Gyre, suggesting that persistent contaminants may accumulate in ocean gyres. The median ΣPFAA surface concentration in the Northern Hemisphere (n = 17) was 105 pg L^-1, while for the Southern Hemisphere (n = 11) it was 28 pg L^-1. Generally, PFAA concentrations decreased with increasing distance to the coast and increasing depth. The C6-C9 PFCAs and C6 and C8 PFSAs dominated in surface waters, while longer-chain PFAAs (C10-C11 PFCAs) peaked at intermediate depths (500-1500 m). This profile may be explained by stronger sedimentation of longer-chain PFAAs, as they sorb more strongly to particulate organic matter.