Distribution and dry deposition of alternative and legacy perfluoroalkyl and polyfluoroalkyl substances in the air above the Bohai and Yellow Seas, China

A total of 26 alternative and legacy perfluoroalkyl and polyfluoroalkyl substances (PFASs) were investigated in air collected above the Bohai and Yellow Seas during a research cruise between June 28 and July 15, 2016. Sigma PFAS concentrations ranged from 70 pg m(-3) to 430 pg m(-3) (mean 230 +/- 100 pg m(-3)). Trifluoroacetic acid (TFA, mean 120 +/- 80 pg m(-3)) and 8:2 fluorotelomer alcohol (8:2 FTOH, mean 34 +/- 46 pg m(-3)) were the predominating compounds of ionizable PFASs (i-PFASs) and neutral PFASs (n-PFASs), respectively. The contributions of C-4 and C-6 i-PFASs were higher than those of C-8 i-PFASs. Alternative substances, such as chlorinated 6:2 polyfluoroalkyl ether sulfonic acids (Cl-6:2 PFESA, mean 1.6 +/- 1.2 pg m(-3)) and diPAPs (mean 1.6 +/- 1.3 pg m(-3)), were only detected on the filter. The distribution coefficient of 10:2 FTOH was higher than 8:2 FTOH, which could be explained by the length of the carbon chain. The gas phase dry deposition velocities were simulated, and the values ranged from 0.08 +/- 0.12 cm s(-1) to 0.85 +/- 0.28 cm s(-1). For i-PFASs and diPAPs, the estimated fluxes of the particle phase were higher than those of the gas phase. For n-PFASs and TFA, the gas phase deposition played a key role. The Sigma PFASs dry deposition fluxes were 11-290 ng (m(2) d)(-1) (mean 72 +/- 67 ng (m(2) d)(-1)). The measurement of the concentrations in the gas and particle phases simultaneously provided a more comprehensive understanding of PFAS behaviours in air.