Neutral polyfluoroalkyl substances in the atmosphere over the northern South China Sea

Abstract

a b s t r a c tNeutral Polyfluoroalkyl substances (PFASs) in the atmosphere were measured during a cruise campaign over the northern South China Sea (SCS) from September to October 2013. Four groups of PFASs, i.e., fluorotelomer alcohols (FTOHs), fluorotelomer acrylates (FTAs), fluorooctane sulfonamides (FOSAs) and fluorooctane sulfonamidoethanols (FASEs), were detected in gas samples. FTOHs was the predominant PFAS group, accounting for 95.2e99.3% of total PFASs (SPFASs), while the other PFASs accounted for a small fraction of SPFASs. The concentrations of SPFASs ranged from 18.0 to 109.9 pg m À3 with an average of 54.5 pg m À3 . The concentrations are comparable to those reported in other marine atmosphere. Higher concentrations of SPFASs were observed in the continental-influenced samples than those in other samples, pointing to the substantial contribution of anthropogenic sources. Long-range transport is suggested to be a major pathway for introducing gaseous PFASs into the atmosphere over the northern SCS. In order to further understand the fate of gaseous PFASs during transport, the atmospheric decay of neutral PFASs under the influence of reaction with OH radicals and atmospheric physical processes were estimated. Concentrations of 8:2 FTOH, 6:2 FTOH and MeFBSE from selected source region to the atmosphere over the SCS after long-range transport were predicted and compared with the observed concentrations. It suggests that the reaction with OH radicals may play an important role in the atmospheric decay of PFAS during long-range transport, especially for shorted-lived species. Moreover, the influence of atmospheric physical processes on the decay of PFAS should be further considered.

Perfluoroalkyl and polyfluoroalkyl substances in the lower atmosphere and surface waters of the Chinese Bohai Sea, Yellow Sea, and Yangtze River estuary

“…Comparing with other coastal regions worldwide, ∑FTOHs and 8:2 FTOH concentrations in the air above the Bohai and Yellow Seas were significantly higher than those of the air above the South China Sea (17.8 to 106 pg/m 3 , and12.5 to 75.5 pg/m 3 , respectively) (Lai et al, 2016), German coast (7.3 to 146 pg/m 3 , and 4.5to 85 pg/m 3 , respectively) (Z. , Japanese coast (b 0.4 to 5.0 pg/m 3 ) (Piekarz et al, 2007), and east coast of the USA (5.46 to 156 pg/m 3 , and 1.65 to 91.3 pg/m 3 , respectively) (Shoeib et al, 2010). Concentrations of MeFBSA/E in the air were higher than those in the air above the North Atlantic Ocean (0.11 to 0.44 pg/m 3 , and 0.09 to 0.57 pg/m 3 , respectively) (Z. , but lower than those in the North Sea coastal air (0.1 to 3.9 pg/m 3 , and nd to 4.6 pg/m 3 , respectively) (Z. , and western Antarctic Peninsula coastal air (0.4 to 5.4 pg/m 3 , and 0.2 to 14.1 pg/m 3 , respectively) (Del Vento et al, 2012).…”

“…FASAs last longer in air than FASEs and have the potential to be transported across longer distances than FASEs (D'Eon et al, 2006). MeFBSA and MeFBSE were detected in all samples, and showed higher concentrations than those of MeFOSA and Me/EtFOSE, which may be attributed to the replacement of C 8 -PFASs (Lai et al, 2016). In the air samples from the Bohai and Yellow Seas, only 8:2 FTAC was detected at low levels (b 0.20-1.4 pg/m 3 ) in the gas phase.…”

“…However, the 10:2 to 8:2 FTOH ratios were lower than the products (10:2 to 8:2 FTOH ratio: 0.6) Washington et al, 2014). One possible reason for the lower 10:2 to 8:2 FTOH ratio may be the higher 10:2 FTOH removal rate as compared to that of 8:2 FTOH in air given that the residence time of 10:2 FTOH (70 days) was shorter than 8:2 FTOH (80 days) (Lai et al, 2016). Another possible reason may be the higher affinity to particles due to the longer of 10:2 FTOH chain than that of 8:2 FTOH (Z. .…”

Per- and poly-fluoroalkyl substances (PFASs) in the urban, industrial, and background atmosphere of Northeastern China coast around the Bohai Sea: Occurrence, partitioning, and seasonal variation

“…) were generally higher than those from the Atlantic Ocean (19.9 pg m À3 ) (Wang et al, 2015b), Station Nord, Greenland (9.34 pg m À3 ) (Bossi et al, 2016), and Ny-Ålesund, Norway (14 pg m À3 ) ; they are comparable to those close to source regions such as the North Sea (77.0 pg m À3 ) (Xie et al, 2013) and the South China Sea (53.0 pg m À3 ) (Lai et al, 2016), and lower than those from mobile cruise sampling in the Bohai Sea (104 pg m À3 ), North and South Yellow Seas (184e288 pg m À3 ) (Zhao et al, 2017), and the Japan Sea (178 pg m À3 ) (Cai et al, 2012). In addition, the levels of neutral PFASs at NHI were slightly lower than the samples from the landbased background site of Jixian, Tianjin, but they shared a similar composition profile, suggesting common sources (Yao et al, 2016a).…”

“…A ubiquitous occurrence of both neutral and ionic PFASs in the outdoor dust on a continental scale and an association with possible atmospheric transport have been reported (Yao et al, 2016b). Partitioning to particles and their subsequent deposition were suggested as a major loss mechanism during the atmospheric transport of neutral PFASs from a source region to the open ocean (Lai et al, 2016). This process may be influenced by the level of total suspended particles (TSP) (Wang et al, 2015a;Yuan et al, 2016), and more field evidence is needed to clarify partitioning behaviors, especially in a source region with high TSP levels.…”