A critical assessment of passive air samplers for per- and polyfluoroalkyl substances

Occurrence and source apportionment of perfluoroalkyl acids (PFAAs) in the atmosphere in China

“…We should keep in mind that the unimpeded movement of particle-bound PFAAs would be captured during sampling using XAD-PAS, which cannot differentiate PFAAs between gas and particle phases. Despite some research suggest the sampling efficiency of gasand particle-phase PFAAs were similar (Karásková et al, 2018). In the present study, the reported PFAAs sampled by XAD-PAS represent a combination of gaseous and particulate PFAA concentrations.…”

“…The sampling rate of XAD-PAS is a crucial factor to derive the chemical concentrations accumulated in the XAD resin. Ahrens et al (2013) found that sampling rate of PF-CAs and PFASs ranged from 1.80 to 5.50 m 3 d −1 with XADimpregnated sorbent, and the sampling rate increased as the carbon chain adding, while Karásková et al (2018) suggested that the sampling rate of XAD-PAS of 0.21-15.00 m 3 d −1 for PFAAs. The loss of depuration compounds could be used to calculate the sampling rate, assessing the impacts from meteorological factors like temperature and wind speed.…”

“…As expected, the western mountain and highland areas, e.g., Xinjiang and Yunnan (20.88 pg m −3 ), with relatively low population densities and high latitudes, displayed significantly lower PFAA concentrations. It was reported that high orographic conditions have a cold trapping effect on atmospheric PFASs, and the transport of PFAAs involving particles (or not) should be dramatically reduced (Konstantinos et al, 2010;Yao et al, 2016a). Given that altitudes increase gradually from several meters in EC, NC and SC coastal areas to nearly 2000 m in SW and NW highland regions in China, the high-altitude blocking effect on atmospheric PFAAs transport should not be neglected.…”

“…The PFAAs precursors such as fluorotelomer alcohols (FTOHs), which can form the corresponding PFAAs through oxidation reactions initiated by hydroxyl radicals (OH q ) in the atmosphere (Thackray and Selin, 2017), are more volatile than PFAAs and can reach remote areas via long-range transport (Martin et al, 2006;Wang et al, 2018). Due to the lower acid dissociation coefficient (pK A ), 0-3.8 for PFCAs and −3.3 for PFSAs, PFAAs are expected to be mainly associated with aerosols in the non-volatile anionic form (Lai et al, 2018;Karásková et al, 2018). However, recent field studies have confirmed their occurrence in gaseous phase Ahrens et al, 2013); e.g., Fang et al (2018) found the total concentrations of C 2 and C 4 -C 10 PFCAs and C 6 and C 8 PFSAs in the gas phase to be 0.076-4.0 pg m −3 in the air above the Bohai and Yellow seas, China.…”

“…Despite several publications suggested XAD-PAS collects primarily gaseous PFAAs in the environment (Melymuk et al, 2014;Lai et al, 2018), current findings are not consistent. Due to the unimpeded movements of particles into the sampler, XAD-PAS was indicated to collect a representative sample of both gas and particle phases (Ahrens et al, 2013;Okeme et al, 2016;Karásková et al, 2018). Moreover, the dominant sorbent for fluorinated compounds was reported as XAD resin in the XAD-impregnated SIP-PAS, instead of polyurethane foam (PUF) themselves (Krogseth et al, 2013).…”