Abstract
Abstract. Due to their properties of bioaccumulation, toxicity, and long-range atmospheric transport, polyfluoroalkyl and perfluoroalkyl substances (PFASs) and cyclic volatile methylsiloxanes (cVMSs) are currently being considered as emerging persistent organic pollutants (POPs) for regulation. To date, there are limited data on PFASs and cVMSs in the atmosphere of the Tibetan Plateau (TP), a remote environment which can provide information on global background conditions. Sorbent-impregnated polyurethane foam (SIP) disc passive air samplers were therefore deployed for 3 months (May to July 2011 and 2013) at 16 locations across the TP. Using previously reported methods for estimating the air volume sampled by SIP discs, the derived atmospheric concentrations ranged as follows: 18–565 ng m−3 for ΣcVMS (including D3, D4, D5, and D6); 65–223 pg m−3 for fluorotelomer alcohols (ΣFTOHs); 1.2–12.8 pg m−3 for fluorinated sulfonamides (ΣFOSA); and 0.29–1.02 pg m−3 for fluorinated sulfonamidoethanols (ΣFOSE). The highest ΣcVMS occurred at Lhasa, the capital city of the TP, indicating the local contribution to the emerging pollutants. Higher levels of ΣFTOHs were observed at sites close to the transport channel of the Yarlung Tsangpo Grand Canyon, indicating possible long-range atmospheric transport (LRAT). Elevated concentrations of shorter-chain volatile PFAS precursors (4 : 2 FTOH and fluorobutane sulfonamidoethanol) were found in most air samples, reflecting the shift in production from long- to short-chain PFASs in Asia. Overall, concentrations of emerging POPs at background sites of the TP were 1–3 orders of magnitude higher than those reported for legacy POPs.
Highlights
Persistent organic pollutants (POPs) have attracted significant attention due to their wide distribution in the environment and high toxicity to humans and wildlife (Hung et al, 2016a, b; Magulova and Priceputu, 2016; Rigét et al, 2010)
Sorbent-impregnated polyurethane foam (SIP) disc passive air samplers were deployed across the Tibetan Plateau (TP) (16 sites) to obtain the spatial distribution of perfluoroalkyl substances (PFASs) and cyclic volatile methylsiloxanes (cVMSs) in the atmosphere
SIP-polyurethane foam (PUF) discs were dried under vacuum, and an average of 435 ± 30 mg of XAD-4 coated each disc (n = 80; each sampling had 32 samples and 8 field blanks), which was similar to the Global Passive Atmospheric Sampling programme (Genualdi et al, 2010)
Summary
Persistent organic pollutants (POPs) have attracted significant attention due to their wide distribution in the environment and high toxicity to humans and wildlife (Hung et al, 2016a, b; Magulova and Priceputu, 2016; Rigét et al, 2010). Cyclic volatile methylsiloxanes (cVMSs) include hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), and their rearrangement products such as decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) These chemicals are the subject of increasing concern because of their high emissions, long persistence (Navea et al, 2011), and toxicities (Mackay et al, 2015). Of legacy POPs in the Tibetan environment have already been investigated; there is still a gap in knowledge regarding the distribution of emerging organic contaminants, such as PFASs and cVMSs. In this study, sorbent-impregnated polyurethane foam (SIP) disc passive air samplers were deployed across the TP (16 sites) to obtain the spatial distribution of PFASs and cVMSs in the atmosphere. Sorbent-impregnated polyurethane foam (SIP) disc passive air samplers were deployed across the TP (16 sites) to obtain the spatial distribution of PFASs and cVMSs in the atmosphere These sites include densely populated cities and background sites in order to test how local emission and LRAT contaminate the TP.
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