Novel brominated flame retardants in West Antarctic atmosphere (2011-2018): Temporal trends, sources and chiral signature

摘要

Novel brominated flame retardants (NBFRs) were comprehensively investigated in both gaseous and particle phase samples collected using a high-volume active air sampler (HV-AAS) at the Chinese Great Wall Station in King George Island. West Antarctica from 2011 to 2018. The concentrations of ∑_(12) NBFRs ranged from 0.27 to 3.0 pg m~(-3), with a mean value of 1.1 ± 0.50 pg m~(-3) and the levels showed a slightly increasing trend over the eight years. Decabromodiphenyl ethane (DBDPE) was the predominant NBFR with a relative contribution of 50% on average. Most of the studied NBFRs tended to distribute in gaseous phase with an average ratio of 72 ± 16% while NBFRs with higher log K_(OA) values had higher proportions in particle phase. The gas/particle partitioning models were employed to evaluate the environmental behavior of NBFRs. Compared to the equilibrium-state-based model, the steady-state-based model performed much better to predict the gas/particle partitioning of NBFRs in the West Antarctic atmosphere. Additionally, no temperature dependence was found for NBFRs except rac-(1R,2R,5R,6R)-l,2,5,6-tetrabromocyclooctane (β-TBCO). The annual mean concentrations of Σ_(12)NBFRs showed a significantly negative correlation with the frequency of east-southeast (ESE, 112.5°) wind and calm wind (～0 m s~(-1)) (p < 0.05), and a significantly positive correlation with the frequency of wind from northwest interval (west to north-northwest, 270° to 337.5°) (p < 0.05), suggesting a significant effect of air mass from the ocean area. Furthermore, the chiral signature of NBFRs showed commonly non-racemic residue in the atmosphere. The enantiomer fractions (EF) of rac-(1R.2R)-1,2-dibromo-(4S)-4-((1R)-1,2-dibromoethly) cyclohexane (α-TBECH) and β-TBCO were 0.115-0.962 and 0.281-0.795, revealing secondary sources of NBFRs, e.g., seawater-air exchange and/or non-racemic residue in the source regions. As far as we know, this is one of very few studies on NBFRs in the Antarctic atmosphere.