Three-year monitoring of atmospheric PCBs and PBDEs at the Chinese Great Wall Station, West Antarctica: Levels, chiral signature, environmental behaviors and source implication

Abstract

A three-year monitoring campaign (Jan 2011–2014) of polychlorinated biphenyl (PCBs) and polybrominated diphenyl ethers (PBDEs) was conducted using a high-volume air sampler at the Chinese Great Wall Station in King George Island, West Antarctica. The results showed that the Σ20PCB and Σ27PBDE concentrations (gas + particle) were 5.87–72.7 pg m−3 and 0.60–16.1 pg m−3, respectively. The lighter congeners especially PCB-11 (a non-Aroclor congener) dominated Σ20PCBs, while BDE-209 made a significant contribution to Σ27PBDEs apart from the lighter congeners (e.g., BDE-28 and -17). The chiral signature indicated nonracemic residues of chiral PCBs in the samples, suggesting potential influence of the secondary source, i.e. air-seawater exchange, on the atropisomer composition of chiral PCBs in air. Lighter PCBs (excluding PCB-11) showed significant temperature dependence in 2011 and 2012, reflecting the influence of revolatilization emission from the local surface. However, the shallow slopes of the regression lines for gaseous concentrations of POPs against reciprocal temperature (1/T) suggested long-range atmospheric transport (LRAT) as an important pathway for both PCBs and PBDEs into the Antarctic environment. Furthermore, correlations and ratios between different signature congeners deriving from the technical formulations indicated a local source of Deca-BDE and photodegradation of higher brominated BDEs. The gas/particle partitioning of POPs was also evaluated and the newly developed steady-state-based model generally showed a better performance than the equilibrium-state-based model. However, the former still underestimated the partitioning of most PCBs (log KOA <11) in particle phase, implying that further optimization is necessary when using it for those compounds with lower log KOA.