Are atmospheric PBDE levels declining in central Europe? Examination of the seasonal and semi-long-term variations, gas-particle partitioning and implications for long-range atmospheric transport

This study presents multi-year monitoring data on atmospheric polybrominated diphenyl ethers (PBDEs) in central Europe. Air was sampled on a weekly basis at a background site in the central Czech Republic from 2011 to 2014 (N = 114). Sigma 8PBDEs (without BDE209) total (gas and particulate) concentrations ranged from 0.084 to 6.08 pg m(-3), while BDE209 was at 0.05-5.01 pg m(-3). BDE47, BDE99 and BDE183 were the major contributors to Sigma 8PBDEs. Overall, the atmospheric concentrations of individual PBDEs were controlled by deposition processes, meteorological parameters and long-range atmospheric transport. Regarding gas particle partitioning, with the exception of BDE28 (gaseous) and BDE209 (particulate), all congeners were consistently detected in both phases. Clear seasonal variations with significantly higher measured particulate fraction (theta(measured)) in winter compared to summer was found for all PBDEs except BDE209. For example, while the average theta(measured) of BDE47 was 0.53 +/- 0.19 in winter, this was only 0.01 +/- 0.02 in summer. Similarly, for BDE99, theta(measured) was 0.89 +/- 0.13 in winter, while it was only 0.12 +/- 0.08 in summer. The observed gas-particle partitioning coefficient (K-p, in m(3) mu g(-1)) was compared with three model predictions, assuming equilibrium or a steady state. None of the models could provide a satisfactory prediction of the partitioning, suggesting the need for a universally applicable model. Statistically significant decreases of the atmospheric concentrations during 2011-2014 were found for BDE99, 100, 153 and 209. Estimated apparent atmospheric halving times for these congeners ranged from 2.8 (BDE209) to 4.8 (BDE153) years. The results suggest that photolytic debromination to lower brominated congeners may significantly influence PBDE concentration levels and patterns in the atmosphere. Statistically significant decreases of the atmospheric concentrations during 2011-2014 were found for BDE99, 100, 153 and 209. Estimated apparent atmospheric halving times for these congeners ranged from 2.8 (BDE209) to 4.8 (BDE153) years. The results suggest that photolytic debromination to lower brominated congeners may significantly influence PBDE concentration levels and patterns in the atmosphere.