Phase partitioning, concentration variation and risk assessment of polybrominated diphenyl ethers (PBDEs) in the...

The daytime and nighttime air samples were collected from an e-waste recycling site in Guiyu (GY) and its upwind and downwind direction sites in Chendian (CD) and Gurao (GR), respectively, during September and December 2005 to determine the phase partitioning, seasonal and diurnal variation of polybrominated diphenyl ethers (PBDEs). The three sites showed similar congener compositions with BDEs-28, -47, -99, -207 and -209 as the dominant congeners. The gas phase contribution ranged from 42.1% ± 17.1% of the total PBDEs in summer to 9.0% ± 8.6% in winter. Partitioning of PBDEs between gas and particulate phases was well correlated with the subcooled liquid vapor pressure (P(L)(0)) for all samples. Both Junge-Pankow adsorption model and K(OA)-based absorption model fitted well the PBDEs data in winter but overestimated the sorption of PBDEs in summer. The mean atmospheric concentrations of BDEs-47 (2748 pg m(-3) in summer and 6146 pg m(-3) in winter) and -99 (1656 pg m(-3) in summer and 4911 pg m(-3) in winter) in GY were much higher than those from other places around the world. Additionally, the time series of PBDEs in GY demonstrated a pronounced diurnal variation pattern, but not CD and GR, where PBDEs appeared partly associated with regional accumulation. Source characterization from local emissions may be the major factor controlling the diurnal variation of PBDEs in GY air. The risk assessment showed that the total daily intakes of BDE-99 in GY was 9.0-34.9 ng kg(-1)-bwd(-1), which is higher than the maximal allowed intake level (0.26 ng kg(-1)-bwd(-1)) with factors of 35-135, indicating possible health risk for GY residents with exposure to PBDEs.