Particle-Phase Dry Deposition and Air−Soil Gas-Exchange of Polybrominated Diphenyl Ethers (PBDEs) in Izmir, Turkey

The particle-phase dry deposition and soil−air gas-exchange of polybrominated diphenyl ethers (PBDEs) were measured in Izmir, Turkey. Relative contributions of different deposition mechanisms (dry particle, dry gas, and wet deposition) were also determined. BDE-209 was the dominating congener in all types of samples (air, deposition, and soil). Average dry deposition fluxes of total PBDEs (∑7PBDE) for suburban and urban sites were 67.6 and 128.8 ng m-2 day-1, respectively. Particulate dry deposition velocities ranged from 11.5 (BDE-28) to 3.9 cm s-1 (BDE-209) for suburban sites and 7.8 (BDE-28) to 2.8 cm s-1 (BDE-154) for urban sites with an overall average of 5.8 ± 3.7 cm s-1. The highest ∑7PBDE concentration (2.84 × 106 ng kg-1 dry wt) was found around an electronic factory among the 13 soil samples collected from different sites. The concentration in a bag filter dust from a steel plant was also high (2.05 × 105 ng kg-1), indicating that these industries are significant PBDE sources. Calculated net soil−air gas exchange flux of Σ7PBDE ranged from 11.8 (urban) to 23.4 (industrial) ng m-2 day-1 in summer, while in winter it ranged from 3.2 (urban) to 11.6 (suburban) ng m-2 day-1. All congeners were deposited at all three sites in winter and summer. It was estimated that the wet deposition also contributes significantly to the total PBDE deposition to soil. Dry particle, wet, and gas deposition contribute 60, 32, and 8%, respectively, to annual PBDE flux to the suburban soil.