Atmospheric deposition and air–soil exchange of polybrominated diphenyl ethers (PBDEs) in a background site in Central China

Jinsha (JSH) is one of the regional background sites in Central China. In this study, eight polybrominated diphenyl ethers (PBDEs) were measured in atmospheric deposition samples (dry particle, wet particle, and wet dissolved), air (gaseous and particle) samples, and soil samples that were collected from March 2012 to March 2013. Of all eight PBDEs, BDE-209 was the most abundant congener in both deposition samples and air/soil samples. Average dry particle, wet particle, and wet dissolved deposition fluxes of Σ₈PBDEs were 270 ± 310 pg m⁻² day⁻¹, 130 ± 210 pg m⁻² day⁻¹, and 250 ± 330 pg m⁻² day⁻¹, respectively, while those of BDE-209 were 210 ± 290 pg m⁻² day⁻¹, 80 ± 120 pg m⁻² day⁻¹, and 160 ± 290 pg m⁻² day⁻¹, respectively. Dry deposition velocities of individual PBDE ranged from 0.11 ± 0.15 cm s⁻¹ (BDE-183) to 0.24 ± 0.38 cm s⁻¹ (BDE-209), and total washout ratios ranged from 5.0 × 10³ (BDE-28) to 4.2 × 10⁴ (BDE-209). The calculated net air–soil gas exchange flux of Σ₈PBDEs was − 16 ± 13 pg m⁻² day⁻¹, suggesting the deposition status of PBDEs. The gas exchange flux at the air–soil interface was significantly lower than the deposition flux, which only accounted for 2.5% of the total deposition flux, implying that atmospheric deposition was an important input pathway for PBDEs to soils. Overall, the pollution level of the soil was relatively low, and the soil serves as a sink for PBDEs from adjacent regions.