Polybrominated diphenyl ethers, dechlorane plus, and polychlorinated biphenyls in tree bark near the upper Yellow...

Willow tree bark samples from urban and rural sites in Inner Mongolia, Ningxia Province, and Gansu Province, in the Yellow River basin, were analyzed for polybrominated diphenyl ethers (PBDEs), dechlorane plus (DP), and dioxin-like polychlorinated biphenyls (DL-PCBs) to compare their relative levels in air in these areas (i.e., treating bark as a passive air sampler). No difference was found between the pollutant concentrations in Salix matsudana and Salix babylonica bark samples. The mean concentrations of the total PBDEs, DP, and total DL-PCBs were 13000 ± 6400, 46 ± 44, and 26 ± 17 pg/g dry weight, respectively, with urban samples containing much higher concentrations (19000 ± 5700 pg/g, 51 ± 27 pg/g, and 37 ± 29 pg/g dry wt in PBDEs, DP, and DL-PCBs, respectively) than rural samples (10000 ± 5200 pg/g, 45 ± 53 pg/g, 22 ± 9 pg/g dry wt). A strong positive correlation between PBDEs and DP was found in all of the samples (r=0.712, p=0.006), but correlations between PCBs and the other pollutants were only found in the rural samples. The total DL-PCB concentration in the tree bark correlated with population density.