Polychlorinated dibenzo-p-dioxins and dibenzofurans and polychlorinated biphenyls in surface soil from the Tibetan Plateau

Zhenyu Tian , Haifeng Li , Huiting Xie , Chen Tang , Ying Han , Mengjing Wang , Wenbin Liu


Received November 15, 2013,Revised February 24, 2014, Accepted , Available online October 22, 2014

Volume 26,2014,Pages 2041-2047

Concentrations of Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in soil samples from Tibetan Plateau were determined. The average concentration of total 2,3,7,8-PCDD/Fs was (2.30 ± 1.02) pg/g, and World Health Organization Toxicity Equivalency (WHO-TEQ) average concentration was (0.013 ± 0.010) pg WHO-TEQ/g. The average concentration of ΣPCBs (7 indicator PCB and 12 dioxin like-PCB congeners) was (16.2 ± 9.25) pg/g, and WHO-TEQ average concentration was 0.043 ± 0.049 pg WHO-TEQ/g. Comparing to previous studies in similar environmental conditions, PCDD/Fs and PCBs in this study showed a relatively lower concentration. The altitude dependences of PCDD/Fs and PCBs were also studied. Total organic carbon (TOC) normalized concentrations presented a quadratic relation with the altitudes, and an inflection could be found on the parabola of the total concentrations and some congeners of high concentration. The concentrations decreased with altitudes below about 4500 mabove sea level (a.s.l.), while they increased with altitudes above it. These phenomena indicate that cold condensation of PCDD/Fs and PCBs would happen above 4500 m a.s.l, on the Tibetan Plateau.

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