Altitudinal distributions of PCDD/Fs, dioxin-like PCBs and PCNs in soil and yak samples from Wolong high mountain area, eastern Tibet-Qinghai Plateau, China.

Topsoil along the altitudinal gradient (2086-4487 m above sea level) and yak samples, collected from Wolong high mountain area of Sichuan Province, western China, were analyzed for polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), dioxin-like polychlorinated biphenyls (dl-PCBs) and polychlorinated naphthalenes (PCNs) using HRGC-HRMS. The total concentrations of PCDD/Fs, dl-PCBs, and PCNs in soils were: 2.48-4.30 pg g(-1) dw (dry weight), 7.6-10.5 pg g(-1) dw, and 13.0-29.0 pg g(-1) dw, respectively; the greatest concentrations were found at sampling sites of 3,927 m, 4487 m and 3,345 m, correspondingly. The total PCDD/Fs and dl-PCBs concentrations showed positive correlations with increasing altitudinal gradient. The congener profiles of both 2,3,7,8-PCDD/Fs and dl-PCBs at different altitudes showed similar patterns. PCNs were dominated by Tri-CNs. The long-range atmospheric transport and subsequent aerial deposition are likely the sources for these POPs in area examined. The total TEQs in soils were in the range of 0.28-0.42 pg g(-1) dw, and the total TEQs in the yak muscle and fatty tissue samples were 3.81-4.09 pg TEQ g(-1) lipid weight. The daily intake of TEQs was estimated to be below the WHO's tolerable daily intake according to the local people's dietary habits in Wolong area, which is unlikely to cause any adverse health effects to the yak muscle consuming people.