Distribution Pattern of Dioxins in Sediment Cores from the Xiangxi River, a Tributary of Three Gorges Reservoir, China

Sediment cores were collected from the Xiangxi River, a tributary of Three Gorges Reservoir, deposition time in longest sediment core (90 cm) was measured by radiometry (137Cs, 210Pb) activities and polychlorinated dibenzo-p-dioxins/furan (PCDD/F) concentrations different depths measured. The results indicated that mean rate 1.01 cm/a. total PCDD/F ranged 19.28 to 70.07 pg/g d.w. with 35.06 PCDD/Fs 1960–1990s higher than others, which significantly various layers (p < 0.05). PCDD occupied 63.42–87.33% PCDD/Fs, octachlorianted debenzo-p-dioxin (OCDD) predominant congener. ratio PCDF 2.26–8.08. correlated organic carbon (TOC) 0.01). toxic equivalent (TEQ) 0.15 0.98 No significant difference found TEQ > It concluded spatio-temporal heterogeneity determined hydrodynamics distribution pattern low, low environmental pollution risk, by-products sodium pentachlorophenate might be main source.