Thallium (Tl) is a non-essential and toxic trace metal found in many plants, but it can accumulate at particularly high concentration in green cabbage (Brassica oleracea L var. capitata L.). The aim of this study is to explore the transfer and accumulation of Tl at the interface of rhizospheric soil and green cabbage from a long-term Tl contaminated site in southwestern Guizhou Province, China. Influencing factors such as Tl distribution in various soil fractions and physical-chemical characteristics of rhizospheric soil were also investigated. Our results demonstrated that green cabbage had high accumulation of Tl, with most bioconcentration factor (BF) values exceeding 1, and up to a maximum level of 11. The enrichment of Tl in the green cabbage tissues followed a descending order, i.e. old leaves > fresh leaves > stems, approximate to roots. The stems functioned as a channel for Tl transportation to the leaves, where most of the Tl (greater than 80%) was found to accumulate. In the rhizospheric soils, 62-95% of Tl existed in the residual fraction, while lower concentrations of Tl (on average, 1.7% of total T1 in rhizospheric soil) were found in the water and acid soluble fractions. The major fraction of labile Tl was located in the reducible fraction (9%). Our results also suggested that the uptake and enrichment of Tl in green cabbage were affected by Tl concentrations, soil water content, soil pH, soil organic material (SOM) and cation exchange capacity (CEC) in rhizospheric soil. (C) 2013 Elsevier B.V. All rights reserved.

Publication name	SCIENCE OF THE TOTAL ENVIRONMENT　Volume: 450　 Pages: 140-147　Published: APR 15 2013
Author(s)	Jia, Yanlong; Xiao, Tangfu; Zhou, Guangzhu; Ning, Zengping
Corresponding author	XIAO Tangfu  xiaotangfu@vip.gyig.ac.cn  Chinese Acad Sci, Inst Geochem, State Key Lab Environm Geochem, Guiyang 550002, Peoples R China.

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