Bioaccumulation, transfer characteristics of metals in six vascular plants, and soil pollution assessment from Wachangping karst bauxite residue areas.

Bauxite residue (BR) is a large volume by-product generated during bauxite smelting process and metal pollution problem is becoming increasingly prominent in residue areas. Accumulation and transfer of metals in six vascular plants were analyzed and soil environment was evaluated. Results found levels of Al (2,110-26,280 mg kg), Fe (990 to 9,880 mg kg), Ca (8,020 to 49,250 mg kg), Mg (2,060 to 17,190 mg kg), K (16,840 to 39,670 mg kg), and Ti (80 to 1,240 mg kg) in plants. Metal concentrations in soils exceeded background levels. Bioconcentration factor (BCF) found that Al, Fe, and Ti in plants (roots, stems, and leaves) were relatively depleted (BCF <1). Transfer factor (TF) of Al, Fe, Ca, K, and Ti in plants was distinctly higher than 1 and mainly concentrated in stems and leaves. Pollution indices revealed that soil environment was at moderated to serious contaminated risk. Principal components analysis (PCA) showed that Buch. and L. plants had a good ability to absorb Al and Fe, which can be used as biological indicators and restoration materials.