Distribution and phytoavailability of antimony at an antimony mining and smelting area, Hunan, China

Abstract

An investigation of the distribution, fractionation and phytoavailability of antimony (Sb) and other heavy metals in soil sampled at various locations in the vicinity of a Sb mine revealed elevated levels of Sb, most certainly due to the mining activities. The concentration of Sb in the soil samples was 100.6–5045 mg kg⁻¹; in comparison, the maximum permissible concentration for Sb in soil in The Netherlands is 3.5 mg kg⁻¹, and the maximum permissible concentration of pollutant Sb in receiving soils recommended by the World Health Organization is 36 mg kg⁻¹. The soil sampled near the Sb mine areas had also contained high concentrations of As and Hg. Root and leaf samples from plants growing in the Sb mine area contained high concentrations of Sb, with the concentration of Sb in the leaves of radish positively correlating with Sb concentrations in soil. The distribution of Sb in the soil showed the following order: strongly bound to the crystalline matrix > adsorbed on Fe/Mn hydrous oxides, complexed to organic/sulfides, bound to carbonates > weakly bound and soluble. Solvents showed varying levels of effectiveness in extracting Sb (based on concentration) from the soil, with ${\hbox{Sb}}_{{\hbox{NH}}_{\hbox{4}} {\hbox{NO}}_{\hbox{3}} } {\hbox{ $ > $ Sb}}_{{\hbox{EDTA}}} {\hbox{ $ > $ Sb}}_{{\hbox{HAc}}} {\hbox{, Sb}}_{{\hbox{H}}_{\hbox{2}} {\hbox{O}}} {\hbox{ $ > $ Sb}}_{{\hbox{NH}}_{\hbox{4}} {\hbox{OAc}}}$, in decreasing order. The concentration of easily phytoavailable Sb was high and varied from 2.5 to 13.2 mg kg⁻¹, the percentage of moderately phytoavailable Sb ranged from 1.62 to 8.26%, and the not phytoavailable fraction represented 88.2–97.9% of total Sb in soils.