Speciation of antimony and arsenic in the soils and plants in an old antimony mine

• We sampled plants and associated soils in an old antimony mine.
• We analyzed the variations in antimony and arsenic speciation in the soils and plants.
• TMSb was found in a few rhizosphere soils and in the leaves of the plants at five sites.
• DMA was absent in the soils but was observed in various plant tissues at all of the sites.
• Antimony may be methylated within the plants in the same manner as arsenic, but primarily in the leaves.

The speciation changes of antimony (Sb) in soil–plant system are largely unknown as compared with those of arsenic (As). In this study, indigenous plants and associated soils were sampled at the Xikuangshan Sb mine (XKS), China. The Sb in the soils (441–1472 mg/kg) were far greater than As (32–354 mg/kg), and the Sb and As availabilities in the soils, were 5.5% and 3.9% in average, respectively. HPLC-ICP-MS revealed the presence of four species of Sb in the soils and plants, including SbIII, SbV, TMSb and UnkSb (unknown). The use of XANES revealed that the UnkSb consisted of inorganic Sb in the form of SbV. Inorganic Sb were prevalent in the soil and plant samples at the eight sites, whereas TMSb was observed in only a few of the rhizosphere soils, and, in plants at a few of the sites, primarily in the leaves and to a lesser extent in the stems. Arsenic was detected in the soils primarily as inorganic forms, while, DMA was detected in high proportions in all of the plant tissues at all of the sites. The methylation of Sb was far less than that of As in the indigenous plants at XKS. The results suggest that As and Sb differ in transformation characteristics in the soil–plant system in XKS.

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