Studies on Speciation of Antimony in Soil Contaminated by Industrial Activity

Abstract

Antimony is a toxic trace element of growing environmental interest due to its increased anthropogenic input into the environment. Very little is known about the chemical and biological behavior of antimony compounds in soils and sediments. Three soil samples with substantially elevated Sb concentrations (area contaminated by extensive industrial use of Sb compounds), and a soil standard reference material have been analyzed by using conventional single and sequential extraction procedures in order to get information about the chemical forms and availability of Sb in the soil. The antimony concentrations in the extraction solutions were determined by inductively coupled plasma mass spectrometry (ICP-MS). Additionally, Sb(III) and Sb(V) were determined in some extracts by using high-performance liquid chromatography coupled on-line to the ICP-MS (HPLC-ICP-MS). The total Sb concentrations were in the upper mg kg⁻¹ range, but only small amounts were found to be easily available from the soils. The main antimony was bound to relatively immobile Fe and Al oxides. Substantial amounts were also found in the alkaline and EDTA extracts, indicating association of Sb to organic substances. Although contamination was caused by the production of Sb(III) compounds, Sb(III) was not dedected in any of the extracts. The behavior of Sb(III) (as Sb(III) tartrate and Sb₂O₃) and Sb(V) (as Sb(OH)₆ ⁻) added to the soil samples was investigated in detail.