Distributions and concentrations of thallium in korean soils determined by single and sequential extraction procedures

The objectives of this study were to investigate the distribution of thallium in soils collected near suspected areas such as cement plants, active and closed mines, and smelters and to examine the extraction of thallium in the soils using 19 single chemical and sequential chemical extraction procedures. Thallium concentrations in soils near cement plants were distributed between 1.20 and 12.91 mg kg^-1. However, soils near mines and smelters contained relatively low thallium concentrations ranging from 0.18 to 1.09 mg kg^-1. Thallium extractability with 19 single chemical extractants from selected soils near cement plants ranged from 0.10 % to 8.20 % of the total thallium concentration. In particular, 1.0 M NH₄Cl, 1.0 M (NH₄)₂SO₄, and 1.0 M CH₃COONH₄ extracted more thallium than other extractants. Sequential fractionation results of thallium from different soils such as industrially and artificially contaminated soils varied with the soil properties, especially soil pH and the duration of thallium contamination.