Comparison of several soil extractants for determination of thallium
2002
Zbiral, J. | Pavlickova, J. | Havlikova, S. | Cizmarova, E. | Nemec, P. | Sanka, M. | Kuban, V. | Medek, P.
Thallium (Tl) and its compounds are toxic to all organisms. Relatively high levels of thallium of pedogeochemical origin have been found in some areas of the Czech Republic. The contents of > 2 mg kg(-1) of Tl have been found in aqua regia soil extracts of soils originated from melanocratic porphyric hornblende-biotite granite or from hornblende-biotite granodiorite. The contents of Tl in the range of 0.45-1 mg kg(-1) have occurred mainly in soils originated from paragneiss. A detailed study of some of these sites has been made. Content of thallium in soils was determined after extraction with aqua regia, 2 M HNO3, DTPA-TEA and 1 M NH4NO3. Plant samples (whole rapeseed kernels) were wet ashed and the total content of Tl was determined. The amount of Tl in soils extracted by the different extracting methods in comparison to aqua regia (100%) was approximately 14% for 2 M HNO3, 0.8% for 1 M NH4NO3 and only about 0.03% for DTPA-TEA. The content of Tl in the rapeseeds was approximately 75% of this element determined in soils after extraction by aqua regia. The relationships among the extractants were found to be relatively close except for 1 M NH4NO3. It was found that the transfer of Tl into rapeseeds depends on the status of this element in the particular soil and that the soil substrate is the main factor influencing this status.
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