Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Nkoane, B. B. M. Articles by Torto, N. Search for Related Content GeoRef GeoRef Citation

A multi-element study on metallophytes from mineralized areas in Botswana using ICP-AES and ICP-MS

¹ Department of Chemistry, University of Botswana, Private Bag UB 00704, Gaborone, Botswana (e-mail: nkoanebbm@hotmail.com or bonangn@gmail.com)
² Department of Chemistry, University of Oslo, PO Box 1033, N-0315 Oslo, Norway

A multi-element study was performed for metal-tolerant plants and the associated soils collected from four mineralized areas in Botswana using ICP-AES and ICP-MS. The elements were determined in the roots, stems and leaves of the three metallophytes, Blepharis aspera, Blepharis diversispina and Helichrysum candolleanum, previously known to accumulate Cu and Ni. The limits of detection (LOD) obtained for ICP-AES were in the ppm range while those for ICP-MS were down to sub-ppb level, allowing determination of elements in a wide concentration range.

Of the 62 elements studied, the following were found in higher concentrations than normal for plants: Al, Co, Cr, Cu, Fe and Ni in B. aspera; Al, Fe and Ti in B. diversispina; and Al, Ba, Cd, Cr, Cu, Fe, Ti and V in H. candolleanum. The rare earth elements (REEs) were also found in concentrations above normal for all plants: about one order of magnitude higher for the light REEs and two to three orders of magnitude for the heavy REEs. When the total contents of metals present in higher than normal amounts in the leaves were calculated, the concentrations were c. 0.3% for B. aspera, 0.1–0.2% for B. diversispina and 0.4–1% for H. candolleanum. When the macronutrient metals (Ca, Mg, Mn, K, Na, Si and Zn) were included, the leaf total metal burden was in the range 6–9% for B. diversispina and c. 3% for both H. candolleanum and B. aspera which grew side by side. The three plants showed different metal distribution patterns and levels. The elements that were found in the plants in amounts higher than normal also had elevated concentrations in the host soil.

KEYWORDS: Helichrysum candolleanum, Blepharis diversispina, Blepharis aspera, metallophytes, ICP-AES, ICP-MS, Botswana