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Keywords:

  • cadmium (Cd);
  • dynamic analysis;
  • metal hyperaccumulation;
  • mineral nutrients;
  • nuclear microprobe;
  • Thlaspi praecox;
  • true elemental mapping;
  • X-ray micronalysis

Summary

  • • 
    Localization of cadmium (Cd) and other elements was studied in the leaves of the field-collected cadmium/zinc (Cd/Zn) hyperaccumulator Thlaspi praecox from an area polluted with heavy metals near a lead mine and smelter in Slovenia, using micro-PIXE (proton-induced X-ray emission).
  • • 
    The samples were prepared using cryofixation. Quantitative elemental maps and average concentrations in whole-leaf cross-sections and selected tissues were obtained.
  • • 
    Cd was preferentially localized in the lower epidermis (820 µg g−1 DW), vascular bundles and upper epidermis, whereas about twice the lower concentrations were found in the mesophyll.
  • • 
    Taking into account the large volume of the mesophyll compared with the epidermis, the mesophyll is indicated as a relatively large pool of Cd, possibly involved in Cd detoxification/dilution at the tissue and cellular level.