Utilization of X-ray radiography and femtosecond Laser Induced Breakdown Spectroscopy (fs-LIBS) for monitoring of the heavy-metal hyperaccumulation in vegetal tissues

conference paper

English

Very promising and natural method for detection and subsequent removal of the (toxic) metals accumulated in the environment seems to be the phytoremediation [1]. This technique is based on the removal of the contaminants by means of their absorption in the above-ground part of the plants, specially cultivated for this purpose and then harvested and liquidated properly [2]. In order to select appropriate species for environmental-cleaning and to minimize the possibility to transfer the toxic elements into the human body through the food-chain, detailed study of the exact mechanism of phytoremediation is needed. The study of these problems presents various aspects, and consists in the detection of contaminants, in the comparison of accumulation properties of the various plants and in the mapping of possible biological structures, which can specifically accumulate metals within a given tissue. Among the different diagnostic techniques for metal-detection in vegetal tissues here we are focusing on two particular one – X-ray radiography (using synchrotron radiation) and Laser Induced Breakdown Spectroscopy (LIBS). A monochromatic synchrotron radiation beam allows to select a very thin spectral range and, by a specific optical set-up, to localize in the observed sample the absorption of a given chemical element. This possibility has greatly enhanced the interest of microscopic elemental analysis. X-rays from a synchrotron are in an energy range much higher than the energy of chemical bonds (typically of the order of few eV), so that the absorbing electrons are the K or L, M… electrons. Since this absorption is independent from any chemical bond, an absorption measurement can give directly the number of contaminant atoms/cm which are present in the sample [3]. Here we report on the results of dual-energy X-ray micro-radiography and micro-tomography experiments at ELETTRA Synchrotron, Trieste (Italy). 2 The capability of the LIBS technique for direct determination of Pb, Al, Ca, Cu, Mn, Zn, Mg and Fe in plant materials was shown already in 1999 for powdered leaves of different plants [4]. More recently the possibility of high-spatial resolution analysis on Helianthus annuus leaf was presented [5]. Presently this technique is capable of in situ heavy metal detection with sub-micron spatial-resolution. Here we report on a possible utilization of LIBS for preliminary qualification of a big number of 2D (leaf) samples. Literature [1] Lasat M.M.: J. Environ. Qual. 31, 2002, 109 [2] Kramer U. et al.: Appl. Microbiol. Biotech. 55, 2001, 661 [3] Kaiser J. et al.: Europ. Phys. J. D 32, 2005, 113 [4]Sun Q. et al.: Canadian J. Analytical Sci. Spectr. 44, 1999, 164 [5]Assion A. et al.: Appl. Phys. B 77, 2003, 391 Acknowledgements This work was supported by the Ministry of Education of Czech Republic (grant MSM0021630508).

X-ray radiography, femtosecond Laser Induced Breakdown Spectroscopy (fs-LIBS), heavy-metal hyperaccumulation in vegetal tissues

J. KAISER, L. REALE, M. LIŠKA, O. SAMEK, A. POMA, A. TUCCI, L. MANCINI, G. TROMBA, R. MALINA, K. PÁLENÍKOVÁ

2006

20. 5. 2006

ICTP Trieste

Trieste, Italy

36

36

1

http://www.elettra.trieste.it/xri2006/Brochure_XRI3CTP2006.pdf