Elemental uptake and root-leaves transfer in Cistus ladanifer L. growing in a contaminated pyrite mining area (Aljustrel-Portugal)

Soils at the contaminated Aljustrel mining area situated in SW Portugal in the Iberian Pyrite Belt, and Cistus ladanifer L., an autochthonal aromatic bush, were investigated to quantify the most relevant elements present in soils and in the plant, and to evaluate the possibility of phytore-mediation of that area, particularly concerning the elements of higher pollutant potential. Multielemental (Mg, S, Cl, K, Ca, Cr, Mn, Fe, Cu, Zn, As, Br and Pb) characterisation of the soils and C. ladanifer leaves was carried out by Energy-Dispersive X-Ray Fluorescence spectrometry (EDXRF). Subsequently, due to their abundance in the soil and significant elevation compared to the control site, potential toxicity and/or biological significance, Mn, Cu, Zn, and Pb were determined by Atomic Absorption Spectrometry (AAS) in samples of soils, as well as in the roots and leaves of plants. C. ladanifer is able to survive and grow in soils having high concentrations of such toxic elements and to accumulate Mn. The bioavailability of Mn, Cu, Zn and Pb in the soils was evaluated by determining the contents of the elements in a solution of 0.5 M ammonium acetate, 0.5 M acetic acid and 0.02 M EDTA, pH 4.7, after soil extraction. Comparison of the values obtained with the corresponding element concentration in leaves give us a model of C. ladanifer's capacity to avoid these metals to reach toxic levels in the plant or their toxic effects when such levels are exceed, as in the case of Mn.