Assessment of metal accumulation capacity of Dittrichia viscosa (L.) Greuter in two different Italian mine areas for contaminated soils remediation

The study aimed at assessing the capacity of Dittrichia viscosa (L.) Greuter to absorb and accumulate in its tissues some potentially harmful elements (PHEs), as Cd, Cu, Fe, Ni, Pb and Zn, in order to verify its possible use as phytoremediation in polluted mine soils. Plants from two different Italian mine areas, Montevecchio and Libiola, were considered and compared with plants from unpolluted areas. In each site (n = 21), both rhizospheric soil materials and D. viscosa plants were sampled, suitably prepared and analyzed. Soil samples were examined for both total composition (XRF) and bioavailable fractions (DTPA-extraction). Dittrichia viscosa roots, stems and leaves were analyzed separately to quantify the metal presence in the different plant parts. The root/soil ratio values calculated on the basis of the total soil concentrations, displayed a generally scarce capacity of D. viscosa to absorb soils PHEs, especially those more concentrated in the substrata. Concerning the root/soil ratio calculated on the basis of DTPA-extractable soil metals, values displayed instead a greater capacity of D. viscosa to absorb metals in the roots thus behaving as a potential phytostabilization plant in both mine areas. Regarding the leaf/root ratio, this species also displayed a greater capacity, in sub alkaline mine areas, to shift PHEs from roots to aboveground tissues, along with Ca transfer, revealing interesting characteristics for phytoextraction. In sub acid mine areas, this tendency was instead weaker and PHEs tended to be accumulated in all plant parts. Dittrichia viscosa seems to be appropriate for mine soil stabilization in both sub acid and sub alkaline environments and also for phytoextraction in the latter.