In this study we focused not only on the absolute concentrations of
Pb in plant tissues, but also on the translocation and bioaccumulation
factors that were calculated as they are the usual criteria to highlight
phytoremediator plant species. Table 4 presents the TF and BCF for
each species at each site. To categorize results, TF N 1 indicates that
plant translocatesmetals effectively fromroot to shoots; BCF N 10 indicates
hyper-accumulator species, BCF N 1 means accumulator species,
and BCF b 1 points excluder species (Bu-Olayan and Thomas, 2009).
Consequently, almost all of the species studied behave as effective Pb
translocators from roots to shoots when soils are not polluted
(TF N 1 at sites 8, 9 and 10). Taking into account the BCF, most species
presented higher BCF at non-polluted sites (BCF8, 9 and 10 N BCF1–5),
none of thembehaved as hyper-accumulators, fewdid as accumulators,
and most of them were excluder species. These translocation and accumulation
capabilities are limited by increased Pb content in soils, so
those species behave as excluder in polluted soils.Whereby, these species
can be considered as good candidates for phytostabilization, mainly
S. halepense, due to the high tolerance demonstrated in this study,
preventing a metal transfer to the food web. This is an important result;
as it was pointed by Närhi et al. (2012) recognition of plant species
that tolerate high concentration of toxic elements is essential to
phytostabilize them.