<p class="first" id="d2993346e117">In Southern Europe, soil contamination by heavy
metals (HM) due to mining and industrial
activities is a long-known problem. Yet, despite soils being widely contaminated through
decades, some plants are still able to grow. Some of these plants, like giant reed
(Arundo donax) or common reed (Phragmites australis) are capable of accumulating substantial
amount of HM. These reeds also contain small silica structures in their shoots, called
phytoliths. However, the role of phytoliths in reducing stress caused by these HM
remains unknown. The aim of this work is then to determine if phytoliths represent
a preferential structure for the bioacccumulation of HM in plants. Therefore, plants
from mining-contaminated sites in Spain and France were sampled and HM concentrations
in total plant shoots were compared to those in phytoliths for eight metal(oid)s:
As, Cd, Cu, Mn, Pb, Sb, Sn and Zn. Results show that Arundo donax and Phragmites australis
tend to accumulate Cd, Sb and Sn but limit the uptake of As, Cu, Mn, Pb and Zn in
plant shoots despite that the concentration of these HM in soil is quite high. Therefore,
reeds appear as tolerant to high metal concentrations in soils, and phytoliths are
identified as preferential structures for encapsulation of As, Cu, Mn, Pb and Zn,
while Cd, Sb and Sn were mainly found to be accumulated in organic tissues rather
than in phytoliths.
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