Accumulation of heavy metals in phytoliths from reeds growing on mining environments in Southern Europe

In Southern Europe, soil contamination by heavy metals (HM) due W mining and industrial activities is a lung 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 dorm) or common recd (Phrugmites austrulis) are capable of accumulating subsLintial 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 he 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 Phi agmites 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. (C) 2019 Elsevier B.V. All rights reserved.