Distribution of Metals and Cell Wall Compounds in Leaf Parts of Three Tree Species Suitable for the Phytomanagement of Heavy Metal–Contaminated Soils

Abstract

Phytomanagement used on soils contaminated with metals aims to stabilize them in the soil. It generally uses less demanding tree species such as maple, poplar, and black locust. However, it is important to consider the rate of accumulation of metals in the leaves as well as their location (leaf blade/petiole) together with the contents of cell wall compounds (hemicelluloses, cellulose, lignin). These two aspects are likely not only to have repercussions on the decomposition of litter but also to lead to a possible transfer of metal contamination into the food chain via soil decomposers/detritivorous. A successful phytoremediation is therefore the result of compromise: no tree species can meet all these criteria. The results obtained show that poplar is not recommended due to a high accumulation of Cd and Zn. The most appropriate species among our 3 studied species, which seem the most suitable in terms of remediation of metal polluted soils, could be the black locust and the maple which are less susceptible to contribute to the transfer of exogenous metals such as Cd to the trophic chain. However, maple strongly accumulates Pb in the leaf blade and it is susceptible to degrade quickly due to its high hemicelluloses and cellulose contents and low lignin content. The black locust accumulates metals mainly in the petiole (little consumed by detritivorous). However, its exotic character and high lignin content may limit the interest of its use.