Influence of fly ash aided phytostabilisation of Pb, Cd and Zn highly contaminated site on tree species oxidative stress.
Résumé
Combined use of in situ stabilization and energy production from forest biomass is a cost
effective technique being explored to confront the problem of phytomanagement of metal
contaminated sites. Between different amendments studied, Coil Fly Ash (CFA) has been shown
to reduce metals mobility and to limit physico-chemical characteristics modifications of the soils
due to the afforestation. Moreover, others studies revealed CFA efficiency to impair metal
accumulation and to alleviate stress in several plants species. However, little is known about the
plant health promoting action of these amendments, especially benefits on tree species growing
in TEs polluted sites. This in situ study aimed at evaluating the long-term effects of CFA as
metal immobilizing agent in aided phytostabilization of a former agricultural field highly
contaminated with cadmium, lead and zinc, affected by the activity of the Metaleurop Nord
smelter (Noyelles-Godault, North of France), using four tree species (Alnus glutinosa L., Acer
pseudoplatanus L., Salix Alba L., and Robinia pseudoacacia L.). Before being planted with a
tree mix in 2000, the site was divided in a reference plot (R) with no amendment and two plots
amended with silico-aluminos (FA1) and sulfo-calcic fly ash (FA2). Eleven years after plantation,
antioxidants systems (glutathione status, superoxide dismutase and peroxidase activities) and
oxidative damages (malondialdehyde production and 8- hydroxydeoxyguanosine formation) in
leaves were monitored as biological indicators of the trees health. Metallic stress was also
evaluated by analysis of lipid composition and content, the determination of saturated fatty
acids/ insaturated fatty acids ratio and omega 3 index: C18:3/(C18:0+C18:1+C18:2). Taken
together, information on physiological response of trees to metallic pollution will help us to select
species and soil amendments suitable for the phytoremediation of the experimental site.