Effect of biochar amendments on As and Pb mobility and phytoavailability in contaminated mine technosols phytoremediated by SalixReport as inadecuate

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1 LBLGC - Laboratoire de Biologie des Ligneux et des Grandes Cultures 2 ISTO - Institut des Sciences de la Terre d-Orléans - UMR7327

Abstract : Mining activities lead to widespread environmental pollution of terrestrial ecosystems due to the presence of metalloids in tailings. These contaminated areas present a health risk and hence need to be rehabilitated. Ex situ methods for soil remediation have been used for a long time but are expensive and disruptive to soil. Phytoremediation techniques for the stabilization or extraction of metalloids could be an efficient alternative as they provide a low-cost and environmentally friendly option. However, due to the often poor nutrient content of these contaminated soils, amendments must be added to enhance plant growth and to improve phytoremediation efficiency. Biochar, a pyrogenic product, is a promising amendment for assisted phytoremediation. The aims of our study were i to evaluate the effect of a pinewood biochar on the physicochemical properties of a former mine contaminated technosol, ii to assess the mobility and phytoavailability of As and Pb and iii to investigate the remediation potential of three willow species Salix alba, Salix viminalis and Salix purpurea. A greenhouse experiment was conducted with contaminated technosols amended with biochar and garden soil, single or combined, revegetated with the 3 willow species. The physicochemical properties of soil pore water SPW as well as metalloid concentrations were determined. Plant growth, Salix organ dry weight and metalloid uptake were determined in order to evaluate the phytoremediation potential of the three Salix species studied. Biochar increased the pH and electrical conductivity of SPW. Biochar addition had no effect on As mobility but decreased SPW Pb concentration by 70%. For the three Salix species investigated, biochar addition to the polluted soil induced a better growth and a higher dry weight production. In most modalities tested, the metalloid content in the Salix organs increased due to the biochar application. Globally, a positive effect of biochar was noticed on the soil qualities pH and electrical conductivity increase and plant growth. Metalloids were mostly confined to the roots. Among the species tested, Salix alba presented the lowest metalloid concentrations in the aerial parts, making it a particularly suitable tool for Pb soil phytostabilization.

Keywords : Phytoremediation Technosol Willow Biochar Metalloids

Author: Manhattan Lebrun - Carmelo Macri - Florie Miard - Nour Hattab-Hambli - Mikael Motelica-Heino - Domenico Morabito - Sylvain Bourge

Source: https://hal.archives-ouvertes.fr/


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