Assessment of fly ash-aided phytostabilisation of highly contaminated soils after an 8-year field trial

• DOI: 10.1016/j.scitotenv.2010.10.040
• Publication Date: 2010-11-24T09:25:49Z
• Authors: Alena Lopareva-Pohu; Bertrand Pourrut; Christophe Waterlot; Guillaume Garçon; Géraldine Bidar; Christelle Pruvot; Pirouz Shirali; Francis Douay
• Keywords: 15. Life on land; Coal Ash; Zea mays; 01 natural sciences; Carbon; 6. Clean water; Trace Elements; 12. Responsible consumption; Kinetics; Soil; Biodegradation, Environmental; Metals; Soil Pollutants; Particulate Matter; Triticum; 0105 earth and related environmental sciences

Sustainable management of large surface areas contaminated with trace elements is a real challenge, since currently applied remediation techniques are too expensive for these areas. Aided phytostabilisation appears to be a cost efficient technique to reduce metal mobility in contaminated soils and contaminated particle spread. In this context, this study aimed at evaluating the long-term efficiency of aided phytostabilisation on former agricultural soils highly contaminated with trace elements. The influence of afforestation and fly ash amendments to reduce metal mobility was investigated. Before being planted with a tree mix, the study site was divided into three plots: a reference plot with no amendment, the second amended with silico-aluminous fly ash and the third with sulfo-calcic fly ash. After eight years, some soil physico-chemical parameters, including cadmium (Cd), lead (Pb) and zinc (Zn) extractability were modified. In particular, pH decreased on the whole site while organic carbon content increased. The alteration of these parameters influencing trace element mobility is explained by afforestation. Over time, concentrations of CaCl(2)-extractable metals increased and were correlated with the soil pH decrease. In the amended soils, extractable Cd, Pb and Zn concentrations were lower than in the reference soil. The results indicated that the two fly ashes buffered natural soil acidification due to vegetation development and limited trace element mobility and thus could limit their bioavailability. For long-term phytostabilisation, special attention should be focused on the soil pH, metal mobility and phytoavailability analysis.