Assessment of Miscanthus × giganteus for rhizoremediation of long term PAH contaminated soils

The purpose of this study was to investigate the potential of Miscanthus × giganteus (M × G) for rhizoremediation of long term PAH-polluted soils. To evaluate its growth ability on contaminated substrates, a pot experiment was a pot experiment was conducted. Plant development was compared to that obtained in a reference soil. Pollutant dissipation with several other physico-chemical and microbiological parameters (including bacterial community diversity molecular analysis) were investigated in order to better characterize the rhizosphere effects of M × G. Field trials were also conducted to confirm the feasibility of crop installation in situ. Plants demonstrated a physiological adaptation to soils from various PAH contamination levels (from 26 to 364 mg PAH kg−1 dry soil) both in laboratory and in field scale conditions. Changes in rhizosphere bacterial community were observed via specific bacterial phylotype selection in the root vicinity. Despite the lack of conclusive trends for phytoremediation, slight decreases in total 4-ring PAH concentration would suggest a positive influence of growing plants in the long term. Furthermore, significant organic carbon inputs and nitrate losses were measured after 17 weeks of laboratory cultivation, indicating a global improvement of soil agronomic quality.

► Laboratory and field experiments confirm plant growth capacity on polluted soils.
► Specific bacterial phylotypes are selected in the rhizoplane of plants.
► Little evidence of total four-ring PAH dissipation after 17 weeks of cultivation.
► Input of organic carbon and decrease in nitrate indicate improvements of soil quality.