Phytoremediation potential of Juncus subsecundus in soils contaminated with cadmium and polynuclear aromatic hydrocarbons (PAHs)

A phytoremediation potential of emergent wetland species may be influenced by co-contamination by metals and polynuclear aromatic hydrocarbons (PAHs) in soils. A glasshouse experiment was conducted to investigate effects of Cd (0, 5, 10 and 20 mg kg− 1) without or with PAHs (50 + 50 mg kg− 1 with phenanthrene + pyrene in 1:1 proportion) on growth of Juncus subsecundus, removal of pollutant from soils and the abundance of PAH-degrading bacteria in the rhizosphere/non-rhizosphere. After 10 weeks, plant growth and biomass were significantly influenced by interaction of Cd and PAHs. The shoot concentration of Cd significantly increased by Cd additions, but not by PAHs (except at Cd treatment of 20 mg kg− 1). Cadmium accumulation and removal (except for Cd removal at 20 mg Cd kg− 1) by plants was significantly higher in Cd treatments with than without PAHs, whereas accumulation of PAHs by plants (except for pyrene in roots at 0 added Cd) and dissipation of PAHs from soils were not significantly influenced by Cd additions. The abundance of PAH-degrading bacteria in soil increased significantly in Cd treatments with PAHs, particularly in the rhizosphere. The results indicate that it is feasible to use wetland species for phytoremediation of soil co-contaminated with Cd and PAHs, but further work in naturally contaminated soils under field conditions is needed.