Influence of inoculating earthworms on removal of pyrene in soils growing Festuca arundinacea

The aim of this study was to examine the potential of inoculating earthworms (Pheretima sp.) in order to enhance phytoremediation of polycyclic aromatic hydrocarbons (PAH) present in soils with the use of tall fescue (Festuca arundinacea). In particular, experiments with or without inoculating earthworms for removal of pyrene was investigated. Results showed that planting of F. arundinacea enhanced the removal of pyrene at initial content over 70 days approximately 54%-80% but only 12%-24% occurred in non-planted soils. After inoculating earthworms, the dissipation rates of pyrene in planted soils were increased up to 61%-86%, which was 6%-12% higher than those in corresponding soils without inoculating earthworms. Among all possible pathways, the contribution of plant-microbial interactions on removal of pyrene was predominant, either with (46%) or without inoculating earthworms (52%), is the primary mechanism of contaminant removal. Data suggest inoculating earthworms may be a feasible way for reinforcing removal of PAH in contaminated sites.