Phytoremediation is one of the most promising green methods for remediation of petroleum hydrocarbons (PHs) contaminated soil, while the remediation efficiencies and the key rhizospheric regulatory mechanisms exhibit significant variations across different plant taxa. To address this, four plant species were selected in this study for the remediation experiments of PHs contaminated soil. The results showed that the biomass of plants from the Liliaceae and Iridaceae families was higher than that from the Crassulaceae family, and the degradation rates of PHs followed the order: Hylotelephium spectabile (Boreau) H. Ohba (27.99%-44.61%) > Hemerocallis middendorfii Trautv. et Mey. (24.23%-44.53%) > Iris lactea Pall. (29.45%-36.48%) > Iris dichotoma Pall. (21.55%-31.54%). Further study indicated that plants from the Crassulaceae and Iridaceae families preferred to enrich Alcanivorax and other alkane-degrading bacteria in the rhizosphere, thereby enhancing the degradation of alkanes. Whereas plants from the Liliaceae family preferentially enriched Sphingomonas, leading to efficient removal of aromatic hydrocarbons. The relative abundances of alkB genes and PAH-RHDα genes were also quantified, which were confirmed to be significantly correlated with residual PHs in soil (p < 0.05). These findings provide technical guidance for the screening of efficient remediation plants and enrich the theoretical basis for research on phytoremediation mechanisms.
Chen et al. (Wed,) studied this question.