Effect of rhizodeposition on alterations of soil structure and microbial community in pyrene-lead co-contaminated soils

Rhizodeposition is considered as a main strategy for plants to regulate its rhizospheric microorganisms. However, effect of rhizodeposition on degradation of polycyclic aromatic hydrocarbons (PAHs), and the alterations of soil structure and microbial community are still unclear, especially in metal-PAHs co-contaminated soils. The study focused on illustrating the microcosm changed by rhizodeposition to find out the dominating factors for the dissipation of pyrene. The analysis results with Fourier transform infrared spectroscopy (FT-IR) showed that the relative abundance of some functional groups in humic acids was amplified by rhizodeposition effect. A result was observed that soluble fraction of lead was rapidly transformed into other fractions by the rhizodeposits. It was found that the rhizodeposition effect exhibited considerable improvement in the degradation of pyrene especially in the lead-pyrene co-contaminated soils. Phospholipid fatty acid analysis (PLFA) showed substantial differences in microbial communities between incubation time and rhizodeposition effect. The studied results further revealed the removal mechanism of pyrene in pyrene-lead co-contaminated soils.