Influence of root components of celery on pyrene bioaccessibility, soil enzymes and microbial communities in pyrene and pyrene-diesel spiked soils

Though phytoremediation is deemed as a promising approach to restore polycyclic aromatic hydrocarbon (PAHs) contaminated sites, studies about how the biodegradation of PAHs is enhanced still remains incomprehensive. Effects of root components on pyrene bioaccessibility, soil enzymes and microbial communities were explored in the paper, and their interactions in simulated pyrene and pyrene-diesel spiked microcosms were tried to give a reasonable explanation. Results indicated that root components enhanced the pyrene removal of bioaccessible and adsorbed fractions by 16.10 and 1.80 mg kg^− 1, respectively, in pyrene-spiked soils at the end of the experiment. By contrast, root components increased the degradation of bioaccessible fraction by only 3.3 mg kg^− 1 in pyrene-diesel spiked soils. Although the bound fractions of pyrene increased over time in treatments without root components, they remained relatively stable, ranging from 0.02 to 0.03 mg kg^− 1, in root components amended treatments. Activities of soil enzymes (polyphenol oxidase, catalase, invertase, urease and alkaline phosphatase) varied differently in response to pollutants and root components. Analysis of phospholipid fatty acids revealed that root components increased the biomass of soil microorganisms and altered the microbial structure. Pearson correlation analysis proved positive correlations between all the microbial subgroups and pyrene removal in pyrene-spiked soils, but the degradation of bioaccessible pyrene was only positively related with microorganisms confirmed by monounsaturated fatty acids in pyrene-diesel spiked soils.