Insights into ecotoxicity effects of PAHs and ecosystem responses of remediation strategies under cold stress: From PAHs degradation to ecological restoration regulated by signal molecular

Abstract

Polycyclic aromatic hydrocarbons (PAHs) known as persistent contaminants have been detected in soils worldwide, especially in cryogenic environment. Although researchers have conducted lots of researches on PAHs, the ecological toxicity of PAHs and the remediation mechanism of PAHs polluted soils under low temperature are still unclear. Herein, we attempted to characterize remediation of PAHs polluted environment by coupling the PAH degradation with ecological restoration. PAHs could not degrade completely in natural and multiple metabolites accumulate in soil under low temperature. Long-term accumulation of pollutants could cause severe oxidative stress, inhibit the growth of plants and normal process and transformation of substances of microorganisms, while increased the relative abundance of PAHs degrading bacteria (Sphingobacterium, Pseudomonas, Rhodococcus and Massilia etc) and degradation genes (nidA nidB, nahAa, nahAb, nahAc, nidD, phdJ and phdG). As soil amendents, biochar, microbial agent, biochar together with microbial agent could remove 75%, 83%, and 93% of PAHs from soil, and 47%, 50%, and 58% of PAHs from plants, respectively. Under the bioaugmentation of soil amendments, soil microorganisms played an important role in PAHs degradation and ecological restoration. Meanwhile, we identified three signal molecules related to ecological restoration which play a crucial role in regulating pollution removal and ecological restoration by indigenous microorganisms. OOHL and C10-HSL are involved in environmental resistance, degradation of PAHs and transformation of nutrients. 3-oxo-C14-HSL promoted the degradation of PAHs and cold adaption of microorganism. Our study provided an innovative strategy for controlling PAHs degradation and ecological restoration from the perspective of microbial transboundary informatics.