Effects of soil organic matter on biochar application in developing the biodegradation potentials of polycyclic aromatic hydrocarbons (PAHs)

Abstract

This study investigated polycyclic aromatic hydrocarbons (PAHs) removal with wheat straw–derived biochar prepared at 500 °C (WS500) in three different petroleum–contaminated soils. Biochar decreased the contents of PAHs, and its effect has been shown to be dependent upon soil type, especially the soil organic matter (SOM). WS500 exhibited strong adsorptive ability towards PAHs in Jingxing (JX) soil, while it enhanced the PAHs removal by adsorption in combination with biodegradation in Luquan (LQ) soil. No significant effect on PAHs removal was observed in WS500–amended Jinzhou (JZ) soil. PAHs with 4 rings were the most impacted by adding biochar. Principal Coordinates Analysis (PCoA) and clustering analysis indicated that microbial community's distribution was more soil type-related than biochar-related. Illumina MiSeq sequencing results revealed that Proteobacteria, Acidobacteria, Actinobacteria and Verrucomicrobia were the most dominant in all the investigated samples, and that most of the strains were Gram–negative. However, at the genus level a large shift in the bacterial community was observed in LQ soil after adding biochar with increased abundance of the potential PAHs degraders. Thus, the current study highlights the potential of SOM in affecting the PAHs biodegradation by biochar, which may be attributed to the impacted sorption behavior of pollutants and selective enrichment of PAHs degraders.