Effects of composite electron acceptors on soil benzopyrene removal and bacterial community structure

Microbial metabolism of PAHs under anaerobic conditions depends on appropriate electron acceptors. Current research shows that the same electron acceptor has different degradation-promoting effects on different PAHs. On the other hand, different electron acceptors promote the degradation of the same PAHs differently, not always in line with their redox potential order (NO3-> Fe3+ > SO42-> CO2), and will change with environmental conditions . It can be seen that there may be some optimal matching association between environmental factors, PAHs and electron acceptor types, but the mechanism behind this is still unclear. The existing studies on anaerobic degradation of soil PAHs mainly focus on the reduction system constructed by a single electron acceptor, while the related research on composite reduction system is still rare. The results of the previous chapter show that the addition of denitrifying electron acceptors promotes the removal of low molecular weight PAH (phenanthrene) in soil than high molecular weight benzopyrene. In view of this, anaerobic soil culture experiments without electron acceptors, single electron acceptors, and composite electron acceptors (including sulfate reduction inhibitor treatment) are carried out for high molecular weight PAH (benzopyrene) and electron acceptors commonly found in the environment (nitrate and sulfate). The objective was to compare the promotion effects of single and composite electron acceptors on anaerobic removal of soil benzopyrene. The potential contribution of single electron acceptors in soil PAHs removal under the composite reduction system was preliminarily evaluated, and the possible microbial mechanisms were revealed at the community level.