Black carbon derived from pyrolysis of maize straw and polystyrene microplastics affects soil biodiversity

Understanding the environmental correlation of microbial community under external stimulation is significant for ecological restoration. However, few studies focused on the response of soil biodiversity induced by black carbon (BC) derived from pyrolysis of straw and microplastics (MPs) due to their widespread existence in natural environment. In this study, polystyrene MPs (PS) and maize straw with different mass ratios were used as raw materials to prepare BC by pyrolysis. The surface morphology, chemical composition and sequential variations of different functional groups of BC were systematically analyzed. The leachate from BC was identified by three-dimensional excitation emission matrice (3D-EEM). The corresponding results showed that yield, value of O/C and N element content of BC decreased with more PS. The changed C content and oxygen-containing functional groups occurred. The order of functional groups of BC formed by co-pyrolysis was: C=C > C-O > C-H > Si-O-Si. The main component of leaching from BC was humic-like and fulvic-like acid. Simultaneously, the input of exogenous BC into soil affected abundance, composition and metabolic pathways of microorganisms. The study helps to understand environmental implication of BC which was pyrolyzed from maize straw and MPs, providing an idea for improving biogeochemical cycle process in soil.