Microplastic-mediated interactions with antibiotics and antibiotic resistance genes in sludge: combined effects and environmental implications

Microplastics, antibiotics and antibiotic resistance genes (ARGs) are widely detected in sludge, and their interactions become a topic of research interest in recent years. This paper firstly summarized the occurrence of microplastics, antibiotics and ARGs, and their combined pollution in sludge. Although the concentrations of these pollutants varied significantly in sludge environments, their frequent detection suggested serious combined pollution. Then, the interactions between microplastics, antibiotics and ARGs and their key mechanisms were emphatically revealed, where their interactions were mainly controlled by hydrogen bonding, hydrophobic and electrostatic interactions. Additionally, the biofilm formation crucially affected the interactions between microplastics and ARGs. The interaction potentials were influenced by multiple factors, mostly by the intrinsic properties (functional groups and structure) of pollutants and the surrounding environments (pH and ionic strength, etc.). Finally, the ecological risks of single and combined pollutants when sludge entered the soil were discussed, which negatively affected the soil microorganisms, plants and animals, and even element cycling in the biogeochemical process. The review paper summarized the interaction and combined risks of ternary pollutants-microplastics, antibiotics, and ARGs, and highlighted the notable concerns in the terrestrial environment.