Geochemical behavior of engineered nanoparticles under biotic and abiotic processes

Engineered nanoparticles (ENPs) are inevitably released into the environment, causing health concerns due to their increased concentrations and negative impacts. In natural settings, organisms may encounter transformed ENPs due to their interactions with diverse environmental substances. While numerous reviews have discussed the environmental behavior and toxicity of ENPs, a comprehensive understanding of their transformation in the environment remains insufficient. This review focused on the behavior of ENPs and their transformations across various environmental compartments, including aggregation, oxidation, dissolution and vulcanization, which is essential for understanding their environmental fate, bioavailability and toxicity. The interactive mechanisms between both pristine and transformed ENPs and microorganisms or crop plants, as well as the negative and positive impacts of the transformed ENPs are discussed in details. Special emphasis is placed on the influence of ENPs on greenhouse gas emissions from microorganisms, the transformation of ENPs in crop plants, and the effects of root exudates on ENPs cycling. Through these discussions, we proposed several important considerations in the applications and implications of ENPs ​in the environment.