Effects of nanoplastics and compound pollutants containing nanoplastics on plants, microorganisms and rhizosphere systems: A review

Nanoplastics (NPs) are the most widespread and least detectable type of plastic pollutant due to their extremely small particle size. The root system of plants has become an important pathway for NPs to enter the food chain from the natural environment. By combining with heavy metals or organic pollutants, NPs can exhibit greater biological toxicity compared to single pollutants. Although many studies have focused on the phytotoxicity and microbial toxicity of NPs separately, to the best of our knowledge, no review summarizes the toxicity of NPs from the perspective of the plant rhizosphere system with a combination of pollutants. By summarizing samples from 2015 to 2025, this review highlights that NPs can affect photosynthesis, gene transcription, and enzyme activity in both plants and microorganisms. NPs with large particle size can also disrupt the chemical balance of the rhizosphere environment and intensify competition for nutrients between plants and microorganisms, ultimately affecting the geochemical cycle. NPs of different particle sizes and concentrations can poison various biological structures, from surface layers to genetic material. In compound pollutants, where NPs combine with other contaminants, they can further disrupt elemental cycles in plants, reduce microbial community diversity, and increase the accumulation of other pollutants in the rhizosphere system compared to single pollutants. These findings provide new insights into the biotoxicity of NPs and the degradation of compound pollutants containing NPs. In addition, combined with the research results of this review, some research prospects on the relationship between NPs and rhizosphere systems are given.