Role of Fe-based nanoparticles introduced into soil–plant systems or contaminated soil–plant systems: toxic substance or remediation agent?

Iron-based nanoparticles (Fe-NPs) exhibit promising potential for soil remediation. However, their toxic effects on plants have also been reported. Typical Fe-NPs have been introduced into soil–plant systems to examine their possible nanotoxicity and other impacts on plants, while Fe-NPs have been added to pollutant–soil–plant systems to evaluate their performance as remediation agents. Mixed opinions and results have been reported regarding interactions between Fe-NPs and soil or plants. Here, meta-analysis was conducted to evaluate the effects of Fe-NPs on plant morphological and physiological characteristics in soil–plant and pollutant–soil–plant systems. Interestingly, morphological characteristics (dry and fresh weight) were significantly improved by Fe-NPs in both soil–plant and pollutant–soil–plant systems. In terms of plant physiological characteristics, Fe-NPs exerted negative effects on plant pigments in soil–plant systems, but positive effects in pollutant–soil–plant systems. In addition, Fe-NPs greatly increased the Fe contents and decreased the pollutant contents of plants. This study also provides a comprehensive review of the positive and negative effects of Fe-NPs on soil-plant systems and summarizes the pollutant remediation mechanisms of Fe-NPs in soil–plant systems. The results underscore the potential of Fe-NPs in agricultural applications and the future development of food safety.