Microplastics (MPs) and cadmium (Cd) are widely distributed in soil ecosystems, posing a potential threat to agricultural production and human health. However, the coupled effects of MPs and Cd in soil-plant systems remain largely unknown, especially on a large scale. In this study, a meta-analysis was conducted to evaluate the influence of MPs on plant growth and Cd accumulation under the Cd contamination conditions. Our results showed that MPs had significantly negative effects on shoot biomass (a decrease of 11.8 %) and root biomass (a decrease of 8.79 %). MPs also significantly increased Cd accumulation in the shoots and roots by 14.6 % and 13.5 %, respectively, revealing that MPs promote plant Cd uptake. Notably, polyethylene displayed a stronger promoting effect (an increase of 29.4 %) on Cd accumulation among these MP types. MPs induced a significantly increase (9.75 %) in concentration of soil available Cd and a slight decrease in soil pH, which may be the main driver promoting plant Cd uptake. MP addition posed physiological toxicity risks to plants by inhibiting photosynthesis and enhancing oxidative damage, directly demonstrating that MPs in combination with Cd can pose synergetic toxicity risks to plants. We further noted that MPs altered microbial diversity, likely influencing Cd bioavailability in soil-plant systems. Overall, our study has important implications for the combined impacts of Cd and MPs on plants and provides new insights into developing guidelines for the sustainable use of MPs in agriculture.

Soil contamination by uranium presents a burgeoning global environmental concern, exerting detrimental effects on both agricultural production and soil health. Biochar, a carbonaceous material derived from biomass pyrolysis, exhibits considerable potential for remediating uranium-contaminated soils. However, a comprehensive review of the effects of biochar on the fate and accumulation of uranium in soil–plant systems remains conspicuously absent. In this paper, uranium sources and contamination are reviewed, and the impact of biochar on uranium immobilization and detoxification in soil–plant systems is analyzed. We reviewed the status of uranium contamination in soils globally and found that mining activities are currently the main sources. Further meta-analysis revealed that biochar addition significantly reduced the soil uranium bioavailability and shoot uranium accumulation, and their effect value is 58.9% (40.8–76.8%) and 39.7% (15.7–63.8%), respectively. Additionally, biochar enhances the soil microenvironment, providing favourable conditions for promoting plant growth and reducing uranium mobility. We focused on the mechanisms governing the interaction between biochar and uranium, emphasising the considerable roles played by surface complexation, reduction, ion exchange, and physical adsorption. The modification of biochar by intensifying these mechanisms can promote uranium immobilisation in soils. Finally, biochar alleviates oxidative stress and reduces uranium accumulation in plant tissues, thereby mitigating the adverse effects of uranium on plant growth and development. Overall, our review highlights the capacity of biochar to remediate uranium contamination in soil–plant systems through diverse mechanisms, providing valuable insights for sustainable environmental remediation.Highlights Biochar reduces uranium mobility through a variety of mechanisms, including surface complexation, reduction, ion exchange, and physical adsorption. Biochar significantly reduces uranium bioavailability in soil and limits its accumulation in plants. Modified biochar has been shown to enhance its effectiveness in immobilising uranium. Biochar application to soil not only promotes uranium remediation but also improves soil quality. Graphical Abstract