Biochar from invasive weed shields rice from toxic nanoplastics and heavy metals

A team of scientists has found that biochar made from an aggressive invasive plant can protect rice from two modern pollutants that threaten global food security: nanoplastics and cadmium. The study, published in Biochar, reveals how biochar biofilters derived from Mikania micrantha, an invasive vine spreading across Asia, can reduce the combined toxicity of these contaminants by regulating plant metabolism and strengthening rice’s natural defense systems.

Nanoplastics, the tiny fragments of degraded plastics, and cadmium, a persistent heavy metal, frequently coexist in agricultural soils and water. Their combined effects are more harmful than either pollutant alone, disrupting photosynthesis, root growth, and cellular structures in crops. In the new research, rice plants exposed to both pollutants suffered a 16 percent loss in biomass. However, when grown with the Mikania biochar biofilter, biomass increased by more than 80 percent, and chlorophyll and protein levels were significantly restored.

Microscopic imaging showed that nanoplastics were able to penetrate rice roots under cadmium stress, acting as carriers that transported the metal deep into plant tissues. The biochar biofilter formed a physical and chemical barrier, trapping the pollutants and reducing their movement within the plant. The biochar also enhanced the rice’s antioxidant activity and gene expression related to stress defense, helping maintain healthier root and leaf cell structures.

Further biochemical and metabolomic analyses revealed that biochar-treated plants had better nutrient balance and more stable energy cycles, including improved nitrogen transport and tricarboxylic acid (TCA) pathways. In contrast, nanoplastics interfered with hormone signaling and ATP-binding transporters, intensifying cadmium uptake and toxicity.

The findings point to an innovative, sustainable strategy for mitigating pollution in farmlands. Using an invasive weed to produce biochar not only converts ecological waste into a useful soil amendment but also offers a low-cost solution for protecting crops from emerging contaminants. The researchers say the dual benefit, controlling an invasive species while improving soil and plant health, could be valuable for cleaner and safer food production systems.

The study underscores the potential of biochar biofilters as a green technology to combat the intertwined challenges of plastic pollution, heavy metal contamination, and invasive plant management in agriculture.

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Journal Reference: Rana, M.S., Ren, R., Imran, M. et al. Mitigating combined internalized toxicity of nanoplastics and cadmium in rice through metabolic and biochemical regulations under supply of biochar biofilters derived from Mikania Micrantha. Biochar 7, 98 (2025). https://doi.org/10.1007/s42773-025-00488-6  

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About Biochar

Biochar is the first journal dedicated exclusively to biochar research, spanning agronomy, environmental science, and materials science. It publishes original studies on biochar production, processing, and applications—such as bioenergy, environmental remediation, soil enhancement, climate mitigation, water treatment, and sustainability analysis. The journal serves as an innovative and professional platform for global researchers to share advances in this rapidly expanding field. 

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