Utilization of SiO2-NP-modified biochar from invasive plants to mitigate heavy metal stress in Allium hookeri
Minmin Su, Haowen Tian, Zicheng Guo, GuiJuan Luo, Xu gong, Xueer Li, Hongyan Yan, Linchong Shen, Sanwei Yang, Tengyuan He, Guandi He
Abstract
Guizhou's karst geology facilitates the accumulation of heavy metals in Allium hookeri , raising significant concerns for food safety and human health. Concurrently, the proliferation of invasive species such as Sonchus oleraceus L. (a terrestrial plant) and Myriophyllum verticillatum L. (an aquatic plant) exacerbates ecological challenges. This study explores a novel approach to address these issues by focusing on four interconnected aspects: biochar production from invasive plants, nanosilica modification, chive cultivation, and soil improvement. The findings reveal that silicon modification increased the mass fraction of silicon in biochar derived from a terrestrial plant (Si-KBC) and an aquatic plant (Si-HBC) by 9.10 % and 4.67 %, respectively. Compared to KBC, Si-KBC enhanced chlorophyll A by 1.07 mg/g, chlorophyll B by 0.5 mg/g, and total chlorophyll by 1.57 mg/g. The proportion of leaf tip superoxide anion (O 2 - ) staining decreased to 18 % (48 % lower than CK). Terrestrial Si-KBC significantly increased chlorophyll A , chlorophyll B, and chlorophyll T by 0.57, 0.32, and 0.89 mg/g, respectively, compared to aquatic Si-HBC. Growth indicators for Si-KBC, HBC, and Si-HBC exceeded those of CK and KBC. Regarding heavy metal passivation and soil improvement, Si-HBC is most suitable for yellow soil contaminated by the combined presence of Cd, Cu, and Pb, while HBC is best suited for the remediation of Fe and Zn contaminated brown soil. In summary, silica-modified biochar mitigates heavy metal toxicity in polluted soils and reduces heavy metal accumulation in Allium hookeri . This research provides novel silicon-rich biochar conditioners and application guidelines for various contaminated soil types.