Research Progress on the Effects and Mechanisms of Mineralized Microbiota-Biochar in Soil Heavy Metal Remediation

Soil heavy metal pollution has become a serious environmental problem threatening the safe utilization of land resources and the sustainable development of agriculture. The combined remediation technology of mineralized microorganisms and biochar, as a green and efficient strategy for heavy metal pollution control, has attracted much attention in recent years. However, the intrinsic mechanism of their synergistic effect and the multi-factor interaction relationship have not yet been systematically clarified. Based on bibliometric analysis methods, this paper reviews the individual and combined action mechanisms of mineralizing microorganisms and biochar in the immobilization of heavy metals in soil. It focuses on analyzing the morphological transformation pathways of heavy metals, the regulatory effects of soil microenvironment, and key influencing factors, and assesses their practical application potential and challenges. The literature review indicates that mineralizing microorganisms mainly promote the transformation of heavy metals to stable forms through processes such as biomineralization, extracellular complexation and biotransformation. Biochar achieves efficient adsorption and fixation of heavy metals by virtue of its high specific surface area, rich functional groups and porous structure, while optimizing the physical and chemical properties of soil. The synergy of the two can significantly promote the transformation of heavy metals from the available state to the residual state and the organically bound state, enhance the soil pH and REDOX potential regulation capacity, increase the metabolic activity and colonization efficiency of microorganisms, and the remediation effect is significantly better than that of single treatment. This synergistic effect is jointly influenced by multiple factors such as the characteristics of biochar, the metabolic activity of microorganisms, the types and forms of heavy metals, and soil environmental conditions. At present, this combined technology has been applied in the demonstration of farmland and complex contaminated site remediation, which can reduce the heavy metal content in crops by more than half. However, it still faces challenges such as limited environmental adaptability, high cost for large-scale application, and uncertain long-term stability. Future research should focus on the targeted construction of functional strains and modified biochar, deepen the analysis of microscopic molecular mechanisms, promote the establishment of multi-technology integration and standardized application systems, and provide theoretical basis and technical solutions for the efficient and green remediation of soil heavy metal pollution.