Effect of Biochar and Metal Resistant Bacteria on Heavy Metals Homeostasis of Selected Crops

Abstract

Biochar, a versatile material with immense potential in environmental applications, has been at the forefront of recent research endeavors. In our study, an innovative approach was used to transform parthenium weed-derived raw biochar into electromagnetic biochar (EM) through electrolysis and Fe2+ co-precipitation. This electromagnetic biochar exhibited increased magnetism, surface area, and modified surface chemistry, enabling it to adsorb 73% more Cd from industrial wastewater compared to its raw biochar (RB). The adsorption kinetics pointed to chemical interactions, possibly chelation, as the driving force behind this efficacy. Moreover, the electromagnetic biochar demonstrated exceptional stability in extreme aquatic conditions, underlining its promise as a Cd-removal tool. In another investigation, we enhanced biochar's adsorption capacity by immersing it in nitric acid (NB), resulting in enhanced oxygenated functional groups, porosity, and surface area. This modified biochar exhibited an 84% increase in Pb adsorption and a 77% increase in Cd adsorption compared to RB. The accelerated adsorption kinetics demonstrated the effectiveness of this novel approach, with potential applications in rapid heavy metal removal from wastewater. FTIR and XRD analysis confirmed successful metal adsorption and SEM-EDX mapping revealed ion exchange and complexation mechanisms, solidifying the role of modified biochar as an eco-friendly and efficient heavy metal removal material. We also explored the synergistic effects of biochar and metal-tolerant bacteria, Serratia marcescens (Sm) on the remediation of metals-contaminated soil. This collaboration led to significant improvements in soil properties, including a 23% increase in soil organic content (OC) and notable enhancements in nutrient availability. While it reduced pH and certain soil parameters, it effectively decreased Cd, Cr, Cu, and Pb concentrations in the soil. Soil enzyme activities were also stimulated, highlighting the intricate interplay between biochar, bacteria, and metal immobilization. The combined treatment's potential in metals-contaminated soil remediation was further confirmed through its influence on plant growth, physiological responses, and antioxidant defense mechanisms. The combined effects of biochar and Serratia marcescens on Zea mays L. grown in multi-metal-contaminated soil were also investigated. This synergistic approach not only mitigated the negative impacts of heavy metals but also significantly improved plant growth, physiological attributes, and antioxidant defenses. Notably, the combined treatment reduced metal uptake and bioaccumulation in Z. mays while individually applied bacteria exhibited a dual role in copper concentration modulation. The interactive use of biochar and S. marcescens thus emerged as a potent strategy for mitigating heavy metal-induced disturbances in Z. mays. In conclusion, Effect of Biochar and Metal Resistant Bacteria on Heavy Metals Homeostasis of Selected Crops 1 these studies collectively demonstrate the multifunctional potential of biochar-based solutions in addressing toxic metal contamination and enhancing environmental quality. These innovative approaches offer promising avenues for sustainable remediation and mitigation strategies, contributing to the broader goal of environmental protection and resource management. Keywords: Heavy metal adsorption, biochar modification, Metal-tolerant bacteria, Serratia marcescens, Soil remediation, Plant growth, Antioxidant defence mechanisms, Metal contaminated soil