The feedstock used to prepare biochar plays a leading role in its physicochemical properties, and the physicochemical properties of biochar determine the remediation potential for heavy metal. Therefore, it is of great theoretical and practical value to systematically compare the physicochemical properties of biochar from different feedstocks and analyze its remediation behaviors on heavy metal contaminated soil. In this study, three typical feedstock biochar, straw biochar (SB), coconut shell biochar (CSB) and sludge-derived biochar (SSDB) are mixed with heavy metal contaminated soil at a ratio of 0.5%, 2.5% and 5% respectively, and incubation at 25 °C and 70% field water holding capacity for 30 days. The results showed that the three biochar could significantly reduce the leaching concentration and acid soluble fraction of heavy metals, and the remediation effect of biochar on heavy metals improved with the increase of dosage and the extension of incubation time. Among them, 5% dosage of SSDB obtains the optimal remediation effect. Redundancy analysis shows that the pore diameter and C contents of biochar are negatively correlated with short-term leaching of heavy metals; the electrical conductivity, available phosphorus and anion content are negatively correlated with the long-term leaching of heavy metals. The SB has higher available phosphorus and manifests a microporous structure with vascular bundles, making it have a larger specific surface area, and suitable for heavy metal remediation through complexation, adsorption and precipitation. The CSB has a higher pH value, a large pore diameter, and a high H/C atomic ratio and hydrophobicity, and is suitable for heavy metal remediation through complexation, electrostatic attraction and adsorption. The SSDB has a higher electrical conductivity anion content, but a lower degree of aromatization, and is suitable for heavy metal remediation by precipitation.

原料用于制备生物炭对其理化性质起着主导作用，而生物炭的理化性质决定了其对重金属的修复潜力。因此，系统比较不同原料生物炭的理化性质，分析其对重金属污染土壤的修复行为具有重要的理论和实践价值。本研究将三种典型的原料生物炭、秸秆生物炭（SB）、椰壳生物炭（CSB）和污泥衍生生物炭（SSDB）分别以0.5%、2.5%和5%的比例与重金属污染土壤混合，并在 25°C 和 70% 田间持水量下孵育 30 天。结果表明，三种生物炭均能显着降低重金属的浸出浓度和酸溶分数，且生物炭对重金属的修复效果随着用量的增加和培养时间的延长而提高。其中，5%的SSDB用量可获得最佳的修复效果。冗余分析表明，生物炭的孔径和C含量与重金属的短期浸出呈负相关；电导率，有效磷和阴离子含量与重金属的长期浸出呈负相关。SB具有较高的有效磷，并表现为带有维管束的微孔结构，使其具有较大的比表面积，适合通过络合、吸附和沉淀的方式修复重金属。CSB具有较高的pH值、较大的孔径、较高的H/C原子比和疏水性，适合通过络合、静电吸引和吸附等方式修复重金属。SSDB具有较高的电导阴离子含量，但芳构化程度较低，适用于沉淀法修复重金属。