Guangdong Industrial Contaminated Site Remediation Technology and Equipment Engineering Research Center, School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou, 510006, PR China.
Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China.
Chemosphere. 2022 Aug;301:134551. doi: 10.1016/j.chemosphere.2022.134551. Epub 2022 Apr 8.
Biochar can be effective in immobilizing soil cadmium (Cd), but the difference in its immobilization mechanisms for different levels of Cd-contaminated soils was overlooked. In this study, rice straw biochar (BC) was added to three Cd-contaminated soils following 180 days of incubation, in the process of which the dynamic changes of Cd speciation, soil properties and microbial community diversity were determined. BC could significantly reduce the ratio of acid-soluble in the three soils, especially in light and medium Cd-contaminated soils by more than 20%. The addition of biochar could significantly increase the soil pH, soil organic matter, cation exchange capacity, and the activities of catalase, but decrease the richness and diversity of bacterial communities in all soils. The associations between microbial communities were inhibited in light and medium Cd-contaminated soils, but promoted in heavy Cd-contaminated soils. Furthermore, the main pathway of BC effect on soil Cd availability was also analyzed by partial least squares model (PLS-PM), which indicated that BC indirectly reduced Cd availability mainly by regulating the microbial community in light Cd-contaminated soil, whereas BC directly reduced Cd availability primarily by its own adsorption in medium and heavy Cd-contaminated soils. This research deepened understanding of the mechanisms of stabilization of Cd by biochar for agricultural soils.
生物炭可以有效地固定土壤中的镉（Cd），但不同程度 Cd 污染土壤中生物炭固定机制的差异却被忽视了。本研究通过 180 天的培养，向三种 Cd 污染土壤中添加水稻秸秆生物炭（BC），测定了 Cd 形态、土壤性质和微生物群落多样性的动态变化。BC 可显著降低三种土壤中酸溶态 Cd 的比例，尤其是在轻中度 Cd 污染土壤中，降低比例超过 20%。生物炭的添加可显著增加土壤 pH 值、土壤有机质、阳离子交换量和过氧化氢酶活性，但降低所有土壤中细菌群落的丰富度和多样性。在轻中度 Cd 污染土壤中，微生物群落之间的关联受到抑制，而在重度 Cd 污染土壤中则受到促进。此外，还通过偏最小二乘模型（PLS-PM）分析了 BC 对土壤 Cd 有效性的主要影响途径，结果表明，BC 通过调节轻度 Cd 污染土壤中的微生物群落间接降低了土壤 Cd 的有效性，而在中重度 Cd 污染土壤中，BC 主要通过自身吸附直接降低了土壤 Cd 的有效性。本研究深化了对生物炭稳定农业土壤中 Cd 机制的认识。
