Kang Xirui, Geng Na, Li Xu, Yu Jinpeng, Wang Hui, Pan Hong, Yang Quangang, Zhuge Yuping, Lou Yanhong
National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Tai'an, China.
Front Plant Sci. 2022 Mar 25;13:782963. doi: 10.3389/fpls.2022.782963. eCollection 2022.
Soil contamination with multiple heavy metals is a global environmental issue that poses a serious threat to public health and ecological safety. Biochar passivation is an efficient and economical technology to prevent heavy metal contamination of Cd; however, its effects on compound-contaminated and weakly alkaline soil remain unclear. Further, the mechanisms mediating the immobilization effects of biochar have not been evaluated. In this study, three biochar treated at different pyrolytic temperatures [300°C (BC300), 400°C (BC400), and 500°C (BC500)] were applied to Cd-/Zn-contaminated soils, and their effects on plant growth, photosynthetic characteristics, Cd/Zn accumulation and distribution in foxtail millet were evaluated. Further, the effect of biochar application on the soil physicochemical characteristics, as well as the diversity and composition of the soil microbiota were investigated. Biochar significantly alleviated the phytotoxicity of Cd and Zn. DTPA (diethylenetriamine pentaacetic acid)-Cd and DTPA-Zn content was significantly reduced following biochar treatment the transformation of exchangeable components to stable forms. BC500 had a lower DTPA-Cd content than BC300 and BC400 by 42.87% and 39.29%, respectively. The BC500 passivation ratio of Cd was significantly higher than that of Zn. Biochar application also promoted the growth of foxtail millet, alleviated oxidative stress, and reduced heavy metal bioaccumulation in shoots, and transport of Cd from the roots to the shoots in the foxtail millet. The plant height, stem diameter, biomass, and photosynthetic rates of the foxtail millet were the highest in BC500, whereas the Cd and Zn content in each organ and malondialdehyde and hydrogen peroxide content in the leaves were the lowest. Moreover, biochar application significantly increased the abundance of soil bacteria and fungi, as well as increasing the fungal species richness compared to no-biochar treatment. Overall, biochar was an effective agent for the remediation of heavy metal-contaminated soil. The passivation effect of biochar exerted on heavy metals in soil was affected by the biochar pyrolysis temperature, with BC500 showing the best passivation effect.
多种重金属对土壤的污染是一个全球性环境问题，对公众健康和生态安全构成严重威胁。生物炭钝化是一种有效且经济的防止镉污染土壤的技术；然而，其对复合污染和弱碱性土壤的影响仍不清楚。此外，介导生物炭固定作用的机制尚未得到评估。在本研究中，将三种在不同热解温度下处理的生物炭[300°C（BC300）、400°C（BC400）和500°C（BC500）]施用于镉/锌污染土壤，并评估其对谷子生长、光合特性、镉/锌积累和分布的影响。此外，研究了生物炭施用对土壤理化特性以及土壤微生物群多样性和组成的影响。生物炭显著减轻了镉和锌的植物毒性。生物炭处理后，二乙三胺五乙酸（DTPA）-镉和DTPA-锌含量显著降低，可交换组分向稳定形态转化。BC500的DTPA-镉含量分别比BC300和BC400低42.87%和39.29%。镉的BC500钝化率显著高于锌。生物炭的施用还促进了谷子的生长，减轻了氧化应激，减少了地上部重金属生物积累以及镉从谷子根部向地上部的转运。谷子的株高、茎粗、生物量和光合速率在BC500处理中最高，而各器官中的镉和锌含量以及叶片中的丙二醛和过氧化氢含量最低。此外，与不施用生物炭处理相比，生物炭的施用显著增加了土壤细菌和真菌的丰度，同时增加了真菌物种丰富度。总体而言，生物炭是修复重金属污染土壤的有效剂。生物炭对土壤中重金属的钝化效果受生物炭热解温度的影响，BC500表现出最佳钝化效果。
