玉米秸秆水热生物炭施用对土壤重金属Cd生物有效性和微生物群落的影响

Effects of corn stalk hydrothermal biochar application on the Cd bioavailability and microbial community in soil

为了探究玉米秸秆水热生物炭(简称水热炭)施用对镉(Cd)污染土壤的修复效果及作用机制,通过盆栽试验,分析了不同水热炭在不同添加率下(1%和3%)对土壤Cd生物有效性和作物吸收的影响,并探究了不同条件下的微生物群落结构。结果表明:与对照相比,水热炭施用显著提高了土壤有机质和溶解性有机碳含量,土壤中二乙烯三胺五乙酸提取的Cd(DTPA-Cd)和油菜叶片Cd含量分别降低了5.01%~20.98%和10.82%~34.16%。提高水热温度和水热炭添加率有助于降低土壤DTPA-Cd含量。此外,施用水热炭显著增强了根际土壤细菌的多样性和丰度,且明显改变了微生物群落结构。与对照组相比,施用水热炭显著降低了根际土壤中Actinobacteriota的相对丰度,提高了Proteobacteria和Bacteroidota的相对丰度。冗余分析表明土壤溶解性有机碳含量是影响根际土壤细菌群落结构的关键因素。因此,水热炭对重金属污染土壤有很大的修复潜力,但其对土壤重金属的长期效应有待进一步研究。

To explore the remediation effects of hydrothermal biochar derived from corn stalk(abbreviated as hydrochar)application on cadmium(Cd)-contaminated soil and the corresponding mechanism,a pot experiment was conducted to analyze the effects of different corn stalk hydrochars under different application ratios(1%and 3%)on the Cd bioavailability in soil and plant uptake.The microbial community structures under different conditions were also explored.Results showed that compared with the blank control(CK),hydrochar application significantly increased the soil organic and organic carbon contents,and diethylenetriamine pentaacetic acid extracted Cd(DTPA-Cd)content in soil and Cd content in rape leaf were decreased by 5.01%–20.98%and 10.82%–4.16%,respectively.The increased hydrothermal temperature and hydrochar application ratio contributed to reducing the DTPA-Cd content in soil.In addition,hydrochar application substantially enhanced the bacterial diversity and abundance in rhizosphere soils and obviously changed the microbial community structure.Compared with the CK,hydrochar application significantly reduced the relative abundance of Actinobacteriota and increased the relative abundances of Proteobacteria and Bacteroidota in rhizosphere soils.Redundancy analysis revealed that the soil dissolved organic carbon content was the key factor that influences the bacterial community structure in rhizosphere soil.Therefore,hydrochar has great potential for the remediation of metal-contaminated soils.However,its long-term effects on soil heavy metals requires further research.