Zhao Wei, Cao Xiaoxu, Pan Hong, Lou Yanhong, Wang Hui, Yang Quangang, Zhuge Yuping
National Engineering Research Center for Efficient Utilization of Soil and Fertilizer Resources, College of Resources and Environment, Shandong Agricultural University, Tai'an 271018, China.
Microorganisms. 2025 Apr 7;13(4):839. doi: 10.3390/microorganisms13040839.
Cadmium (Cd) contamination poses severe threats to agricultural productivity and ecosystem health. Biochar has shown promise in immobilizing Cd and enhancing microbial functions, yet its pH-dependent mechanisms remain underexplored. This study aimed to elucidate pH-dependent variations in biochar-mediated cadmium (Cd) immobilization efficiency, nitrification activity, and bacterial community diversity across soils of contrasting pH levels, with mechanistic insights into the synergistic interplay between biochar properties and soil pH. Real-time quantitative PCR (qPCR) and high-throughput sequencing were used to investigate the effects of a 1% () biochar amendment on ammonia-oxidizing microorganism abundance and microbial diversity in neutral Shandong soil (SD, pH 7.46) and acidic Yunnan soil (YN, pH 5.88). In neutral SD soil, available Cd decreased from 0.22 mg kg (day 0) to 0.1 mg kg (day 56) and stabilized, accompanied by insignificant changes in ammonia-oxidizing bacteria (AOB) abundance. However, nitrification activity was enhanced through the enrichment of (nitrite-oxidizing bacteria within Nitrospirales and Nitrospiraceae). In acidic YN soil, biochar reduced available Cd by 53.37% over 56 days, concurrent with a 34.28% increase in AOB gene abundance (predominantly ), driving pH-dependent nitrification enhancement. These findings demonstrated that biochar efficacy was critically modulated by soil pH; the acidic soils require higher biochar dosages (>1% , adjusted to local soil properties and agronomic conditions) for optimal Cd immobilization. Meanwhile, pH-specific nitrifier taxa ( in acidic vs. in neutral soils) underpinned biochar-induced nitrification dynamics. The study provided a mechanistic framework for tailoring biochar remediation strategies to soil pH gradients, emphasizing the synergistic regulation of Cd immobilization and microbial nitrogen cycling.
镉（Cd）污染对农业生产力和生态系统健康构成严重威胁。生物炭在固定镉和增强微生物功能方面显示出潜力，但其pH依赖性机制仍未得到充分研究。本研究旨在阐明不同pH水平土壤中生物炭介导的镉（Cd）固定效率、硝化活性和细菌群落多样性的pH依赖性变化，并深入了解生物炭性质与土壤pH之间的协同相互作用机制。采用实时定量PCR（qPCR）和高通量测序技术，研究了1%（）生物炭添加对中性山东土壤（SD，pH 7.46）和酸性云南土壤（YN，pH 5.88）中氨氧化微生物丰度和微生物多样性的影响。在中性SD土壤中，有效镉从0.22 mg/kg（第0天）降至0.1 mg/kg（第56天）并稳定下来，同时氨氧化细菌（AOB）丰度变化不显著。然而，通过富集（硝化螺旋菌科和硝化螺菌属中的亚硝酸盐氧化细菌）增强了硝化活性。在酸性YN土壤中，生物炭在56天内使有效镉降低了53.37%，同时AOB基因丰度增加了34.28%（主要是），推动了pH依赖性硝化作用增强。这些发现表明，生物炭的功效受到土壤pH的关键调节；酸性土壤需要更高剂量的生物炭（>1%，根据当地土壤性质和农艺条件调整）才能实现最佳的镉固定。同时，pH特异性硝化菌类群（酸性土壤中的与中性土壤中的）支撑了生物炭诱导的硝化动力学。该研究为根据土壤pH梯度定制生物炭修复策略提供了一个机制框架，强调了镉固定和微生物氮循环的协同调节。
