College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, PR China.
College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi, 712100, PR China.
Environ Pollut. 2021 Mar 1;272:116040. doi: 10.1016/j.envpol.2020.116040. Epub 2020 Nov 27.
Biochar has the potential to remediate heavy metals in agricultural soil and mitigate nitrous oxide (NO) emissions; however, the effects of biochar on heavy metal remediation, the soil microbial community and NO emissions are not completely understood. In this study, we conducted a pot experiment in which Glycine max L. (soybean) was cultivated in two cadmium (Cd)-contaminated soils (low, 3.14 mg kg; high, 10.80 mg kg) to investigate the effects of biochar on the bioremediation of Cd, NO emissions and the rhizosphere microbial community structure. The bioaccumulation of Cd in the plant shoots and roots increased with all biochar addition rates (0%, 1%, 5% and 10%); unexpectedly, the translocation capacity of Cd to the edible parts of the plant significantly decreased to 0.58 mg kg, which was close to the edible threshold (0.4 mg kg). The abundance and activities of functional marker genes of microbial nitrification (amoA) and denitrification (nirK, nirS and nosZ) were quantified with quantitative PCR, and we found that biochar addition reduced the precursor production of rhizoshpere NO by inhibiting the transcription of the nirK gene. In addition, the nitrogenase activity during anthesis (S) was significantly (P < 0.05) increased with 1% (v/v) biochar addition. Noticeably, biochar addition only changed the microbial community structure in the very first stage before eventually stabilize. This study highlighted that biochar has the potential ability to maintain the quality of agricultural crops, remediate Cd-contaminated soils and may help reduce NO emissions without disturbing the microbial community.
生物炭具有修复农业土壤中重金属和减少氧化亚氮（NO）排放的潜力；然而，生物炭对重金属修复、土壤微生物群落和 NO 排放的影响尚不完全清楚。在这项研究中，我们进行了一项盆栽实验，在其中种植了大豆（Glycine max L.），以研究生物炭对两种镉（Cd）污染土壤（低污染，3.14 mg kg；高污染，10.80 mg kg）中 Cd 的生物修复、NO 排放和根际微生物群落结构的影响。植物地上部和根部对 Cd 的生物积累随着生物炭添加率（0%、1%、5%和 10%）的增加而增加；出乎意料的是，Cd 向可食用部分的迁移能力显著降低至 0.58 mg kg，接近可食用阈值（0.4 mg kg）。用定量 PCR 定量了微生物硝化（amoA）和反硝化（nirK、nirS 和 nosZ）功能标记基因的丰度和活性，我们发现生物炭添加通过抑制 nirK 基因的转录来减少根际 NO 的前体生成。此外，在开花期（S）的固氮酶活性随着 1%（v/v）生物炭添加而显著（P < 0.05）增加。值得注意的是，生物炭添加仅在前几个阶段改变了微生物群落结构，最终会稳定下来。本研究强调了生物炭具有维持农业作物质量、修复 Cd 污染土壤并可能有助于减少 NO 排放而不干扰微生物群落的潜力。
