Abstract：
In previous studies, iron-based nanomaterials, especially biochar (BC)-supported sulfidized nanoscale zero-valent iron (S-nZVI/BC), have been widely used for the remediation of soil contaminants. However, its potential risks to the soil ecological environment are still unknown. This study aims to explore the effects of 3% added S-nZVI/BC on soil environment and microorganisms during the remediation of Cd contaminated yellow-brown soil of paddy field. The results showed that after 49 d of incubation, S-nZVI/BC significantly reduced physiologically based extraction test (PBET) extractable Cd concentration (P < 0.05), and increased the immobilization efficiency of Cd by 16.51% and 17.43% compared with S-nZVI and nZVI/BC alone, respectively. Meanwhile, the application of S-nZVI/BC significantly increased soil urease and sucrase activities by 0.153 and 0.446 times, respectively (P < 0.05), improving the soil environmental quality and promoting the soil nitrogen cycle and carbon cycle. The results from the analysis of the 16S rRNA genes indicated that S-nZVI/BC treatment had a minimal effect on the bacterial community and did not appreciably alter the species of the original dominant bacterial phylum. Importantly, compared to other iron-based nanomaterials, incorporating S-nZVI/BC significantly increased the soil organic carbon (OC) content and decreased the excessive release of iron (P < 0.05). This study also found a significant negative correlation between OC content and Fe(II) content (P < 0.05). It might originate from the reducing effect of Fe-reducing bacteria, which consumed OC to promote the reduction of Fe(III). Accompanying this process, the redistribution of Cd and Fe mineral phases in the soil as well as the generation of secondary Fe(II) minerals facilitated Cd immobilization. Overall, S-nZVI/BC could effectively reduce the bioavailability of Cd, increase soil nutrients and enzyme activities, with less toxic impacts on the soil microorganisms.
摘要：
在以往的研究中,铁基纳米材料，特别是生物炭（BC）负载的硫化纳米零价铁（S-nZVI/BC），已被广泛用于土壤污染物的修复。然而,其对土壤生态环境的潜在风险仍然未知。本研究旨在探讨添加3%S-nZVI/BC对Cd污染稻田黄棕壤修复过程中土壤环境和微生物的影响。结果表明，经过49d的培养，S-nZVI/BC显著降低生理提取试验(PBET)可提取Cd浓度(P<0.05),与单独的S-nZVI和nZVI/BC相比，Cd的固定化效率分别提高了16.51％和17.43％，分别。同时,施用S-nZVI/BC可显著提高土壤脲酶和蔗糖酶活性0.153和0.446倍,分别为(P<0.05)，改善土壤环境质量,促进土壤氮循环和碳循环。16SrRNA基因分析的结果表明，S-nZVI/BC处理对细菌群落的影响很小，并且没有明显改变原始优势细菌门的物种。重要的是,与其他铁基纳米材料相比，掺入S-nZVI/BC显著提高了土壤有机碳(OC)含量,降低了铁的过量释放(P<0.05)。本研究还发现OC含量与Fe(Ⅱ)含量呈显著负相关(P<0.05)。它可能源于铁还原菌的还原作用，消耗OC以促进Fe(III)的还原。伴随着这个过程，土壤中Cd和Fe矿物相的重新分布以及次生Fe（II）矿物的生成促进了Cd的固定。总的来说,S-nZVI/BC能有效降低Cd的生物有效性,增加土壤养分和酶活性，对土壤微生物的毒性影响较小。
