Lan Yibo, Gai Shuang, Cheng Kui, Liu Zhuqing, Antonietti Markus, Yang Fan
School of Water Conservancy and Civil Engineering, Northeast Agricultural University, Harbin 150030, China.
International Cooperation Joint Laboratory of Health in Cold Region Black Soil Habitat of the Ministry of Education, Harbin 150030, China.
Research (Wash D C). 2024 Feb 19;7:0308. doi: 10.34133/research.0308. eCollection 2024.
Fe (hydr)oxides have a substantial impact on the structure and stability of soil organic carbon (SOC) pools and also drive organic carbon turnover processes via reduction-oxidation reactions. Currently, many studies have paid much attention to organic matter-Fe mineral-microbial interactions on SOC turnover, while there is few research on how exogenous carbon addition abiotically regulates the intrinsic mechanisms of Fe-mediated organic carbon conversion. The study investigated the coupling process of artificial humic acid (A-HA) and Fe(hydr)oxide, the mechanism of inner-sphere ligands, and the capacity for carbon sequestration using transmission electron microscopy, thermogravimetric, x-ray photoelectron spectroscopy, and wet-chemical disposal. Furthermore, spherical aberration-corrected scanning transmission electron microscopy-electron energy loss spectroscopy and Mössbauer spectra have been carried out to demonstrate the spatial heterogeneity of A-HA/Fe (hydr)oxides and reveal the relationship between the increase in Fe-phase crystallinity and redox sensitivity and the accumulation of organic carbon. Additionally, the dynamics of soil structures on a microscale, distribution of carbon-iron microdomains, and the cementing-gluing effect can be observed in the constructing nonliving anthropogenic soils, confirming that the formation of stable aggregates is an effective approach to achieving organic carbon indirect protection. We propose that exogenous organic carbon inputs, specifically A-HA, could exert a substantial but hitherto unexplored effect on the geochemistry of iron-carbon turnover and sequestration in anoxic water/solid soils and sediments.
铁的（氢）氧化物对土壤有机碳（SOC）库的结构和稳定性有重大影响，还通过氧化还原反应驱动有机碳周转过程。目前，许多研究非常关注有机物质-铁矿物-微生物相互作用对SOC周转的影响，而关于外源碳添加如何非生物调节铁介导的有机碳转化的内在机制的研究却很少。该研究利用透射电子显微镜、热重分析、X射线光电子能谱和湿化学处理方法，研究了人工腐殖酸（A-HA）与铁的（氢）氧化物的耦合过程、内球配体的机制以及碳固存能力。此外，还进行了球差校正扫描透射电子显微镜-电子能量损失谱和穆斯堡尔谱分析，以证明A-HA/铁的（氢）氧化物的空间异质性，并揭示铁相结晶度的增加与氧化还原敏感性以及有机碳积累之间的关系。此外，在构建非生物人为土壤中可以观察到微观尺度上土壤结构的动态变化、碳-铁微域的分布以及胶结-粘合效应，证实形成稳定团聚体是实现有机碳间接保护的有效途径。我们提出，外源有机碳输入，特别是A-HA，可能对缺氧水/固体土壤和沉积物中铁-碳周转和固存的地球化学产生重大但迄今未被探索的影响。
