Co-precipitation induces changes to iron and carbon chemistry and spatial distribution at the nanometer scale
Co-precipitation induces changes to iron and carbon chemistry and spatial distribution at the nanometer scale
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共沉淀引起纳米尺度铁和碳化学和空间分布的变化
DOI：
10.1016/j.gca.2021.09.003
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发表时间：
2021
影响因子：
5
通讯作者：
Lehmann, Johannes
中科院分区：
文献类型：
--
作者：
Possinger, Angela R.;Zachman, Michael J.;Dynes, James J.;Regier, Tom Z.;Kourkoutis, Lena F.;Lehmann, Johannes
在有机质 (OM) 输入量高、矿物溶解和再沉淀频繁的环境中，通过共沉淀将有机质 (OM) 与矿物相结合预计将是一个广泛的过程。与表面积有限的吸附过程相比，共沉淀可以允许更多的碳 (C) 积累。然而，影响共沉淀碳生物利用度的潜在亚微米级结构和成分差异在很大程度上尚不清楚。在这项研究中，我们结合使用高分辨率分析电子显微镜和本体光谱来探测矿物相（水铁矿，名义上为Fe2O3·0.5H2O）和有机土壤中的水可提取OM（WEOM）之间的相互作用。在共沉淀 WEOM-Fe 中，纳米级扫描透射电子显微镜与电子能量损失光谱 (STEM-EELS) 显示，相对于吸附的 WEOM-Fe，Fe(II) 增加，Fe 聚集减少。在吸附和共沉淀的 WEOM-Fe 中检测到空间上不同的低能和高能 C 区域。在共沉淀物中，较低能量的芳香族和/或取代芳香族 C 在空间上与还原的 Fe(II) 相关，但较高能量的氧化 C 在氧化 Fe(III) 界面处富集。因此，我们表明，共沉淀并不构成仅影响Fe化学和空间分布的C的非特异性物理封装，而是可能引起一系列双向反应，导致Fe和C形式的空间分离和转变。特别是，我们提出 Fe 和 C 之间通过取代的芳香族基团（例如对苯二酚）发生的非生物氧化还原反应在产生独特的共沉淀物成分方面发挥着作用，对其矿化具有潜在影响。
Association of organic matter (OM) with mineral phases via co-precipitation is expected to be a widespread process in environments with high OM input and frequent mineral dissolution and re-precipitation. In contrast to surface area-limited adsorption processes, co-precipitation may allow for greater carbon (C) accumulation. However, the potential sub-micrometer scale structural and compositional differences that affect the bioavailability of co-precipitated C are largely unknown. In this study, we used a combination of high-resolution analytical electron microscopy and bulk spectroscopy to probe interactions between a mineral phase (ferrihydrite, nominally Fe2O3•0.5H2O) and organic soil-derived water-extractable OM (WEOM). In co-precipitated WEOM-Fe, nanometer-scale scanning transmission electron microscopy with electron energy loss spectroscopy (STEM-EELS) revealed increased Fe(II) and less Fe aggregation relative to adsorbed WEOM-Fe. Spatially distinct lower- and higher-energy C regions were detected in both adsorbed and co-precipitated WEOM-Fe. In co-precipitates, lower-energy aromatic and/or substituted aromatic C was spatially associated with reduced Fe(II), but higher-energy oxidized C was enriched at the oxidized Fe(III) interface. Therefore, we show that co-precipitation does not constitute a non-specific physical encapsulation of C that only affects Fe chemistry and spatial distribution, but may cause a bi-directional set of reactions that lead to spatial separation and transformation of both Fe and C forms. In particular, we propose that abiotic redox reactions between Fe and C via substituted aromatic groups (e.g., hydroquinones) play a role in creating distinct co-precipitate composition, with potential implications for its mineralization.
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影响因子：
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通讯作者：
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影响因子：
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