Biogeochemical interface formation in soils as controlled by different components

我们认为粘土矿物、铁氧化物和木炭是控制与有机化学物质吸附相关的界面形成的主要成分，因为它们控制着有机质和矿物颗粒的组合。研究了人工土壤接种模型化合物(粘土矿物、氧化铁、焦炭)和天然土样的间歇培养实验中界面的形成。结果表明，铁氧化物和粘土矿物作为疏水化合物的吸附界面对有机质的形成有一定的贡献。因此，我们打算将第二阶段的工作重点放在由与粘土矿物和铁氧化物伴生的有机物形成的界面的表征上。界面将用BET-N_2和乙二醇单乙醚(Egme)方法以及129Xe和13C核磁共振波谱来表征，以确定比表面积、有机物中的吸附结构域和微孔率。通过反射光学显微镜(毫米级)、扫描电子显微镜(扫描电子显微镜，微米级)和纳米级二次离子质谱仪(NanSIMS)对不同分辨率的界面成分进行分析，有望取得重大进展。结合合作伙伴的研究结果，将有助于揭示不同类型土壤成分对生物地球化学界面的形成和特征的贡献及其对有机化学吸附的影响。

We consider clay minerals, iron oxides and charcoal as major components controlling the formation of interfaces relevant for sorption of organic chemicals, as they control the assemblage of organic matter and mineral particles. We studied the formation of interfaces in batch incubation experiments with inoculated artificial soils consisting of model compounds (clay minerals, iron oxide, char) and natural soil samples. Results show a relevant contribution of both iron oxides and clay minerals to the formation of organic matter as sorptive interfaces for hydrophobic compounds. Thus, we intend to focus our work in the second phase on the characterization of the interface as formed by organic matter associated with clay minerals and iron oxides. The interfaces will be characterized by the BET-N2 and ethylene glycol monoethyl ether (EGME) methods and 129Xe and 13C NMR spectroscopy for determination of specific surface area, sorptive domains in the organic matter and microporosity. A major step forward is expected by the analysis of the composition of the interface at different resolution by reflected-light microscopy (mm scale), SEM (scanning electron microscopy, micrometer scale) and secondary ion mass spectrometry at the nanometer scale (nanoSIMS). The outcomes obtained in combination with findings from cooperation partners will help to unravel the contribution of different types of soil components on the formation and characteristics of the biogeochemical interfaces and their effect on organic chemical sorption.