Elucidating the 3D chemical and physical architecture of soil microstructures by combining spectromicroscopic techniques and developing of novel computational approaches

土壤微观结构仍然被视为无机和有机成分随机排列的异质混合物，而在微观尺度上对结构形成的建筑原理缺乏深入的了解。特别是微团聚体（小于250 µm的土壤微观结构），不同尺寸和化学成分的矿物和有机成分的高度复杂的组合，已知对长期有机质（OM）封存起着非常重要的作用。虽然以前不可能以必要的微米至纳米空间分辨率研究复杂的土壤微环境，但如今，通过显微镜和光谱技术的组合，可以空间分辨组成，完整土壤微结构的三维结构和结构特征：我们假设同一土壤基质上土壤微结构的三维结构强烈依赖于有机质土壤有机质含量（贫碳、中碳、富碳）和有机质质量（高C/N比、低C/N比）与土壤矿物的空间分布密切相关。为了验证我们的假设，我们将使用具有可比矿物成分但有机质含量不同的天然土壤材料。使用天然土壤系统将确保研究有意义的结构特性（例如表面粗糙度，孔隙大小，空腔结构）以及化学信息（例如，G.通过将LIST的AFM模块集成到TUM的NanoSIMS中，我们可以将AFM高度轮廓与NanoSIMS获得的元素2D/3D信息联合收割机结合起来，准确构建复杂结构的3D样品表面。通过使用13 C和15 N标记的有机质作为有机质源，在自然土壤样品的培养过程中，HIM-SIMS将允许在高空间分辨率的不同微结构点确定有利于有机-矿物协会的表面特征，而AFM-NanoSIMS组合将提供地形校正数据，用于在高质量分辨率下准确确定元素和同位素有机质组成。我们的目标是为HIM-SIMS和AFM-NanoSIMS开发相关的表面和体积重建工作流程，以准确确定微观尺度下矿物相关OM的位置和化学性质。我们的研究将提供一个很好的机会来追踪微观尺度上自然土壤发育的结构原理，并将实现土壤3D微观结构中有机矿物协会形成的3D/4D建模。

Soil microstructures are still seen as heterogeneous mixtures of mineral and organic components in random arrangement, while the thorough knowledge about architectural principles governing structure formation at the microscale is lacking. Especially microaggregates (soil microstructures smaller than 250 µm), highly complex associations of mineral and organic constituents of different sizes and chemical composition, are known to play a very important role for long term organic matter (OM) sequestration. While it has previously been impossible to study complex soil microenvironments at the necessary micro- to nanometer spatial resolution, nowadays, by the combination of microscopic and spectroscopic techniques it is possible to spatially resolve the composition, 3D architecture and structural characteristics of intact soil microstructures.We hypothesize that the 3D architecture of soil microstructures on the same soil substrate strongly depends on the bulk OM content (C-depleted, C-intermediate, C-rich) and OM quality (high C/N ratio, low C/N ratio) interconnected with the specific spatial arrangement of soil minerals. To test our hypotheses, we will make use of natural soil material with comparable mineralogical composition but different organic matter content. Using natural soil systems will ensure the study of meaningful structural properties (e.g. surface roughness, pore sizes, cavity structure) together with chemical information (e. g. C and N distribution) fostering the formation of natural soil microstructures.By using the AFM module from LIST integrated into the NanoSIMS at the TUM we can combine the AFM height profiles with the elemental 2D/3D information obtained by NanoSIMS to build the 3D sample surface of complex structures accurately. By using 13C and 15N labelled OM as OM source during the incubation of the natural soil samples, HIM-SIMS will allow the determination of surface characteristics favouring organo-mineral associations at distinct microstructure spots at high spatial resolution, while the AFM-NanoSIMS combination will provide topography corrected data for the accurate determination of the elemental and isotopic OM composition at high mass resolution. We aim to develop correlative surface and volume reconstruction workflows for HIM-SIMS and AFM-NanoSIMS to accurately determine the location and chemical properties of mineral associated OM at the micro-scale. Our study will offer the great opportunity to trace structural principles governing natural soil development at the microscale and will enable a 3D/4D modelling of the formation of organo-mineral associations in soil 3D microstructures.