Abstract Suspended cohesive sediments form aggregates or ‘flocs’ and are often closely associated with carbon, nutrients, pathogens and pollutants, which makes understanding their composition, transport and fate highly desirable. Accurate prediction of floc behaviour requires the quantification of 3-dimensional (3D) properties (size, shape and internal structure) that span several scales (i.e. nanometre [nm] to millimetre [mm]-scale). Traditional techniques (optical cameras and electron microscopy [EM]), however, can only provide 2-dimensional (2D) simplifications of 3D floc geometries. Additionally, the existence of a resolution gap between conventional optical microscopy (COM) and transmission EM (TEM) prevents an understanding of how floc nm-scale constituents and internal structure influence mm-scale floc properties. Here, we develop a novel correlative imaging workflow combining 3D X-ray micro-computed tomography (μCT), 3D focused ion beam nanotomography (FIB-nt) and 2D scanning EM (SEM) and TEM (STEM) which allows us to stabilise, visualise and quantify the composition and multi-scale structure of sediment flocs for the first time. This new technique allowed the quantification of 3D floc geometries, the identification of individual floc components (e.g., clays, non-clay minerals and bacteria), and characterisation of particle-particle and structural associations across scales. This novel dataset demonstrates the truly complex structure of natural flocs at multiple scales. The integration of multi scale, state-of-the-art instrumentation/techniques offers the potential to generate fundamental new understanding of floc composition, structure and behaviour.

中文翻译：

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开发新型 2D 和 3D 相关显微镜以表征悬浮沉积物聚集体的组成和多尺度结构。

摘要 悬浮的粘性沉积物形成聚集体或“絮状物”，通常与碳、营养物质、病原体和污染物密切相关，这使得了解它们的组成、运输和归宿非常有必要。絮体行为的准确预测需要对跨越多个尺度（即纳米 [nm] 至毫米 [mm] 尺度）的 3 维 (3D) 特性（尺寸、形状和内部结构）进行量化。然而，传统技术（光学相机和电子显微镜 [EM]）只能提供 3D 絮体几何形状的二维 (2D) 简化。此外，传统光学显微镜 (COM) 和透射电镜 (TEM) 之间存在分辨率差距，因此无法了解絮体纳米级成分和内部结构如何影响毫米级絮体特性。这里，我们开发了一种新的相关成像工作流程，结合了 3D X 射线显微计算机断层扫描 (μCT)、3D 聚焦离子束纳米断层扫描 (FIB-nt) 和 2D 扫描 EM (SEM) 和 TEM (STEM)，这使我们能够稳定、可视化和首次量化沉积絮凝体的组成和多尺度结构。这种新技术允许量化 3D 絮体几何形状，识别单个絮体成分（例如，粘土、非粘土矿物和细菌），以及跨尺度的颗粒-颗粒和结构关联的表征。这个新颖的数据集展示了天然絮体在多个尺度上真正复杂的结构。多尺度、最先进的仪器/技术的集成提供了对絮体成分、结构和行为产生根本性新理解的潜力。