Characterising the composition and multiscale structure of suspended sediment aggregates using 2D and 3D correlative microscopy

Wheatland, Jonathan A., Spencer, Kate L., Droppo, Ian G., Carr, Simon and Bushby, Andrew J. (2019) Characterising the composition and multiscale structure of suspended sediment aggregates using 2D and 3D correlative microscopy. Continental Shelf Research . (Submitted to Publisher) Item availability may be restricted.

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Abstract

Suspended cohesive sediments form aggregates or ‘flocs’, the physical properties of which dictate their hydrodynamics. Flocs are often closely associated with carbon, nutrients, pathogens and pollutants, which makes understanding their transport and fate highly desirable. Accurate prediction of floc behaviour requires the quantification of 3D properties (size, shape, composition 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 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 mmscale floc properties. Here, we develop a correlative imaging workflow combining 3D Xray micro-computed tomography (μCT), 3D focused ion beam nanotomography (FIBnt) and 2D scanning EM (SEM) and TEM (STEM) to visualise and quantify the composition and multiscale structure of sediment flocs. Natural estuarine flocs were successfully stabilised and sequentially imaged at increasing resolutions to focus on submerged regions of interest (RoI) within the floc. This allowed floc components (e.g., clays, non-clay minerals and bacteria, etc.) to be identified and particle-particle and structural associations to be characterised and related across scales. This novel dataset demonstrates the truly complex structure of natural flocs, whose characteristics vary according to the scale of observation.

Item Type: Article
Journal / Publication Title: Continental Shelf Research
Publisher: Elsevier for Pergamon
ISSN: 1873-6955
Departments: STEM
Depositing User: Anna Lupton
Date Deposited: 10 Oct 2019 12:36
Last Modified: 11 Oct 2019 12:40
URI: http://insight.cumbria.ac.uk/id/eprint/5141

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