School of Geography

RESIST at Queen Mary University of London – sediment structure and geochemistry

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Our team at QMUL focuses on Work Package 2 (WP2) of the wider UK-RESIST project: visualising and understanding sediment structure and geochemistry and their relation to marsh resistance to eroding forces. Sediment structure, especially the spatial distribution of voids and roots, is expected to play an important role in marsh functioning and resilience (Spencer et al., 2017*). We also explore whether the belowground structure can be predicted by the aboveground vegetation cover and sediment type to improve future monitoring efforts.

Twenty-four sediment core samples were taken at two saltmarshes to analyse the e­ffect of diff­erent substrates and vegetation species on the belowground structure: Warton Sands (Lancashire, sandy substrate) and Tillingham (Essex, muddy substrate). Three main vegetation covers were considered for each site: Spartina, Salicornia and Puccinellia, plus bare ground samples as reference. Three replicates were taken at each sampling location. Their internal structure are analysed using X-ray 3D Computed Tomography and processed using semi-automated 3D image analysis scripts and macros developed on Matlab and ImageJ (Figures 2-3). These data will be coupled with geochemical and mineralogical investigations to provide a multi-disciplinary understanding of the drivers of saltmarsh resistance to erosion.

Figure 2: X-Ray Computed Tomography data acquisition and processing workflow for complex, heterogeneous, wet unconsolidated sediment from saltmarshes.

Figure 3: Example CT results showing the voids (grey) and organics (green) within sediment core samples from Tillingham and Warton Sands under different vegetation covers (Spartina, Puccinellia).

 * Spencer, K.L., Carr, S.J., Diggens, L.M., Tempest, J.A., Morris, M.A., Harvey, G.L. (2017). The impact of pre-restoration land-use and disturbance on sediment structure, hydrology and the sediment geochemical environment in restored saltmarshes, Science of the Total Environment, 587–588: 47–58.