Functional assessment of differential sediment slurry applications in a deteriorating brackish marsh

We applied sediment slurries of varying thicknesses to deteriorating vegetated brackish marsh areas with organic soils. Our objective was to determine if overall elevation change and its component processes of soil compression and sediment consolidation are differentially affected by different amoun...

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Bibliographic Details
Published in:Ecological engineering 2013-02, Vol.51, p.264-274
Main Authors: Graham, Sean A., Mendelssohn, Irving A.
Format: Article
Language:English
Subjects:
Animal, plant and microbial ecology
Applied ecology
Biological and medical sciences
Brackish marsh
Bulk density
Compressing
Conservation, protection and management of environment and wildlife
Consolidation
Ecosystem function
Ecosystems
Elevation
Elevation change
Environmental degradation: ecosystems survey and restoration
Fundamental and applied biological sciences. Psychology
General aspects
Louisiana
Primary production
Restoration
Sediment slurry
Sediments
Slurries
Soils
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Summary:We applied sediment slurries of varying thicknesses to deteriorating vegetated brackish marsh areas with organic soils. Our objective was to determine if overall elevation change and its component processes of soil compression and sediment consolidation are differentially affected by different amounts of sediment and to assess sediment effects on key ecosystem functions and physico-chemical drivers. We found that sediment nourishment (2.3–20.3cm) increased soil surface elevation initially, but by the end of the ∼2.5 year study period, sediment-nourished areas, averaged over all thicknesses, subsided to pre-sediment surface elevations, and were no different from reference area surface elevations. Rates of elevation change, soil compression, and sediment consolidation were all strongly related to applied sediment thickness; plots that received more sediment lost elevation at faster rates. Elevation change following sediment nourishment was driven by soil compression that occurred within the underlying native soil. In contrast, applied sediment consolidation over time had little negative influence on elevation change, though applied sediment bulk density increased linearly with increasing sediment thickness. Sediment nourishment 15cm of sediment nourishment had both small elevation gains (
ISSN:0925-8574
1872-6992
DOI:10.1016/j.ecoleng.2012.12.031