Date of Award

1-1-2009

Document Type

Campus Access Thesis

Department

Marine Science

First Advisor

Raymond Torres

Abstract

The occurrences of pollutants in salt marsh, especially metals, have been widely studied due to their adverse effects on ecosystem. However, most of the studies use single measurement to assess the metal contamination and ignore the spatial variability of sediment metal concentration. In this study, I conducted a high frequency sampling strategy to quantify the spatial variability of sediment metal concentration and characterize processes controlling it. 51 surface sediment samples were taken along two transects across a 0.5km2, similarly vegetated salt marsh island; the two transects are 800m apart and sampling interval is approximately 10m. It appears that physical processes and geomorphic structure exert important controls over spatial variations in metal concentrations in salt marsh surface sediment. Due to the hydrological conditions in subtidal channel, the studied salt marsh island is composed of new sediment, deposited less than 50 years ago Winyah bay input, and older sediment originally from the mature marsh. Multivariate statistical analyses reveal that older marsh and newer marsh have different controls on sediment metal distribution. Metal distribution in older marsh is significantly influenced by distance to creek, distance to subtidal channel and elevation. The spatial variability of metals is relatively small and the influence of sample location is not significant in new marsh. These observations suggest that spatial variability of metals is not negligible. Data collected at a single site are unlikely to provide representative results of metal availability over larger spatial scales. Therefore, studies on salt marsh sediment should explicitly consider the significant variability imposed by differing distance to creek, distance to sub-tidal channel, elevation, sub-tidal flow conditions, even over relatively small distances within a single marsh island.

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