Effects of Geomorphology on the Distribution of Metal Abundance in Salt Marsh Sediment

The purpose of this study is to investigate the effects of salt marsh geomorphology on the distribution of surface metal content. Surface sediment samples (46) were taken along two transects across an intertidal salt marsh island. Abundance of Ca, Al, Fe, Ni, Cr, Cu, Zn, Rb, Sr, As, and Zr vary up to 300 % with statistically significant differences along transects and between transects. Along transect, metal abundances are strongly influenced by elevation and distance from the subtidal channel. Between transects, salt marsh morphodynamics, relative marsh age, and water sources seem to affect metal distribution. These observations lead us to hypothesize that at least three scales of variability can be expected for assessing salt marsh sediment metal distributions. Larger-scale variations associated with salt marsh sediment sources and age, and another related to local salt marsh geomorphic structure. Therefore, studies that characterize salt marsh metal loading should explicitly consider the variability imposed over a range of spatial scales.