Spatial Variability in Mineral Sediment Accumulation in a Brackish Marsh, Piermont, New York

Coastal wetlands are being lost at increasing rates in the US and worldwide due to sea level rise and salt water inundation. It is essential to understand fundamental processes of mineral sediment accumulation to inform restoration and preservation. However, many processes important to sedimentation are still unconstrained: specifically, the relationships between the salinity gradient, vegetation, historical mineral sediment flux, and marsh accretion all need further investigation. In this project, we examine a west-east transect of 1-m depth sediment cores from Piermont Marsh in Piermont, NY to better model local influences on sediment accumulation in a brackish marsh. Cores were sampled directly next to surface elevation tables (SETs) monitored by the Hudson River National Estuarine Research Reserve (HRNERR) to better compare the two methods. We analyzed two cores using X-Ray Fluorescence spectroscopy (XRF), Loss on Ignition (LOI), 15N, 13C, pollen and macrofossil analysis. Preliminary results from XRF show an increase in Pb which correlates to historic lead pollution from the industrial revolution, and a subsequent decline at 10 cm due to changing environmental policies on leaded gasoline. Ti, K and Zr variability indicate that mineral sediment sources change over time through the 1m core, some indicative of watershed disturbance due to human impact. LOI data show large amounts of variability in inorganic sediment flux. In general, there appears to be higher sediment accumulation closer to the Hudson River versus inland, which is consistent with data from the SETs. This work is important because it will inform the best responses to preserve this landscape in the face of future sea level rise and storms.