SEDIMENT DEPOSITION AND ACCRETION IN A HUDSON RIVER TIDAL MARSH

Surface sediment samples were collected from Piermont Marsh located in New York State. Twenty-nine sites were measured to determine the sediment accumulation rate from 2013 to 2015 along the banks of the three creeks (Tidal, Crumkill, and Sparkill) using feldspar marker horizons as a base. In addition, organic matter content was measured in fifty-eight samples using loss on ignition (LOI). The overall average sediment accumulation rate between 2013 and 2015 was 7.62 mm/ year indicating an increase when compared to the average sediment accumulation rate reported by Peteet et al in 1998 (0.26 cm/yr). The overall organic matter content for the 2015 samples was 15.79%. Measurements of sediment accumulation from 2015 had greater variation than in 2014. Greater accumulation was found at the edges of the creek than deeper into the marsh. However, no significant difference in organic matter content was measured between the two distances from creek. A 5 meter distance from the creeks had an average sediment accumulation rate of 9.69 mm/year and an average organic matter content of 15. 79% compared to a 25 meter distance from the creeks, which had an average sediment accumulation rate of 5.26 mm/year and an average organic matter content of 16.51%.