Celeste Gambino

Advisor: Don Barber

Geology

 

Analyzing Saltmarsh Carbon Isotopes and Heavy Metal Abundances to Enhance Late Holocene Sea Level Reconstructions in Coastal North Carolina

 

This study will analyze the chemical composition of Late Holocene saltmarsh peat deposits in coastal North Carolina. Coastal saltmarsh peat deposits record changes in sea level rise rates. High-resolution sea level reconstructions require precisely constrained age and paleomarsh elevation data. Analysis of heavy metal abundances provides age information because the regional metal pollution has varied through time. Analysis of carbon isotopes provides paleomarsh elevation information because high marsh plants have different carbon isotopic compositions from low marsh plants.

Cavity Ring-Down Spectroscopy (CRDS) will be used to examine the 13C/12C isotope ratios to determine the composition of the peat. Lower 13C/12C values indicate peat composed primarily of Juncus roemarianus, a C3 plant with an indicative range of Mean High Water to Mean Higher High Water (i.e.- a high marsh plant). Higher 13C/12C values indicate peat composed primarily of Spartina alterniflora, a C4 plant with an indicative range of Mean Tide Level to Mean High Water (i.e.- a low marsh plant). Inductively Coupled Plasma Mass Spectrometry (ICP-MS) will be used to determine heavy metal abundances with depth in the peat core samples. These analyses will be applied to peat core samples from Jarrett Bay and Sand Hill Point, North Carolina. 

The new data from this study will be combined with previous results to enhance high-resolution sea level curves for coastal North Carolina. High-resolution sea level reconstructions are required to compare with high-resolution paleotemperature reconstructions in order to establish the relationship between temperature and sea level. This ultimately will improve future sea level rise predictions.