Semester of Graduation
Master of Science (MS)
Geology and Geophysics
Over the last century, ~60% of the saltmarsh wetlands in Jamaica Bay (in the Gateway National Recreation Area of the Greater New York City region) have been converted to intertidal or subtidal unvegetated mudflats and projections suggest that all of Jamaica Bay’s saltmarsh wetlands may disappear within the next two decades. After landfall of Hurricane Sandy in 2012 and to better understand environmental controls on the maintenance of the remaining Jamaica Bay wetlands, cores were collected from twelve saltmarsh locations in the bay to study the chronology of wetland vertical accretion and mineral sediment accumulation. In association with the United States Geological Survey Wetland and Aquatic Research Center (formerly National Wetlands Research Center), cores were analyzed for 137Cs /210Pb geochronology, percent mineral content, and total water content. Results show that averaged sediment accumulation rates for the wetlands are 0.48 cm-yr-1. Analysis of sediment core mineral content indicates the uneven presence of a mineral-rich surface layer that is likely the result of sediment delivery from Hurricane Sandy. Results also document the presence of numerous subsurface layers of mineral-rich sediment interbedded between zones of organic-rich sediment. Based on various radionuclide chronologies, the estimated time of deposition, mineral-rich layers correspond to the known landfalls of major hurricanes near Jamaica Bay over the last nine decades. Collectively, these results suggest that sediments are delivered unevenly by landfalling hurricanes to coastal wetlands and that other phenomena that flood coastal wetlands with suspended sediments, such as extra-tropical storms, are important sediment sources as well.
Clarke, Ryan Christopher, "Vertical Sediment Accretion in Jamaica Bay Wetlands, New York" (2018). LSU Master's Theses. 4641.