COI Funded Project: Tritium/helium Studies of Groundwater Discharge in Coastal Environments


Project Duration: 6/1/99-12/31/00
Key Words: groundwater discharge, tritium-helium isotopes, source aquifers, Carolina coastal plain

Proposed Research

We propose to use tritium/helium analyses of groundwater in coastal settings to help distinguish between two possible sources of groundwater inputs into coastal waters - surficial and subsurface aquifers. Our work will focus on groundwater discharges into Onslow Bay, NC and North Inlet, S.C. Published radium isotope data and preliminary carbon isotope results from these two study areas show clear evidence of direct groundwater discharge into North Inlet and into the Intra-Coastal Waterway in Onslow Bay. However, we have not yet unambiguously identified the source aquifers for the groundwater discharge at either site. In particular, at each site the relative contributions from the surficial (water table) aquifer and from subsurface (confined) aquifers are unclear. A small number of tritium/helium analyses in each study area will provide quantitative estimates of the relative contributions from surficial and deep aquifers. These estimates will make a valuable contribution to ongoing groundwater carbon isotope work in McCorkle's lab, and to radium isotope studies by colleagues in North and South Carolina. Also, by enabling us to demonstrate our ability to generate and interpret groundwater 3H/3He data in the WHOI Helium Isotope Lab, this project will make it much easier for WHOI scientists to write competitive extramural proposals for future groundwater 3H/3He work.