Collaborative Research: A Multiple Tracer Approach to Evaluate Groundwater Discharge into River Dominated Coastal Waters

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ABSTRACTOCE-0220215 / OCE-0221161 / OCE-0217164In this project researchers at East Carolina University, Tulane University, and the University of Miami will attempt to a comprehensive approach to allow a quantitative estimate of groundwater discharge and associated dissolved constituents to continental shelf waters. A number of recent studies have shown that he transport of groundwater into coastal zones may be a significant process in the geochemical, nutrient, and carbon budgets of many marine nearshore waters. This project will address the manner in which we may evaluate interactions between groundwater and surface water a major river-dominated margin, the Mississippi River delta.The research team will develop and apply a novel multiple-tracer approach involving the use of 222Rn/ 226Ra, 4He/3He/tritium, and short-lived radium isotopes as natural tracers of groundwater flow to examine the margin adjacent to the Mississippi River. Water samples will be collected from land-based groundwater wells near the Louisiana coast, deep porewaters via Kasten core, and surface waters from the lower Mississippi and adjacent continental shelf throughout the project. To evaluate the connection between groundwater inputs and surface water tracer inventories, we team will construct a balance of all possible inputs and outputs of these natural tracers.. This field-based research will be used to develop and constrain a numerical hydrologic model for the study area. Model results will be compared to estimates of groundwater flow obtained from geochemical modeling.