David Genereux: NC State – MEAS |

Title: The Nitrate Goes In, But When Will It Come Out?  Groundwater Transit Times in the NC Coastal Plain |

Abstract:  This talk will address what we’ve learned during our research on groundwater transit times and contaminant nitrate flux through the surficial (unconfined) aquifer in the NC coastal plain.  Novel groundwater sampling at the groundwater – stream interface (i.e., the streambed) has created new options and insights for quantifying (1) the rate of discharge of nitrate from the groundwater system to streams, (2) the distribution of water and nitrate transit times through the unconfined aquifer, from recharge at the water table to discharge at the streambed, and (3) the future nitrate discharge from aquifer to stream in coming decades.  Progress on these three issues was made using combined measurements of groundwater flux and the concentrations of nitrate and age-dating tracers in groundwater.  Insights into all these processes and others were derived from measurements in or below streambeds, without the need for long-term groundwater monitoring, complex numerical models of groundwater flow, or even wells.