James W. Jawitz, Ph.D., P.E. Associate Professor Environmental Hydrology Graduate Coordinator Soil and Water Science Department University of Florida

Dr. Jawitz earned a PhD in environmental engineering at the University of Florida in 1999. After teaching in the civil engineering departments at Purdue University and the University of Illinois at Chicago, he is now an associate professor in the Soil and Water Science Department at the University of Florida. He directs the Environmental Hydrology Laboratory and studies human impacts on hydrologic systems with emphases on groundwater and wetlands. He has worked on field remediation research projects in Delaware, Florida, Utah, and Ontario, Canada.

Presentation Description
Reactive tracer techniques for predicting DNAPL mass depletion and flux reduction
Aquifer heterogeneity and contaminant architecture are important factors controlling nonaqueous phase liquid dissolution dynamics. Nonreactive and reactive tracers that traverse contaminant source zones enable quantification of aquifer and contaminant heterogeneity such that remediation performance can be predicted with simple source depletion models. Here we present analytical, numerical, and laboratory experimental applications of these techniques. Nonreactive tracers are commonly used to provide information about travel time distributions in hydrologic systems.  Reactive tracers have more recently been introduced as a tool to quantify the amount of NAPL contaminant present within the tracer swept volume. Our group has extended reactive tracer techniques to also characterize NAPL spatial distribution heterogeneity. By conceptualizing the flow field through an aquifer as a collection of streamtubes, the aquifer hydrodynamic heterogeneities may be characterized by a nonreactive tracer travel time distribution, and NAPL spatial distribution heterogeneity may be similarly described using reactive travel time distributions. The combined statistics of these distributions are used to derive a Lagrangian analytical solution for contaminant dissolution. Thus, performance of dissolution-based remedial techniques can be predicted (both in terms of breakthrough curves and mass reduction/flux reduction relationship) using parameters obtained from tracer tests. Illustrative applications are presented from numerical simulations of aqueous dissolution, and laboratory and field-scale experiments of cosolvent- and surfactant-enhanced NAPL remediation.