Field Tracer Investigations of Transport Behavior
in Fractured Crystalline Rocks
 

Matthew W. Becker, Ph.D.,
Department of Geology,
University at Buffalo

Allen M. Shapiro, Ph.D.,
Water Resources Division,
U.S. Geological Survey, Reston, Virginia

Funded by the USGS Toxic Substances Hydrology Program

 Objective:  Tracer and hydraulic tests are being conducted at the Mirror Lake Site to better understand how water, solutes, and particles move through fractured bedrock.   Previous investigations have demonstrated that prolonged tracer breakthrough (tailing) may be caused by advective transport, and not necessarily matrix diffusion, as previously thought.  Current efforts are underway to learn how advection can cause this behavior.  In addition, we are trying to improve methods of tracer testing in fractured bedrock, but investigating the influence of tracer test design and tracer solution density.

Tracer investigations are being conducted in the bedrock of the Hubbard Brook Experimental Forest in the southern part of the White Mountains in Grafton County, New Hampshire, USA.    This site which is maintained by the U.S. Forest Service, has been a focal point of U. S. Geological Survey research in fractured rock terrain.