The Use Of Nanoparticles To Assess Subsurface Flow Heterogeneity

Understanding subsurface flow condition is difficult, but very important. Tracer tests have been done as a diagnostic tool to assess the subsurface fluid flow conditions. However conventional ionic tracers are very diffusive, thus during a prolonged field test, the resolution of the breakthrough curve are usually tempered by their rapid rate of diffusion. Inert nanoparticle tracers are much larger than ionic tracers, and not very diffusive. Laboratory scaled dual nanoparticle and chemical tracer experiments in both aqueous and CO2 based systems are demonstrated in this dissertation, as well as a field test in a "single crack" sub-horizontal bedrock fracture system. These tests demonstrated the CDot nanoparticles behave inertly both in the laboratory and in the natural groundwater conditions. Differential arrival patterns between inert nanoparticle tracers and ionic tracers suggest that the particle tracers give higher resolution breakthroughs. Moreover, in the field test, channelized flow is hinted by the erratic arrival of inert particle tracer, which is further confirmed by the largely retarded arrival of surface area dependent sorbing ionic trace injected simultaneously