Tim Ginn
University of California, Davis
The fate of subsurface solutes is controlled as much by geochemical as by physical
properties, as is reflected in the importance of attenuation/ sequestration
in solute fate. Research in quantitative hydrogeology has long been focused
on transport and remains out of balance with these natural processes. Characterization
technologies are also more advanced for physical properties. Consequently the
role of geochemical heterogeneity on solute fate remains a rich and relevant
research field. Here we review some important aspects of realistic reactive
transport in geochemically heterogeneous natural media. Of particular focus
is the upscaling problem. A lagrangean approach is proposed from the precedent
of using multiple tracers for NAPL characterization. Here, multiple reactive
tracers are used in conjunction with an inverse problem to characterize geochemical
heterogeneity in terms of distributions of flux over both travel time and "cumulative
reactivity." The flux distribution is useful in forward modeling of reactive
transport. Future work includes extensions to more realistic reaction systems.