Geochemical Heterogeneity in Reactive Transport; Review and Lagrangean Upscaling

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.

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