We present results from the first meso-scale column study of flow and bioreductive reactive transport in a porous media using Single-Photon Emission Computed Tomography (SPECT) to obtain time-resolved flow field structure. SPECT allows us to detect the 3D distribution of a radioactive tracer and how it evolves through time as flow proceeds through a packed sediment column. The column size for the experiment is 10 cm diameter by 30 cm length, and the approximate spatial resolution is 4.4 mm (86 mm 3 by volume). Our experiments involve a biologically mediated reduction reaction that partially immobilizes a conservative 99mTc-DTPA tracer. The procedure results in a 3D tomographic movie of the tracer distribution and concentration during the course of the flow-through experiment. The derived data represent an unprecedentedly detailed representation of reactive flow and transport that can be modeled to …