Arsenic is a redox active toxin that can severely impact environmental quality and human health. One of the principal phases controlling dissolved concentrations and transport of this element within aerobic environments is iron (hydr)oxides. As a consequence, reductive transformation of iron has pronounced influences on arsenic partitioning. A transition from aerobic to anaerobic conditions appears to be the major means by which arsenic is displaced from solids. Using packed iron oxide coated sand columns, we reveal the desorption of arsenite relative to arsenate in the presence and absence of iron oxide transformations. Reductive transformation, inclusive of dissolution and recrystallization, invokes a displacement of As(III) and As(V). However, desorption and transport of As(V) is transitory whereas As(III) undergoes prolonged and pronounced desorption. Moreover, desorption of As(III) occurs independent of iron reduction. Thus, although As(III) has a greater binding capacity on iron (hydr)oxides than As(V), surface complexes of the reduced species, arsenite, are appreciably more labile than for the oxidized counterpart.