Tidally driven water column hydro-geochemistry in a remediating acidic wetland

► We investigate water column hydro-geochemistry in a tidally inundated acid wetland. ► High spatial and temporal dynamism occurred during tidal cycles with pH fluctuating over 3 units. ► Tidal forcing drives spatially heterogeneous transport of solutes to the water column. ► Persistent, elevated water column Fe2+ was driven by contrasting geochemical processes that exhibited distinct spatial zonation. ► Arsenic was mobilised in the lower intertidal water column and correlated with Fe2+.