Iron geochemical zonation in a tidally inundated acid sulfate soil wetland

► We conduct an integrated hydro-geochemical study of tidally inundated coastal acid sulfate soils. ► Tidal inundation radically alters the biogeochemical cycling of Fe in a complex manner. ► Fe mobilisation, redistribution and mineralogy are controlled by topography-tide interactions. ► A conceptual model of Fe hydro-geochemical zonation across the tidal fringe is presented.