Data for: Iron-bound carbon increases along a freshwater−oligohaline gradient in a subtropical tidal wetland

Soil properties and plant biomass: salinity, pH, bulk density, moisture content, ORP; aboveground and belowground biomass; root Fe piaque; Enzyme activity and bacterial abundance: cellobiohydrolase, phenol oxidase, Geobacter and Gallionella; Solid-phase Fe species: non-sulfidic Fe(II), Fe sulfides, amorphous Fe(III), crystalline Fe(III) and molar Fe(II):Fe(III) ratios; Soil C and Fe-bound C pool: SOC pool, molar OC:Fe ratio, Fe-bound C pool and the ratio of Fe-bound C pool to SOC pool.