Translocation of Iron In Acid Sulfate Soils: II. Production and Diffusion of Dissolved Ferrous Iron
1975
Harmsen, K. | Breemen, N. van
Field and laboratory data on one acid sulfate soil are used to compute the concentration of dissolved Fe²⁺ with depth and time by means of a mathematical model that considers simultaneous production and diffusion of aqueous Fe²⁺ during submergence. Calculated ferrous iron concentrations compare well with concentrations measured in the course of 175 days at six depths down to 150 cm below the soil surface. Discrepancies between the model and field data for one depth may be attributed to mass flow induced by sampling of the soil solution. The results are useful in interpreting the processes involved in the typical ferric oxide and jarosite accumulations observed in the B horizon of most acid sulfate soils in Thailand. During flooding small but significant amounts of iron diffuse towards the B horizon. The calculated fluxes of iron are too small to explain the observed ferric iron accumulation by diffusion of Fe²⁺ during the flooding period only. Diffusion and evaporative mass flow of Fe²⁺ liberated by pyrite oxidation in the C horizon during the dry season appear to be more important.
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