Soil phase iron in high salt marsh soils in relation to redox potential

Abstract:

A total of 6 soils from different physiographical positions in a high salt marsh were studied. The Fe species considered were: amorphous-Fe (III), crystalline-Fe (III), pyrite-Fe and acid volatile sulfide of Fe (AVS-Fe). The results showed significant changes in the concentrations of the Fe species with position and depth. In soils with oxic (Eh>300mV) and suboxic conditions (Eh =100-300mV) the dominant forms of Fe were amorphous and crystalline oxyhydroxides of Fe. In contrast, in strongly reduced soils or horizons (Eh< -100 mV; soil 6) pyrite-Fe was the most abundant form. Where conditions were oxic or slightly reduced at the surface and anoxic at depth, high concentrations of amorphous and crystalline oxyhydroxides of Fe were found in the top 10 cm. In these soils, the amorphous oxyhydroxides of Fe quickly disappeared with depth, while pyrite-Fe levels increased significantly. The amount of crystalline oxyhydroxides of Fe also decreased with depth, but more gradually.

Año de publicación:

2001

Keywords:

• pyrite
• Iron oxyhydroxides
• Salt marsh soils
• Redox potential

Fuente:

scopus