The Diffusion and Consumption of Oxygen in Submerged Soils1
- R. H. Howeler and
- D. R. Bouldin2
Six O2 diffusion models, which included several oxygen consumption processes, were evaluated by measuring O2 consumption rates under conditions which approached the steady state and under transient-state conditions. Consumption rates under approximately steady-state conditions were determined by placing undisturbed lake-bottom cores in water and measuring the decrease in O2 concentration of the water. Transient-state consumption rates were determined from the amount of O2 gas that had to be injected above an initially reduced soil to maintain a constant O2 concentration at the soil surface. The distribution of extractable Fe in the cores was obtained by sectioning frozen soil cores and extracting the sections with NaOAc at pH 2.8 and with dithionite in EDTA.
Considerable amounts of Fe2+ were found to diffuse from the reduced zone to the oxidized zone where it accumulated as precipitated Fe3+. The oxygen consumption was best described by models which included consumption by microbial respiration in the aerobic zone and oxidation of mobile and nonmobile reductants such as Fe2+. The latter components of oxygen consumption accounted for about 50% of the consumption by cores after 11 days when the cores were initially uniformly reduced.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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