Presence of Molecular Oxygen in Restricted Zones

When oxygen is limited, as is the case in wetland soils, unique conditions are set in motion that differentiate wetlands from uplands in snch a way as to increase organic matter in the soil, which may even resnlt in the formation of thick layers of peat, and a change in the distribntion of microorganisms (with anaerobic bacteria being more active) and chemical properties of wetland soil. 

In wetlands, oxygen cannot always move into the soil rapidly enongh to take care of the BOD of organisms becanse of the blockage of soil pores by water. The fate of oxygen in wetlands is discussed in Chapter 6. 

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