Floodwater oxygen concentration

Floodwater oxygen concentration in wetlands remains relatively high dne to ... 

In flooded and waterlogged soils, the pores are filled with water and any dissolved oxygen is rapidly consumed. Under these conditions, oxygen is introduced into the wetland soil profiles by diffusion and mass flow through the floodwater and plants. The oxygen concentration in the soil pore space is lower than that in the atmosphere. In wetland soils, the net movement is restricted by the presence of water in the pore space. The diffusion of oxygen in water is 10,000 times slower than that in air. 

Several factors influence the thickness of an oxidized surface layer. These include the oxygen concentration of the floodwater, the soil organic matter content, the amount of reduced compounds in the reduced or anaerobic soil zone, the photosynthetic activity of periphyton and aquatic macrophytes, and the bioturbation by macroorganisms. 

The concentration of oxygen in soil pore waters is generally lower than that in the atmosphere above the soil, so that the net movement is downward, that is, from the atmosphere to soil. In wetlands, this net movement is prevented by the presence of floodwater within the pore space. However, when the water table is below the soil surface, the oxygen movement into soil is similar to uplands. 

---