Transport Processes in Submerged Soils

Considering the mass balance of a solute moving in soil between two planes of unit cross-section at distances x and x - - 5x, the rate of change in mass is equal to the rate of entry across the plane at x less the rate of removal across the plane at x - - 5x. Hence 

The Biogeochemistry of Submerged Soils Guy Kirk 2004 John Wiley Sons, Ltd ISBN 0-470-86301-3 

If the movement is solely by diffusion, then from Pick s first law, 

The continuity equation for combined diffusion and mass flow is obtained by combining Equations (2.2) and (2.4)  

The concentration of the solute may also change as a result of processes occurring within the volume Sx. This is allowed for by adding a term R(C,x, t) to Equation (2.2) to give 

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This chapter is concerned with how ions and uncharged solutes in the water and soil solution in submerged soils interchange between the solid, liquid and gas phases present. This is a large topic. 1 give here the bare essentials needed to understand the transport and transformation processes discussed elsewhere in the book, and 1 give references to more detailed treatments where appropriate. The water and atmosphere overlying the soil are dealt with first and then the additional complexities in the soil. 

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