6. Release from Sediments
This content explores the complexities of mass balance within sediment systems, particularly focusing on the processes of diffusion and the roles of porosity and adsorption. It emphasizes the critical concept of effective diffusivity in porous media and presents equations governing these processes, including the Millington Quirk expression for diffusion coefficients. The chapter also addresses local equilibrium assumptions in the context of adsorption and desorption dynamics.
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What we have learnt
- Understanding mass balance in sediment systems requires consideration of both fluid and solid phases.
- Effective diffusivity plays a crucial role in determining how substances move through porous media.
- Local equilibrium assumptions can simplify complex adsorption scenarios when considering fluid-solid interactions.
Key Concepts
- -- Mass Balance
- A fundamental principle used to describe the flow of mass within a system, applicable in analyzing sediment volumes.
- -- Effective Diffusivity
- The reduced diffusion coefficient in porous media, reflecting the complexity introduced by solid phase interactions.
- -- Local Equilibrium Assumption
- An assumption that allows simplification of adsorption processes under certain conditions, implying quick equilibration of concentrations between solid and fluid.
- -- Millington Quirk Expression
- A formula used to describe the relationship between diffusion coefficients and the porosity of the medium.
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