Transport mechanisms

Introduction
Molecular diffusion in a medium
Transfer accross phase boundaries
Examples for application
Advective and dispersive transport
References and links

Selftest
Problems
     Problem 1
           Hint
           Answer
     Problem 2
           Hint
           Answer
     Problem 3
           Answer
     Problem 4
     Problem 5

Problem 1

Imagine the following situation: There is a lake with well mixed water. In the sediment at 1 m depth below the sediment-water-interface, methane production by bacteria is going on. Thus methane is diffusing into the lake where it is quickly diluted due to turbulent mixing, and then gassing out at the lake surface (here we ignore all processs that may consume methane). What is the concentration profile of methane between the layer where it is produced and the sediment-water-interface (neglect what is happening further down in the sediment)?