Evaporation of a Solute to the Atmosphere

During its passage through the basin, which is assumed to be uniform in concentration, the pollutant is partially transferred to the atmosphere by evaporation and leaves at the concentration C (kg/m ), which prevails in 

Two environmental models (a) evaporation from a basin (b) reaeration of a river. 

Drawing on the scheme represented by Equation 2.1 and assuming the basin contact to be well mixed, we write 

If one assumes mass transfer to be controlled by the water phase, we can write 

Before setting aside the solution of a model, it is always useful to verify its validity and to examine it for unusual features. This is done by first setting time t = 0. This yields C = 0 as required. Next we allow t to go to infinity. This reduces the exponential term to zero and we obtain 

---