Tipping bucket model

In soils, phosphate sorption data usually take the shape of a high-affinity (H-type) isotherm, like that of Figure 9.6. Because of this and the nonreversible behavior of sorption, the downward movement of phosphate and other strongly bonded elements can be approximated by the tipping bucket model. This model visualizes the layers... 

It is perhaps worthwhile to use a simple problem to illustrate the application of the tipping bucket model. 

---