Fig. 4. Simulated breakthrough results for a two-layered soil column under different layering orders (R1R2 and R2R1). Here R1 is for a nonreactive layer and R2 is a reactive layer with nonlinear adsorption with b values (Eq. [11]) of 0.5, 0.7, 0.9, 1.25, and 1.5. The Brenner numbers, B, used were 2, 10, and 40, respectively.