Herbicide pollution rarely stays where it's sprayed. This 2D cross-section simulator models a real solute-transport process: a pulse of herbicide applied at the soil surface advects downward with infiltrating rainwater while continuously partitioning between dissolved and soil-bound phases, exactly as described by the linear equilibrium sorption model used in hydrogeology. Switch between four real herbicides spanning three orders of magnitude in soil affinity (dicamba, 2,4-D, atrazine, glyphosate), tune organic-carbon content and rainfall, drag on the column to probe any depth, and read a live breakthrough curve showing whether the plume reaches the water table in weeks or effectively never leaves the topsoil.