Fig. 1. Adsorption isotherms of brilliant sulfaflavine (BF) and sulforhodamine B (SB) of soil from the top (0- to 0.1-m layer) and subsoil (0.5- to 0.6-m layer). C, solute concentration in the soil solution; C_0.5, dissolved equilibrium concentration at 50% of S_max; K_d, linear distribution coefficient. S, sorbed dye mass per mass of dry soil; and S_max, sorbed dye mass per mass of dry soil at maximum sorption.