Fig. 4. Desorption of (A) ¹⁴C-isoproturon (IPU), (B) ¹⁴C-monodesmethyl-isoproturon (MDIPU), and (C) ¹⁴C-4-isopropyl-aniline (4IA). Each figure shows the sorbed ¹⁴C in percent of initially sorbed ¹⁴C versus time for initial concentrations of 0.5 (crosses), 1.0 (closed triangles), 5.0 (open triangles), 10.0 (closed squares), and 25.0 mg L^-1 (open squares). The values are the mean of two or three replicates. The vertical bars indicate ±1 SD.