Calculated vertical column densities down to the A_V = 10 surface (solid lines) and down to the midplane (dashed lines) of H₂O, OH, and simple organics as a function of radius r for the T Tauri (left panel) and Herbig Ae/Be (right panel) disks. For HNC, only the total column density down to the midplane is shown. Column densities derived from observations are indicated by vertical lines (when there are ranges of values) or by squares (when only one value is available), with their radial locations corresponding to the approximate region probed by observations (see Table 3).