Modeling results of the total flux as a function of the carbon depletion factor defined as f_depl = (C/H)/(C/H)_ISM. Observations are plotted at the interpolated carbon depletion fraction. For DO Tau, we plot two values for the total flux: the star is the corrected flux for absorption with a constant value, and the diamond is only masked for absorption, as discussed in the main text. The derived carbon depletion fraction by interpolation with the model is presented in the top-right corner, with errors given by the measurement uncertainty of the [C I] observations.