Examples of spectral synthesis around Pd i λ3404.9 Å used in this analysis. The dots represent the observational data and solid lines the synthesis spectra. Offsets of 0.3 were added for better visualization. See also Fig. 5 for details. For G 192-43, the absorption feature exhibits a W shape, as shown in the partial enlarged drawing of the spectrum in the lower right of the middle panel. Two synthesis spectra with [Pd/Fe] = 0.20 and 0.39 are overplotted, respectively. A similar plot is shown for G 88-10 (right panel), for which the lower synthesis ([Pd/Fe] = 1.50) was adopted as an upper limit.