Comment on Kierlik et al. Application of Mössbauer Spectroscopy for Identification of Iron-Containing Components in Upper Silesian Topsoil Being under Industrial Anthropopressure. Materials 2020, 13, 5206

Kierlik et al. recently reported their study in this journal on the application of Mössbauer spectroscopy in identifying the iron-containing components in Upper Silesian topsoil as being under industrial anthropopressure. While the presented work is an excellent example of characterizing topsoil, a significant part of the study involving iron-bearing samples using (57)Fe Mössbauer spectroscopy is erroneous. In the spectral fitting routine for the obtained Mössbauer spectra of the sample IIA (Figure 2; Table 3), the authors have erroneously fitted only a single sextet for magnetite, which is unacceptable. The line width obtained by them is also incorrectly mentioned in Figure 2, as evident from fitting D1 and D2 doublets as well as of magnetite tetrahedral and octahedral sites, making the relative abundances of individual phases meaningless. The inaccurate line width makes the authors fit the inadequate number of doublets necessary for the iron-bearing phases present in these samples, resulting in incorrect relative abundance for the other phases found in the materials, making the subsequent discussion not much useful.