Fig. 4

Spectral changes expressed as categories as they were assigned by manually comparing the post-treatment spectra to the pre-treatment references. Asterisks (*) indicate spectra with newly evolved bands which, however, could be traced back to inorganic impurities originating from the rising water (not used in category assignment). White tiles indicate data not available (measurements were not taken due to expected unexploitable spectra, as other measurements of the same polymers indicated)