Fig. 5 illustrates the 3DEEM fluorescence spectra in the first
240 min of UV irradiation at a pH of 6.5. At 0 min, the fluorescence
spectra display the presence of humic-like, fulvic-like and proteinlike
fluorophores in the solution. However, the intensities of all the
fluorophores decrease as the irradiation time increases. After
60 min of irradiation, there is no humic-like fluorophore remaining,
and the intensities of the fulvic-like and protein-like fluorophores
decrease. The intensities of the fulvic-like and protein-like fluorophores
continue decreasing as the UV irradiation increases.