Photochemical release of dissolved organic matter from particulate organic matter: Spectroscopic characteristics and disinfection by-product formation potential

In this study, we investigated the photochemical release of dissolved organic matter (DOM) from the particulate organic matter (POM) of soil and litter leaves (broad leaves; coniferous leaves) and compared the releasing characteristics of the DOM using UV-visible and fluorescence spectroscopy. The disinfection by-product formation potential (DBPFP) of the released DOM was also examined. Additional dissolved organic carbon (DOC) was released by UV irradiation for all POM sources (10.58 ± 2.7 mg-C L⁻¹ g⁻¹ for BL, 8.32 ± 2.6 mg-C L⁻¹ g⁻¹ for CL, and 0.20 ± 0.1 mg-C L⁻¹ g⁻¹ for soil). The excitation-emission matrix combined with parallel factor analysis results showed that the photo-released DOM from soil was mainly humic-like components (C1, C3) produced by photodesorption, resulting in high trihalomethane formation potential, while protein-like component (C2) was the major component of the photodissolved DOM from litter leaves, resulting in high haloaceticacid formation potential. Further, DBPFP from soil and litter leaves showed high correlation with humic-like components (C1+C3) and SUVA₂₅₄, respectively. In conclusion, this study demonstrates that significant amounts of DOM could be released from POM under UV irradiation, although the characteristics and DBP formation of the photo-released DOM were highly dependent upon the POM source.