IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 BOOK OF ABSTRACTS 186 Poster Session / Analysis and Characterization Hall A molecular reservoirs and contextdependent assembly patterns. In this design, sample-level descriptors are used to assess fraction separation and subtype structure, whereas formula-level and reactomic descriptors are used to identify enriched signatures, differential transformation motifs, and pathwayscale contrasts. By combining FT-ICR-MS with interpretable machine learning and molecular transformation analysis, the present framework aims to move beyond descriptive fraction labels such as HA and FA and to test whether historically defined humic fractions correspond to stable molecular entities or to environmentally conditioned signatures within a broader dissolved humic continuum. This sourceaware perspective is expected to provide a more mechanistic basis for understanding humic-substance continuity, environmental origin effects, and transformation connectivity across natural systems. References 1. A. Piccolo, Soil Science 166 (2001) 810-832. 2. K.E. Norris, J.J. Pignatello, E.A. Vialykh, M. Sander, K. McNeill, F.L. Rosario-Ortiz, Environmental Science & Technology 59 (2025). 3. Q.-L. Fu, M. Fujii, T. Riedel, Analytica Chimica Acta 1125 (2020) 247-257. 4. Q.-L. Fu, M. Fujii, R. Ma, Analytical Chemistry 95 (2023) 2796-2803. 5. E. Kitson, W.R. Kew, W. Ding, N.G.A. Bell, Journal of the American Society for Mass Spectrometry 32 (2021) 1263-1267. 6. B.P. Koch, T. Dittmar, Rapid Communications in Mass Spectrometry 20 (2006) 926-932. Acknowledgement The author would like to thank Dr. Akio Miyazato from the Mass Spectrometry Center for Nano Materials and Technology, Japan Advanced Institute of Science and Technology, for his support for the FT-ICR-MS measurement.
RkJQdWJsaXNoZXIy NDA4Mjc=