La biodegradación remodela la reactividad del cloro de la materia orgánica disuelta derivada de hojarasca de plantas...

Litter-derived dissolved organic matter (DOM) is a major source of disinfection byproduct (DBP) precursors in vegetated catchments. However, the composition difference and DBP formation potential (DBP-FP) between DOM derived from herbaceous (HCP-DOM) and woody (WDP-DOM) plant litter, especially after biodegradation, remain poorly understood. Here, DOM was extracted from ten types of plant litter, categorized into HCP- and WDP-DOM, and subjected to controlled biodegradation. Both pristine and biodegraded DOM were characterized using UV-vis and fluorescence spectroscopies, Fourier transform ion cyclotron resonance mass spectrometry, and DBP-FP assays. HCP-DOM featured a greater abundance of protein- and amino sugar-like compounds, whereas WDP-DOM contained more lignin- and condensed aromatic-like components. Biodegradation led to a decrease in protein-like compounds, along with increases in terrestrial and microbial humic-like components in both DOM types. These compositional shifts drove 57-82% reductions in the formation of trihalomethanes, haloacetic acids, and chloral hydrate, yet triggered up to 147% increase in haloacetonitrile (HAN) production. Notably, biodegraded WDP-DOM generated over 50% more HAN than biodegraded HCP-DOM, highlighting its elevated nitrogenous DBP formation risk. Correlation analysis and random forest modeling further identified nitrogen-associated transformations and dynamic shifts in protein-, amino sugar-, and lignin-like components as key drivers of DBP formation. Overall, both vegetation type and microbial processing critically shape the chlorine reactivity of litter-derived DOM. Our findings underscore the need to prioritize monitoring and managing HAN precursors in source waters influenced by woody vegetation.