Soil enzyme-catalyzed humification of phenolic compounds: implications for the environmental fate and risk of emerging contaminants

Emerging contaminants (ECs), such as pharmaceuticals, endocrine-disrupting compounds (EDCs), and microplastics, increasingly accumulate in soils, posing ecological and health risks. Phenolic compounds, derived from natural and anthropogenic sources, undergo enzyme-mediated humification that governs interactions with co-occurring ECs. This review systematically evaluates multidisciplinary studies to elucidate enzyme-driven phenolic transformations and their influence on ECs dynamics, with emphasis on oxidative enzymes (e.g., phenol oxidase, laccase) that catalyze lignin-like polymerization. Evidence regarding the generation of reactive intermediates and humic polymers, and their regulatory roles in adsorption, degradation, mobility, and persistence of ECs, is synthesized. Representative case studies illustrate the environmental implications of these processes. Results show that phenolic humification produces radical intermediates and humic substances (HS) enriched with redox-active and functional groups, which modulate ECs speciation, enhance degradation or transformation pathways, and alter transport in soils. Humic polymers function as both sorbents and carriers, exerting dual effects on risk propagation. Enzyme activity, substrate availability, and soil physicochemical conditions are critical factors controlling these interactions. Overall, soil enzyme-catalyzed humification of phenolic compounds plays a central role in shaping ECs behavior and ecological risks. Elucidating these mechanisms provides a scientific foundation for risk assessment and supports the integration of enzymatic processes into predictive models and remediation practices for sustainable management of ECs.