Authors
Hongke Feng, Yuyue Li, Fuxuan Ren, Xingzhi Jin, Xiaohu Zhang, Yi Yang, Hao Chen, Peng Cai, Xing Ding
Published in
Environmental science & technology. Volume 60. Issue 43. Pages 30376-30387. Nov 03, 2026.
Abstract
Roxarsone (ROX) degradation in soil environments is a recognized source of arsenic contamination, but the concurrent evolution of persistent free radicals (PFRs) presents an overlooked hazard. Here, we report the generation of unique nitrogen-centered PFRs during ROX phototransformation on soil mineral surfaces. Unlike typical environmental PFRs, these species exhibit a distinct triple-peak EPR signature, which is proposed to arise from the magnetic coupling between •NO and •NHR radicals following C-As bond cleavage. Mineral composition strongly governs radical evolution, with MnO2 enhancing and Fe2O3 suppressing PFR stability. These nitrogen-centered radicals act as efficient electron shuttles, sustaining the production of reactive oxygen species (•OH, •O2-, H2O2). Multitrophic toxicity tests (bacteria-plant-earthworm) combined with rigorous arsenic-controlled conditions (As(V)≤150 ppb, As(III)≤20 ppb) reveal that the observed growth inhibition, oxidative damage, and histopathological effects are predominantly driven by PFR-mediated processes rather than by released inorganic arsenic. These findings uncover a previously unrecognized pathway for nitrogen-centered radical formation and highlight the necessity of incorporating radical-driven toxicity into environmental risk assessments of organoarsenic contaminants.
PMID:
42975443
Bibliographic data and abstract were imported from PubMed on 03 Nov 2026.
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