| 论文摘要： |
Algal organic matter (AOM) significantly influences the photochemical behavior of dissolved organic matter in aquatic environments. This study investigated the effects of chlorination on the photophysical and photochemical properties of AOM derived from Microcystis aeruginosa, compared these alterations with those observed for natural organic matter (NOM), and examined their impact on the photodegradation of organic contaminants, with a particular focus on N,N-diethyl-m-toluamide (DEET) as a model substrate. The results demonstrated that chlorination substantially altered the photochemical reactivity of AOM. AOM and NOM exhibit distinct reactivities, reflecting their varied molecular compositions and functional groups. Specifically, chlorination reduced the aromaticity (SUVA(254) decreased by similar to 42 %) and molecular weight (decreased by similar to 30 %) of AOM, resulting in a shift of fluorescence peaks to lower wavelengths. It also enhanced the formation of singlet oxygen (O-1(2)) and hydroxyl radical ((OH)-O-center dot). Chlorinated extracellular organic matter (EOM) exhibited a remarkable increase in (OH)-O-center dot quantum yield, with a 200-fold enhancement at a high free available chlorine (FAC) dose (FAC/TOC ratio of 2.0). The photodegradation of DEET, involved H-abstraction and hydroxylation by (OH)-O-center dot, was significantly accelerated in chlorinated EOM, highlighting the critical role of chlorinated AOM in driving photosensitized degradation processes. The findings emphasized the role of chlorination in altering AOM's photochemical properties, with significant implications for the enhanced transformation of contaminants in natural and engineered aquatic systems. |
