State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKLESPC), Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China.
State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKLESPC), Beijing Key Laboratory for Emerging Organic Contaminants Control, School of Environment, Tsinghua University, Beijing, 100084, China; Advanced Interdisciplinary Institute of Environmental and Ecology, Beijing Normal University, Zhuhai, 519087, China.
Water Res. 2024 Jun 1;256:121604. doi: 10.1016/j.watres.2024.121604. Epub 2024 Apr 11.
Notable differences in photo-physical and chemical properties were found between bulk water and solid phase extraction (SPE) isolates for dissolved organic matter (DOM). The moieties extracted using modified styrene divinylbenzene cartridges, which predominantly consist of conjugated aromatic molecules like humic acids, contribute mainly to light absorption but exhibit lower quantum yields of fluorescence and photo-produced reactive intermediates (PPRIs). Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) revealed lignin as the moieties displaying most significant variance in abundance. In Van Krevelen-Spearman plot, we observed molecules positively or negatively correlated with DOM's optical and photochemical properties (including SUVA, steady-state concentrations of ·OH, O quantum yield, etc.) were confined to specific regions, which can be delineated using a threshold modified aromaticity index (AI) of 0.3. Based on the relationships between optical properties and PPRI production, it is suggested that the energy gap between ground state and excited singlet state (△E), governing the inner conversion rate, serves as a determinant for apparent quantum yield of PPRIs in DOM, with intra-molecular charge transfer (CT) interactions potentially playing a pivotal role. Regarding DOM's photoreactivity with pollutants, this study has revealed, for the first time, that protein/amino sugars/amino acids could act as antioxidant groups in addition to phenols on the photolysis of sulfadiazine. These findings provide valuable insights into DOM photochemistry and are expected to stimulate further research in this area.
在溶解有机物（DOM）的光物理和化学性质方面，散装水和固相萃取（SPE）分离物之间存在显著差异。使用改性苯乙烯二乙烯基苯盒提取的部分，主要由类腐殖酸的共轭芳香族分子组成，主要贡献于光吸收，但荧光和光产生的反应中间体（PPRIs）的量子产率较低。傅里叶变换离子回旋共振质谱（FT-ICR MS）显示木质素是丰度变化最大的部分。在范克里夫-斯皮尔曼图中，我们观察到与 DOM 的光学和光化学性质（包括 SUVA、·OH 的稳态浓度、O 量子产率等）正相关或负相关的分子局限于特定区域，可以使用修改后的芳香度指数（AI）为 0.3 来划定这些区域。基于光学性质和 PPRI 产生之间的关系，建议决定 DOM 中 PPRI 表观量子产率的是基态和激发单线态之间的能隙（△E），控制内转换速率，而分子内电荷转移（CT）相互作用可能起着关键作用。关于 DOM 与污染物的光反应性，本研究首次揭示了在磺胺嘧啶的光解过程中，除了酚类外，蛋白质/氨基糖/氨基酸还可以作为抗氧化基团。这些发现为 DOM 光化学提供了有价值的见解，并有望激发该领域的进一步研究。
