Department of Chemistry, University of Toronto Scarborough, Scarborough, ON M1C1A4, Canada.
Water Res. 2013 Sep 15;47(14):5189-99. doi: 10.1016/j.watres.2013.05.059. Epub 2013 Jun 13.
Laser flash photolysis (LFP) was used to characterize a triplet excited state species isolated from Black River and San Joaquin wetlands particulate organic matter (POM). The solubilized organic matter, isolated from POM by pH-independent diffusion in distilled water, was named PdOM. UV-visible absorption spectroscopy, excitation-emission matrix spectroscopy (EEMs), and (1)H NMR were used to characterize the PdOM. While LFP of dissolved organic matter (DOM) is known to generate the solvated electron, LFP of the PdOM transient in argon-, air-, and nitrous oxide-saturated solutions indicated that this was a triplet excited state species ((3)PdOM*). The lifetime and the reactivity of (3)PdOM* with sorbic acid, a triplet state quencher, were compared with that of the triplet excited state of benzophenone, a DOM proxy. A second excited state species (designated DOM*), with a longer lifetime, was reported in a number of previous studies but not characterized. The lifetime of DOM*, measured for seventeen organic matter isolates, lignin, tannic acid, and three wetlands plant extracts, was shown to differentiate allochthonous from autochthonous DOM. (3)POM* and DOM* were also observed in lake water and a constructed wetlands' water. Aqueous extracts of fresh and aged plant material from the same wetland were shown to be one source of these excited state species. This study provides evidence of a role for POM in the photochemistry of natural and constructed wetland waters.
激光闪光光解（LFP）被用于表征从黑河和圣华金湿地颗粒有机物质（POM）中分离出的三重激发态物质。通过在蒸馏水中进行与 pH 无关的扩散从 POM 中分离出来的可溶性有机物，被命名为 PdOM。使用紫外可见吸收光谱、激发-发射矩阵光谱（EEMs）和（1）H NMR 对 PdOM 进行了表征。尽管已知溶解有机物质（DOM）的 LFP 会产生溶剂化电子，但在氩气、空气和氧化亚氮饱和溶液中 PdOM 的 LFP 瞬态表明，这是一种三重激发态物质（（3）PdOM*）。（3）PdOM与山梨酸的寿命和反应性，山梨酸是一种三重态猝灭剂，与苯甲酮的 DOM 类似物的三重激发态进行了比较。在许多先前的研究中报道了第二种激发态物质（称为 DOM），但没有对其进行表征。寿命为十七种有机物分离物、木质素、单宁酸和三种湿地植物提取物测量的 DOM*，表明其可以区分异源 DOM 和同源 DOM。（3）POM和 DOM也在湖水和人工湿地水中观察到。来自同一湿地的新鲜和老化植物材料的水提物被证明是这些激发态物质的来源之一。这项研究为 POM 在自然和人工湿地水的光化学中所起的作用提供了证据。
