Institute of Biogeochemistry and Pollutant Dynamics (IBP), Department of Environmental Systems Science, ETH Zurich, 8092 Zurich, Switzerland.
Department of Chemistry, Seattle University, Seattle, Washington 98122, United States.
Environ Sci Technol. 2020 Mar 17;54(6):3316-3324. doi: 10.1021/acs.est.9b07246. Epub 2020 Mar 2.
Singlet oxygen (O) generation quantum yields from chromophoric dissolved organic matter (CDOM) have been reported for many samples over the past 4 decades. Yet even for standardized isolates such as those from the International Humic Substance Society (IHSS), wide-ranging values exist in the literature. In this manuscript, time-resolved O phosphorescence was used to determine the O quantum yields (Φ) of a variety of dissolved organic matter (DOM) isolates and natural waters. In general, the O quantum yield values in this study are in the middle, although below the median of the range of past reported values (e.g., for Suwannee River Natural Organic Matter IHSS isolate: 1.8% vs 0.23-2.89%). Notably, hydrophobic neutral fractions of DOM isolates were found to possess the highest O quantum yields, an interesting result given that these fractions are not retained in typical humic and fulvic acid isolation procedures that use XAD resins. The excitation wavelength dependence of O generation from CDOM was also examined, and an approximate linear decrease with longer excitation wavelength was observed. This work advances the understanding of CDOM photoprocesses, especially in relation to wavelength-dependent O production, which is valuable for assessing real-world environmental behavior.
过去 40 年来，已有许多研究报告了发色溶解有机质（CDOM）的单线态氧（O）生成量子产率。然而，即使对于国际腐殖质协会（IHSS）等标准化分离物，文献中也存在广泛的数值。在本研究中，我们使用时间分辨 O 磷光法测定了各种溶解有机质（DOM）分离物和天然水的 O 量子产率（Φ）。总的来说，本研究中的 O 量子产率值处于中等水平，尽管低于过去报道值范围的中位数（例如，对于苏万尼河天然有机物质 IHSS 分离物：1.8% 对 0.23-2.89%）。值得注意的是，DOM 分离物的疏水性中性部分被发现具有最高的 O 量子产率，这是一个有趣的结果，因为这些部分不会被使用 XAD 树脂的典型腐殖质和富里酸分离程序保留。我们还研究了 CDOM 光解过程中 O 生成的激发波长依赖性，观察到随着激发波长的增加而近似线性下降。这项工作增进了对 CDOM 光解过程的理解，特别是与波长依赖性 O 生成有关的理解，这对于评估实际环境行为非常有价值。
