Eawag, Swiss Federal Institute of Aquatic Science and Technology, CH-8600, Dübendorf, Switzerland.
Environ Sci Technol. 2011 Feb 15;45(4):1334-40. doi: 10.1021/es102212t. Epub 2011 Jan 27.
Dissolved organic matter (DOM) has recently been shown to reduce the transformation rate of various aqueous organic contaminants submitted to oxidation by excited triplet states, apparently by inhibiting the transformation of oxidation intermediates. The main goals of the present study were to evaluate in more detail the effect of concentration and type of DOM on the triplet-induced transformation rate of four selected organic compounds and to check for an analogous inhibition effect in the case of oxidation induced by hydroxyl radical. A marked inhibition by DOM of triplet-induced oxidation was observed for N,N-dimethylaniline (DMA) and the two antibiotics sulfamethoxazole (SMX) and trimethoprim (TRI), with DOM of terrestrial origin being a more effective inhibitor than DOM of aquatic origin. The results are important to understand the role of DOM both as a photosensitizer and as an inhibitor for the triplet-induced transformation of aquatic contaminants. In contrast, no DOM-induced reduction in second-order rate constant could be observed in competition kinetics experiments for the reaction of hydroxyl radical with a series of 15 organic compounds, covering several classes of aromatic contaminants, indicating that Suwannee River fulvic acid (SRFA) used as reference DOM does not affect this reaction mechanism.
溶解有机物 (DOM) 最近被证明会降低各种水溶液中有机污染物在被激发三重态氧化时的转化速率，显然是通过抑制氧化中间产物的转化来实现的。本研究的主要目的是更详细地评估 DOM 的浓度和类型对四种选定有机化合物的三重态诱导转化速率的影响，并检查在羟基自由基氧化的情况下是否存在类似的抑制效应。实验观察到 DOM 对 N,N-二甲基苯胺 (DMA) 和两种抗生素磺胺甲恶唑 (SMX) 和甲氧苄啶 (TRI) 的三重态诱导氧化有明显的抑制作用，而来自陆地的 DOM 比来自水生环境的 DOM 更具有抑制作用。这些结果对于理解 DOM 作为光敏剂和作为水生污染物三重态诱导转化的抑制剂的作用非常重要。相比之下，在与一系列 15 种有机化合物反应的竞争动力学实验中，没有观察到 DOM 诱导的羟基自由基二级速率常数的降低，这表明作为参比 DOM 的苏万尼河富里酸 (SRFA) 不会影响这种反应机制。
