We introduced superoxide as potassium superoxide (KO2) to artificial lake water containing dissolved organic matter (DOM) without or with introduced ferric iron complexes (DOM-Fe(III)), and monitored the production rate of hydroxyl radicals as well as changes in the absorption and fluorescence properties of DOM. The introduction of KO2 decreased the absorption by DOM but increased the spectral slope coefficient of DOM more with complexed ferric Fe than without it. The introduction of KO2 increased the fluorescence of humic-like components in DOM without introduced ferric Fe but resulted in the loss of fluorescence in DOM with introduced ferric Fe. A single introduction of 13 μmol L-1 KO2 produced 10 μmol L-1 and 104 μmol L-1 hydroxyl radicals during a week-long experiment without and with the introduced DOM-Fe(III) complexes, respectively. The production rate of hydroxyl radicals decreased exponentially with time but levelled off and continued several days in DOM with introduced ferric Fe. These findings suggest that in the presence of DOM-Fe complexes, superoxide can trigger an autocatalytic Fenton reaction that produces hydroxyl radicals and breaks down DOM.

中文翻译：

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在天然溶解的有机物和铁的络合物存在下，由超氧化物驱动的羟基自由基的自动催化暗生成。

我们将超氧化物（KO2）作为超氧化钾（KO2）引入到含有溶解有机物（DOM）的人工湖水中，该水中不含有或不引入三价铁配合物（DOM-Fe（III）），并监测羟基自由基的产生速率以及DOM的吸收和荧光性质。KO2的引入降低了DOM对DOM的吸收，但是增加了铁复合Fe的DOM的光谱斜率系数，而没有配合物则增加了。KO2的引入增加了未引入铁铁的DOM中腐殖质样成分的荧光，但导致了引入铁铁的DOM中荧光的损失。在为期一周的实验中，一次引入13μmolL-1 KO2会分别产生10μmolL-1和104μmolL-1羟基，分别没有和没有DOM-Fe（III）配合物。羟基自由基的生成速率随时间呈指数下降，但趋于平稳并在引入铁铁的情况下持续数天。这些发现表明，在DOM-Fe络合物的存在下，超氧化物可以触发Fenton自催化反应，产生羟基自由基并破坏DOM。