Marine dissolved organic matter (DOM) is a massive elemental pool on Earth and is thought to consist of a chemically complex mixture of molecules. Part of marine DOM is fluorescent (FDOM) and includes humic‐like compounds. The chemical composition of, and biochemical pathways that yield, autochthonous humic‐like FDOM in the ocean is largely unknown. Inspired by medical and biochemical research detailing the formation of colored and fluorescent dityrosine via peroxidase mediated reactions, we used fluorometry and spectroscopy and found dityrosine exhibits humic‐like fluorescence similar to that of marine FDOM. Investigating its recalcitrance, we conducted short‐term nutrient‐addition and light exposure experiments with dityrosine and found it is resistant to respiration or assimilation by marine microbial communities, yet readily photodegraded. The formation and characteristics of dityrosine newly points to polymerization via reactive oxygen quenching, under aphotic and putatively photic conditions, as an explanation for autochthonous, humic‐like, (semi‐)recalcitrant DOM in the ocean.

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通过消耗活性氧形成二酪氨酸在海洋中产生越来越顽强的腐殖质样荧光有机物

海洋溶解的有机物（DOM）是地球上的大量元素库，被认为由化学上复杂的分子混合物组成。海洋DOM的一部分是荧光（FDOM），包括类腐殖质化合物。在海洋中，类似腐殖质的FDOM产生的化学成分和产生生化的途径尚不清楚。受医学和生化研究的启发，该研究详细介绍了过氧化物酶介导的反应形成有色和荧光二氢酪氨酸的形成，我们使用了荧光测定法和光谱学，发现二氢酪氨酸表现出类似于海洋FDOM的腐殖质样荧光。为了研究其顽固性，我们用二氢酪氨酸进行了短期营养添加和光照试验，发现其对海洋微生物群落的呼吸或吸收具有抵抗力，但易于光降解。