Macroalgae are important primary producers in the coastal ocean, and they release a large fraction of their net primary production as dissolved organic carbon (DOC). It is assumed that much of this DOC is recalcitrant and results in the sequestration of large amounts of carbon. We lack sufficient knowledge about the bioavailability of this material and the role of other sinks such as photooxidation. We conducted dark remineralization and photooxidation experiments on DOC derived from an abundant brown macroalga and quantified the fraction of amended DOC that was remineralized by both processes. The bioavailability of the amended DOC ranged from 14% to 99% and was significantly negatively correlated with its phenolic content. Upon exposure to light, the biologically recalcitrant compounds were quickly oxidized to CO2, indicating that photooxidation is an important sink for recalcitrant brown macroalgal DOC. These results are especially important as macroalgae cultivation is being considered to sequester atmospheric CO2.

中文翻译：

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光氧化去除大型藻类马尾藻 （Sargassum natans） 释放的生物顽固溶解有机碳


大型藻类是沿海海洋中重要的初级生产者，它们以溶解有机碳 （DOC） 的形式释放出其净初级产量的很大一部分。据推测，这种 DOC 中的大部分是顽固的，并导致大量碳的封存。我们对这种材料的生物利用度和其他汇（如光氧化）的作用缺乏足够的了解。我们对来自丰富棕色大型藻类的 DOC 进行了暗再矿化和光氧化实验，并量化了通过两种过程再矿化的修正 DOC 的分数。修正后的 DOC 的生物利用度在 14% 到 99% 之间，并且与其酚类含量呈显著负相关。暴露在光线下，生物顽固的化合物迅速被氧化成 CO2，表明光氧化是顽固的棕色大型藻类 DOC 的重要汇。这些结果尤为重要，因为正在考虑使用大型藻类培养来封存大气中的 CO2。