The transformation of dissolved organic carbon (DOC) released by macroalgae into refractory dissolved organic carbon (RDOC) through microbial carbon pump (MCP) represents a crucial carbon sequestration process. This process mainly takes place in coastal areas, where it is likely affected by marine anoxia. The interactions between the components of DOC released by kelp and the community structure of heterotrophic bacteria both under normoxic and anoxic conditions were studied by three-dimensional fluorescence parallel factor analysis (PARAFAC), Fourier Transform-Ion Cyclotron Resonance-Mass Spectrometry (FT-ICR-MS) and 16S rRNA high-throughput sequencing. Following 240 days of decomposition, we found that the proportion of labile dissolved organic carbon (LDOC) was 4.61 % greater under anoxic conditions compared to normoxic conditions. Conversely, the proportion of RDOC was 8.06 % lower under anoxic conditions than under normoxic conditions. These findings suggest that anoxia hinders the conversion of LDOC to RDOC in the DOC released by kelp. Although normoxic conditions favor RDOC production, anoxic conditions could be more advantageous for the transport of DOC to the deep ocean, potentially enhancing carbon sequestration. The cultivation of macroalgae in anoxic zones may further boost their carbon sequestration potential.

中文翻译：

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海洋缺氧阻碍了海带释放的溶解有机碳转化为难降解有机碳


大型藻类通过微生物碳泵 （MCP） 将大型藻类释放的溶解有机碳 （DOC） 转化为难降解的溶解有机碳 （RDOC） 是一个关键的碳封存过程。这个过程主要发生在沿海地区，在那里它可能受到海洋缺氧的影响。采用三维荧光平行因子分析 （PARAFAC）、傅里叶变换离子回旋共振质谱 （FT-ICR-MS） 和 16S rRNA 高通量测序研究常氧和缺氧条件下海带释放的 DOC 组分与异养细菌群落结构之间的相互作用。分解 240 天后，我们发现与常氧条件相比，在缺氧条件下不稳定的溶解有机碳 （LDOC） 的比例高出 4.61%。相反，在缺氧条件下，RDOC 的比例比在常氧条件下低 8.06%。这些发现表明，缺氧阻碍了海带释放的 DOC 中 LDOC 向 RDOC 的转化。尽管常氧条件有利于 RDOC 的产生，但缺氧条件可能更有利于将 DOC 运输到深海，从而可能增强碳封存。在缺氧区培养大型藻类可能会进一步提高它们的碳封存潜力。