More than two-thirds of global biomass consists of vascular plants. A portion of the detritus they generate is carried into the oceans from land and highly productive blue carbon ecosystems-salt marshes, mangrove forests, and seagrass meadows. This large detrital input receives scant attention in current models of the global carbon cycle, though for blue carbon ecosystems, increasingly well-constrained estimates of biomass, productivity, and carbon fluxes, reviewed in this article, are now available. We show that the fate of this detritus differs markedly from that of strictly marine origin, because the former contains lignocellulose-an energy-rich polymer complex of cellulose, hemicelluloses, and lignin that is resistant to enzymatic breakdown. This complex can be depolymerized for nutritional purposes by specialized marine prokaryotes, fungi, protists, and invertebrates using enzymes such as glycoside hydrolases and lytic polysaccharide monooxygenases to release sugar monomers. The lignin component, however, is less readily depolymerized, and detritus therefore becomes lignin enriched, particularly in anoxic sediments, and forms a major carbon sink in blue carbon ecosystems. Eventual lignin breakdown releases a wide variety of small molecules that may contribute significantly to the oceanic pool of recalcitrant dissolved organic carbon. Marine carbon fluxes and sinks dependent on lignocellulosic detritus are important ecosystem services that are vulnerable to human interventions. These services must be considered when protecting blue carbon ecosystems and planning initiatives aimed at mitigating anthropogenic carbon emissions.

中文翻译：

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维管植物是全球海洋碳通量和汇的重要贡献者。

全球三分之二以上的生物量由维管植物组成。它们产生的一部分碎屑从陆地和高产蓝碳生态系统（盐沼、红树林和海草草地）进入海洋。在当前的全球碳循环模型中，这种大量的碎屑输入很少受到关注，尽管对于蓝碳生态系统，本文所回顾的生物量、生产力和碳通量的日益受到约束的估计现在可用。我们表明，这种碎屑的命运与严格的海洋来源明显不同，因为前者含有木质纤维素——一种富含能量的纤维素、半纤维素和木质素聚合物复合物，可抵抗酶促分解。这种复合物可以通过专门的海洋原核生物、真菌、原生生物和无脊椎动物使用糖苷水解酶和裂解多糖单加氧酶等酶释放糖单体。然而，木质素成分不太容易解聚，因此碎屑变得富含木质素，特别是在缺氧沉积物中，并在蓝碳生态系统中形成主要的碳汇。最终的木质素分解会释放出各种各样的小分子，这些小分子可能对顽固溶解有机碳的海洋池做出重大贡献。依赖于木质纤维素碎屑的海洋碳通量和汇是重要的生态系统服务，容易受到人类干预的影响。在保护蓝碳生态系统和规划旨在减少人为碳排放的举措时，必须考虑这些服务。和无脊椎动物使用诸如糖苷水解酶和裂解多糖单加氧酶等酶来释放糖单体。然而，木质素成分不太容易解聚，因此碎屑变得富含木质素，特别是在缺氧沉积物中，并在蓝碳生态系统中形成主要的碳汇。最终的木质素分解会释放出各种各样的小分子，这些小分子可能对顽固溶解有机碳的海洋池做出重大贡献。依赖于木质纤维素碎屑的海洋碳通量和汇是重要的生态系统服务，容易受到人类干预的影响。在保护蓝碳生态系统和规划旨在减少人为碳排放的举措时，必须考虑这些服务。和无脊椎动物使用诸如糖苷水解酶和裂解多糖单加氧酶等酶来释放糖单体。然而，木质素成分不太容易解聚，因此碎屑变得富含木质素，特别是在缺氧沉积物中，并在蓝碳生态系统中形成主要的碳汇。最终的木质素分解会释放出各种各样的小分子，这些小分子可能对顽固溶解有机碳的海洋池做出重大贡献。依赖于木质纤维素碎屑的海洋碳通量和汇是重要的生态系统服务，容易受到人类干预的影响。在保护蓝碳生态系统和规划旨在减少人为碳排放的举措时，必须考虑这些服务。