Efficient export of carbon to the deep ocean through dissolved organic matter
Efficient export of carbon to the deep ocean through dissolved organic matter
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DOI：
10.1038/nature03191
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发表时间：
2005-01-13
期刊：
影响因子：
64.8
通讯作者：
Vallino, JJ
中科院分区：
文献类型：
--
作者：
Hopkinson, CS;Vallino, JJ
海洋溶解有机碳（DOC）是生物圈中最大的还原碳库之一。据估计，从海洋表层输出的DOC占流向深海的有机碳总通量的20%(1-3)，这构成了对大气二氧化碳水平的主要控制(4)。DOC是溶解有机物（DOM）的碳组分，因此准确量化DOM库、通量及其控制对了解海洋碳循环至关重要。DOC的出口与溶解有机氮和磷的出口直接相关。然而，DOM动力学的C:N:P化学计量学（通过原子）知之甚少。本文研究了大陆架、陆坡和中央海洋环流环境下DOM池和DOM分解的化学计量学特征。我们发现DOM的再矿化和生成的C:N:P化学计量为199:20:1，大大低于大块池（通常为bbb775:54:1），但高于颗粒有机质（106:16:1- Redfield比率）。因此，对于引入地表水的新N和P的给定质量，输出的DOC比在Redfield比下会出现的多。这可能会导致估计发生在内陆海洋的过度呼吸(5)。我们的研究结果通过平流途径对全球碳出口和元素平衡提出了明确的限制。
Oceanic dissolved organic carbon (DOC) constitutes one of the largest pools of reduced carbon in the biosphere. Estimated DOC export from the surface ocean represents 20% of total organic carbon flux to the deep ocean(1-3), which constitutes a primary control on atmospheric carbon dioxide levels(4). DOC is the carbon component of dissolved organic matter (DOM) and an accurate quantification of DOM pools, fluxes and their controls is therefore critical to understanding oceanic carbon cycling. DOC export is directly coupled with dissolved organic nitrogen and phosphorus export. However, the C:N:P stoichiometry (by atoms) of DOM dynamics is poorly understood. Here we study the stoichiometry of the DOM pool and of DOM decomposition in continental shelf, continental slope and central ocean gyre environments. We find that DOM is remineralized and produced with a C:N:P stoichiometry of 199:20:1 that is substantially lower than for bulk pools (typically >775:54:1), but greater than for particulate organic matter (106:16:1-the Redfield ratio). Thus for a given mass of new N and P introduced into surface water, more DOC can be exported than would occur at the Redfield ratio. This may contribute to the excess respiration estimated to occur in the interior ocean(5). Our results place an explicit constraint on global carbon export and elemental balance via advective pathways.