Variable ageing and storage of dissolved organic components in the open ocean
Variable ageing and storage of dissolved organic components in the open ocean
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DOI：
10.1038/nature02780
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发表时间：
2004-08-19
期刊：
影响因子：
64.8
通讯作者：
Druffel, ERM
中科院分区：
文献类型：
--
作者：
Loh, AN;Bauer, JE;Druffel, ERM
海水溶解有机质（DOM）是海洋中最大的可交换有机碳储存库，其数量可与大气中的二氧化碳相媲美（1,2）。然而，除了少数浮游生物成分外，这些物质的组成、周转时间和命运在很大程度上是未知的（3,4）。因此，海洋碳循环模型受到限制，因为需要关于DOM子成分中碳储存的时间尺度的信息，这些成分是通过“生物泵”产生的，相对于它们被细菌回收（3,4）。在这里，我们展示了大西洋和太平洋开放海洋中的碳水化合物和蛋白质样物质，尽管通常明显老化，但包含了DOM的年轻部分，而溶解的亲脂物质显示出高达90%的化石特征。与整个水柱观测到的DOM的千年平均年龄相比，海洋表面DOM的加权平均周转时间仅为年代际。观察到的尺寸-年龄连续体进一步表明，溶解的小分子是最古老的有机物形式，比更大、更年轻的溶解和颗粒前体循环得慢得多，并将海洋有机物的年龄和尺寸与反应性直接联系起来（3,5）。
Seawater dissolved organic matter (DOM) is the largest reservoir of exchangeable organic carbon in the ocean, comparable in quantity to atmospheric carbon dioxide(1,2). The composition, turnover times and fate of all but a few planktonic constituents of this material are, however, largely unknown(3,4). Models of ocean carbon cycling are thus limited by the need for information on temporal scales of carbon storage in DOM subcomponents, produced via the 'biological pump', relative to their recycling by bacteria(3,4). Here we show that carbohydrate- and protein-like substances in the open Atlantic and Pacific oceans, though often significantly aged, comprise younger fractions of the DOM, whereas dissolved lipophilic material exhibits up to similar to90 per cent fossil character. In contrast to the millennial mean ages of DOM observed throughout the water column, weighted mean turnover times of DOM in the surface ocean are only decadal in magnitude. An observed size-age continuum further demonstrates that small dissolved molecules are the most highly aged forms of organic matter, cycling much more slowly than larger, younger dissolved and particulate precursors, and directly links oceanic organic matter age and size with reactivity(3,5).