Subduction of carbon, nitrogen, and oxygen in the northeast Atlantic
Subduction of carbon, nitrogen, and oxygen in the northeast Atlantic
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东北大西洋碳、氮和氧的俯冲
DOI：
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
L. Mémery
中科院分区：
文献类型：
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作者：
P. Karleskind;M. Lévy;L. Mémery
[1] 东北大西洋模态水域 (NEAMW) 是由已知大气二氧化碳强汇区域的俯冲作用形成的。这项研究调查了该汇中涉及的生物和物理碳泵。为此，我们估算了每年通过 NEAMW 俯冲作用从地表到海洋内部的碳、氮和氧转移量。我们的估算基于模型模拟，该模型模拟受到海洋多学科中层阶梯计划 (POMME) 期间收集的数据的约束。我们发现，俯冲作用在POMME地区（38°N–45°N，16°W–22°W）混合层以下的碳输出中占很大比例。 50% 的活性有机碳通过生物泵输出，50% 通过俯冲输出；混合层下方总碳通量的 98% 归因于碳俯冲，主要以溶解的无机碳和更难熔的溶解有机物的形式存在。这是因为它们是主要的碳库，并且正在经历该地区特征的冬季混合层深度梯度。我们的结果强调，碳的净输出仅占通过俯冲和仰冲过程穿过混合层的碳通量的一小部分。此外，我们的结果表明 NEAMW 俯冲发生在春季开花之前。这意味着NEAMW主要是在冬末特征下俯冲的，特别是营养物含量相对较高。这反映了养分利用效率相对较低，并与亚热带模式水域形成鲜明对比，亚热带模式水域在水华期间俯冲，因此在俯冲时营养物质相对贫乏。
[1] Northeast Atlantic mode waters (NEAMW) are formed by subduction in a region known to be a strong sink of atmospheric CO2. This study investigates the biological and physical carbon pumps involved in this sink. For that purpose, we estimate the annual transfer of carbon, nitrogen, and oxygen from the surface into the ocean interior through NEAMW subduction. Our estimates are based on a model simulation constrained with data collected during the Programme Ocean Multidisciplinaire Meso Echelle (POMME). We found that subduction accounts for a large proportion of carbon export below the mixed layer in the POMME region (38°N–45°N, 16°W–22°W). Fifty percent of labile organic carbon is exported by the biological pump and 50% by subduction; 98% of the total carbon flux below the mixed layer is due to carbon subduction, essentially in the form of dissolved inorganic carbon and of more refractory dissolved organic matter. This is because they are the dominant pools of carbon and are passing through the winter mixed-layer depth gradient that characterizes the region. Our results emphasize that the net export of carbon represents a small fraction of the fluxes of carbon across the mixed layer through the processes of subduction and obduction. Moreover, our results indicate that NEAMW subduction occurs before the spring bloom. This implies that NEAMW is mostly subducted with end-winter characteristics with, in particular, relatively high nutrient content. This reflects a relative inefficiency in nutrient utilization and contrasts with subtropical mode waters, which are subducted during the bloom and are thus relatively poor in nutrients when they are subducted.