Nitrogen cycling driven by organic matter export in the South Pacific oxygen minimum zone
Nitrogen cycling driven by organic matter export in the South Pacific oxygen minimum zone
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DOI：
10.1038/ngeo1739
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发表时间：
2013-03-01
影响因子：
18.3
通讯作者：
Kuypers, Marcel M. M.
中科院分区：
文献类型：
--
作者：
Kalvelage, Tim;Lavik, Gaute;Kuypers, Marcel M. M.
氧气最小区域在全球范围内正在扩大，目前约占海洋氮素损失的20%-40%。异养反硝化和厌氧氨氧化--亚硝酸盐的厌氧氨氧化--是这些低氧水域中大部分氮损失的原因。Anammox在热带南太平洋东部特别重要，它是全球最大的氧气最少区之一。然而，调控厌氧氨氧化引起的氮损失的因素仍然不清楚。在这里，我们提出了一个综合的氮收支的东部热带南太平洋氧气极小区，使用养分浓度的测量，实验确定的氮素转化速率和一个出口生产的数值模式。在采样时，厌氧氨氧化是氮素流失的主要方式。厌氧氨氧化和相关的氮素转化速率在多产的陆架水域最大，并随着距离海岸的距离而逐渐下降。在大陆架区域内，Anammox的活动在上层和底层水域都达到了峰值。总体而言，包括厌氧氨氧化在内的氮素转化速率与有机物质的出口密切相关。我们认为，有机物的下沉，从而释放到水柱中的铵，以及底栖生物铵的释放，是燃料氮从氧气最小区域的损失。
Oxygen minimum zones are expanding globally, and at present account for around 20-40% of oceanic nitrogen loss. Heterotrophic denitrification and anammox-anaerobic ammonium oxidation with nitrite-are responsible for most nitrogen loss in these low-oxygen waters. Anammox is particularly significant in the eastern tropical South Pacific, one of the largest oxygen minimum zones globally. However, the factors that regulate anammox-driven nitrogen loss have remained unclear. Here, we present a comprehensive nitrogen budget for the eastern tropical South Pacific oxygen minimum zone, using measurements of nutrient concentrations, experimentally determined rates of nitrogen transformation and a numerical model of export production. Anammox was the dominant mode of nitrogen loss at the time of sampling. Rates of anammox, and related nitrogen transformations, were greatest in the productive shelf waters, and tailed off with distance from the coast. Within the shelf region, anammox activity peaked in both upper and bottom waters. Overall, rates of nitrogen transformation, including anammox, were strongly correlated with the export of organic matter. We suggest that the sinking of organic matter, and thus the release of ammonium into the water column, together with benthic ammonium release, fuel nitrogen loss from oxygen minimum zones.