Massive nitrous oxide emissions from the tropical South Pacific Ocean
Massive nitrous oxide emissions from the tropical South Pacific Ocean
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DOI：
10.1038/ngeo2469
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发表时间：
2015-07-01
影响因子：
18.3
通讯作者：
Bange, H. W.
中科院分区：
文献类型：
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作者：
Arevalo-Martinez, D. L.;Kock, A.;Bange, H. W.
一氧化二氮是一种强效温室气体(1)，也是平流层臭氧消耗的关键化合物(2)。在海洋中，一氧化二氮是在中等深度通过硝化和反硝化作用产生的，特别是在低氧浓度下(3)。尽管向大气中自然排放的一氧化二氮有三分之一来自海洋(1)，但排放的分布和规模仍然存在相当大的不确定性(4)。在这里，我们提供一氧化二氮的高分辨率表面测量和垂直剖面，其中包括海洋表层水中报告的最高一氧化二氮浓度，这表明秘鲁海岸沿线的高生产力上升流生态系统中存在一氧化二氮排放的热点。我们估计，在秘鲁海域，我们观察到的极高的一氧化二氮过饱和度每年会导致 0.2-0.9 Tg 的氮以一氧化二氮的形式大量外流，相当于之前估计的全球海洋一氧化二氮排放量的 5-22%。营养物和基因丰度数据表明，上层含氧最低区的硝化-反硝化耦合作用以及通过上升流将一氧化二氮输送到地表导致高一氧化二氮浓度。我们对秘鲁海岸一氧化二氮排放量的估计超过了类似高产地区的排放量。
Nitrous oxide is a potent greenhouse gas(1) and a key compound in stratospheric ozone depletion(2). In the ocean, nitrous oxide is produced at intermediate depths through nitrification and denitrification, in particular at low oxygen concentrations(3). Although a third of natural emissions of nitrous oxide to the atmosphere originate from the ocean(1), considerable uncertainties in the distribution and magnitude of the emissions still exist(4). Here we present high-resolution surface measurements and vertical profiles of nitrous oxide that include the highest reported nitrous oxide concentrations in marine surface waters, suggesting that there is a hotspot of nitrous oxide emissions in high-productivity upwelling ecosystems along the Peruvian coast. We estimate that off Peru, the extremely high nitrous oxide supersaturations we observed drive a massive efflux of 0.2-0.9 Tg of nitrogen emitted as nitrous oxide per year, equivalent to 5-22% of previous estimates of global marine nitrous oxide emissions. Nutrient and gene abundance data suggest that coupled nitrification-denitrification in the upper oxygen minimum zone and transport of resulting nitrous oxide to the surface by upwelling lead to the high nitrous oxide concentrations. Our estimate of nitrous oxide emissions from the Peruvian coast surpasses values from similar, highly productive areas.