Organic nutrients and excess nitrogen in the North Atlantic subtropical gyre
Organic nutrients and excess nitrogen in the North Atlantic subtropical gyre
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DOI：
10.5194/bg-5-1199-2008
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发表时间：
2008-09
期刊：
影响因子：
4.9
通讯作者：
A. Landolfi;A. Oschlies;R. Sanders
中科院分区：
文献类型：
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作者：
A. Landolfi;A. Oschlies;R. Sanders
抽象的。为了准确估算北大西洋总过量氮（N），定义了一种新的示踪剂TNxs，它包括有机营养盐对N：P化学计量异常评估的贡献。利用2004年横跨24.5° N的跨大西洋断面的数据，我们测量了亚热带北大西洋TNx的空间分布。然后，我们采用三种不同的方法来推断总过量氮积累率使用pCFC-12衍生的通风年龄（TNxs垂直积分，一端成员和两端成员混合模型）。尽管不同方法之间存在一些差异，但溶解有机营养物部分总是贡献了TNxs积累的一半左右，约为9.38±4.18×1011 mol N y−1。我们认为，忽略有机营养盐的化学计量平衡的海洋N和P库存可能会导致系统误差时，估计偏差的氮过剩或赤字相对于Redfield比率在海洋中。对于北大西洋，将有机部分纳入过量氮库导致通过N2固定的N供应向上修正为10.2±6.9×1011 mol N y−1。
Abstract. To enable an accurate estimate of total excess nitrogen (N) in the North Atlantic, a new tracer TNxs is defined, which includes the contribution of organic nutrients to the assessment of N:P stoichiometric anomalies. We measured the spatial distribution of TNxs within the subtropical North Atlantic using data from a trans-Atlantic section across 24.5° N occupied in 2004. We then employ three different approaches to infer rates of total excess nitrogen accumulation using pCFC-12 derived ventilation ages (a TNxs vertical integration, a one end-member and a two-end member mixing model). Despite some variability among the different methods the dissolved organic nutrient fraction always contributes to about half of the TNxs accumulation, which is in the order of 9.38±4.18×1011 mol N y−1. We suggest that neglecting organic nutrients in stoichiometric balances of the marine N and P inventories can lead to systematic errors when estimating deviations of nitrogen excess or deficit relative to the Redfield ratio in the oceans. For the North Atlantic the inclusion of the organic fraction to the excess nitrogen pool leads to an upward revision of the N supply by N2 fixation to 10.2±6.9×1011 mol N y−1.