Global rates of water-column denitrification derived from nitrogen gas measurements
Global rates of water-column denitrification derived from nitrogen gas measurements
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DOI：
10.1038/ngeo1515
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发表时间：
2012-08-01
影响因子：
18.3
通讯作者：
Devol, Allan
中科院分区：
文献类型：
--
作者：
DeVries, Tim;Deutsch, Curtis;Devol, Allan
生物上可利用的氮(N)限制了海洋大部分浮游植物的生长。反硝化细菌从当代海洋中去除氮的速率是高度不确定的（1-3）。一些研究表明，氮的损失超过了输入（2,4-6）；其他人则主张平衡预算（3,7,8）。本文采用全球海洋环流模型，模拟了反硝化细菌产生的N-2气体在公海三个主要缺氧带的分布。通过将模型拟合到测量的N-2气体浓度，我们推断水柱反硝化的全球综合速率为66 +/- 6 TgN /年（-1）。考虑到水柱与海洋沉积物中反硝化作用的同位素限制，我们估计海洋沉积物和海洋水柱的全球N损失率合计约为230 +/- 60 TgN yr（-1）。根据目前对氮输入率的估计，我们的研究结果表明，每年全球海洋的氮净损失约为20 +/- 70 Tg，与平衡预算几乎没有区别。一个平衡的N预算，反过来，意味着海洋N循环是由强大的调节反馈控制的。
Biologically available nitrogen (N) limits phytoplankton growth over much of the ocean. The rate at which N is removed from the contemporary ocean by denitrifying bacteria is highly uncertain(1-3). Some studies suggest that N losses exceed inputs(2,4-6); others argue for a balanced budget(3,7,8). Here, we use a global ocean circulation model to simulate the distribution of N-2 gas produced by denitrifying bacteria in the three main suboxic zones in the open ocean. By fitting the model to measured N-2 gas concentrations, we infer a globally integrated rate of water-column denitrification of 66 +/- 6 TgN yr(-1). Taking into account isotopic constraints on the fraction of denitrification occurring in the water column versus marine sediments, we estimate that the global rate of N loss from marine sediments and the oceanic water column combined amounts to around 230 +/- 60 TgN yr(-1). Given present estimates of N input rates, our findings imply a net loss of around 20 +/- 70 Tg of N from the global ocean each year, indistinguishable from a balanced budget. A balanced N budget, in turn, implies that the marine N cycle is governed by strong regulatory feedbacks.