Dinitrogen fixation in the world's oceans
Dinitrogen fixation in the world's oceans
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DOI：
10.1023/a:1015798105851
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发表时间：
2002-04-01
期刊：
影响因子：
4
通讯作者：
Stal, L
中科院分区：
文献类型：
--
作者：
Karl, D;Michaels, A;Stal, L
传统上，海洋环境的地表水被视为氮（N）有限的栖息地，这指导了概念性生物地球化学模型的发展，该模型主要关注硝酸盐库，作为维持初级生产力的关键氮源。然而，某些细菌（包括蓝细菌和古细菌）可以利用二氮 (N-2) 作为替代氮源。在海洋环境中，这些微生物可以对净群落生产过程产生深远影响，并可以影响 C-N-P 循环的耦合以及大气二氧化碳的净海洋封存。作为综合“氮运输和转化”项目的一部分，我们已开始重新评估我们对以下方面的理解：(1) 世界海洋中 N-2 固定的生物来源和速率，(2) 海洋 N-2 固定速率的主要控制因素，(3) 这种 N-2 固定对全球碳循环的重要性，以及 (4) 人类活动在改变海洋 N-2 固定中的作用。初步结果表明，N-2 固定率，特别是在亚热带和热带公海栖息地，在全球海洋氮预算中发挥着重要作用。铁 (Fe) 生物利用度似乎是一个重要的控制因素，因此对于外推 N-2 固定率的全局至关重要。人为扰动可能会通过生境破坏和富营养化改变沿海环境中的 N-2 固定，而变暖和上层水柱分层的增加可能会增强公海 N-2 固定。全球人为和气候变化也可能影响 N-2 固定率，例如通过改变灰尘输入（即 Fe）或扩大亚热带边界。最近对全球海洋 N-2 固定的一些估计在 100-200 Tg N (1-2 x 10(14) g N) yr(-1) 范围内，但具有很大的不确定性。这些估计值比 1980 年之前的历史估计值高出近一个数量级，但接近现代对海洋反硝化的估计值。
The surface water of the marine environment has traditionally been viewed as a nitrogen (N) limited habitat, and this has guided the development of conceptual biogeochemical models focusing largely on the reservoir of nitrate as the critical source of N to sustain primary productivity. However, selected groups of Bacteria, including cyanobacteria, and Archaea can utilize dinitrogen (N-2) as an alternative N source. In the marine environment, these microorganisms can have profound effects on net community production processes and can impact the coupling of C-N-P cycles as well as the net oceanic sequestration of atmospheric carbon dioxide. As one component of an integrated 'Nitrogen Transport and Transformations' project, we have begun to re-assess our understanding of (1) the biotic sources and rates of N-2 fixation in the world's oceans, (2) the major controls on rates of oceanic N-2 fixation, (3) the significance of this N-2 fixation for the global carbon cycle and (4) the role of human activities in the alteration of oceanic N-2 fixation. Preliminary results indicate that rates of N-2 fixation, especially in subtropical and tropical open ocean habitats, have a major role in the global marine N budget. Iron (Fe) bioavailability appears to be an important control and is, therefore, critical in extrapolation to global rates of N-2 fixation. Anthropogenic perturbations may alter N-2 fixation in coastal environments through habitat destruction and eutrophication, and open ocean N-2 fixation may be enhanced by warming and increased stratification of the upper water column. Global anthropogenic and climatic changes may also affect N-2 fixation rates, for example by altering dust inputs (i.e. Fe) or by expansion of subtropical boundaries. Some recent estimates of global ocean N-2 fixation are in the range of 100-200 Tg N (1-2 x 10(14) g N) yr(-1), but have large uncertainties. These estimates are nearly an order of magnitude greater than historical, pre-1980 estimates, but approach modern estimates of oceanic denitrification.