Spatial coupling of nitrogen inputs and losses in the ocean
Spatial coupling of nitrogen inputs and losses in the ocean
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DOI：
10.1038/nature05392
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发表时间：
2007-01-11
期刊：
影响因子：
64.8
通讯作者：
Dunne, John P.
中科院分区：
文献类型：
--
作者：
Deutsch, Curtis;Sarmiento, Jorge L.;Dunne, John P.
固氮对于维持海洋中的生物生产力至关重要，因为它取代了通过反硝化作用失去的生物可用氮。但是，由于海洋固氮在时间和空间上的变异性，很难通过船上的直接测量来确定海洋固氮的全球分布。这种不确定性限制了我们对影响固氮的因素的理解，这些因素可能包括铁、氮磷比和物理条件，如温度。在这里，我们使用海洋环流模型，通过海洋对表层水中硝酸盐和磷酸盐浓度的影响来确定世界海洋的固氮率。我们的结果表明，太平洋的固氮率最高，那里的水柱反硝化率较高，但大气中铁的沉降率较低。我们的结论是，海洋固氮与反硝化带中缺氮水域的产生密切相关，支持了固氮随着时间的推移稳定海洋固定氮库存的观点。
Nitrogen fixation is crucial for maintaining biological productivity in the oceans, because it replaces the biologically available nitrogen that is lost through denitrification. But, owing to its temporal and spatial variability, the global distribution of marine nitrogen fixation is difficult to determine from direct shipboard measurements. This uncertainty limits our understanding of the factors that influence nitrogen fixation, which may include iron, nitrogen-to-phosphorus ratios, and physical conditions such as temperature. Here we determine nitrogen fixation rates in the world's oceans through their impact on nitrate and phosphate concentrations in surface waters, using an ocean circulation model. Our results indicate that nitrogen fixation rates are highest in the Pacific Ocean, where water column denitrification rates are high but the rate of atmospheric iron deposition is low. We conclude that oceanic nitrogen fixation is closely tied to the generation of nitrogen-deficient waters in denitrification zones, supporting the view that nitrogen fixation stabilizes the oceanic inventory of fixed nitrogen over time.