An eddy-stimulated hotspot for fixed nitrogen-loss from the Peru oxygen minimum zone
An eddy-stimulated hotspot for fixed nitrogen-loss from the Peru oxygen minimum zone
复制标题
秘鲁最低氧气区的涡流刺激固定氮损失热点
DOI：
10.5194/bg-9-4897-2012
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发表时间：
2012
期刊：
影响因子：
4.9
通讯作者：
G. Lavik
中科院分区：
文献类型：
--
作者：
M. Altabet;E. Ryabenko;L. Stramma;D. Wallace;M. Frank;P. Grasse;G. Lavik
摘要。海洋强氧最小带（OMZ）的固定氮(N)向生物源氮的损失占全球氮汇的很大一部分，是海洋氮收支的重要控制因素。然而，主要的不确定性存在于微生物途径以及对n损失幅度和海洋总体n收支的净影响。在这里，我们报告在秘鲁OMZ发现了一个n损失热点，该热点与沿海捕获的中尺度涡有关，其特征是极端n赤字，与生物成因的N2生产相匹配，高NO2 -水平，以及迄今为止在OMZ观察到的最高同位素富集。在向海流动的拖缆中，高海面叶绿素提供了高生产力近岸水的近海涡输送的证据。由此产生的颗粒向下流动的脉冲可能刺激了OMZ内异养异化的NO3−还原和随后的生物源性N2的产生。氧斜内较浅的生物成因N2极大值可能是陆架涡流平流的特征。由局部微生物过程的演替介导的与涡旋相关的氮损失的时空异质性可能解释了先前研究中观察到的不一致性。类似的氮损失的瞬态增强可能发生在所有其他主要的OMZ中，对全球海洋氮和氮同位素收支产生重大影响。
Abstract. Fixed nitrogen (N) loss to biogenic N2 in intense oceanic O2 minimum zones (OMZ) accounts for a large fraction of the global N sink and is an essential control on the ocean's N-budget. However, major uncertainties exist regarding microbial pathways as well as net impact on the magnitude of N-loss and the ocean's overall N-budget. Here we report the discovery of a N-loss hotspot in the Peru OMZ associated with a coastally trapped mesoscale eddy that is marked by an extreme N-deficit matched by biogenic N2 production, high NO2− levels, and the highest isotope enrichments observed so far in OMZ's for the residual NO3−. High sea surface chlorophyll in seaward flowing streamers provides evidence for offshore eddy transport of highly productive, inshore water. Resulting pulses in the downward flux of particles likely stimulated heterotrophic dissimilatory NO3− reduction and subsequent production of biogenic N2 within the OMZ. A shallower biogenic N2 maximum within the oxycline is likely a feature advected by the eddy streamer from the shelf. Eddy-associated temporal-spatial heterogeneity of N-loss, mediated by a local succession of microbial processes, may explain inconsistencies observed among prior studies. Similar transient enhancements of N-loss likely occur within all other major OMZ's exerting a major influence on global ocean N and N isotope budgets.
影响因子：
56.9
作者：
Stramma, Lothar;Johnson, Gregory C.;Mohrholz, Volker
通讯作者：
Mohrholz, Volker