Seasonal and spatial patterns of sedimentary denitrification rates in the Chukchi sea
Seasonal and spatial patterns of sedimentary denitrification rates in the Chukchi sea
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DOI：
10.1016/j.dsr2.2008.10.024
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发表时间：
2009-08-01
影响因子：
3
通讯作者：
Devol, Allan H.
中科院分区：
文献类型：
--
作者：
Chang, Bonnie X.;Devol, Allan H.
最近构建的全球氮收支估计，海洋中至少一半的固定氮因沉积反硝化作用而丧失，其中大部分发生在大陆架上。北极拥有全球约20%的大陆架，这表明它是全球沉积反硝化速率的重要贡献者。在2002年夏季和2004年春季的两次航次中，根据北极西部楚科奇海陆架和斜坡沉积物中硝酸盐向下扩散的通量计算了反硝化速率。此外，在2004年春季，通过全核心培养测定了沉积物中氮气的通量，从而确定了反硝化速率。沿横跨陆架和斜坡(50-3000米)的三个横断面进行测量，每个横断面具有不同的上覆水特征。反硝化速率一般随着水深的增加而降低：从浅水沉积物的约1.6 mmolNm(-2)d(-1)到深水沉积物中检测不到的。这两个季节的房价几乎没有变化。然而，研究发现，增长率与年度上覆初级生产力和颗粒有机碳出口通量的差异相一致。外推到整个北极，北极沉积反硝化速率平均为13TgNyr(-1)。在全球氮收支的背景下，它约占海洋中固定氮总沉降量的4%-13%。(C)2008爱思唯尔有限公司。保留所有权利。
Recent constructions of the global nitrogen budget estimate that at least half of the ocean's fixed nitrogen is lost by sedimentary denitrification, the majority of which occurs in continental shelves. The Arctic contains approximately 20% of the world's continental shelf, suggesting it is a substantial contributor to the global sedimentary denitrification rate. During two cruises in the summer and spring of 2002 and 2004, respectively, denitrification rates were calculated from the downward diffusive flux of nitrate in the shelf and slope sediments of the Chukchi Sea in the western Arctic. Additionally, in the spring of 2004, denitrification rates were determined by whole-core incubations in which the flux of nitrogen gas out of the sediments was measured. Measurements were made along three transects crossing the shelf and slope (50-3000 m), each transect having different overlying water characteristics. Denitrification rates generally decreased with increasing water depth: rates varied from about 1.6 mmol N m(-2) d(-1) for the shallow-water sediments to undetectable in deep-water sediments. Rates showed little variation between the two seasons. However, rates were found to correspond with differences in annual overlying primary productivities and particulate organic carbon export fluxes. An extrapolation to the whole Arctic yielded an average Arctic sedimentary denitrification rate of 13 Tg N yr(-1). Taken in the context of the global nitrogen budget, it is about 4-13% of the total sink of fixed nitrogen in the ocean. (c) 2008 Elsevier Ltd. All rights reserved.