Nitrogen isotopic constraints on nutrient transport to the upper ocean
Nitrogen isotopic constraints on nutrient transport to the upper ocean
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DOI：
10.1038/s41561-021-00836-8
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发表时间：
2021-11-01
影响因子：
18.3
通讯作者：
Haug, Gerald H.
中科院分区：
文献类型：
--
作者：
Fripiat, Francois;Martinez-Garcia, Alfredo;Haug, Gerald H.
海洋环流为表层海洋提供营养物质，为全球海洋生产力提供动力。然而，水和营养物质从深海到上层海洋的运输机制和速率却鲜为人知。在这里，我们使用硝酸盐的氮同位素组成来对营养物质从南大洋表面进入全球跃层(大约上层1.2公里)的运输施加观测限制，而不是直接从深海运输。我们估计62+/-5%的跃层硝酸盐和磷酸盐来自南大洋。混合，而不是平流，占了大部分进入跃层的总营养输入。然而，在网中，混合将营养物质从碧云跃层带走。尽管混合在总营养物质输送中占主导地位，但跃层的营养丰富依赖于大范围的平流流动，通过这种流动，营养丰富的水被转化为营养不良的地表水，最终流向北大西洋。根据对海洋硝酸盐同位素组成的盒子模型分析，大部分营养物质从深海进入海洋上层水柱的过程是通过南大洋进行的，混合和平流起着互补的作用。
Ocean circulation supplies the surface ocean with the nutrients that fuel global ocean productivity. However, the mechanisms and rates of water and nutrient transport from the deep ocean to the upper ocean are poorly known. Here, we use the nitrogen isotopic composition of nitrate to place observational constraints on nutrient transport from the Southern Ocean surface into the global pycnocline (roughly the upper 1.2 km), as opposed to directly from the deep ocean. We estimate that 62 +/- 5% of the pycnocline nitrate and phosphate originate from the Southern Ocean. Mixing, as opposed to advection, accounts for most of the gross nutrient input to the pycnocline. However, in net, mixing carries nutrients away from the pycnocline. Despite the quantitative dominance of mixing in the gross nutrient transport, the nutrient richness of the pycnocline relies on the large-scale advective flow, through which nutrient-rich water is converted to nutrient-poor surface water that eventually flows to the North Atlantic.Much of the nutrient transport from the deep ocean into the ocean's upper water column occurs through the Southern Ocean, with mixing and advection playing complementary roles, according to a box model analysis of the isotopic composition of ocean nitrate.