The Transpolar Drift as a Source of Riverine and Shelf-Derived Trace Elements to the Central Arctic Ocean
The Transpolar Drift as a Source of Riverine and Shelf-Derived Trace Elements to the Central Arctic Ocean
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DOI：
10.1029/2019jc015920
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发表时间：
2020-05-01
影响因子：
3.6
通讯作者：
Zhang, Ruifeng
中科院分区：
文献类型：
--
作者：
Charette, Matthew A.;Kipp, Lauren E.;Zhang, Ruifeng
北冰洋的一个主要表面环流特征是跨极漂移（TPD），这是一种将受河流影响的陆架水从拉普捷夫海和东西伯利亚海输送到盆地中心和弗拉姆海峡的海流。2015年，国际GEOTRACES计划包括对碳，营养物质和一套微量元素和同位素（TEI）的高分辨率泛北极调查。考察在中央海盆的两个地点将TPD一分为二，这两个地点是由水平跨度为600公里、垂直跨度为25-50米的大气降水和溶解有机碳浓度的最大值确定的。溶解的TEIs，如铁，钴，镍，铜，汞，钕，钍，这是一般的颗粒反应，但可以由有机物络合，观察到的浓度远高于预期的开放海洋设置。其他微量元素的浓度，如铝，钒，镓，铅低于预期，由于清除生产东西伯利亚和拉普捷夫陆架海。结合使用放射性核素示踪剂和冰漂移模型，TPD核心的迁移率估计为0.9 +/- 0.4 Sv（10（6）m（3）s（-1））。这个速率被用来推导出TEIs的质量通量，富集在TPD，揭示了横向运输的重要性，在冰下的中央北冰洋和潜在的北大西洋通过弗拉姆海峡供应材料。北极水文循环的持续加剧和永久冻土的退化可能会导致进入北冰洋的TEI通量增加。简明语言摘要北冰洋环流的一个主要特征是跨极漂移（TPD），这是一种表层流，将冰和大陆架衍生的物质从西伯利亚穿过北极带到北大西洋。2015年，一个国际海洋学家团队在北冰洋进行了一项微量元素调查，穿越了TPD。在北极附近，他们观察到表层沃茨中的微量元素浓度比洋流两侧的区域高得多。这些微量元素来自陆地，它们穿越北冰洋的旅程是通过与主要来自北极河流的溶解有机物发生化学反应而实现的。这项研究揭示了河流和大陆架过程与强洋流相结合，在向北冰洋中部和大西洋提供微量元素方面的重要性。这些微量元素的输入预计会增加，因为北极的永久冻土融化和河流径流增加，北极的变暖速度比地球上其他任何地方都快。由于许多微量元素是海洋生物的基本组成部分，这些过程可能导致北冰洋海洋生态系统和渔业发生重大变化。
A major surface circulation feature of the Arctic Ocean is the Transpolar Drift (TPD), a current that transports river-influenced shelf water from the Laptev and East Siberian Seas toward the center of the basin and Fram Strait. In 2015, the international GEOTRACES program included a high-resolution pan-Arctic survey of carbon, nutrients, and a suite of trace elements and isotopes (TEIs). The cruises bisected the TPD at two locations in the central basin, which were defined by maxima in meteoric water and dissolved organic carbon concentrations that spanned 600 km horizontally and similar to 25-50 m vertically. Dissolved TEIs such as Fe, Co, Ni, Cu, Hg, Nd, and Th, which are generally particle-reactive but can be complexed by organic matter, were observed at concentrations much higher than expected for the open ocean setting. Other trace element concentrations such as Al, V, Ga, and Pb were lower than expected due to scavenging over the productive East Siberian and Laptev shelf seas. Using a combination of radionuclide tracers and ice drift modeling, the transport rate for the core of the TPD was estimated at 0.9 +/- 0.4 Sv (10(6) m(3)s(-1)). This rate was used to derive the mass flux for TEIs that were enriched in the TPD, revealing the importance of lateral transport in supplying materials beneath the ice to the central Arctic Ocean and potentially to the North Atlantic Ocean via Fram Strait. Continued intensification of the Arctic hydrologic cycle and permafrost degradation will likely lead to an increase in the flux of TEIs into the Arctic Ocean.Plain Language Summary A major feature of the Arctic Ocean circulation is the Transpolar Drift (TPD), a surface current that carries ice and continental shelf-derived materials from Siberia across the North Pole to the North Atlantic Ocean. In 2015, an international team of oceanographers conducted a survey of trace elements in the Arctic Ocean, traversing the TPD. Near the North Pole, they observed much higher concentrations of trace elements in surface waters than in regions on either side of the current. These trace elements originated from land, and their journey across the Arctic Ocean is made possible by chemical reactions with dissolved organic matter that originates mainly in Arctic rivers. This study reveals the importance of rivers and shelf processes combined with strong ocean currents in supplying trace elements to the central Arctic Ocean and onward to the Atlantic. These trace element inputs are expected to increase as a result of permafrost thawing and increased river runoff in the Arctic, which is warming at a rate much faster than anywhere else on Earth. Since many of the trace elements are essential building blocks for ocean life, these processes could lead to significant changes in the marine ecosystems and fisheries of the Arctic Ocean.