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首页> 外文期刊>Marine Chemistry >The ~(210)Po/~(210)Pb method to calculate particle export: Lessons learned from the results of three GEOTRACES transects
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The ~(210)Po/~(210)Pb method to calculate particle export: Lessons learned from the results of three GEOTRACES transects

机译：〜（210）Po /〜（210）Pb方法计算粒子输出：从三个GEOTRACES样条的结果中学到的教训

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摘要

The deviation from secular equilibrium between the natural radionuclide Po-210 (half-life: 138.4 d) and its radioactive grandparent Pb-210 (half-life: 22.3 y) has been used to examine particle export from the surface ocean. Here we combine Po-210 and Pb-210 activity results from three GEOTRACES transects: two transects of the North Atlantic Ocean (GA03: 15-40 N, and GA01: 40-60 N) and one transect of the South Pacific Ocean (GP16: 10-15 S), and estimate Po-210 export fluxes at the base of the primary production zone (PPZ) by assuming steady state (SS) without advection or diffusion of the isotopes. The SS Po-210 flux was sometimes lower at basin margins than at the open-ocean stations along the transects. High SS Po-210 flux estimations derived in the North Atlantic subtropical gyre may be associated with the atmospheric deposition of Pb-210 to the surface ocean. In this paper we also question the validity of the SS assumption and discuss the influence of vertical advection and diffusion on the overall Po-210 activity balance. The SS model may have underestimated the export flux of Po-210 at margin stations in the GA03 and GP16 transects and along the GA01 cruise track. We found that upwelling in the Peruvian coastal region and near the Greenland shelf had a dramatic impact on the estimated Po-210 flux balance. Vertical diffusion had limited influence on the Po-210 export fluxes along GA03 and GA01 in the North Atlantic whereas it added Po-210 export fluxes by as much as 190% in GP16 in the Pacific, especially at the shelf stations 1 and 4. Further, analysis of the partitioning coefficient suggested the importance of small particles in the scavenging of radionuclides. This suggests it is wise to sample small particles along with large particles to determine the ratio of the concentration of particulate organic carbon (POC) to Po-210 activity (POC/Po-210) for the lower limit of POC export flux estimations. Finally, the observation of the deficit of Po-210 relative to Pb-210 activity (ziopo/ziopb < 1) in seawater concurrent with a deficit of Po-210 in particles contradicts our understanding of the conceptual Po-210 flux model, which assumes that Po-210 activity is more effectively removed from the surface ocean via particles than Pb-210 activity. While this observation deserves more attention, we propose two possible solutions: (1) the deficit of total Po-210 relative to Pb-210 activity in the surface ocean may be due to an input of Pb-210 activity instead of/concurrent with a relative removal of Po-210 activity via particle export; or (2) the particles collected may not be identical to the ones that have originally created the observed deficit in total Po-210 activity.
机译：天然放射性核素Po-210（半衰期：138.4 d）与其放射性祖父母Pb-210（半衰期：22.3 y）之间的长期平衡偏差已被用于检验从表层海洋输出的颗粒。在这里，我们结合了三个GEOTRACES样带的Po-210和Pb-210活性结果：北大西洋的两个样带（GA03：15-40 N，GA01：40-60 N）和南太平洋的一个样带（GP16） ：10-15 S），并通过假设稳态（SS）没有对流或同位素扩散来估算主要生产区（PPZ）底部的Po-210出口通量。在盆地边缘，SS Po-210通量有时会比沿样带的开放海洋站的通量要低。在北大西洋亚热带回旋中获得的高SS Po-210通量估计值可能与Pb-210在大气中向地面海洋的沉积有关。在本文中，我们还质疑SS假设的有效性，并讨论垂直对流和扩散对Po-210总体活动平衡的影响。 SS模型可能低估了GA03和GP16样带的边缘站以及沿GA01航迹的Po-210的出口通量。我们发现，秘鲁沿海地区和格陵兰陆架附近的上升流对估计的Po-210通量平衡产生了显着影响。垂直扩散对北大西洋沿GA03和GA01的Po-210出口通量的影响有限，而它在太平洋的GP16中增加了Po-210的出口通量，高达190％，特别是在架子站1和4。 ，对分配系数的分析表明小颗粒在清除放射性核素中的重要性。这表明明智的做法是，对小颗粒和大颗粒进行采样，以确定POC出口通量估计值下限的颗粒有机碳（POC）浓度与Po-210活性（POC / Po-210）的比率。最后，观察到Po-210相对于海水中Pb-210活性的不足（ziopo / ziopb <1）以及颗粒中Po-210的缺乏与我们对概念性Po-210通量模型的理解相矛盾。与Pb-210活性相比，Po-210活性通过颗粒更有效地从海面清除。尽管这一观察值得更多关注，但我们提出了两种可能的解决方案：（1）表层海洋中总Po-210相对于Pb-210活性的亏空可能是由于Pb-210活性的输入而不是同时存在。通过粒子出口相对去除Po-210活性； （2）收集到的颗粒可能与最初在Po-210的总活性中造成观察到的缺陷的颗粒不同。

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  • 来源
    《Marine Chemistry》 |2019年第20期|103692.1-103692.16|共16页
  • 作者

    Tang Yi; Stewart Gillian;

  • 作者单位

    CUNY Grad Ctr Earth & Environm Sci New York NY USA|CUNY Queens Coll Sch Earth & Environm Sci Flushing NY USA;

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