Using silicon isotopes to understand the role of the Southern Ocean in modern and ancient biogeochemistry and climate
Using silicon isotopes to understand the role of the Southern Ocean in modern and ancient biogeochemistry and climate
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DOI：
10.1016/j.quascirev.2014.01.019
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发表时间：
2014-04-01
影响因子：
4
通讯作者：
Brzezinski, Mark A.
中科院分区：
文献类型：
--
作者：
Hendry, Katharine R.;Brzezinski, Mark A.
南大洋硅质浮游植物（主要是硅藻）的生长在全球范围内影响着海洋中预先形成的营养物清单。硅藻对硅酸的利用和深层循环结合在一起，将溶解的硅困在南大洋中，导致高水平的二氧化硅产生，并在南大洋沉积物中形成膨胀的硅藻软泥。对生物成因二氧化硅（或蛋白石）和溶解硅酸的硅同位素组成的分析，有助于深入了解全球海洋硅循环的运作，以及南大洋在现代和过去的营养供应和碳减少中所起的作用。硅藻的硅同位素研究提供了对地表水二氧化硅生产历史的深入了解，而深海海绵针状体的分析则定义了水柱中硅酸浓度的空间和时间变化；这些指标和其他指标共同揭示了南大洋中间和模态水向北流动的变化，以及南大洋生产力的变化如何改变了它们的预形成营养成分含量。本文提出了一个新的假说——“硅酸通风假说”（SAVH）来解释蛋白石代用记录的地理差异，特别是在低纬度和高纬度地区发现的蛋白石埋藏变化的对比模式。通过了解现代蛋白石和硅酸的硅同位素系统，我们将能够利用蛋白石为基础的代用物来重建过去南大洋的变化，从而研究其在全球碳循环和气候中的作用。(c) 2014 Elsevier Ltd.版权所有。
The growth of siliceous phytoplankton, mainly diatoms, in the Southern Ocean influences the preformed nutrient inventory in the ocean on a global scale. Silicic acid use by diatoms and deep circulation combine to trap dissolved Si in the Southern Ocean resulting in high levels of silica production and expansive diatom oozes in Southern Ocean sediments. The analysis of the silicon isotope composition of biogenic silica, or opal, and dissolved silicic acid provide insight into the operation of the global marine silicon cycle and the role played by the Southern Ocean in nutrient supply and carbon drawdown, both in the modern and in the past. Silicon isotope studies of diatoms have provided insight into the history of silica production in surface waters, while the analysis of spicules from deep sea sponges has defined both the spatial and the temporal variability of silicic acid concentrations in the water column; together these and other proxies reveal variations in the northward flow of Southern Ocean intermediate and mode waters and how changes in Southern Ocean productivity altered their preformed nutrient content. We present a new hypothesis the "Silicic Acid Ventilation Hypothesis" (SAVH) to explain the geographical variation of opal-based proxy records, in particular the contrasting patterns of opal burial change found in the low and high latitudes. By understanding the silicon isotope systematics of opal and silicic acid in the modern, we will be able to use opal-based proxies to reconstruct past changes in the Southern Ocean and so investigate its role in global carbon cycling and climate. (c) 2014 Elsevier Ltd. All rights reserved.