Towards explaining the Nd paradox using reversible scavenging in an ocean general circulation model
Towards explaining the Nd paradox using reversible scavenging in an ocean general circulation model
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DOI：
10.1016/j.epsl.2008.07.044
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发表时间：
2008-10
影响因子：
5.3
通讯作者：
M. Siddall;S. Khatiwala;T. Flierdt;K. Jones;S. Goldstein;S. Hemming;R. Anderson
中科院分区：
文献类型：
--
作者：
M. Siddall;S. Khatiwala;T. Flierdt;K. Jones;S. Goldstein;S. Hemming;R. Anderson
稀土元素钕 (Nd) 的同位素组成具有作为水质量示踪剂的潜力，因为它被具有不同年龄和岩性的大陆源自然标记。然而，为了了解这种方法的局限性，我们需要更多地了解控制现代海洋中 Nd 分布的物理和生物地球化学过程。例如，Nd 同位素比率表现出准保守的行为，而水体中的浓度通常随着深度的增加而增加，表现出大致类似营养物的行为。我们将这种 Nd 浓度和同位素组成的解耦定义为“Nd 悖论”。我们首次同时模拟 Nd 浓度和同位素组成，并提出了 Nd 悖论可以通过横向平流和可逆清除相结合来解释的假设。我们使用传输矩阵方法，将 MIT 大气环流模型中的 Nd 从海洋中去除的可逆清除模型强加到海洋环流场上。我们得出的结论是，可逆清除是海洋中 Nd 循环的一个活跃且重要的组成部分。在缺乏充分的替代解释的情况下，可逆清除应被视为解释 Nd 悖论的必要组成部分。
The isotopic composition of the rare earth element neodymium (Nd) has the potential to serve as water-mass tracer, because it is naturally tagged by continental sources with distinct ages and lithologies. However, in order to understand the limitations of this approach we need to know more about the physical and biogeochemical processes controlling the distribution of Nd in the modern ocean. For example, Nd isotope ratios behave quasi-conservatively, while concentrations in the water column generally increase with depth, showing a broadly nutrient-like behaviour. We define this decoupling of Nd concentrations and isotopic compositions as the “Nd paradox”. For the first time we model Nd concentrations and isotopic compositions simultaneously and address the hypothesis that the Nd paradox can be explained by a combination of lateral advection and reversible scavenging. We impose a reversible-scavenging model of Nd removal from the ocean on the ocean circulation fields from the MIT general circulation model using the transport matrix method. We conclude that reversible scavenging is an active and important component in the cycling of Nd in the ocean. In the absence of an adequate alternative explanation, reversible scavenging should be considered a necessary component in explaining the Nd paradox.