The large-scale oceanic distribution of trace elements: disentangling preformed contributions, regenerative processes, subsurface sources and sinks

微量元素的大规模海洋分布：解开预先形成的贡献、再生过程、地下源和汇

• 批准号: NE/M017826/1
• 负责人: Yves Plancherel
• 金额: $ 63.9万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Fellowship
• 财政年份: 2015
• 资助国家: 英国
• 起止时间: 2015 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FM017826%2F1
• 关键词: large; scale; oceanic; distribution; trace

Elements present in seawater in quantities so small that they do not affect salinity are called "trace elements". In spite of their low abundances, trace metals can play disproportionally large roles in controlling the dynamics of marine ecosystems. This is because some are necessary for the proper functioning of important enzymes and proteins and must thus be supplied in sufficient quantities to maintain phytoplankton populations. There are regions in the ocean where key metals, particularly iron (Fe), are lacking in proportion to the other nutrients, what limits biological productivity. Why some micronutrients are lacking in some region and not others is not fully understood; the processes that govern the natural cycles of these metals are not well known. This gap in understanding is partly due to the difficulty of measuring trace metals in the ocean: trace metals are present in very small quantities and water samples are taken from metallic research ships, making measurements prone to contamination. Reliable techniques to routinely measure trace metals in seawater have only been recently developed. Thanks to them, the accuracy of the data and data coverage over the oceans have improved dramatically over the last few years. With this project, I aim to improve the general understanding of the cycling of trace metals, particularly the micronutrients, by analyzing the newest and most complete trace metal databases available.The difficulty when trying to interpret measurements of dissolved trace metal concentrations, or other nutrients, in the deep sea is that one cannot easily distinguish between the amount that is present because it has been transported to the point of sampling from somewhere else and the amount that has been added or removed due to local, internal processes. Yet, one must be able to isolate that later component to quantify and interpret the influence of subsurface biogeochemical processes on trace metal cycles. Without this ability, one's interpretation of the measured concentration field could be wrong, mistaking transport phenomena for internal cycling mechanisms. This work will directly address this issue by applying statistical deconvolution techniques to explicitly quantify the amount that is transported. By taking the difference between the measured concentrations and the calculated transported component, it is possible to quantify the fraction that is due to biogeochemical processes and map these residual quantities.One of the most important processes influencing the distribution of trace metals in the sea is "scavenging"; that is the propensity for dissolved metals to stick to particles and sink along with them. Scavenging affects metals more than other nutrients. It is an important process because it is omnipresent (particles are everywhere) and can redistribute the metals within the ocean interior. It is hypothesized that if scavenging is strong, or operating for a long time, the scavenging process can fractionate metals relative to the other nutrients. When layers that are affected strongly by this process are transported back to the surface, they will bring with them waters that are depleted in the metal relative to the other nutrients. If the metal abundance is too low, this will limit surface productivity. Preliminary modeling experiments support the view that scavenging exerts a first order control on the distribution of some metals, such as thorium, beryllium, the rare earth elements and aluminium. It is, however, not clear how much micronutrient metals scavenge and if this effect is able to explain the distribution and characteristics of micronutrient-limited regions. This project will test this hypothesis. First, the statistical deconvolution results from the data will inform on the degree of fractionation imposed by scavenging on each metal. Secondly, models will be used to simulate scavenging and the fractionation process and quantify the influence on surface ecosystems.

海水中存在的元素数量很少，不会影响盐度，这种元素被称为“微量元素”。尽管痕量金属的丰度很低，但它们在控制海洋生态系统的动态方面可能发挥着不成比例的巨大作用。这是因为一些对于重要的酶和蛋白质的正常运作是必要的，因此必须提供足够的数量来维持浮游植物的种群。在海洋中的一些地区，关键金属，特别是铁(Fe)与其他营养物质的比例缺乏，这限制了生物生产力。为什么有些地区缺乏某些微量营养素，而另一些地区则不是，这一点还不完全清楚；支配这些金属自然循环的过程也不是很清楚。理解上的差距部分是由于测量海洋中痕量金属的困难：痕量金属的存在数量很少，水样取自金属研究船，使测量容易受到污染。直到最近才开发出可靠的技术来常规测量海水中的痕量金属。多亏了它们，在过去的几年里，海洋数据的准确性和数据覆盖范围都有了显著的提高。通过这个项目，我的目标是通过分析现有的最新和最完整的痕量金属数据库，提高对痕量金属，特别是微量营养素循环的一般理解。试图解释深海中溶解的痕量金属浓度或其他营养物质的测量时的困难是，人们不能轻易区分存在的量，因为它已经从其他地方输送到采样点，以及由于本地的内部过程而添加或移除的量。然而，人们必须能够分离出后一组分，以量化和解释地下生物地球化学过程对痕量金属循环的影响。如果没有这种能力，人们对测量到的浓度场的解释可能是错误的，将传输现象误认为是内部循环机制。这项工作将通过应用统计反卷积技术来明确量化运输量，从而直接解决这一问题。通过测量的浓度和计算的传输组分之间的差异，可以量化生物地球化学过程产生的部分，并绘制这些残留量的地图。影响海洋中痕量金属分布的最重要的过程之一是“清除”；即溶解金属附着在颗粒上并随其下沉的倾向。与其他营养素相比，拾荒者对金属的影响更大。这是一个重要的过程，因为它无处不在(颗粒无处不在)，并可以重新分布海洋内部的金属。据推测，如果清除作用很强，或运行时间较长，则清除过程可以相对于其他营养物质分离金属。当受到这一过程强烈影响的岩层被运回地表时，它们会带来相对于其他营养物质而言在金属中耗尽的水分。如果金属丰度太低，这将限制地表生产率。初步的模拟实验支持这样的观点，即清除作用对某些金属的分布起一级控制作用，如Th、Be、稀土元素和铝。然而，尚不清楚微量营养素金属清除了多少，以及这种效应是否能够解释微量营养素限制区的分布和特征。这个项目将检验这一假设。首先，数据的统计反卷积结果将告知每种金属因拾取而产生的分馏程度。其次，模型将用于模拟清扫和分馏过程，并量化其对地表生态系统的影响。

项目成果

Rare earth elements (REEs) in the tropical South Atlantic and quantitative deconvolution of their non-conservative behavior

• DOI: 10.1016/j.gca.2016.01.018
• 发表时间: 2016-03
• 期刊: Geochimica et Cosmochimica Acta
• 影响因子: 5
• 作者: Xin-Yuan Zheng;Y. Plancherel;M. Saito;Peter Scott;G. Henderson

Particle-Seawater Interaction of Neodymium in the North Atlantic

北大西洋钕的粒子与海水相互作用

• DOI: 10.1021/acsearthspacechem.0c00034
• 发表时间: 2020
• 期刊: ACS Earth and Space Chemistry
• 影响因子: 3.4
• 作者: Stichel T

Rare earth element distribution in Caribbean seawater: Continental inputs versus lateral transport of distinct REE compositions in subsurface water masses

• DOI: 10.1016/j.marchem.2015.03.013
• 发表时间: 2015-12
• 期刊: Marine Chemistry
• 影响因子: 3
• 作者: Anne H. Osborne;B. Haley;E. Hathorne;Y. Plancherel;M. Frank

The formation of the ocean's anthropogenic carbon reservoir.

• DOI: 10.1038/srep35473
• 发表时间: 2016-11-03
• 期刊: Scientific reports
• 影响因子: 4.6
• 作者: Iudicone D;Rodgers KB;Plancherel Y;Aumont O;Ito T;Key RM;Madec G;Ishii M
• 通讯作者: Ishii M

Correction to: Emergence of deep convection in the Arctic Ocean under a warming climate

修正：气候变暖下北冰洋深层对流的出现

• DOI: 10.1007/s00382-017-3999-9
• 发表时间: 2017
• 期刊: Climate Dynamics
• 影响因子: 4.6
• 作者: Lique C