REVISITING THE NEODYMIUM PARADOX IN THE OCEAN

重新审视海洋中的钕悖论

基本信息

批准号：
NE/J021636/1
负责人：
Tina Van De Flierdt
金额：
$ 46.59万
依托单位：
Imperial College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2012
资助国家：
英国
起止时间：
2012 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FJ021636%2F1
关键词：
REVISITING NEODYMIUM PARADOX OCEAN

项目摘要

Global climate change is one of the big challenges society faces today. Warming of the climate system is unequivocal, and evident from observations of increasing global average temperatures. Warming is also observed in the oceans, and is accompanied by a change in salinity, with the high latitudes becoming 'fresher' (i.e., less saline) and the subtropics and tropics becoming more saline - a redistribution of properties that has the potential to affect ocean circulation. There are also clear effects of climate change on the chemistry of the oceans. Whilst increased uptake of more abundant atmospheric carbon dioxide leads to an acidification of the oceans that threatens marine ecosystems, only little is known about the effects of higher concentrations of certain trace metals, as a result of anthropogenic pollution and changing erosion patterns on land. Such changes are very important, however, as the ability of the ocean to take up carbon dioxide from the atmosphere is strongly coupled to the supply of so-called nutrients, elements that are essential for life in the ocean. As part of this project, we will develop a better understanding of such 'biogeochemical cycles'. We picked out three trace metals, neodymium (Nd), cadmium (Cd), and lead (Pb), which together represent the behaviour of many different elements in the ocean. For example, both Cd and Pb are today supplied to the environment by human activity and this may alter their natural cycles. As Cd is an important micronutrient in the ocean, such changes could also affect the global carbon cycle. As part of our project, a PhD student will focus on understanding whether the natural flux of dust from desert areas to the ocean and the anthropogenic particles the dust scavenges in the atmosphere have an important impact on the marine Cd and Pb cycles. The student will furthermore study, how the cycling of these elements in the ocean is altered by changing oxygen concentrations. Oxygen is (next to the nutrients) another important player in biogeochemical cycles, and its solubility in seawater is temperature dependent. Climate models predict that extended zones with low oxygen concentrations will develop in the future oceans.Another important aspect of the ocean system is that ocean currents are the key mechanism for distributing heat, and thus they have a significant impact on regional and local climate. Furthermore, water mass movements (both vertical and lateral) are very important for the carbon cycle, as the deep ocean contains 50-60 times more carbon than the atmosphere. Today we can monitor ocean circulation by measuring the physical properties of seawater. Observations over the past 50 years, however, do not give us any clear indication whether the pattern of ocean circulation is changing. From studies of the past we know, however, that ocean water masses had a different configuration during the ice ages and past periods of extreme warmth. Neodymium isotopes in seawater are often used for such reconstructions, and the results show stunning relationships between past temperatures, carbon dioxide levels, and ocean circulation.A patchy understanding the modern Nd cycle however limits our confidence in such reconstructions, and thus our ability to transfer the inferred mechanisms to future models. In particular, it is generally assumed that away from ocean margins, Nd isotopes are an ideal ocean circulation tracer as they are only modified by mixing between water masses. However, there are many potential marine processes, which may not be in accord with this simplistic view. Such uncertainties will be addressed by the current project, based on a comprehensive suite of new observational data that will be collected for samples from strategic locations in the Atlantic Ocean. In conjunction with modelling efforts, our new data will shed light on the processes governing the marine Nd cycle and the suitability of Nd isotopes as circulation tracer.

全球气候变化是当今社会面临的重大挑战之一。气候系统变暖是明确的，从全球平均气温上升的观察中可以明显看出。海洋中也观察到变暖，并伴随着盐度的变化，高纬度地区变得“更新鲜”（即盐度减少），而亚热带和热带地区的盐度变得更高——这种特性的重新分配可能会影响海洋环流。气候变化对海洋化学也有明显影响。虽然大气中二氧化碳的吸收增加导致海洋酸化，威胁海洋生态系统，但由于人为污染和陆地侵蚀模式的变化，某些微量金属浓度升高的影响却知之甚少。然而，这种变化非常重要，因为海洋从大气中吸收二氧化碳的能力与所谓的营养物（海洋生命所必需的元素）的供应密切相关。作为该项目的一部分，我们将更好地理解这种“生物地球化学循环”。我们挑选了三种痕量金属：钕 (Nd)、镉 (Cd) 和铅 (Pb)，它们共同代表了海洋中许多不同元素的行为。例如，今天的镉和铅都是通过人类活动排放到环境中的，这可能会改变它们的自然循环。由于镉是海洋中重要的微量营养素，这种变化也可能影响全球碳循环。作为我们项目的一部分，一名博士生将重点了解从沙漠地区到海洋的灰尘自然通量以及灰尘在大气中清除的人为颗粒是否对海洋镉和铅循环产生重要影响。学生还将进一步研究海洋中这些元素的循环如何通过改变氧气浓度而改变。氧气（仅次于营养物质）是生物地球化学循环中的另一个重要参与者，其在海水中的溶解度取决于温度。气候模型预测，未来海洋中将出现低氧浓度的扩展区域。海洋系统的另一个重要方面是洋流是分配热量的关键机制，因此对区域和局地气候产生重大影响。此外，水团运动（垂直和横向）对于碳循环非常重要，因为深海的碳含量是大气的 50-60 倍。今天，我们可以通过测量海水的物理特性来监测海洋环流。然而，过去 50 年的观测并没有给我们任何明确的迹象表明海洋环流的模式是否正在发生变化。然而，从过去的研究中我们知道，海洋水团在冰河时期和过去的极端温暖时期具有不同的构造。海水中的钕同位素经常被用于此类重建，其结果显示了过去的温度、二氧化碳水平和海洋环流之间惊人的关系。然而，对现代钕循环的不完整了解限制了我们对此类重建的信心，从而限制了我们转移的能力未来模型的推断机制。特别是，人们普遍认为，在远离海洋边缘的地方，Nd 同位素是理想的海洋环流示踪剂，因为它们仅通过水团之间的混合而改变。然而，存在许多潜在的海洋过程，这可能与这种简单化的观点不符。当前的项目将基于一套全面的新观测数据来解决此类不确定性，这些数据将从大西洋战略地点收集样本。结合建模工作，我们的新数据将揭示海洋 Nd 循环的控制过程以及 Nd 同位素作为循环示踪剂的适用性。

项目成果

期刊论文数量（10）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Discovering the Ocean's Past through Geochemistry

通过地球化学发现海洋的过去

DOI：
http://dx.10.2138/gselements.14.6.397
发表时间：
2018
期刊：
Elements
影响因子：
4.5
作者：
Chase Z
通讯作者：
Chase Z

The Neodymium Isotope Fingerprint of Adélie Coast Bottom Water

阿德利海岸底层水的钕同位素指纹图谱

DOI：
http://dx.10.1029/2018gl080074
发表时间：
2018
期刊：
Geophysical Research Letters
影响因子：
5.2
作者：
Lambelet M
通讯作者：
Lambelet M

The distribution of lead concentrations and isotope compositions in the eastern Tropical Atlantic Ocean

热带大西洋东部铅浓度和同位素组成的分布

DOI：
10.1016/j.gca.2018.01.018
发表时间：
2018-03-15
期刊：
Geochimica et Cosmochimica Acta
影响因子：
5
作者：
Luke Bridgestock;M. Rehkämper;T. Flierdt;M. Paul;A. Milne;M. Lohan;E. Achterberg
通讯作者：
E. Achterberg

New constraints on elemental and Pb and Nd isotope compositions of South American and Southern African aerosol sources to the South Atlantic Ocean

对南美洲和南部非洲进入南大西洋的气溶胶源的元素以及 Pb 和 Nd 同位素组成的新限制