The impact of Mid-Ocean Ridges on the Ocean's Iron cycle

大洋中脊对海洋铁循环的影响

基本信息

批准号：
NE/N009525/1
负责人：
Alessandro Tagliabue
金额：
$ 30.14万
依托单位：
University of Liverpool
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2017
资助国家：
英国
起止时间：
2017 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FN009525%2F1
关键词：
impact Mid Ocean Ridges Iron

项目摘要

Photosynthesis by marine phytoplankton provides energy to higher trophic levels (such as fish and marine mammals), as well as contributing to the partitioning of carbon dioxide between the atmosphere and the ocean. Iron is essential for phytoplankton growth as it is required for a number of important enzymes that participate in both photosynthesis and respiration. In contrast with terrestrial systems, iron is present at very low concentrations (less than 1 iron atom to every billion water molecules) in the open ocean. Thus phytoplankton photosynthesis is limited by iron over large parts of the ocean. This iron deficiency has important ramifications for the earth system since phytoplankton photosynthesis is an important means by which the ocean regulates global climate. Mid-ocean ridges are an important source of iron with estimates suggesting that ridge-derived iron makes up 25-75% of global ocean iron stocks. These mid-ocean ridges are the deep-sea mountain ranges that form a single global mid-ocean ridge system throughout the world's ocean, making it the longest mountain range in the world. At these ridges, new magma mixes with seawater and is exhaled as a high temperature fluid. While this ridge fluid has been noted to be a large source of iron to the deep-sea, the far field influence of this iron depends on its retention in dissolved forms by ocean chemistry. Our recent work shows that iron from mid-ocean ridges appears to have a much longer lifetime than previously thought and be exported up to 4000km away from the ridge. Despite the emerging role for ridge-derived iron, we do not understand its impact on deep ocean iron stocks, as well as how iron is mixed into surface waters to drive biological activity. We have highlighted that understanding the fate of ridge-derived iron and its ultimate influence on the ocean requires more information on the quantity and chemical form of iron supplied by ridges (e.g. dissolved or particles) and how these change with distance from source. To do this we need to appraise the role of small organic molecules called ligands and so-called iron nanoparticles, which have been invoked to control the lifetime of ridge-derived iron. Accounting for the specificity of iron within hydrothermal systems is key to constraining its wider impact. In addition, recent work by our colleagues has shown that interactions between the deep ocean tide and the ridge itself can elevate rates of physical mixing. If increased vertical mixing typifies mid-ocean ridges it implies that these regions may also exhibit efficient transfer of iron to surface waters. Given the ubiquity of mid-ocean ridges, the synergistic combination of these phenomena may be key to the large-scale supply of iron to surface waters.Sampling and measurement of iron at very low concentrations in seawater is challenging and the applicants are among the few research groups in the world who are able to do this reliably. Our group is at the forefront of representing the role of iron is global ocean models, which are crucial tools for assessing larger scale impacts on biological productivity. This project will participate in a NERC funded research cruise where scientists with expertise in measuring mixing and other macronutrients will be studying the nutrient and carbon pump over mid-ocean ridges. This proposal will therefore benefit from these measurements and will add value to this cruise by determining the associated role for iron.Overall, this project will provide state of the art observational and modelling constraints on two important aspects of the ocean iron cycle: 1) How does the ocean ridge impact physical mixing of iron to the surface and 2) what chemical processes control the large scale influence of the iron directly supplied by mid-ocean ridges. Ultimately we will be able to address the broader question of how the amount and chemical form of iron from mid-ocean ridges can influence phytoplankton growth in the open ocean.

海洋浮游植物的光合作用为较高营养级（例如鱼类和海洋哺乳动物）提供能量，并有助于二氧化碳在大气和海洋之间的分配。铁对于浮游植物的生长至关重要，因为许多参与光合作用和呼吸的重要酶都需要铁。与陆地系统相比，公海中铁的浓度非常低（每十亿个水分子中含有不到 1 个铁原子）。因此，在大部分海洋中，浮游植物的光合作用受到铁的限制。这种缺铁对地球系统具有重要影响，因为浮游植物光合作用是海洋调节全球气候的重要手段。大洋中脊是铁的重要来源，据估计，洋中脊产生的铁占全球海洋铁储量的 25-75%。这些洋中脊是深海山脉，形成了遍布世界海洋的单一全球洋中脊系统，使其成为世界上最长的山脉。在这些山脊处，新的岩浆与海水混合，并以高温流体的形式喷出。虽然这种海脊流体被认为是深海铁的大量来源，但这种铁的远场影响取决于其通过海洋化学以溶解形式保留。我们最近的研究表明，来自洋中脊的铁的寿命似乎比之前想象的要长得多，并且可以出口到距离洋脊 4000 公里的地方。尽管来自海脊的铁的作用正在显现，但我们不了解其对深海铁库存的影响，也不了解铁如何混合到地表水中以驱动生物活动。我们强调，要了解山脊产生的铁的命运及其对海洋的最终影响，需要更多关于山脊提供的铁的数量和化学形式（例如溶解或颗粒）以及这些铁如何随着距来源距离的变化而变化的信息。为此，我们需要评估称为配体的有机小分子和所谓的铁纳米颗粒的作用，它们已被用来控制脊衍生铁的寿命。考虑热液系统中铁的特殊性是限制其更广泛影响的关键。此外，我们同事最近的研究表明，深海潮汐和海脊本身之间的相互作用可以提高物理混合的速率。如果垂直混合的增加是洋中脊的典型特征，则意味着这些区域也可能表现出铁向地表水的有效转移。鉴于洋中脊的普遍存在，这些现象的协同组合可能是向地表水大规模供应铁的关键。对海水中极低浓度的铁进行采样和测量具有挑战性，申请人是少数。世界上有能力可靠地做到这一点的研究小组。我们的团队处于代表铁在全球海洋模型中的作用的最前沿，这些模型是评估对生物生产力的更大规模影响的重要工具。该项目将参加 NERC 资助的研究巡航，在测量混合和其他常量营养素方面具有专业知识的科学家将研究洋中脊上的养分和碳泵。因此，该提案将从这些测量中受益，并将通过确定铁的相关作用来为这次航行增加价值。总体而言，该项目将为海洋铁循环的两个重要方面提供最先进的观测和建模约束：1）如何海脊是否会影响铁到地表的物理混合？2）哪些化学过程控制着由洋中脊直接供应的铁的大规模影响。最终，我们将能够解决更广泛的问题，即洋中脊铁的数量和化学形式如何影响公海浮游植物的生长。

项目成果

期刊论文数量（9）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Variability in iron (II) oxidation kinetics across diverse hydrothermal sites on the northern Mid Atlantic Ridge

DOI：
10.1016/j.gca.2021.01.013
发表时间：
2021-02-04
期刊：
GEOCHIMICA ET COSMOCHIMICA ACTA
影响因子：
5
作者：
Gonzalez-Santana, David;Gonzalez-Davila, Melchor;Santana-Casiano, J. Magdalena
通讯作者：
Santana-Casiano, J. Magdalena

The unaccounted dissolved iron (II) sink: Insights from dFe(II) concentrations in the deep Atlantic Ocean.

未解释的溶解铁 (II) 沉降：来自大西洋深海 dFe(II) 浓度的见解。

DOI：
10.1016/j.scitotenv.2022.161179
发表时间：
2023
期刊：
The Science of the total environment
影响因子：
0
作者：
González-Santana D
通讯作者：
González-Santana D

Mechanisms Driving the Dispersal of Hydrothermal Iron From the Northern Mid Atlantic Ridge

驱动北大西洋中脊热液铁扩散的机制

DOI：
10.1029/2022gl100615
发表时间：
2022
期刊：
Geophysical Research Letters
影响因子：
5.2
作者：
Tagliabue, Alessandro;Lough, Alastair J. M.;Vic, Clément;Roussenov, Vassil;Gula, Jonathan;Lohan, Maeve C.;Resing, Joseph A.;Williams, Richard G.
通讯作者：
Williams, Richard G.

Constraining the Contribution of Hydrothermal Iron to Southern Ocean Export Production Using Deep Ocean Iron Observations

利用深海铁观测限制热液铁对南大洋出口生产的贡献