A nutrient and carbon pump over mid-ocean ridges (RidgeMix)

大洋中脊上的营养物和碳泵 (RidgeMix)

基本信息

批准号：
NE/L003449/1
负责人：
Alberto Naveira Garabato
金额：
$ 28.22万
依托单位：
University of Southampton
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FL003449%2F1
关键词：
nutrient carbon pump over mid

项目摘要

Phytoplankton are aquatic, single-celled plants that lie at the heart of the global cycling of carbon between the atmosphere and the oceans. Like other plants, phytoplankton require sunlight and nutrients to grow and flourish. However, in the ocean sunlight is confined to the upper few tens of metres, while nutrient concentrations are low at the sea surface and greatest at depths of a kilometre or more. The growth of phytoplankton is thus fundamentally dependent on processes that transfer nutrients from depth up to the sunlit surface.Over the mid latitudes the problem of acquiring nutrients appears to be particularly stark. The winds at mid latitudes provide a widespread downward transport of water, which inhibits the transfer of nutrient-rich deeper waters up into the sunlit, surface waters. Thus, one might expect much of the mid latitude ocean to be a desert due to a lack of nutrients. However, phytoplankton growth in the mid latitude ocean is more than might initially be expected, and is globally very important as it drives about half of the oceans' biological removal of carbon out of the atmosphere. Oceanographers have calculated the amount of nutrient required to support this growth, based upon the concentrations of inert tracers in the upper ocean. However, adding together the known nutrient supplies falls significantly short of this total nutrient requirement. Hence, there is a conundrum as to how the biological growth over the mid latitude ocean is sustained. If we want to understand how carbon is cycled between the atmosphere and oceans, and how it affects our climate, we need to answer this problem.In this proposal, we address the problem of how deep nutrients are transported into the surface waters in mid-latitudes. We propose to test a new view: tides passing over the mid-Atlantic ridge generate enhanced turbulence and mixing, which in turn provides a nutrient supply to the upper thermocline waters. These nutrients are then transported horizontally along density surfaces over the western side of the basin, probably being swept along the Gulf Stream and eventually passing into the winter mixed surface layer. When this surface layer shallows and warms in spring, the nutrients are then available to the phytoplankton. The work plan involves two main components. We will carry out a field programme collecting measurements of the turbulence and nutrient concentrations over and adjacent to the mid-Atlantic ridge. This fieldwork will involve collecting data from a novel long-term moored array of instruments on the ridge along with a focused 5 week research cruise. Our work involves sampling sufficiently quickly to be able to resolve tidal changes in currents and mixing over the ridge: this has never been done before, and we have brought together scientists with expertise in tidal measurements in shallower shelf seas with others who are expert in deep ocean mixing and transports in order to do this. The 2nd component of our work will use computer models of circulation in the Atlantic to explore the wider implications of the fieldwork observations, allowing us to decide whether or not mixing over the mid-Atlantic ridge really does provide enough nutrients to explain the phytoplankton production in the mid-latitude N Atlantic.

浮游植物是水生的单细胞植物，位于大气和海洋之间全球碳循环的核心。像其他植物一样，浮游植物需要阳光和养分才能生长和繁殖。但是，在海洋中，阳光仅限于上几十米，而在海面的营养浓度较低，在一公里或更高的深度处最大。因此，浮游植物的生长从根本上取决于将营养物质从深度转移到阳光表面的过程。在中间，获得营养成分的问题似乎特别明显。中纬度的风提供了广泛的水的向下运输，从而抑制了养分丰富的深水的转移到阳光，地表水中。因此，由于缺乏营养，人们可能会期望大部分纬度海洋成为沙漠。但是，中等纬度海洋中的浮游植物生长远远超出了最初的预期，并且在全球范围内非常重要，因为它驱动了大约一半的海洋生物学清除碳从大气中脱离大气。海洋学家已经根据上海上的惰性示踪剂浓度计算了支持这种生长所需的养分量。但是，添加已知的养分供应量明显不足这种总营养需求。因此，关于如何维持纬度海洋的生物生长如何持续存在一个难题。如果我们想了解碳在大气和海洋之间的循环方式，以及它如何影响我们的气候，我们需要回答这个问题。在此提案中，我们解决了在纬度中期如何将其深层养分传输到地表水中的问题。我们建议测试一种新的视图：潮汐经过中大西洋山脊产生增强的湍流和混合，这又为上层热跃层水提供了营养供应。然后将这些营养物质沿着盆地西侧的密度表面水平运输，可能沿着墨西哥湾流扫除，并最终进入冬季混合表面层。当该表面层在春季变浅和温暖时，养分就可以用于浮游植物。工作计划涉及两个主要组成部分。我们将执行一项现场计划，以收集湍流和养分浓度的测量，并与中大西洋山脊相邻。该野外工作将涉及从山脊上新型停泊阵列仪器以及重点为5周的研究巡游中收集数据。我们的工作涉及足够快速的采样，以便能够解决电流的潮汐变化并在山脊上混合：这从未做过，我们已经将科学家与较浅的货架海洋中的潮汐测量方面的专业知识汇集在一起，并与其他在深海混合和运输中的专家融合在一起。我们工作的第二个组成部分将使用大西洋中的计算机循环模型来探索现场工作观测的更广泛含义，从而使我们能够决定是否在中大西洋山脊上混合在一起确实提供了足够的营养来解释中层中层中植物中的植物浮游生物。

项目成果

期刊论文数量（6）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Sensitivity of Deep Ocean Mixing to Local Internal Tide Breaking and Mixing Efficiency

DOI：
10.1029/2019gl085056
发表时间：
2019-12
期刊：
Geophysical Research Letters
影响因子：
5.2
作者：
L. Cimoli;Colm‐cille P. Caulfield;H. Johnson;D. Marshall;A. Mashayek;A. N. Naveira Garabato;C. Vic
通讯作者：
L. Cimoli;Colm‐cille P. Caulfield;H. Johnson;D. Marshall;A. Mashayek;A. N. Naveira Garabato;C. Vic

The lifecycle of semidiurnal internal tides over the northern Mid-Atlantic Ridge

DOI：
10.1175/jpo-d-17-0121.1
发表时间：
2018-01
期刊：
Journal of Physical Oceanography
影响因子：
3.5
作者：
C. Vic;A. N. Naveira Garabato;J. Green;C. Spingys;A. Forryan;Zhong‐Kuo Zhao;J. Sharples
通讯作者：
C. Vic;A. N. Naveira Garabato;J. Green;C. Spingys;A. Forryan;Zhong‐Kuo Zhao;J. Sharples

Internal Tides Drive Nutrient Fluxes Into the Deep Chlorophyll Maximum Over Mid-ocean Ridges

内潮汐将养分通量推入大洋中脊的叶绿素深部最大值