Bottom boundary layer mediation of chemical fluxes from ocean margins

海洋沉积物是海洋必需微量营养素的重要来源，但测量这些输入是有问题的。我的目标是观察和了解靠近海底的微量营养素输入，特别是铁的行为，在那里，沉积物和海水之间的交换被认为通过光合作用调节表层海洋对碳的吸收。为了改进地球气候的海洋耦合模型，需要将这一关键来源提炼成海洋。这项工作的一个关键方面将是在靠近海床的垂直横断面上收集溶解和悬浮颗粒物质的样本，那里海洋中的物理混合和化学交换与海洋内部完全不同。这种“底边界层”中的化学过程在很大程度上是未知的，因为从海洋表面对其进行采样是困难的；距离考察船很远的地方，在靠近海底的地方会传播不准确的信息，并有可能损坏或丢失昂贵的设备。该项目的一个新奇之处将是开发和优化一种自由落体仪器，它可以远程停留在海床上，并使用远程和自主控制跨10至100米厚的海洋采集底层水和颗粒物样本。该仪器将在国家海洋学中心海洋技术和工程小组的支持下开发，并由牛津大学的吉迪恩·亨德森教授提供额外的资金来自皇家学会。新仪器将首先与计划于2014年底在英国北大西洋的NERC大陆架海洋生物地球化学计划一起使用。将在实验室实验中模拟观察到的条件，以确定沉积物和海水之间的化学交换机制。该奖学金将受益于美国南卡罗来纳大学海洋微量元素实验室的分析专业知识，通过该实验室将对海水中新开发的金属同位素进行观测。通过与国际GEOTRACES计划的互动，新仪器的未来部署计划在该研究金的有生之年内进行。这项工作的一项遗产将是改进对海洋边缘微营养素供应的估计，以改进海洋气候模型，并为在地球系统未被开发的部分进行广泛的化学观测建立一个业务平台。未来的潜在研究途径包括：提炼海洋过程的化学示踪剂；监测海洋生物栖息地和污染物迁移过程；以及随时间观察海洋动态冰盖区域或火山区域海底的化学过程。

Marine sediments are an important source of essential micronutrients to the ocean, but measuring these inputs is problematic. I aim to observe and understand the behavior of micronutrient inputs, in particular iron, close to the seafloor, where exchanges between sediments and seawater are thought to mediate the uptake of carbon via photosynthesis in the surface ocean. Refining this critical source to the ocean is needed to improved ocean-coupled models of the Earth's climate. A key aspect of this work will be to collect samples of dissolved and suspended particulate material in vertical transects close to the seabed, where the physical mixing and chemical exchanges in the ocean are completely different from the ocean interior. Chemical processes in this 'bottom boundary layer' are largely unknown, because sampling it from the ocean surface is difficult; large distances from a research vessel propagates inaccuracy close to the seafloor and risks damage or loss of costly equipment. A novelty of this project will be to develop and optimize a free-falling instrument that can rest remotely on the seabed and collect bottom water and particulate samples across a 10 to 100 meter thick layer of the ocean using remote and autonomous controls. The instrument will be developed with support from the Ocean Technology and Engineering Group at the National Oceanography Centre, with additional funds from the Royal Society provided by Prof. Gideon Henderson at the University of Oxford. The new instrument will be first used in conjunction with the NERC Shelf Sea Biogeochemistry Programme in the UK North Atlantic planned for late 2014. Observed conditions will be simulated in laboratory experiments to identify chemical exchange mechanisms between sediments and seawater. The fellowship will benefit from analytical expertise at the Marine Trace Element Laboratory of University of South Carolina, USA, through which newly developed metal isotope observations in seawater will be made. Future deployments of the new instrument are planned within the lifetime of this fellowship through interaction with the international GEOTRACES program. A legacy of this work will be to refine estimates of micronutrient supply from ocean margins to improve ocean climate models, and to establish an operational platform for a broad range of chemical observations across an under-explored part of the Earth system. Potential research avenues for the future include refining chemical tracers of ocean processes; monitoring marine habitats and contaminant transport processes; and observing chemical processes at the seafloor in dynamic ice-covered or volcanic regions of the ocean over time.