Collaborative Research: Carbon Flux Through the Twilight Zone - New Tools to Measure Change

海洋中碳分布的变化是由物理化学和生物过程共同引起的。溶解度泵通过高纬度冷水的下沉将碳注入深海，在那里二氧化碳的溶解度增强。海洋生物泵具有很强的动态性和时空性。这一过程包括由表层海洋中的生物产生有机碳，并随后将这种物质固定在冬季混合层之下。在了解生物泵的控制方面已经做出了重大努力，虽然了解了一般功能，但细节仍然难以捉摸。目前，对地表真光区的过程比对暮光区(即中层)的过程有更好的理解。正是在知之甚少的黄昏地带，下沉颗粒上的碳衰减和下沉物质的组成发生变化，对表层海洋与大气的C吸收和交换速率以及深海长期的C固存产生重要影响。这项建议将开发改进的颗粒通量收集器，并利用这些装置回答与百慕大大西洋时间序列研究(BATS)站点的C通量和下沉颗粒交换相关的关键科学问题。目前在BATS，表层海洋C的预算是不平衡的，生产和群落结构无法预测颗粒输出。与此同时，这些问题正在用一个不完美的工具--漂流泥沙捕集器来解决，这是一个自上世纪80年代初S以来没有显著变化的装置。这个项目包括在收集时间序列数据的同时开发和设计新工具。该项目建立在最近开发的中性浮力沉积物捕集器(NBST)的基础上，该捕集器将进行改进，以用于连续的通量收集和自由游泳样本：暮光区探测器(TZEX)。在地球系统中的碳和水计划的背景下，该建议通过结合以下多学科元素来促进我们对碳循环的理解：(1)从基于船舶的观测和遥感获得的海洋生物学基础研究；(2)颗粒和水的地球化学及其随深度和时间的变化；(3)生物过程和颗粒在移动流体中的传输的模拟；以及(4)捕获下沉粒子的新型观测设备的设计和应用。这些独特的沉积物捕集器将打开一个新的窗口，评估海洋作为碳汇的作用，以及海洋出口生产将如何随着气候变化而变化。广泛影响：通过增进对中层海洋昏暗地带碳循环的了解，该项目将有助于提高社会预测全球气候变化影响以及制定补救战略的能力。教育和公共宣传影响包括为高中生、本科生和研究生、记者、一名本科生研究员和两名研究生提供铺位。最后，重要的仪器开发和应用部分可能会给更广泛的海洋学社区带来重大成果。

Changes in the distribution of carbon within the ocean are caused by a combination of physicochemical and biological processes. The solubility pump injects carbon into the deep sea through the sinking of cold waters at high latitudes where CO2 solubility is enhanced. The oceanic biological pump is highly dynamic and variable in space and time. This process consists in the production of organic carbon by organisms in the surface ocean and the subsequent sequestration of this material below the winter mixed layer. Significant effort has gone into understanding the controls of the biological pump and while the general function is understood, the details remain elusive. At present, processes in the surface euphotic zone are much better understood than those of the Twilight Zone (i.e. mesopelagic). It is within the poorly understood Twilight Zone that changes in C attenuation on sinking particles and the composition of sinking material occur, with important consequences for the rates of C uptake and exchange at the surface ocean with the atmosphere and for longer term C sequestration in the deep sea.This proposal will develop improved particle flux collectors and use these to answer key science questions associated with C fluxes and exchange via sinking particles at the Bermuda Atlantic Time-series Study (BATS) site. Currently at BATS, the surface ocean C budgets are unbalanced, and production and community structure fail to predict particle export. At the same time, these questions are being addressed with an imperfect tool, the drifting sediment trap, a device that has not changed significantly since the early 1980's. This program includes the development and engineering of new tools while collecting time-series data. The project builds upon the recently developed neutrally buoyant sediment trap (NBST), which will be modified for continuous flux collection and swimmer free samples to a new design: the Twilight Zone EXplorer (TZEX).In context of the C and Water in the Earth System Program, this proposal advances our understanding of the carbon cycle by combining the following multidisciplinary elements: (1) basic research in ocean biology obtained from ship based observations and remote sensing; (2) geochemistry of particles and waters and how these change with depth and time; (3) modeling of biological processes and particle transport in moving fluids; and (4) the engineering and application of novel observational equipment to capture sinking particles. These unique sediment trap devices will open up a new window to assess the ocean's role as a C sink and how marine export production will change in response to climate change.Broader Impacts: By improving understanding of the carbon cycle in the mesopelagic twilight zone, this project will contribute to society's ability to anticipate the impacts of global climate change as well as to formulate remediation strategies. Educational and public outreach impact include berth space for high school, undergraduate and graduate students, journalists, an undergraduate student fellow and two graduate students. Finally, the significant instrumentation development and application component will likely bear significant fruit for the broader oceanographic community.