Collaborative Research: Investigating the Source and Flux of Dissolved Organic Carbon Released from Methane Seeps to the Deep-ocean

合作研究：调查甲烷渗漏释放到深海的溶解有机碳的来源和通量

• 批准号: 2048357
• 负责人: Jeffrey Seewald
• 金额: $ 44.89万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2048357&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Source; Flux

Dissolved organic carbon (DOC) is a key component of the ocean’s food web and carbon cycle, and carbon exchanged between oceanic DOC and the atmosphere has influenced atmospheric CO2 levels on timescales ranging from recent decades to the geologic past. Production by marine algae in the surface ocean is the largest source of DOC and its effects on the ocean carbon cycle are widely appreciated. However, the contribution of DOC from additional sources such as rivers, hydrothermal vents, and methane seeps and their impact on ocean ecology and chemistry are not well understood. Each source differs in terms of its biological utilization and age, which affects the storage and distribution of DOC among the ocean basins. Methane seeps located along continental margins are particularly significant because they may transfer globally significant quantities of carbon stored below the seafloor as natural gas and gas hydrate to the oceans. This project will investigate the production, flux, composition and potential for biological utilization of DOC at Hydrate Ridge, located offshore Oregon. Hydrate Ridge is a prominent methane seep with massive accumulations of gas hydrate and a node of the Ocean Observatories Initiative telecommunications cabled array on the Juan De Fuca tectonic plate, which provides a continuous stream of real-time regional oceanographic data. We will sample and chemically characterize methane, DOC, and other materials to provide information about where the materials originated (deep vs shallow), how they have been chemically altered, to what extent they may feed deep ocean organisms, or contribute to the long term storage of DOC in the ocean. Experiments and analysis will be conducted using sediment cores and bottom water samples collected using either the remotely operated vehicle Jason or the human occupied vehicle Alvin during a 7-day ocean expedition. Additionally, this project will place osmotically-driven pumps on the seafloor to continuously sample fluids for approximately one year, thereby allowing us to monitor the movement of methane and DOC expelled from the seafloor to the ocean and constrain processes that regulate the release of carbon to the oceans at methane seeps. This project will support one graduate student and several undergraduates from a community college in Maryland and a college located in a lower-income urban center in southeastern Massachusetts. We will disseminate project findings to the public with a series of videos for public TV. This study will investigate the production, flux and reactivity of methane-derived dissolved organic carbon (DOC) from methane (CH4) seeps at Hydrate Ridge, Offshore Oregon. The study will address four fundamental questions to determine the significance of CH4-derived DOC within the ocean carbon cycle: (1) How much CH4-derived fossil DOC do seeps contribute to the oceans? (2) To what extent is CH4-derived C incorporated into DOC during anaerobic oxidation of CH4? (3) Is seep DOC bioavailable or recalcitrant when released into the deep ocean? (4) How does the flux of DOC to the water column vary over time? We will employ an interdisciplinary strategy that includes in situ sampling, laboratory incubations, and a comprehensive analytical geochemistry program. Data from the Ocean Observatories Initiative Regional Cabled Array at Southern Hydrate Ridge will be used to provide context for field and experimental data. The composition and abundance of organic and inorganic chemical species along with the stable and radiocarbon isotope composition of pore water, bulk sediment, and water column C pools will be used to identify DOC sources and quantify fluxes from cold seeps characterized by a range of advection rates. The centerpiece of the investigation will be a 7-day research cruise to Hydrate Ridge to collect sediments, pore fluids, and water column samples, and deploy OsmoSamplers for continuous time series fluid sampling. The results will form the foundation for estimating the contribution of CH4-derived DOC to the oceanic DOC pool.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

溶解的有机碳（DOC）是海洋食品网和碳循环的关键组成部分，海洋DOC和大气之间交换的碳在最近几十年到地质过去的时间标准上影响了大气二氧化碳水平。海洋藻类在地面海洋中的生产是最大的DOC来源，其对海洋碳循环的影响得到了广泛的认识。但是，尚不清楚DOC的其他来源的贡献，例如河流，水热通风孔和甲烷渗漏及其对海洋生态和化学的影响。每个来源的生物利用率和年龄都不同，这会影响DOC在海洋鲈鱼中的存储和分布。位于连续边缘的甲烷渗漏特别重要，因为它们可能会在海底下以天然气和气体水合物的形式转移全球大量的碳。该项目将调查位于俄勒冈州离岸的水合岭生物利用生物学利用的生产，通量，组成和潜力。水合脊是一种突出的甲烷渗漏，具有大量的气体水合物积聚和海洋天文台的节点，在Juan de Fuca Tectonic板上电信阵列电信阵列，提供了实时的区域海洋学数据的连续流。我们将采样并化学表征甲烷，DOC和其他材料，以提供有关材料起源地点的信息（深度与浅层），如何对其进行化学改变，它们在多大程度上可以喂养深海生物或有助于DOC在海洋中的长期存储。在7天的海洋探险期间，将使用使用远程操作的车辆Jason或人类占领的车辆ALVIN收集的沉积物核心和底部水样进行实验和分析。此外，该项目将在海底上放置渗透驱动的泵，以连续采样一年，从而使我们可以监视从海底到海底探索的甲烷和DOC的移动，并调节甲烷Sees碳向海洋释放到海洋的约束过程。该项目将支持一名来自马里兰州社区大学的研究生和几名大学生，以及位于马萨诸塞州东南部的低收入城市中心的一所大学。我们将通过一系列公共电视视频向公众传播项目调查结果。这项研究将调查甲烷（CH4）甲烷衍生的有机碳（DOC）的产生，通量和反应性，在俄勒冈州海外的水合山脊上看到。该研究将解决四个基本问题，以确定CH4衍生的DOC在海洋碳循环中的重要性：（1）CH4衍生的化石DOC看到多少有助于海洋？ （2）CH4的厌氧氧化过程中CH4衍生的C在多大程度上掺入了DOC中？ （3）当释放到深海时，渗透性生物利用或顽固性是吗？ （4）DOC到水柱的通量会随时间变化吗？我们将采用跨学科策略，包括原位采样，实验室孵化和全面的分析地球化学计划。来自海洋观测站的数据倡议区域有线电视阵列将用于提供现场和实验数据的背景。有机和无机化学物种的组成和抽象以及孔隙水，散装沉积物和C池的稳定和放射性碳同位素组成将用于识别DOC来源，并从寒冷的渗水中量化以一系列广告速度为特征的冷渗水。调查的核心将是一项为期7天的研究巡航，以水合脊，以收集沉积物，孔隙液和水柱样品，并部署用于连续时间序列流体采样的Osmosamplers。结果将构成估计CH4衍生的DOC对Oceanic Doc池的贡献的基础。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响审查标准，认为通过评估被认为是珍贵的支持。