Collaborative Research: Investigating the Fate of Carbon at an Ultraslow Spreading Center

合作研究：调查碳在超慢扩散中心的命运

• 批准号: 1801205
• 负责人: Jeffrey Seewald
• 金额: $ 31.35万
• 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: 2019
• 资助国家: 美国
• 起止时间: 2019-03-01 至 2023-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1801205&HistoricalAwards=false
• 关键词: Collaborative; Research; Investigating; Fate; Carbon

Knowing the cycle of carbon in the Earth and how biological and abiological processes control the composition of the resulting carbon-bearing phases and how those change over time is a major scientific goal that has important implications for our understanding of both ecosystems and global warming. The circulation of seawater through deep-sea hydrothermal vent systems results in the extensive transformation of both inorganic and organic carbon compounds and may have a significant impact on the deep ocean carbon cycle. To date, most reports of organic compounds in deep-sea hydrothermal fluids have focused on methane and light hydrocarbons. The distribution and abundance of other types of organic compounds, however, remains poorly known. As a result, the contribution of hydrothermal systems to organic carbon in the deep ocean and the biogeochemical processes responsible for this input, remain highly uncertain. This research conducts a comprehensive study of the composition and abundance of carbon compounds from fluids discharging from two very different, but closely located, hydrothermal vents on the ultraslow spreading mid-Cayman rise in the Caribbean Sea. The two vent sites are located in substantially different host rocks and occur at very different water depths. They also have very different vent fluid temperatures. Fluids will be collected using multiple, complementary sampling systems and analyzed by various mass spectrometric and other analytical techniques. Comparison between these two sites allows carbon fluxes and chemical transformations to be determined over a range of physical and chemical conditions. Broader impacts of the work include training of graduate and undergraduate students in state-of-the-art geochemical methods and provide them with an opportunity to gain experience and training in sea-going research in a strongly interdisciplinary subject. A graduate and several undergraduate students from the University of South Carolina, an EPSCoR state (i.e., a state that does not receive significant federal dollars); Bridgewater State University, which serves economically disadvantaged communities in Massachusetts; and the University of Colorado at Boulder will be involved in the research and play key roles in both the scientific cruise and supporting laboratory activities.In ocean crust, extensive transformations occur to the carbon compounds present in both the fluids and solids on and below the seafloor due to processes such as heating, precipitation of minerals, injections of magma, and the activity of microorganisms. These processes have consequences for global elemental cycling in the present day and over geologic time. To date, most reports of organic compounds in deep-sea hydrothermal fluids have focused on small, volatile organic molecules such as methane. However, the abundance and fate of other types of organic compounds remains poorly known. To better understand these transformations and the amount of carbon in seafloor hydrothermal systems and their potential impact on deep sea microbes and ecology, samples of hydrothermal fluids emanating from two compositionally and thermally different seafloor vent systems on the mid-Cayman rise (Piccard and von Damm) will be collected on a 16-day oceanographic cruise using a robotic vehicle. Samples will be analyzed for their carbon content and carbon compounds using mass spectrometric and other analytical tools. Goals of the project are to addresses issues such as: (1) the relative contribution of abiotic synthesis, thermal alteration of biomass, fluid-rock interaction, and microbial activity to the inventory of carbon compounds in ridge-crest hydrothermal fluids, (2) how host rock, style of venting, and temperature influence the generation and stability of reduced carbon compounds in axial hot-springs, (3) the fate of seawater-derived dissolved organic carbon during circulation through the oceanic lithosphere, and (4) which organic compounds and signatures are the best geochemical indicators of fluid reaction history. Three different sampling devices will be employed to ensure the full range of carbon containing compounds is captured. Collected samples will be analyzed for bulk characteristics (dissolved organic carbon concentrations and isotopes) and for the composition and isotope characteristics of individual compounds, ranging from volatile (e.g. methane and light hydrocarbons) to non-volatile (e.g. fatty acids), and from labile (e.g. amino acids) to refractory (e.g. polycyclic aromatic hydrocarbons). These data will permit the calculation of carbon and isotope mass balances at each location. From this, a comparison of the fate of carbon in both systems will be carried out to evaluate the importance of rock type, temperature, and style of venting on the carbon-bearing compounds present in seafloor hydrothermal vents. Additional measurements will be made with non-targeted, broad spectrum organic compound analyses to identify alteration trends and carbon compound evolution.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.

了解地球中碳的循环以及生物学和生物学过程如何控制所得碳含量相的组成以及它们如何随着时间的变化是一个主要的科学目标，它对我们对生态系统和全球变暖的理解具有重要意义。 海水通过深海水热系统的循环导致无机和有机碳化合物的广泛转化，并可能对深​​海碳循环产生重大影响。迄今为止，深海热液液中有机化合物的大多数报告都集中在甲烷和轻碳氢化合物上。然而，其他类型的有机化合物的分布和丰度仍然鲜为人知。结果，水热系统对深海中有机碳的贡献以及负责此输入的生物地球化学过程，仍然高度不确定。这项研究对从两个非常不同但位置紧密的水热通风孔排出的液体中的碳化合物的成分和丰度进行了全面研究，在加勒比海中期散布的超湿孔上蔓延。这两个通风口位置位于实质上不同的宿主岩石中，并发生在非常不同的水深。它们的排气液温度也非常不同。 流体将使用多种互补采样系统收集，并通过各种质谱和其他分析技术进行分析。这两个地点之间的比较允许在物理和化学条件范围内确定碳通量和化学转化。这项工作的更广泛影响包括对最先进的地球化学方法的研究生和本科生的培训，并为他们提供了在强烈的跨学科学科中获得经验和培训的机会。来自南卡罗来纳州大学的毕业生和几名本科生，是Epscor州立大学（即一个未获得大量联邦资金的州）；布里奇沃特州立大学（Bridgewater State University）为马萨诸塞州的经济弱势社区提供服务；科罗拉多大学博尔德大学将参与研究，并在科学巡航和支持实验室活动中扮演关键角色。由于加热，矿物质沉淀，岩浆的注射以及微生物的活性。这些过程对当今和地质时间的全球元素循环产生了影响。迄今为止，深海热液液中有机化合物的大多数报道都集中在小的挥发性有机分子（例如甲烷）上。但是，其他类型的有机化合物的丰度和命运仍然鲜为人知。为了更好地了解这些转变以及海底水热系统中的碳量及其对深海微生物和生态学的潜在影响，从两个构图和热不同的海底排气系统中产生的热液水液样品（Piccard和Von Damm） ）将使用机器人车进行16天的海洋学巡航。将使用质谱和其他分析工具分析样品的碳含量和碳化合物。该项目的目标是解决以下问题：（1）非生物合成，生物质的热改变，流体岩石相互作用和微生物活性对山脊 - 克雷斯特水热流体中碳化合物的库存的相对贡献，（2）宿主岩石，排气风格和温度如何影响轴向热弹簧中还原碳化合物的产生和稳定性，（3）在循环过程中，海水衍生的溶解有机碳的命运穿过海洋岩石圈，以及（4）有机有机的化合物和特征是流体反应史的最佳地球化学指标。将采用三种不同的采样设备来确保捕获包含碳的全范围。将分析收集的样品的散装特性（溶解有机碳浓度和同位素），以及各个化合物的组成和同位素特征，从挥发性（例如甲烷和光烃）到非挥发性（例如，脂肪酸），以及脂肪酸（例如脂肪酸），以及脂肪酸的含量（例如，脂肪酸） （例如氨基酸）到难治性（例如多环芳烃）。这些数据将允许在每个位置计算碳和同位素质量平衡。由此，将进行两种系统中碳的命运的比较，以评估岩石类型，温度和风格在海底水热通风口中存在的碳含碳化合物上的重要性。将通过非目标，广泛的有机化合物分析进行其他测量，以确定变化趋势和碳复合进化。该奖项反映了NSF的法定任务，并认为值得通过基金会的智力优点和更广泛的影响来通过评估来进行支持。