OCE-PRF: Biomediated corrosion of methane-derived authigenic carbonates in the deep ocean and its implications for carbon fluxes from methane seeps

OCE-PRF：深海中甲烷衍生的自生碳酸盐的生物介导腐蚀及其对甲烷渗漏碳通量的影响

• 批准号: 2205998
• 负责人: Kira Homola
• 金额: $ 28.69万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-11-01 至 2024-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2205998&HistoricalAwards=false
• 关键词: OCE; PRF; Biomediated; corrosion; methane

This research fellowship investigates the amount of carbon released back into seawater by biological processes that dissolve the carbonate rock structures formed at oceanic methane seeps. Throughout the worlds’ oceans, methane rises through seafloor sediments from subduction zones and old organic material buried below the seafloor. Most of this methane is consumed by unique microbial and chemical activity before it can reach the ocean or atmosphere. Within this “methanosphere”, rocks form in the soft sediments near the seafloor when dissolved or gaseous carbon seeping up from below precipitates as solid carbonate. These rocks provide a hard surface for deep-sea organisms to inhabit and store carbon that would otherwise contribute to increased carbon dioxide in the ocean and atmosphere. Carbonate will dissolve back into seawater when the acid content of surrounding waters increases, which can be caused by the complicated biogeochemical reactions occurring on and around the carbonate rocks. Without accounting for this dissolution of carbonate, the amount of carbon that reaches the atmosphere from the subseafloor on timescales relevant to anthropogenic climate change cannot be fully quantified. This research will support two undergraduates and provide training in Geographic Information Systems; image processing software; database management; and peer-reviewed manuscript development and publication. In addition to training for undergraduate students at UCLA, the investigators are collaborating with the Alaska Native Science and Engineering Program and SoCalSeas, the Southern California network of teachers from 2-year and 4-year colleges designed to bridge education in oceanography. Results of the project will be disseminated to public and academic groups, including the Center of Diverse Leadership in Sciences at UCLA, as a variety of media content for a range of learning styles designed to inform and inspire participation in deep-sea science and related fields. For example, the seafloor maps from this project will be adapted to GIS exercises for high school, community college, and university classroom instruction.While the NSF-funded METHANOSPHERE project aims to redefine the footprint of deep ocean methane seepage for benthic ecosystems, the role of biomediated carbonate corrosion is not addressed. This study aims to directly evaluate the carbon loss over time associated with corrosion-driven dissolution of methane derived authigenic carbonate through U-series chronology to date carbonates; incubation of carbonates inoculated with living microbes to determine the carbon flux associated with different microbiological corrosion processes; scanning electron microscopy to quantify carbonate surface corrosion and identify its source; and geochemical modeling that combines these results with the relevant METHANOSPHERE project results to calculate the carbon loss over time from biomediated carbonate corrosion under canonical deep ocean conditions. The METHANOSPHERE sites will allow the comparison of methane derived authigenic carbonate corrosion under the representative conditions of higher oxygen levels with lower photosynthetic food input (Aleutian) and lower oxygen with higher productivity conditions (California). Carbon fluxes associated with carbonate corrosion at these sites will be calculated and related to the organisms responsible to estimate a flux associated with a given environment and corrosion process. The goals of this study are to produce 1.) An erosion mass balance of the Southern California Borderlands Seep, including experimental data, seafloor photomosaics, and substrate maps, 2.) An erosion mass balance of the Aleutian Margin Seep including experimental data, seafloor photomosaics and substrate maps, and 3.) A methane derived authigenic carbonate corrosion pattern identification guide (including data from both sites). The investigators are addressing these goals by surveying, sampling, and characterizing carbonates through shipboard and laboratory incubations and analyses. Insights from the study will be presented at least once annually at an international conference; and as a guest lecture in the UCLA Freshman class "Methane the other greenhouse problem”, which targets non-STEM students, and the undergraduate/graduate course "Aquatic Geomicrobiology". As methane seeps and relic carbonates are widespread along the continental margins, carbon cycling through seep carbonates is likely a substantial component of the global subseafloor methane budget and its quantification is crucial to estimate long-term burial of methane-derived carbon.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.

这项研究奖学金调查了通过溶解海洋甲烷渗漏形成的碳酸盐岩石结构的生物过程释放回海水的碳量。 在整个世界的海洋中，甲烷通过俯冲带的海底沉积物和埋藏在海底下的古老有机物质上升。大部分甲烷在到达海洋或大气层之前就被独特的微生物和化学活动消耗掉了。在这个"甲烷层"中，当溶解的或气态的碳从下面渗出沉淀成固体碳酸盐时，岩石就在海底附近的软沉积物中形成。这些岩石为深海生物提供了一个坚硬的表面，以栖息和储存碳，否则这些碳将导致海洋和大气中二氧化碳的增加。当周围沃茨中的酸含量增加时，碳酸盐会重新溶解到海水中，这是由于碳酸盐岩及其周围发生了复杂的地球化学反应。如果不考虑碳酸盐的溶解，就无法完全量化在与人为气候变化相关的时间尺度上从海底以下到达大气层的碳量。这项研究将支持两名本科生，并提供地理信息系统培训;图像处理软件;数据库管理;和同行评审的手稿开发和出版。除了为加州大学洛杉矶分校的本科生提供培训外，研究人员还与阿拉斯加土著科学与工程项目和SoCalSeas合作，SoCalSeas是南加州的教师网络，来自两年制和四年制大学，旨在弥合海洋学教育。该项目的成果将分发给公众和学术团体，包括加州大学洛杉矶分校的科学领域多样化领导中心，作为各种学习方式的各种媒体内容，旨在宣传和鼓励参与深海科学和相关领域。例如，该项目的海底地图将适用于高中、社区学院和大学课堂教学的地理信息系统练习。虽然美国国家科学基金会资助的METHONOSPHERE项目旨在重新定义深海甲烷渗漏对底栖生态系统的影响，但生物介导的碳酸盐腐蚀的作用没有得到解决。本研究的目的是直接评估随时间的碳损失与腐蚀驱动的溶解甲烷衍生自生碳酸盐通过U系列年代学来确定碳酸盐;培养的碳酸盐与活微生物接种，以确定与不同的微生物腐蚀过程中的碳通量;扫描电子显微镜，以量化碳酸盐表面腐蚀，并确定其来源;地球化学建模，将这些结果与相关的METHANOSPHERE项目结果相结合，以计算在典型的深海条件下生物介导的碳酸盐腐蚀随时间的碳损失。METHANOSPHERE站点将允许在较高氧气水平和较低光合食物输入（阿留申）以及较低氧气水平和较高生产力条件（加州）的代表性条件下对甲烷衍生自生碳酸盐腐蚀进行比较。将计算这些地点与碳酸盐腐蚀相关的碳通量，并与负责估计与给定环境和腐蚀过程相关的通量的生物体相关。本研究的目标是生产1。南加州边界渗漏的侵蚀质量平衡，包括实验数据、海底照片镶嵌图和基底图。阿留申边缘渗漏的侵蚀质量平衡，包括实验数据，海底照片镶嵌图和基底图，以及3。甲烷衍生自生碳酸盐腐蚀模式识别指南（包括两个站点的数据）。研究人员正在通过船上和实验室培养和分析来测量、取样和表征碳酸盐，以实现这些目标。该研究的见解将每年至少在国际会议上发表一次;并作为加州大学洛杉矶分校新生班的客座讲座“甲烷另一个温室问题”，针对非STEM学生，以及本科/研究生课程“水生地质微生物学”。由于甲烷渗漏和残余碳酸盐沿着大陆边缘广泛分布，通过渗漏碳酸盐的碳循环可能是全球海底甲烷预算的重要组成部分，其量化对于估计甲烷衍生碳的长期埋藏至关重要。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。