Methane Venting from Forearc Faults in the Puget Sound Estuary

普吉特湾河口弧前断层的甲烷排放

• 批准号: 2221821
• 负责人: Harlan Johnson
• 金额: $ 50.86万
• 依托单位: University of Washington
• 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: 2022-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2221821&HistoricalAwards=false
• 关键词: Methane; Venting; Forearc; Faults; Puget

Methane Venting from the Puget Sound EstuaryShallow coastal waters found on the margins of continents are areas of active methane emissions to the air. These areas supply a major part of the greenhouse effect responsible for modern climate warming. Recent studies have shown that methane from shallow coastal waters supply half of all methane emissions to the air that in turn produce global warming. Puget Sound is the largest of these inland seas in North America and is a large source of methane to the air. Gas from newly-discovered bubble plumes from the seafloor increases the amount of methane in the Puget Sound seawater. This gas from the seafloor escapes to the air from the sea surface where it becomes a greenhouse gas. Showing the location of the sub-surface deposits of methane in the newly discovered vents is the primary goal of this research project. The amount of methane gas coming from the seafloor will be measured using a robotic instrument called a Remotely Operated Vehicle (ROV). This robotic device will place measuring instruments directly in the path of the methane bubble stream to show the flow speed and capture fluid from the vents. Five students from under-represented communities of color in the university’s Engineering Department will be invited as members of the science party on the ship. This experience will substantially broaden their education experience in marine sciences.To find the source of methane gas recently discovered venting into Puget Sound seawater, this project will carefully measure changes in the rate of methane gas flowing from the seafloor. The changes in gas and fluid coming from seafloor vents over a six month period will be compared to environmental events that could be causing the flow changes. Examples of events that could cause vent flow changes include unusual water tides, temperature changes due to seasons, passing waves from earthquakes, and unusually large rainfall events in the nearby land. The two research cruises in the program will occur in late Fall 2022 and in Spring of 2023 to see changes in vent flow as the temperature and rainfall vary with the seasons. The shipboard part of the research will use a camera system towed near the seafloor to map the details of the vent field. A small Remotely Operated Vehicle (ROV) will also capture gas and fluid that is flowing from the seafloor vents using specially constructed sample bottles. The ROV will then place instruments on the seafloor to see variations in the gas flow rate for a six-month period. These captured fluid samples will show whether the methane is coming from deep within the earth or if it is coming as runoff of rain from the nearby land. Data from the research program will be freely available to the public through publication on university websites and placed in the federal archives. University of Washington undergraduates from the Engineering Department’s program for under-represented students of color will take part in both ocean field programs on the ship and during the processing of the data in the laboratory. This firsthand experience at sea and in the laboratory will increase the student’s awareness of marine sciences.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.

普吉特湾河口的甲烷排放在大陆边缘的浅海岸沃茨是甲烷排放活跃的地区。这些地区提供了造成现代气候变暖的温室效应的主要部分。最近的研究表明，来自沿海浅沃茨的甲烷提供了一半的甲烷排放到空气中，反过来又导致全球变暖。普吉湾是北美最大的内陆海，也是空气中甲烷的主要来源。新发现的海底气泡羽流中的气体增加了普吉湾海水中的甲烷含量。这种气体从海底逃逸到空气中，从海面变成温室气体。该研究项目的主要目标是显示新发现的喷口中甲烷地下沉积物的位置。来自海底的甲烷气体量将使用一种称为遥控潜水器（Remote Operated Vehicle，简称ROV）的机器人仪器进行测量。这个机器人设备将直接在甲烷气泡流的路径上放置测量仪器，以显示流速并从喷口捕获流体。 来自该大学工程系少数族裔社区的五名学生将被邀请作为船上科学小组的成员。 这一经验将大大拓宽他们在海洋科学方面的教育经验，为了找到最近发现的甲烷气体排入普吉湾海水的来源，该项目将仔细测量甲烷气体从海底流出的速度变化。来自海底喷口的气体和流体在六个月内的变化将与可能导致流动变化的环境事件进行比较。可能导致喷口流量变化的事件包括不寻常的潮汐、季节引起的温度变化、地震引起的波浪以及附近陆地上异常大的降雨事件。该计划中的两次研究航行将于2022年秋季末和2023年春季进行，以观察温度和降雨量随季节变化而发生的喷口流量变化。研究的船上部分将使用拖在海底附近的摄像系统来绘制喷口场的细节。一个小型遥控潜水器也将使用专门建造的样品瓶捕获从海底喷口流出的气体和流体。然后，探测器将在海底放置仪器，观察六个月内气体流速的变化。这些捕获的液体样本将显示甲烷是来自地球深处还是来自附近土地的雨水径流。该研究项目的数据将通过在大学网站上发表并存放在联邦档案馆中向公众免费提供。华盛顿大学工程系的有色人种学生项目的本科生将参加船上的海洋实地项目和实验室的数据处理。 这种在海上和实验室的第一手经验将提高学生对海洋科学的认识。这个奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。