Methan oxidation in the water column and its role in the carbon budget of the coastal ocean

海洋气藏中大量温室气体甲烷的释放被认为是地球历史上变暖事件的提前。然而，海底排放的甲烷部分在海洋中被微生物消耗，减少了到达大气的部分。该项目的主要目的是量化不同渗漏环境下CH4在水柱中氧化的比例与排放、分散在水柱中和逃逸到大气中的量之间的关系。为此，提倡者将在美国加州大学圣巴巴拉分校(UCSB)学习14C/3H示踪剂技术，包括示踪剂的合成，并将该技术应用于测量水柱中甲烷的氧化速率。所获得的技术将得到水柱中CH4浓度分析、洋流测量、气泡羽流测绘和海面气体分析的理想补充。这些调查将在加利福尼亚州圣巴巴拉盆地/海峡的几个喷口地点进行，并与UCSB的SEEPS项目密切合作。该地区非常适合，因为它是世界上天然海相碳氢化合物渗漏最活跃的地区之一。不同喷口地点结果的比较将为关于碳氢化合物渗漏的海洋缓冲系统提供新的见解。这对于评估海洋天然气资源突然释放甲烷的气候响应具有重要价值。

The release of large amounts of the greenhouse gas methane from marine gas reservoirs is believed to have advanced warming episodes in Earth¿s history. However, methane emitted at the seafloor is consumed partly in the ocean by microorganisms, reducing the portion reaching the atmosphere. The main purpose of this project is to quantify the fraction of CH4 oxidized in the water column in relation to the amount discharging, dispersed in the water column and escaping into the atmosphere at different seep settings. For that purpose, the proposer will learn the 14C/3H-tracer technique including the synthesis of the tracers at the University of California, Santa Barbara (UCSB), USA, and apply this technique to measure oxidation rates of CH4 in the water column. The acquired technique will be ideally complemented by CH4 concentration analyses in the water column, ocean current measurements, mapping of bubble plumes, and gas analyses at the sea surface. These investigations will be performed at several vent sites situated in the Santa Barbara Basin/Channel of California in close cooperation with the SEEPS project at the UCSB. The area is ideally suited as it is one of the most active areas of natural marine hydrocarbon seepage in the world. The comparison of results from distinct vent sites will provide new insight to the buffer system of the ocean with regard to hydrocarbon seepage. This is of great value for the assessment of the climatological response of a sudden release of CH4 from marine gas resources.