Particle-Associated and Water-Column Methane Cycling in the Upper Ocean

摘要甲烷是一种重要的温室气体，其在海洋中的产生、循环和损失的地球化学过程目前还不十分清楚。 几条证据表明，海洋密度跃层（海水密度随深度增加相对较快的垂直区域）是一个甲烷生成特别强烈的区域。 倾向于在该区域中积聚并因此为驱动甲烷生成的微生物活性提供界面的悬浮颗粒物可提供该化学活性集中的场所。 在这个项目中，来自夏威夷大学的研究人员将研究北太平洋热带东部密度跃层中颗粒相关和水柱甲烷产生的细节，包括甲烷产生和氧化由藻类分泌物驱动的可能性。 现场研究将占据沿着一个有据可查的氧化-还原梯度的站点，该梯度从墨西哥近海的上升井诱导缺氧区延伸到太平洋中央环流的氧气最低值，从而涵盖一系列氧气浓度、颗粒负荷率和溶解无机氮水平。 这项研究还将研究硝化细菌的作用和溶解无机氮浓度在甲烷氧化中的重要性。

ABSTRACTOCE-9911649The biogeochemistry of the production, cycling, and loss methane, an important greenhouse gas, in the world ocean is very imperfectly understood. Several lines of evidence suggest that the oceanic pycnocline (the vertical zone in which seawater density increases relatively rapidly with depth) is a zone of particularly intense methanogenesis. Suspended particulates, which tend to accumulate in this zone and thus offer an interface for the microbial activity driving methanogenesis, may provide the sites where this chemical activity is concentrated. In this project, investigators from the University of Hawaii will study the details of particle-associated and water-column methane production in the pycnocline of the eastern tropical North Pacific, including the possibility that methane production and oxidation is driven algal exudates. The field study will occupy stations along a well documented oxidation-reduction gradient extending from the upwelling-induced anoxic zone offshore of Mexico and extending to the oxygen minimum of the Pacific central gyre, thus covering a range of oxygen concentrations, particle loading rates, and dissolved inorganic nitrogen levels. The study will also examine the role of nitrifying bacteria and the importance of dissolved inorganic nitrogen concentration in methane oxidation.