The Microbial Carbon Pump and Bacterial Carbon Sequestration in the Ocean

长期以来，生物泵一直被认为是通过在海洋沉积物中封存碳来降低大气CO2浓度的重要汇。细菌对海洋中难溶有机碳（RDOC）库中碳的封存的贡献最近才被认识到。这一过程被概念化为微生物碳泵（MCP），似乎也在碳封存和大气CO2的调节中发挥重要作用。在这个项目中，哥伦比亚的南卡罗来纳州大学的研究人员将建立在MCP的框架上，以解决以下假设：1）细菌DOC的产生和组成随生物量的不同而不同。（如群落结构）和物理化学2）细菌将碳封存在中层沃茨持续数年至数十年的半不稳定DOC（SDOC）中，3）中、深层沃茨中的微生物群落具有产生和降解细菌DOC的代谢潜力。这些沃茨中天然存在的细菌DOC对微生物降解具有很强的抵抗力。4）异养细菌是细菌SDOC和RDOC的主要来源。这些假设将解决使用相结合的领域（西北太平洋和马尾藻海）和实验方法来调查细菌DOC的生产和分解的空间变异性，并将这些过程与社区结构和环境条件。这项研究将提供海洋中细菌SDOC和RDOC库的估计，以及对海洋碳循环和大气CO2浓度调节的重要见解。这也将为解决MCP和细菌固碳如何应对气候变化奠定基础。更广泛的影响： 该项目将加强PI实验室与日本大气和海洋研究所Hiroshi Ogawa博士实验室之间的合作。这一合作包括参加日本赞助的一次北太平洋考察活动，该活动由Hakuro maru号研究船提供。 此外，它将支持一名博士后助理和一名博士生，他们将参加西北太平洋和马尾藻海的研究考察。他们的研究将侧重于MCP，并将在第二年和第三年的全国会议上介绍他们的研究结果。

The Biological Pump has long been recognized as an important sink for atmospheric CO2 concentrations through the sequestration of carbon in ocean sediments. The contributions of bacteria to the sequestration of carbon in the ocean reservoir of refractory dissolved organic carbon (RDOC) have only recently been recognized. This process, conceptualized as the Microbial Carbon Pump (MCP), also appears to play a significant role in carbon sequestration and the regulation of atmospheric CO2. In this project, researchers at the University of South Carolina at Columbia will build upon the framework of the MCP to address the following hypotheses: 1) The production and composition of bacterial DOC vary with biological (e.g. community structure) and physicochemical (e.g. nutrients) parameters in the ocean, 2) Bacteria sequester carbon in semi-labile DOC (SDOC) that persists for years to decades in mesopelagic waters, 3) Microbial communities in mesopelagic and bathypelagic waters have the metabolic potential to produce and degrade bacterial DOC. Naturally-occurring bacterial DOC in these waters is very resistant to microbial degradation, 4) Heterotrophic bacteria are the predominant source of bacterial SDOC and RDOC. These hypotheses will be addressed using a combination of field (NW Pacific Ocean and Sargasso Sea) and experimental approaches to investigate spatial variability in the production and decomposition of bacterial DOC and to relate these processes to community structure and environmental conditions. This study will provide estimates of the reservoirs of bacterial SDOC and RDOC in the ocean and critical insights about the ocean carbon cycle and the regulation of atmospheric CO2 concentrations. It will also lay a foundation for addressing how the MCP and bacterial carbon sequestration will respond to climate change. Broader Impacts: This project will strengthen collaborations between the PI's laboratory and Dr. Hiroshi Ogawa's laboratory at the Atmosphere and Ocean Research Institute in Japan. This collaboration includes participation on a Japanese-sponsored expedition to the North Pacific Ocean aboard the R/V Hakuro maru. Additionally, it will support a postdoctoral associate and a doctoral student who will participate on research expeditions to the NW Pacific Ocean and Sargasso Sea. Their research will focus on the MCP, and they will present their findings at national conferences in years 2 and 3.