The Role of Protozoa in the Carbon Cycle of a Subterranean Estuary

原生动物在地下河口碳循环中的作用

• 批准号: 0525166
• 负责人: Elizabeth Kujawinski
• 金额: $ 38.35万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-10-01 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0525166&HistoricalAwards=false
• 关键词: Role; Protozoa; Carbon; Cycle; Subterranean; Role; Protozoa; Carbon; Cycle; Subterranean

EAR-0525166Elizabeth B. Kujawinski - Woods Hole Oceanographic InstitutionThe carbon cycle in aquifer systems, and particularly the role of prokaryotic and eukaryotic microbes, is poorly understood. A large body of work in marine and freshwater systems has indicated that eukaryotes such as protozoa play fundamental roles in the carbon and nutrient cycles in all aquatic environments - ranging from nutrient-rich coastal systems to nutrient-poor mid-ocean gyres. Nevertheless, the role of protozoa in aquifer systems has been examined by a relatively small number of studies. Given the pivotal role these organisms play in other aquatic environments, it is reasonable to assume that they play fundamental roles in the carbon and nutrient cycles of the subsurface. It is time to investigate which protozoan species are present, which bacteria they graze upon and the impact of protozoan grazing on the carbon and nutrient cycles in groundwater. The goal of this work is to utilize stable isotopes in combination with geochemical and microbial methods to study the effect of protozoa on nutrient regeneration rates and carbon remineralization in a subterranean estuary on Cape Cod MA. This work will use 13C-labeled substrates such as acetate to track the active bacterial and protozoan community. Sediment will be collected from the freshwater and saline end-members of the subterranean estuary and will be used to establish flow-through columns. These columns will be incubated with groundwater pumped from the appropriate site in the estuary to maintain the in situ salinity and ion composition. Groundwater will be amended with 13C-substrates. The movement of the isotopic label from substrate to organic matter will be monitored by isotope-ratio mass spectrometry of inorganic carbon (aqueous CO2 species), bulk organic carbon (TOC / DOC) and small organic molecules (volatile organic acids and amino acids). Incorporation of the label into microbial biomass will be assessed by examination of isotopically-labeled nucleic acids and phospholipid fatty acids (PLFAs). Active bacterial and protozoan species will be identified by their isotopically-labeled rDNA or rRNA sequence. The relative roles of protozoa and bacteria will be assessed by parallel column incubations with 1.0-um filtered and non-filtered groundwater. The proposed work is the first study, to our knowledge, that directly links protozoan community composition to nutrient regeneration and carbon remineralization in fresh and saline aquifers. This group of microbes is vastly under-studied and the results of this study have the potential to elucidate recycling processes outside the current paradigm of microbial activity in aquifer sediments. Furthermore, the methods developed here can be generally applied to ecological and biogeochemical studies in numerous environments, ranging from freshwater systems to marine sediments.

EAR -0525166 elizabeth B. Kujawinski-伍兹孔海洋学机构含水层系统中的碳循环，尤其是原核生物和真核微生物的作用，知之甚少。 在海洋和淡水系统中的大量作品表明，在所有水生环境中，原生动物（例如原生动物）在碳和营养周期中扮演着基本角色 - 从富含营养的沿海系统到营养贫困的中等偏见。 然而，原生动物在含水层系统中的作用已经通过相对较少的研究来研究。 鉴于这些生物在其他水生环境中起关键作用，可以合理地假设它们在地下的碳和营​​养周期中起着基本作用。 现在该研究存在哪种原生动物，它们在哪种细菌上以及原生动物放牧对地下水中碳和营养周期的影响。 这项工作的目的是将稳定的同位素与地球化学和微生物方法结合使用，以研究原生动物对Cape Cod MA上的地下河口中养分再生速率和碳的回忆性的影响。 这项工作将使用13C标记的底物（例如乙酸盐）来跟踪活跃的细菌和原生动物社区。 沉积物将从地下河口的淡水和盐水末端成员中收集，并将用于建立流通柱。 这些柱将与河口适当部位泵送的地下水一起孵育，以保持原位盐度和离子成分。 地下水将通过13c subtrates进行修订。 同位素标签从底物到有机物的运动将通过无机碳（水溶性二氧化碳物种），散装有机碳（TOC / DOC）和小有机分子（伏伏尔利有机酸和氨基酸）的同位素比率质谱法监测。 将标签掺入微生物生物量中，将通过检查同位素标记的核酸和磷脂脂肪酸（PLFAS）来评估。 活性细菌和原生动物将通过其同位标记的rDNA或rRNA序列鉴定。 原生动物和细菌的相对作用将通过与1.0-UM过滤和未过滤的地下水平行柱孵育来评估。据我们所知，拟议的工作是将原生动物社区组成与新鲜和盐水含水层中的养分再生和碳回忆性联系在一起的第一项研究。 这组微生物的研究很大，这项研究的结果有可能阐明含水层沉积物中微生物活性范式之外的回收过程。 此外，这里开发的方法通常可以应用于许多环境中的生态和生物地球化学研究，从淡水系统到海洋沉积物。