Coupled Intensification of Nitrogen and Phosphorus Cycles in the Subtropical North Pacific Ocean

北太平洋副热带氮磷循环的耦合强化

• 批准号: 9906820
• 负责人: David Karl
• 金额: $ 21.18万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-09-01 至 2003-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9906820&HistoricalAwards=false
• 关键词: Coupled; Intensification; Nitrogen; Phosphorus; Cycles

This project seeks fundamental information on the interactions between nitrogen (N) and phosphorus (P) in the oligotrophic North Pacific Ocean, and their relationships to rates and mechanisms of ecosystem production and export. The research is guided by the following general hypothesis: "Climate-related shifts in the structure of the epipelagic habitat have selected for N2-fixing bacteria, resulting in a coupled intensification of N and P cycling rates which has forced the system from N- to P-limitation with numerous ecological and biogeochemical consequences. This hypothesized shift from N- to P-limitation has affected community structure, rates of gross primary production and export, and the elemental (C, N, P) stoichiometry of dissolved and particulate matter pools. The investigators will conduct a series of field and laboratory experiments designed to evaluate several ecological predictions of this coupled intensification model of nutrient dynamics in the North Pacific Subtropical Gyre with a primary focus on P pool dynamics. The field research will be conducted at Sta. ALOHA (22 degrees 45'N, 158 degrees W) and will complement the ongoing Hawaii Ocean Time-series (HOT) core measurement program. These efforts will focus on: (1) dissolved inorganic P uptake and remineralization rates, (2) dissolved organic P pool production rates, chemical characterizations and bioavailability and (3) physiological and biochemical assessments of Trichodesmium and Prochlorococcus. Knowledge derived from this project will be used to refine our understanding of the oligotrophic North Pacific ecosystem and to predict the response of oceanic habitats to environmental variability and global climate change.

本项目旨在了解北太平洋贫营养区氮(N)和磷(P)之间相互作用的基本信息，以及它们与生态系统生产和出口速率和机制的关系。该研究以以下一般假设为指导：“与气候相关的上层海洋栖息地结构变化选择了固氮细菌，导致N和P循环速率的耦合增强，迫使系统从N-限制到P-限制，具有许多生态和生物地球化学后果。”这种从氮限制到磷限制的假设转变影响了群落结构、总初级生产和出口速率以及溶解和颗粒物质池的元素（C， N， P）化学计量。研究人员将进行一系列实地和实验室实验，旨在评估北太平洋副热带环流营养动力学耦合强化模型的几个生态预测，主要关注磷池动力学。实地研究将在上海进行。ALOHA（北纬22度45分，西经158度），并将补充正在进行的夏威夷海洋时间序列（HOT）核心测量计划。这些工作将集中在：(1)溶解无机磷的吸收和再矿化速率；(2)溶解有机磷池的产生速率、化学特征和生物利用度；(3)木霉和原绿球藻的生理生化评估。从该项目中获得的知识将用于完善我们对北太平洋生态系统的理解，并预测海洋栖息地对环境变异性和全球气候变化的响应。