Quantifying the Relationship between Nitrogen Uptake and Net Community Production using a Synthesis of JGOFS Data and 1-D Modeling

使用 JGOFS 数据和一维建模的综合来量化氮吸收和净群落生产之间的关系

• 批准号: 9905136
• 负责人: Mary Lynn Dickson
• 金额: $ 14.23万
• 依托单位: University of Rhode Island
• 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: 1999-03-01 至 2002-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9905136&HistoricalAwards=false
• 关键词: Quantifying; Relationship; between; Nitrogen; Uptake

Dickson The measurement of Net Community Production (NCP) is a robust estimate of the amount of organic material produced in surface waters of the ocean. NCP can serve as a starting point for models of carbon export from surface waters and the ocean's capacity to absorb carbon dioxide from the atmosphere. However, most models of ocean production are based on a limiting nutrient such as phosphorus or nitrogen and the reliability of this class of models therefore will depend on how accurately the consumption of limiting nutrients can be converted to the absorption of carbon dioxide by the ocean. The PIs will calibrate the relationship between NCP and new (nitrate) production in order to assist in the goal of predicting the role of the ocean as a carbon sink. The question of how to best convert between surface ocean elemental cycles will be examined with the a null hypothesis being that the stoichiometric oxidative ratios found in ocean thermocline waters (the Redfield ratios) are a quantitative way to translate between nitrogen and NCP. A comparative approach will be used to examine the extent of coupling between the surface nitrogen and carbon cycles. In instances where carbon and nitrogen appear to be uncoupled in the Redfield sense, possible methodological causes will be carefully evaluated. Following this analysis, the role of early bloom vs. nutrient limited conditions; dominant taxa; dissolved organic matter (DOM) levels; N2 fixation; iron limitation and other factors will be considered as agents modifying the relationship between nitrogen and carbon fluxes. The degree of coupling in representative ocean regions will be evaluated in a one-dimensional numerical model with realistic upper layer physics. These results will allow biogeochemical modelers to judge when the use of Redfield ratios for conversion is appropriate and identify what (if any) circumstances merit an alternate conversion approach. This will contribute to more accurate predictions of carbon flux that are sensitive to the relevant biological processes.

净群落生产量（NCP）的测量是对海洋表面沃茨中产生的有机物质数量的可靠估计。 NCP可以作为地表沃茨碳输出模型和海洋从大气中吸收二氧化碳能力模型的起点。 然而，大多数海洋生产模型都是以磷或氮等限制性营养素为基础的，因此，这类模型的可靠性将取决于如何准确地将限制性营养素的消耗转化为海洋对二氧化碳的吸收。 PI将校准NCP和新（硝酸盐）产量之间的关系，以协助实现预测海洋作为碳汇的作用的目标。 如何最好地转换之间的表面海洋元素循环的问题将检查与零假设是在海洋温跃层沃茨（Redfield比率）的化学计量氧化比是一个定量的方式来转换之间的氮和NCP。 一个比较的方法将被用来检查表面氮和碳循环之间的耦合程度。 在Redfield意义上的碳和氮似乎是解偶联的情况下，将仔细评估可能的方法学原因。 在此分析之后，早期开花与营养限制条件的作用;优势类群;溶解有机质（DOM）水平; N2固定;铁限制和其他因素将被认为是修改氮和碳通量之间关系的代理商。 将在一个具有实际上层物理学的一维数值模型中评估代表性海洋区域的耦合程度。 这些结果将使地球化学建模者能够判断何时使用Redfield比率进行转换是适当的，并确定哪些情况（如果有的话）值得采用替代转换方法。 这将有助于更准确地预测对相关生物过程敏感的碳通量。