Collaborative Research: Dissolved Organic Phosphorus: Quantifying Taxon-specific Rates of Hydrolysis and Uptake

合作研究：溶解有机磷：量化特定分类群的水解和吸收率

• 批准号: 0452904
• 负责人: Robert Chant
• 金额: --
• 依托单位: Rutgers University New Brunswick
• 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: 2005-05-15 至 2011-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0452904&HistoricalAwards=false
• 关键词: Collaborative; Research; Dissolved; Organic; Phosphorus

Photosynthetic uptake of CO2 by oceanic phytoplankton and the export of the resulting organic carbon to the deep sea comprise a "biological pump" capable of extracting globally significant amounts of CO2 from the atmosphere. Mounting evidence suggests that primary production in two of the larger subtropical ocean gyres, the Western Tropical/Subtropical Atlantic (Sargasso Sea) and the North Pacific Subtropical Gyre, may be controlled by phosphorus availability. There are vanishingly low inorganic phosphorus (SRP) concentrations, sub-nanomolar in some locales, and ratios of inorganic N:P greatly exceed the canonical Redfield Ratio in these environments. In these low SRP regions dissolved organic phosphorus (DOP) may help meet biological phosphorus demand: data collected in the Sargasso Sea shows a 30% decline in DOP inventories during summer stratification. The hydrolysis and assimilation of DOP by primary producers is likely dependent on phytoplankton physiology, and highly variable between taxa, and through space and time. The investigators hypothesize that despite rapid turnover times, chronically low and seasonally invariant SRP concentrations at BATS cannot support measured rates of primary production without utilization of additional P from the DOP pool. Furthermore, inherent physiological differences among microbial taxa represent a significant source of temporal and spatial variability in DOP utilization rates that is yet neither understood nor constrained. The PIs propose to use proven taxon-specific methodologies to: quantify temporal and spatial variability in DOP hydrolysis in the Sargasso Sea; quantify temporal and spatial variability in taxon-specific SRP and DOP uptake rates; quantify whole-community total P uptake rates as well as SRP and model compound DOP uptake and regeneration rates; identify factors regulating rates of DOP hydrolysis and assimilation; and evaluate the role of DOP in supporting primary production in the Sargasso Sea. An understanding of ocean ecosystem function is important on a broad scale. Photosynthetic uptake of CO2 by oceanic phytoplankton and the export of the resulting organic carbon to the deep ocean are a "biological pump" that removes globally significant amounts of CO2 from the atmosphere. This project will help to constrain predictions of the strength of the oceanic biological pump in the Sargasso Sea. If dissolved organic phosphorus supports a significant fraction of primary production in the Sargasso Sea, then diversity in biological metabolic processes in the central oceans plays a greater role in the global carbon cycle than is presently recognized. The investigators will sponsor a minimum of three undergraduate researchers each year, as well as two graduate students. Data generated from the project will be used in problem-based learning modules for courses taught by the investigators, and the curriculum will be submitted to an appropriate digital repository such as www.dlese.org.

海洋浮游植物对二氧化碳的光合作用吸收以及由此产生的有机碳向深海的输出构成了一个“生物泵”，能够从全球大气中提取大量的二氧化碳。 越来越多的证据表明，两个较大的副热带海洋环流——西热带/亚热带大西洋（马尾藻海）和北太平洋副热带环流——的初级生产可能受到磷可用性的控制。无机磷 (SRP) 浓度极低，在某些地区为亚纳摩尔浓度，并且这些环境中无机 N:P 的比率大大超过了标准的雷德菲尔德比率。在这些低 SRP 地区，溶解有机磷 (DOP) 可能有助于满足生物磷需求：马尾藻海收集的数据显示，夏季分层期间 DOP 库存下降了 30%。 初级生产者对 DOP 的水解和同化可能取决于浮游植物的生理学，并且在类群之间以及空间和时间上存在很大差异。 研究人员假设，尽管周转时间很快，但 BATS 的 SRP 浓度长期较低且季节性不变，无法支持在不利用 DOP 库中额外磷的情况下测得的初级生产力。此外，微生物类群之间固有的生理差异代表了 DOP 利用率的时间和空间变异性的重要来源，这一点尚未被理解或受到限制。 PI 建议使用经过验证的特定分类方法来： 量化马尾藻海 DOP 水解的时间和空间变化；量化分类单元特异性 SRP 和 DOP 摄取率的时间和空间变异性；量化整个群落总磷吸收率以及 SRP 和模型化合物 DOP 吸收率和再生率；确定调节 DOP 水解和同化速率的因素；并评估 DOP 在支持马尾藻海初级生产中的作用。 对海洋生态系统功能的广泛了解非常重要。海洋浮游植物对二氧化碳的光合作用吸收以及由此产生的有机碳向深海的输出是一个“生物泵”，可以从全球大气中去除大量二氧化碳。 该项目将有助于限制对马尾藻海海洋生物泵强度的预测。如果溶解的有机磷支持了马尾藻海初级生产的很大一部分，那么中部海洋生物代谢过程的多样性在全球碳循环中发挥的作用比目前认识到的更大。 研究人员每年将资助至少三名本科生研究人员以及两名研究生。 该项目生成的数据将用于研究人员教授的课程的基于问题的学习模块，并且课程将提交到适当的数字存储库，例如 www.dlese.org。