Nitrate - Ammonium Interactions and Nitrate Supply in the Regulation of Arabian Sea Regional New Production

9312383加赛德定量地阐明了调节海洋生物生产的过程，这对于理解海洋在地球气候系统中的作用是至关重要的。控制深海营养物质通量上升率和上层洋流漂移的过程的时间和空间变异性决定了海洋浮游生物的分布，并为其生产设定了限制。为实现JGOFS目标，需要对这些物理-生物联系进行调查。它们会影响全球海洋碳封存和释放的速度。过去如何监管这些过程之间的平衡，以及今天如何监管，是美国国家和国际努力理解和预测对全球变化的反应的重要研究组成部分。阿拉伯海季风系统为开展这些研究提供了独特的机会。它在海-气相互作用中的强烈季节循环使得能够开发和测试与气候驱动的物理过程有关的模式、与生物反应的联系以及随后通过气-海气体交换的反馈。除了这些过程的强度及其在阿拉伯海的强烈季节性信号外，海洋化石组合和海洋沉积物中同位素的记录对于开发和测试处理海洋气候系统物理和生物耦合方面的时变模型很有价值。这项研究涉及该系统中的一个特殊环节：通过限制营养物质氮的供应速率来调节初级浮游植物的生产。阿拉伯海的粗季节生产模式是最强烈的，生产与夏季西南季风有关。上升流将营养物质脉冲输送到表层水域，进而刺激浮游生物总体上保持高于其他海洋水域的典型水平。在这项研究中，将在低产量的东北冬季风和两个季风间过渡期对氮的有效性进行区域评估，包括上升态的硝酸盐和再循环形式的铵。对“新的”和“再生的”氮的依赖之间的相互作用决定了在任何时候都可以出口到深海的初级总产量的多少。所应用的技术将允许量化新的产量，并在一年中的低营养部分进行调控。将使用在纳摩尔范围内敏感的营养分析来量化丰度，并在15N标记底物的情况下，计算上层海洋中亚硝酸盐、硝酸盐和铵的供应和利用速度。这项研究将与研究氮循环和生物生产的其他方面的研究人员合作进行。这些补充项目产生的新理解将有助于制定和测试区域模型，这些模型利用关于生物和物理特征和过程的遥感信息，更好地预测阿拉伯海的生产过程将如何应对未来的气候变化。

9312383 Garside Quantitative elucidation of the processes that regulate biological production in the sea is fundamental to an understanding of the role the oceans play in the earth's climate system. Temporal and spatial variability in the processes that govern the upward rate of nutrient flux from the deep-sea, and the drift of currents in the upper ocean, determine the distribution of marine plankton and set limits for their production. Pursuit of JGOFS objective requires investigation into these physical-biological linkages. They influence the global rates of carbon sequestration and release by the sea. How balance between these processes was regulated in the past, and how it is regulated today is an important research component of US national and international endeavors to understand and predict responses to global change. The monsoonal system of the Arabian Sea affords unique opportunity for the pursuit of these studies. Its intense seasonal cycle in air-sea interaction allows for the development and testing of models relating to the physical climate-driven process linkages to biological responses and consequent feedback via air-sea exchange of gases. In addition to the intensity of these processes, and hence their strong seasonal signal in the Arabian Sea, the record in marine fossil assemblages and isotopes in ocean sediments, is valuable in the development and testing of time varying models treating coupled physical and biological aspects of the ocean climate system. This study relates to one particular link in the system: the regulation of primary planktonic production by the supply rate of the limiting nutrient, nitrogen. The coarse seasonal pattern in Arabian Sea production is one of the most intense, production being associated with the summer SW monsoon. Upwelling delivers a pulse of nutrients to surface waters, which in turn stimulates a plankton remain generally higher than those typical of oceanic waters elsewher e. In this study the availability of nitrogen, both in the upwelled form of nitrate and in the recycled form of ammonium, will be assessed regionally during the low production NE winter monsoon and the two inter-monsoon transition periods. The interplay between dependence on the "new" and "regenerated" forms of nitrogen determine what fraction of total primary production is at any time available for export to the deep-sea. The techniques applied will permit the quantification of new production and its regulation throughout the low nutrient portion of the year. Nutrient analyses sensitive in the nanomolar range will be employed for quantifying the abundance, and with 15N labeled substrates, the rates of supply and utilization of nitrite, nitrate and ammonium in the upper ocean. This study will be conducted in collaboration with investigators who are addressing other aspects of the nitrogen cycle and biological production. New understanding resulting from these complementary projects will contribute to the formulation and testing of regional models that use remotely sensed information on biological and physical features and processes to better predict how production processes in the Arabian Sea will respond to future climate change.