Nitrate-Ammonium Interactions And Nitrate Supply In The Regulation Of Arabian Sea Regional New Production.

麦卡锡9310629 对海洋生物生产过程的定量研究是了解海洋在地球气候系统中所起作用的基础。 深海营养物质向上流动的速度和上层海洋洋流的漂移过程的时空变化决定了海洋浮游生物的分布，并为其生产设定了限度。 追求JGOFS目标需要调查这些物理-生物联系。 它们影响着全球海洋固碳和释放碳的速度。 这些过程之间的平衡在过去是如何调节的，以及今天是如何调节的，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。 阿拉伯海的季风系统为进行这些研究提供了独特的机会。 其强烈的海气相互作用的季节性周期使得能够开发和测试与物理气候驱动过程联系的模型，该过程与生物反应以及随后通过海气交换气体的反馈有关。 除了这些过程的强度，因此，它们在阿拉伯海的强烈的季节性信号，过去的记录，记录在海洋化石组合和海洋沉积物中的同位素，是宝贵的发展和测试的时变模型处理耦合的物理和生物方面的海洋气候系统。 本研究涉及系统中的一个特殊环节：限制性营养素氮的供应率对初级营养素生产的调节。 粗糙的季节性模式在阿拉伯海生产是最激烈的，生产与夏季西南季风。 上升流向表面沃茨输送了一股营养物质，这反过来又刺激了北方阿拉伯海的浮游生物大量繁殖。 在一年的其余时间里，生产率较低，但总体上仍高于其他地方海洋沃茨的典型生产率。 在这项研究中，氮的可用性，无论是在上涌形式的硝酸盐和铵的再循环形式，将在低生产东北冬季风和两个季风间的过渡期进行区域评估。 对氮的“新”和“再生”形式的依赖之间的相互作用决定了在任何时候初级生产总量中有多少部分可供出口到深海。 所采用的技术将允许对新产量进行量化，并在一年中的整个低营养部分对其进行调节。 将采用在纳摩尔范围内敏感的营养分析来量化丰度，并使用15 N标记的底物，上层海洋中亚硝酸盐，硝酸盐和铵的供应和利用率。 这项研究将与研究氮循环和生物生产其他方面的研究人员合作进行。 这些补充项目所产生的新认识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及过程的遥感信息，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。 ***

McCarthy 9310629 Quantitative elcucidation 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 objectives 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 of the past, recorded 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 bloom in the northern Arabian Sea. During the balance of the year, production rates are lower, but remain generally higher than those typical of oceanic waters elsewhere. 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. ***