The Fluxes of Dissolved Inorganic Nitrogen and Dissolved Organic Matter during the Spring Bloom in the Temperate North Atlantic: Magnitudes and Control Mechanisms

北大西洋东部浮游生物春季繁殖期，浮游植物和浮游细菌对溶解无机氮（DIN）和溶解有机质（DOM） （N和C）的转化进行了合作研究。对DIN和DOM通量的观察研究刺激了网络模型，这些模型将DIN和DOM流一起考虑为功能定义的生物群体的输入和输出。浮游植物对DIN的固定和浮游细菌对DOM和NH4的固定往往主导着绿化带的氮流。根据浮游生物动力学的概念，该研究将跟踪氮的转化，从春季向上层海洋输送硝酸盐氮（NO3）开始，浮游植物对其进行固定，细菌和其他小型浮游生物对其进行再生和循环。目标包括：a)精确量化光区NO3的供应、存量和利用；B)通过新的高精度技术确定初级生产对新养分和再生养分的依赖；c)评估细菌生产的总体意义，即细菌作为浮游植物对NH4的竞争对手；d)确定微生物NH4再生对初级生产氮有效性的影响；最后e)在数天至数周的时间尺度上评估浮游植物与细菌生产以及PON和POC输出之间的关系。

A collaborative study of the transformations of dissolved inorganic nitrogen (DIN) and dissolved organic matter (DOM) (both N and C) by phytoplankton and bacterioplankton will be conducted during the spring plankton bloom period in the Eastern North Atlantic Ocean. Observational studies of DIN and DOM fluxes have stimulated network models which consider together DIN and DOM flows as inputs and outputs of functionally-define groups of organisms. Fixation of DIN by phytoplankton and of DOM and NH4 by bacterioplankton often dominate the flow of nitrogen in the euphotic zone. Informed by this conceptualization of plankton dynamics, the study will follow the transformations of nitrogen, beginning with the transport of nitrate-nitrogen (NO3) to the upper ocean during the spring, its fixation by phytoplankton, and its regeneration and cycling by bacteria and other microplankton. The objectives include: a) precisely quantifying the euphotic zone supply, stock and utilization of NO3; b) determining via new high precision techniques, the reliance of primary production on new and regenerated nutrients; c) assessing the significance of bacterial production in general, of bacteria as competitors with phytoplankton for NH4; d) determining the impact of microbial regeneration of NH4 on the availability of nitrogen for primary production; and finally e) evaluating the relationship between phytoplankton and bacterial production and the export of PON and POC over time scales of days to weeks.