A Seasonal Study of Nitrogen Cycling in the Saragasso Sea

该项目将结合正在进行的百慕大大西洋时间序列（BATS）研究，在一个季节周期内测量马尾藻海中NH+4和NO-3的同化、硝化和固氮速率。这些测量的目的是评估新产品的速度，包括浮游生物对硝酸盐的吸收和固氮，并评估无机基质的再生速度。通过过滤的粒度分选和流式细胞术的细胞分选将用于确定浮游生物群落不同组成部分对无机氮的同化。对季节性少营养环流中氮循环的研究，以及美国JGOFS的其他研究，将增加我们对新生产和再生生产的物理和生物控制的理解。氮循环测量将在甲板上15N孵育期间采用痕量金属清洁预防措施。最近改进的用于测量低环境浓度NH+4和NO-3的分析技术将用于监测多时间点孵育期间的营养浓度，并确保添加示踪剂水平。应注意考虑基板再生，并建立添加标签的清单。

This project will measure the rates of NH+4 and NO-3 assimilation, nitrification and nitrogen fixation in the Sargasso Sea over a seasonal cycle in conjunction with the ongoing Bermuda Atlantic time series (BATS) study. These measurements are designed to assess the rate of new production, including both nitrate uptake by the plankton and nitrogen fixation, and to assess the regeneration rates of the inorganic substrates. Size fractionation by filtration and cell sorting by flow cytometry will be used to identify the assimilation of inorganic nitrogen by different components of the plankton community. Studies of the nitrogen cycle in an oligotrophic gyre over a seasonal cycle, together with other U.S. JGOFS research, will increase our understanding of the physical and biological controls on new and regenerated production. The nitrogen cycling measurements will employ trace metal clean precautions during ondeck incubations with 15N. Recently improved analytical techniques for measuring low ambient concentrations of NH+4 and NO-3 will be used to monitor nutrient concentrations during the multiple time point incubations and to ensure tracer level additions are made. Care will be taken to account for substrate regeneration and to construct an inventory of the added label.