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，测量马尾藻海的NH+4和NO-3同化、硝化和固氮速率。这些测量旨在评估新产量的速度，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率。过滤的粒度分级和流式细胞仪的细胞分类将用于鉴定浮游生物群落的不同组成部分对无机氮的同化。对一个季节性周期中的少营养环流中氮循环的研究，以及美国JGOFS的其他研究，将增加我们对新的和再生的生产的物理和生物控制的理解。氮气循环测量将在OnDeck与15N孵化期间采用微量金属清洁预防措施。最近，将使用改进的分析技术测量环境中低浓度的NH+4和NO-3，以监测多个时间点培养期间的营养浓度，并确保添加示踪剂水平。应注意考虑底物再生，并建立添加标签的库存。

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.