Acquisition of spectroscopic and mass spectrometric instrumentation for the evaluation of N cycling and provenance

1456430奥斯特罗姆对各种物种中氮同位素组成的研究有助于了解地球化学过程的动力学，最近的结果表明，在北太平洋，表示“长”之义长期氮同位素年代学表明，生态系统状态发生了显著变化，这引发了一个问题，即该信号是否表明人类过度捕捞导致了海洋营养结构的整体变化，食物网和/或与气候相关的环境变化有关的固氮作用的增加。 该补助金支持购买气体源稳定同位素比质谱仪（SIRMS），激光光腔衰荡质谱仪（LCOS），用于构建压缩机系统的材料，用于填充具有一系列N2 O浓度和同位素组成的空气罐，以及能够改进氨基酸Δ 15 N值的气相色谱氮（GC-N）化合物特定同位素分析系统。 该设备将促进研究人员重点研究海洋和水生系统中的全球氮循环，有针对性地研究一氧化二氮（N2 O）中氮的稳定同位素组成，一种温室气体和从水生和海洋生物组织中回收的氨基酸。 所要求的设备将取代密歇根州老化的SIRMS，LCOS将允许对基于激光的同位素分析与传统SIRMS分析的价值和精度进行比较研究，PI将为更广泛的社区准备并提供一套LCOS测量所需的N同位素标准。

1456430OstromStudies of the isotopic composition of Nitrogen in various species yield insights on the dynamics of biogeochemical processes and recent results suggest that within the North Pacific Ocean, long-term nitrogen isotope chronologies are indicating a marked ecosystem state change raising questions as to whether the signal indicates a trophic decline resultant from overfishing by humans that has shifted the entire trophic structure of the oceanic food web and/or an increase in nitrogen fixation linked to climate-coupled changes in the environment. This grant supports acquisition of a gas source stable isotope ratio mass spectrometer (SIRMS), a laser optical cavity ring down mass spectrometer (LCOS), materials to construct a compressor system for filling air tanks with a range of N2O concentrations and isotopic compositions, and a gas chromatography nitrogen (GC-N) compound specific isotope analysis system capable of improved amino acid ä15N values. The equipment will foster investigator research focused on global nitrogen cycling in the oceans and aquatic systems with targeted studies of the stable isotopic composition of Nitrogen in Nitrous Oxide (N2O), a greenhouse gas and within amino acids recovered from aquatic and marine organism tissues. The requested equipment will replace an aging SIRMS at Michigan State, the LCOS will allow comparative studies of the value and precision of laser-based isotopic analysis versus traditional SIRMS analysis and the PI will prepare and make available to the broader community a suite of N isotopic standards needed for LCOS measurements.