The Use of Nitrogen Isotopes of Amino Acids To Understand Marine Sedimentary 15N Records

营养物质的生物利用率在海洋生物生产力、碳循环和气候变化中起着至关重要的作用。 全球海洋氮（N）的存量取决于氮固定（源）和反硝化（汇）的平衡。 在这个为期三年的项目中，来自加州大学圣克鲁斯分校的研究人员将专注于开发氨基酸的化合物特异性N同位素（d15 N）分析，作为了解古储层中有机质的N源和转化的新工具。 个别氨基酸组的同位素比率的偏移可以产生关于营养转移、异养微生物改造以及自养源与异养源的信息。 通过测量和比较浮游生物丝束，沉积物陷阱和多个核心在有氧和亚氧沉积环境中的尺寸分级样品中的散装和氨基酸d15 N，研究人员将：（1）提供平均输出的光自养有机物的d15 N的代理;和（2）提供一个新的细节水平到沉积有机N降解和保存。 更广泛的影响：该项目将提高对d15 N氨基酸模式的基本基础和行为以及它们在对比沉积环境中的行为的理解，同时还将开发潜在的古海洋学代理。 资金将支持该机构的研究生和本科生研究。 研究人员还将以关于代理开发的研讨会/教程的形式开展社区外联活动。

The bioavailability of nutrients plays a crucial role in oceanic biological productivity, the carbon cycle, and climate change. The global ocean inventory of nitrogen (N) is determined by the balance of N-fixation (sources) and denitrification (sinks). In this three-year project, a researcher from the University of California, Santa Cruz, will focus on developing compound-specific N isotope (d15N) analysis of amino acids as a new tool for understanding N source and transformation of organic matter in paleo-reservoirs. The offsets in the isotopic ratios of individual amino acid groups may yield information about trophic transfer, heterotrophic microbial reworking, and autotrophic versus heterotrophic sources. By measuring and comparing the bulk and amino acid d15N in size-fractioned samples from plankton tows, sediments traps, and multi-cores in oxic and suboxic depositional environments, the researcher will: (1) Provide a proxy of the d15N of average exported photoautotrophic organic matter; and (2) Provide a new level of detail into sedimentary organic N degradation and preservation. Broader impacts:This project will improve understanding of the fundamental underpinnings and behaviors of d15N amino acid patterns and how they behave in contrasting sedimentary environments, while also developing a potential paleoceanographic proxy. Funding will support a graduate student and undergraduate research at the institution. The researcher will also conduct community outreach in the form of a workshop/tutorial on the proxy development.