CAREER: Organic Matter Cycling in the Upper Ocean: Insights from time-series measurements of d15N and D14C in the California Current System

职业：上层海洋的有机物质循环：加州洋流系统中 d15N 和 D14C 时间序列测量的见解

• 批准号: 0548275
• 负责人: Lihini Aluwihare
• 金额: $ 84.67万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-03-01 至 2012-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0548275&HistoricalAwards=false
• 关键词: CAREER; Organic; Matter; Cycling; Upper

The marine dissolved organic matter (DOM) reservoir is often conceptualized as a "capacitor" for carbon because of its potential for storage and exchange with the other active reservoirs. Yet, despite its size and potential importance, the dynamics of DOM have not been fully assessed, and therefore the ultimate role of this reservoir for the global and marine carbon and nitrogen cycle remains to be established. To resolve the dynamics of the complex DOM reservoir, a young investigator from the University of California San Diego will develop a spatially resolved time-series of fraction-specific d15N and D14C measurements of DOM. This time series will be placed within the California Current System which experiences physical/climate variability on a variety of timescales (e.g. seasonal, interannual, decadal). The climate-associated disturbances (deepening/shoaling thermocline or nutricline, changes in wind field) are expected to lead to measurable excursions in the isotopic composition of surface inorganic dissolved CO2 and NO3-pools. These excursions are ultimately recorded by organic matter fractions that are recently produced in surface waters; and when placed within the context of a time series, fraction-specific isotopic variability will, for the first time, directly identify DOM cycling on annual to multidecadal timescales. In addition, the time series will also help identify relative proportions of refractory and young DOM components in surface waters and delineate some of the physical and biological processes that control the size and age of the DOM reservoir. As part of this CAREER award, a new, inquiry based, undergraduate course will be created to place the theoretical coupling between large scale phenomena such as climate-ocean-atmosphere and smaller scale phenomena such as ocean physics-chemistry-biology within a tangible, region-specific, real-world framework. A fundamental goal of this course will be for students to learn experientially how science "works"; students will design class projects that use archived time-series data to explore the above connections and collect oceanographic data on a 4-7 day educational cruise to the California Current System. Among the broader impacts, this study will be one of the most comprehensive, long-term investigations of the interrelation between climate and biogeochemistry. The infrastructure of the larger, ongoing scientific programs in the region will provide context, and enhance the dissemination of scientific data collected as part of this proposal to a broad audience through both web-based tools and written and verbal communication. Through the four specific goals of the Education and Outreach plan, the PI will teach and mentor ~100 undergraduates, mentor ~8 high school students, empower both student groups to be more critical, better environmental decision-makers, provide ~8 educators with valuable scientific experience to take back to their own classrooms and so reach even a larger number of students, and also provide ~100,000 citizens with a valuable window into the marine ecosystem in their own backyards. In addition, the high school students that will be targeted represent some of the most under-served youths in San Diego County.

海洋溶解有机物（DOM）库通常被概念化为碳的“电容器”，因为它具有储存和与其他活跃库交换的潜力。然而，尽管其规模和潜在重要性，DOM 的动态尚未得到充分评估，因此该库对全球和海洋碳氮循环的最终作用仍有待确定。为了解决复杂 DOM 储层的动力学问题，加州大学圣地亚哥分校的一位年轻研究人员将开发 DOM 特定分数 d15N 和 D14C 测量的空间分辨时间序列。该时间序列将置于加州洋流系统内，该系统在各种时间尺度（例如季节性、年际、年代际）上经历物理/气候变化。与气候相关的扰动（温跃层或营养线加深/浅滩、风场变化）预计将导致表面无机溶解CO2和NO3库的同位素组成发生可测量的偏移。这些偏移最终由地表水中最近产生的有机物部分记录；当置于时间序列的背景下时，特定组分的同位素变异性将首次直接识别每年到数十年时间尺度上的 DOM 循环。此外，该时间序列还将有助于确定地表水中难熔和年轻 DOM 成分的相对比例，并描述控制 DOM 储层大小和年龄的一些物理和生物过程。作为该职业奖的一部分，将创建一门新的、基于探究的本科课程，将气候-海洋-大气等大规模现象与海洋物理-化学-生物学等较小规模现象之间的理论耦合置于有形的、特定于地区的现实世界框架。 本课程的基本目标是让学生体验式学习科学如何“运作”；学生将设计课堂项目，使用存档的时间序列数据来探索上述联系，并在为期 4-7 天的加州海流系统教育航行中收集海洋学数据。在更广泛的影响中，这项研究将是对气候与生物地球化学之间相互关系最全面、最长期的调查之一。该地区正在进行的大型科学计划的基础设施将提供背景，并通过基于网络的工具以及书面和口头交流，加强作为本提案一部分收集的科学数据向广大受众的传播。通过教育和外展计划的四个具体目标，PI 将教授和指导约 100 名本科生，指导约 8 名高中生，使两个学生群体成为更具批判性、更好的环境决策者，为约 8 名教育工作者提供有价值的知识。将科学经验带回自己的课堂，从而惠及更多的学生，并为约 100,000 名公民提供了解自家后院海洋生态系统的宝贵窗口。此外，目标高中生代表了圣地亚哥县服务最匮乏的一些青少年。