EAR-PF: Transport and Fate of Riverine Organic Carbon in Grassland Ecosystems

EAR-PF：草原生态系统中河流有机碳的运输和归宿

• 批准号: 2053048
• 负责人: Sarah Johnston
• 金额: $ 17.4万
• 依托单位: Johnston, Sarah Ellen
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2023-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2053048&HistoricalAwards=false
• 关键词: EAR; PF; Transport; Fate; Riverine

Dr. Sarah Ellen Johnston has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education activities related to grassland ecosystems at the University of Lethbridge and Virginia Polytechnic Institute and State University. Grassland ecosystems are particularly abundant in North America and, with over 90% converted to human use globally, are among the most disturbed systems on Earth. Rivers flowing through grasslands undergo dramatic changes in chemistry and ecosystem functioning when the landscape is altered by human activities. This project examines a river system in southern Alberta, Canada, which passes through ecosystems that are unaltered, as well as those that have been altered by humans. Using water chemistry and modelling of river systems, Dr. Johnston will investigate the ways that climate and human activities, such as agricultural modifications, may affect the cycling of carbon in the water system. The work will provide information about how water chemistry, in particular organic carbon, changes as the river moves from forested, mountainous terrain in the river headwaters to agricultural and urban grassland downstream. Findings from this research will characterize human effects on river system functioning over short (weeks to months) and long (years to decades) timescales. The resulting data will be compared and scaled to similar systems across North America to better understand the vulnerability of grassland river systems to human activities. This research will be paired with outreach to the local community to educate youth about water resources in this region, and to train local undergraduate students in the field and laboratory. Additionally, the work proposed here will build on existing community connections, partnering with the regional watershed council and the Niitsitapi (Blackfoot) Nation to share the resulting science. This study will define how grassland river systems cycle carbon using a nested watershed approach that integrates data from hydrologic modelling, chemical techniques, remote sensing, and long-term monitoring data to characterize dissolved organic matter (DOM) across a range of temporal (weekly to decadal) and spatial scales (headwater streams to a large river). The fate of DOM exported from these systems, assessed using microbial incubation techniques, depends on the chemical composition of source materials and environmental conditions such as water residence time. Using a combination of technical approaches across broad spatial and temporal scales will delineate sources, fluxes, and fates of DOM throughout the study region. Ultimately, this study seeks to define the impacts of land use and climate oscillations across short and long-term datasets throughout the South Saskatchewan River Basin, a model grassland watershed. The results of this study will help develop a framework to evaluate the ramifications of integrative effects of land use and climatic variability for important ecosystem services provided by grassland river systems.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

Sarah Ellen约翰斯顿博士已获得NSF博士后奖学金，在莱斯布里奇大学、弗吉尼亚理工学院和州立大学开展与草原生态系统有关的研究和教育活动。草原生态系统在北美特别丰富，全球超过90%的草地被人类利用，是地球上最受干扰的系统之一。当人类活动改变了草原的地貌时，流经草原的河流在化学和生态系统功能方面发生了巨大的变化。该项目考察了加拿大阿尔伯塔南部的一个河流系统，该系统穿过未被改变的生态系统，以及那些被人类改变的生态系统。利用水化学和河流系统的建模，约翰斯顿博士将调查气候和人类活动，如农业改造，可能会影响水系统中碳的循环。这项工作将提供有关水化学，特别是有机碳，如何随着河流从河源的森林，山区地形向下游的农业和城市草地移动而变化的信息。这项研究的结果将描述人类对河流系统功能的影响，包括短期（几周到几个月）和长期（几年到几十年）。由此产生的数据将与北美的类似系统进行比较和缩放，以更好地了解草原河流系统对人类活动的脆弱性。这项研究将与当地社区的外联活动相结合，以教育青年了解该地区的水资源，并在实地和实验室培训当地本科生。此外，这里提出的工作将建立在现有的社区联系的基础上，与区域流域理事会和Niitsitapi（黑脚）国家合作，分享由此产生的科学。这项研究将定义草原河流系统如何使用嵌套流域方法循环碳，该方法集成了水文建模，化学技术，遥感和长期监测数据的数据，以表征溶解有机物（DOM）在一系列时间（每周到十年）和空间尺度（上游河流到大河）。从这些系统中输出的DOM的命运，使用微生物培养技术进行评估，取决于源材料的化学成分和环境条件，如水停留时间。在广泛的空间和时间尺度上使用技术方法的组合将描绘整个研究区域的DOM的来源，通量和命运。最终，本研究旨在确定整个南萨斯喀彻温河流域，一个模型草原流域的短期和长期数据集的土地利用和气候振荡的影响。这项研究的结果将有助于开发一个框架，以评估土地利用和气候变化的综合影响的后果，为重要的生态系统服务提供了草原河流system.This奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。

项目成果

Multidecadal Trends in Organic Carbon Flux Through a Grassland River Network Shaped by Human Controls and Climatic Cycles

• DOI: 10.1029/2021gl096885
• 发表时间: 2022-02
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: S. Johnston;Panditha V.S.L. Gunawardana;S. Rood;M. Bogard