RAPID: The effect of El Nino on delivery of organic carbon in the Santa Clara River, CA

RAPID：厄尔尼诺现象对加利福尼亚州圣克拉拉河有机碳输送的影响

• 批准号: 2401563
• 负责人: Ellen Druffel
• 金额: $ 11.95万
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-12-01 至 2024-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2401563&HistoricalAwards=false
• 关键词: RAPID; effect; El; Nino; delivery

El Niño–Southern Oscillation (ENSO) causes changes in winds and sea surface temperature over the tropical eastern Pacific Ocean. Typically, this results in above average rainfall in Southern California. This project aims to understand how high rainfall associated with ENSO influences the delivery of carbon from land to the ocean. Specifically, the scientists will evaluate whether a unique pool of aged carbon derived from eroded soils in the watershed is transported to the ocean during these events. Samples of particulate and sedimentary organic carbon will be collected from the Santa Clara River in California. The samples will be collected under different river flow conditions between December 2023 and April 2024. The chemical composition of these samples will be analyzed and compared to samples collected during previous ENSO and non-ENSO time periods. This unique set of samples will record whether there are differences in the amounts and sources of carbon delivered to the ocean under different river flow conditions. Results from this study will improve global and long-term estimates of carbon export from land to the ocean. This project will support an early career scientist and an undergraduate student at the University of California-Irvine, a Hispanic-serving institution.This study will examine the sources of organic carbon (OC) delivered to the coastal zone of Southern California during the upcoming El Niño event of 2023-24. The project will test the hypothesis that extreme precipitation in the Santa Clara River watershed mobilizes a unique pool of mineral-associated OC that differs from the OC that is mobilized during normal or low precipitation years. Previous studies have shown that the mineral-associated OC mobilized during the strong El Niño of 1997-98 had higher ∆14C and d13C values than the OC exported during low flow periods. The science team will collect particulate OC (POC) and sedimentary OC (SOC) samples from the Santa Clara River under different flow conditions during the 2023-2024 El Niño event. Radiocarbon (∆14C) and stable carbon isotope values (d13C) for bulk OC, and compound specific isotope analyses of n-alkanes will be measured. These data will be compared to data obtained during time periods when precipitation and river flow conditions varied (1997-98, 2002-03, 2021-22). This combination of isotope information will allow the scientists to estimate the relative contributions of organic matter derived from different sources as well as the contribution of eroded mineral associated OC to the sediments. The project will provide research and training opportunities for a postdoc and an undergraduate student at the University of California-Irvine (UCI), a Hispanic-serving institution. The postdoc will participate in the CLEAN Education Program (Climate, Literacy, Empowerment and iNquery) and design phenomenon–based science curricula for use in local high schools and undergraduate labs in the Earth System Science Department at UCI.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.

厄尔尼诺-南方涛动（ENSO）导致热带东太平洋的风和海面温度发生变化。通常，这会导致南加州的降雨量高于平均水平。该项目旨在了解与 ENSO 相关的高降雨量如何影响碳从陆地到海洋的输送。具体来说，科学家们将评估在这些事件期间，来自流域侵蚀土壤的独特老化碳库是否被输送到海洋。颗粒物和沉积有机碳样本将从加利福尼亚州圣克拉拉河采集。这些样本将于 2023 年 12 月至 2024 年 4 月期间在不同河流水流条件下采集。将对这些样本的化学成分进行分析，并与之前 ENSO 和非 ENSO 时间段采集的样本进行比较。这组独特的样本将记录在不同河流水流条件下输送到海洋的碳量和来源是否存在差异。这项研究的结果将改善对从陆地到海洋的碳输出的全球和长期估计。该项目将为加州大学欧文分校（一所西班牙裔服务机构）的一名早期职业科学家和一名本科生提供支持。这项研究将检查在即将到来的 2023-24 年厄尔尼诺事件期间输送到南加州沿海地区的有机碳 (OC) 来源。 该项目将检验以下假设：圣克拉拉河流域的极端降水会调动一个独特的与矿物相关的有机碳库，该库不同于正常或低降水年份所调动的有机碳。先前的研究表明，1997-98年强厄尔尼诺期间动员的与矿物相关的OC比低流量期间输出的OC具有更高的Δ14C和d13C值。科学团队将在2023-2024年厄尔尼诺事件期间收集不同水流条件下圣克拉拉河的颗粒物OC（POC）和沉积物OC（SOC）样本。将测量散装 OC 的放射性碳 (Δ14C) 和稳定碳同位素值 (d13C)，以及正烷烃的化合物特定同位素分析。 这些数据将与降水和河流流量条件变化时期（1997-98、2002-03、2021-22）获得的数据进行比较。这种同位素信息的组合将使科学家能够估计来自不同来源的有机物的相对贡献，以及与沉积物相关的侵蚀矿物的贡献。该项目将为加州大学欧文分校（UCI）（一所西班牙裔服务机构）的博士后和本科生提供研究和培训机会。博士后将参加 CLEAN 教育计划（气候、扫盲、赋权和 iNquery），并设计基于现象的科学课程，供当地高中和 UCI 地球系统科学系的本科实验室使用。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。