RAPID: El Nino Event Impacts on Organic Matter Export and Composition in the Amazon River

RAPID：厄尔尼诺事件对亚马逊河有机物出口和成分的影响

• 批准号: 2333961
• 负责人: Robert Spencer
• 金额: $ 9.88万
• 依托单位: Florida State University
• 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: 2023-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2333961&HistoricalAwards=false
• 关键词: RAPID; El; Nino; Event; Impacts

The Amazon River is one of the largest sources of freshwater and carbon to the ocean. Thus, understanding the factors that influence freshwater delivery from the Amazon River is important for understanding the carbon cycle of the Amazon River and the receiving Atlantic Ocean. El Niño–Southern Oscillation (ENSO) is a periodic event that causes changes in winds and sea surface temperature over the tropical eastern Pacific Ocean and affects climate in the tropics and subtropics. The National Weather Service predicts that El Niño conditions are likely to form across the Pacific during Summer 2023. These conditions are expected to last through February 2024. This event is expected to impact precipitation and air temperatures in the Amazon Basin and freshwater delivery from the Amazon River. This project aims to study the amount and chemical composition of dissolved organic carbon delivered from the Amazon River to the Atlantic Ocean during the 2023-2024 El Niño event. Scientists involved in this project plan to collect samples from late Summer 2023 through late Summer 2024. The study will identify conditions before, during and after this event. This unique set of samples will enable the team of scientists to study how ENSO influences the delivery of organic carbon to the coastal ocean. This project provides support for an early career researcher and promotes international cooperation and inclusivity between researchers from the United States of America and researchers in Brazil who are directly impacted by the changing Amazon River. This project examines how El Niño Southern Oscillation (ENSO) anomalies impact the export of dissolved organic carbon (DOC) and composition of dissolved organic matter (DOM) from the Amazon River to the Atlantic Ocean. Based on recent studies, it has been hypothesized that the upcoming 2023 El Niño event will reduce the annual DOC flux and proportion of exported terrestrial DOM from the Amazon River compared to non-ENSO and La Niña years. This hypothesis will be examined by linking established state-of-the-art optical and molecular-level characterization techniques (e.g., Fourier-transform ion cyclotron resonance mass spectrometry; FT-ICR MS) with DOC flux calculations over the course of an El Niño year. Analyzing both bulk DOC fluxes and the molecular-level composition will reveal how the quantity and quality of DOM export will change monthly in response to reduced precipitation and higher temperature across the Amazon Basin and headwaters. DOC fluxes as well as detailed characterizations (FT-ICR MS, optical, fluorescence analysis) of DOM sampled from the furthest downstream Amazon River gauging station at Óbidos (Brazil) will be directly compared to results obtained from the 2011-2012 La Niña year and the following 2012-2013 hydrologically normal year to determine how global climate anomalies impact the DOC export to marine systems and to create a framework for future predictions. Data obtained from this proposed study will lay the foundations for larger studies investigating how ENSO cycles impact discharge and carbon export from other major tropical-subtropical rivers and ultimately, how ENSO cycles impact global land-ocean carbon export.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.

亚马逊河是海洋最大的淡水和碳源之一，因此，了解影响亚马逊河淡水输送的因素对于了解亚马逊河和接收厄尔尼​​诺现象的大西洋的碳循环非常重要。南方涛动（ENSO）是一种周期性事件，会导致热带东太平洋的风和海面温度发生变化，并影响热带和亚热带的气候。国家气象局预测，整个太平洋可能会出现厄尔尼诺现象。夏天2023 年。这些情况预计将持续到 2024 年 2 月。该事件预计将影响亚马逊盆地的降水和气温以及亚马逊河的淡水输送。该项目旨在研究亚马逊河输送的溶解有机碳的数量和化学成分。参与该项目的科学家计划在 2023 年至 2024 年厄尔尼诺事件期间从亚马逊河到大西洋收集样本。该研究将确定条件。这套独特的样本将使科学家团队能够研究 ENSO 如何影响有机碳向沿海海洋的输送。该项目为早期职业研究人员提供支持，并促进国际合作和包容性。来自美国的研究人员和巴西的研究人员直接受到亚马逊河变化的影响，该项目研究厄尔尼诺南方涛动（ENSO）异常如何影响溶解有机碳（DOC）的出口和溶解有机物的成分（ DOM）来自根据最近的研究，人们普遍认为，与非 ENSO 和拉尼娜年份相比，即将到来的 2023 年厄尔尼诺事件将减少亚马逊河的年度 DOC 通量和输出的陆地 DOM 比例。该假设将通过连接现有的最先进的光学和分子水平表征技术（例如，傅里叶变换离子回旋共振质谱法；FT-ICR）来检验MS）与厄尔尼诺年过程中的 DOC 通量计算分析大量 DOC 通量和分子水平组成将揭示 DOM 出口的数量和质量将如何因亚马逊降水减少和气温升高而发生每月变化。流域和源头的 DOC 通量以及从奥比多斯（巴西）下游最远的亚马逊河测量站采样的 DOM 的详细特征（FT-ICR MS、光学、荧光分析）将被记录。直接与 2011-2012 年拉尼娜年和随后的 2012-2013 年水文正常年获得的结果进行比较，以确定全球气候异常如何影响 DOC 向海洋系统的输出，并为从本拟议研究中获得的未来数据创建一个框架。将为更大规模的研究奠定基础，调查ENSO循环如何影响其他主要热带-亚热带河流的排放和碳输出，以及最终ENSO循环如何影响全球陆地-海洋碳该奖项反映了 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。