Collaborative Research: Seasonal Variability in refractory dissolved organic carbon fluxes associated with primary marine aerosol emitted from the oceans

合作研究：与海洋排放的初级海洋气溶胶相关的难熔溶解有机碳通量的季节变化

• 批准号: 2023104
• 负责人: David Kieber
• 金额: $ 29.76万
• 依托单位: SUNY College of Environmental Science and Forestry
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2023104&HistoricalAwards=false
• 关键词: Collaborative; Research; Seasonal; Variability; refractory

Collaborative Research: Seasonal variability in refractory dissolved organic carbon fluxes associated with primary marine aerosol emitted from the oceansThe oceans hold a massive quantity of organic carbon that is greater than all terrestrial organic carbon biomass combined. Nearly all marine organic carbon is dissolved. On average, it is thousands of years old, chemically stable, and carried throughout the entire ocean several times before complete removal. However, little is known about the processes that produce and remove this old carbon, referred to as refractory dissolved organic carbon (RDOC). One potential removal pathway involves RDOC adhering onto the surfaces of rising bubbles produced by breaking waves. The bubbles ultimately burst at the sea surface, ejecting tiny particles (primary marine aerosol, “PMA”) that carry the RDOC into the atmosphere. Most of this PMA organic carbon is associated with the smallest particles (less than 1 μm diameter) that drift in the atmosphere for several days to weeks. During this time, RDOC in these particles can be degraded photochemically (by sunlight), partially transported landward, and/or returned to the sea. When this RDOC is converted to inorganic carbon (e.g., carbon dioxide) or degraded to more reactive constituents in the atmosphere, it is effectively removed from the marine RDOC reservoir. Based on preliminary results, the annual rate at which RDOC is removed from the ocean by this process is similar to all other known RDOC losses (interactions with particles, biological degradation, and hydrothermal circulation), except for photochemical degradation in seawater. Building on this prior research, this project will identify seasonal changes in the removal of RDOC from the oceans through this process during three research cruises to the northwestern Atlantic Ocean. Results from this project will provide important findings about the coupled ocean-atmosphere loss of RDOC and improve understanding of the role of RDOC in the global carbon cycle and Earth's climate. The research will involve two early career faculty, and will provide training for undergraduate, graduate, and postdoctoral researchers.Radiocarbon (C-14) measurements indicate that RDOC comprises 19 to 40 % of the organic carbon associated with PMA produced by bursting bubbles at the sea surface. Injection of RDOC into the atmosphere in association with PMA is a potentially important process that removes as much as 2 to 20 Tg RDOC yr-1 from the oceans. This project will measure seasonal variations in the PMA-mediated emission of marine RDOC to the atmosphere by quantifying: (1) the fraction of RDOC in PMA OC and (2) its relationship to the abundance of biologically produced labile and semi-labile dissolved organic matter in near surface seawater. These relationships will be evaluated at the Bermuda Atlantic Time-series Station during three research cruises (one in July, two in January). During the cruises, the investigators will measure: (1) the natural abundance C-14 values for PMA and its organic source materials in seawater; (2) the dynamic and equilibrium surface tension and physical properties of seawater, including bubble size distributions; (3) concentrations of major ions, organic carbon, carbohydrates, peptides and proteins, and surfactants in PMA; and (4) chromophoric dissolved organic matter (CDOM) and the concentrations of dissolved organic carbon, chlorophyll a, major ions, carbohydrates, peptides and proteins, and surfactants in near-surface seawater and in the sea-surface microlayer. Based on these chemical measurements and physical properties, this study will reveal the magnitude and potential controls on RDOC inputs into the atmosphere as a component of PMA.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.

协作研究：与从海洋中发出的原代海洋气溶胶相关的难治性溶解有机碳通量的季节性变异性具有大量的有机碳，该有机碳大于所有陆地有机碳生物量合并。几乎所有海洋有机碳都溶解。平均而言，它已有数千年的历史，化学稳定，并在整个海洋中携带了几次，然后才能完全去除。但是，对产生和去除这种旧碳的过程知之甚少，被称为难治性溶解有机碳（RDOC）。一个潜在的去除途径涉及将RDOC粘附在破坏波产生的升高气泡的表面上。气泡最终在海面上爆裂，将RDOC带入大气中的微小颗粒（主要的海洋气溶胶，“ PMA”）。大多数PMA有机碳与在大气中漂移几天到几周的最小颗粒（直径小于1μm）有关。在此期间，这些颗粒中的RDOC可以在光化学（通过阳光下），部分运输的陆地和/或返回到海中。当该RDOC转化为无机碳（例如二氧化碳）或降解为大气中更具反应性的构成时，它有效地从海洋RDOC储层中取出。基于初步结果，除了海水中的光化学降解外，通过此过程从海洋中删除RDOC的年速率类似于所有其他已知的RDOC损失（与颗粒，生物学降解和水热循环的相互作用）。在这项先前研究的基础上，该项目将在三个研究巡游到西北大西洋的过程中通过这一过程从海洋中删除RDOC的季节性变化。该项目的结果将提供有关RDOC的海洋 - 大气损失的重要发现，并提高对RDOC在全球碳循环和地球气候中的作用的理解。这项研究将涉及两位早期职业教师，并将为本科，研究生和博士后研究人员提供培训。亚二碳（C-14）的测量表明，RDOC占与海面破裂气泡产生的PMA相关的有机碳的19％至40％。与PMA相关的RDOC注入大气是一个潜在的重要过程，从海洋中除去了多达2至20 TG RDOC YR-1。该项目将通过量化来衡量PMA介导的海洋RDOC发射到大气中的季节性变化：（1）PMA OC中RDOC的比例，以及（2）其与生物学产生的不稳定和半固定溶解有机物在近地面海水中与生物学产生的不稳定和半标签的有机物的关系。这些关系将在三个研究巡游期间在百慕大大西洋时间序列站进行评估（7月，一月为两次）。在巡航过程中，研究人员将测量：（1）PMA的天然丰度C-14值及其在海水中的有机源材料； （2）海水的动态和平衡表面张力和物理特性，包括气泡尺寸分布； （3）PMA中主要离子，有机碳，碳水合物，碳水化合物和蛋白质以及表面收获的浓度； （4）发色溶解的有机物（CDOR）以及溶解的有机碳，叶绿素A，主要离子，碳氢化物，辣椒和蛋白质以及近面海水和海洋表情Microlayer中的浓度。基于这些化学测量和物理特性，本研究将揭示RDOC输入到大气中的大小和潜在控制，作为PMA的一个组成部分。该奖项反映了NSF的法定任务，并通过使用基金会的智力优点和更广泛的影响标准来评估NSF的法定任务。