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: 2023110
• 负责人: Amanda Frossard
• 金额: $ 27.22万
• 依托单位: University of Georgia Research Foundation Inc
• 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=2023110&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.

合作研究：与海洋排放的初级海洋气溶胶相关的难溶有机碳通量的季节变化海洋中含有大量的有机碳，其数量大于所有陆地有机碳生物量的总和。几乎所有的海洋有机碳都溶解了。平均而言，它有数千年的历史，化学性质稳定，在完全清除之前，它在整个海洋中被携带了好几次。然而，人们对产生和去除这种旧碳的过程知之甚少，这种旧碳被称为难溶有机碳（RDOC）。一个潜在的去除途径涉及RDOC粘附在破碎波产生的上升气泡的表面上。 气泡最终在海面破裂，喷射出携带RDOC进入大气的微小颗粒（初级海洋气溶胶，“PMA”）。 大多数PMA有机碳与在大气中漂浮数天至数周的最小颗粒（直径小于1 μm）有关。在此期间，这些颗粒中的RDOC可以光化学降解（通过阳光），部分向陆地运输，和/或返回海洋。当该RDOC转化为无机碳（例如，二氧化碳）或在大气中降解为更具反应性的成分，它被有效地从海洋RDOC储层中去除。根据初步结果，RDOC从海洋中去除的年速率与所有其他已知的RDOC损失（与颗粒的相互作用，生物降解和热液循环）相似，但海水中的光化学降解除外。在先前研究的基础上，该项目将在三次前往西北大西洋的研究巡航中确定通过这一过程从海洋中去除RDOC的季节性变化。该项目的结果将提供关于RDOC的海洋-大气耦合损失的重要发现，并提高对RDOC在全球碳循环和地球气候中作用的理解。该研究将涉及两个早期职业教师，并将提供本科，研究生和博士后研究人员的培训。放射性碳（C-14）测量表明，RDOC包括19至40%的有机碳与PMA产生的爆破气泡在海面。与PMA一起向大气中注入RDOC是一个潜在的重要过程，可从海洋中去除多达2至20 Tg RDOC yr-1。该项目将通过量化以下两个方面来测量PMA介导的海洋RDOC排放到大气中的季节变化：（1）RDOC在PMA OC中的比例和（2）其与近地表海水中生物产生的不稳定和半不稳定溶解有机物丰度的关系。这些关系将在百慕大大西洋时间序列站进行三次研究航行（一次在7月，两次在1月）期间进行评价。 在航行期间，调查人员将测量：（1）海水中PMA及其有机源物质的天然丰度C-14值;（2）海水的动态和平衡表面张力和物理性质，包括气泡大小分布;（3）PMA中主要离子、有机碳、碳水化合物、肽和蛋白质以及表面活性剂的浓度;（4）近表层海水和海表微层中的发色溶解有机物（CDOM）和溶解有机碳、叶绿素a、主要离子、碳水化合物、肽和蛋白质以及表面活性剂的浓度。基于这些化学测量和物理特性，本研究将揭示RDOC输入到大气中作为PMS.This奖项反映了NSF的法定使命的组成部分的幅度和潜在的控制，并已被认为是值得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的支持。