US GEOTRACES OCE: Measuring the distribution of stable carbon isotopes and estimating organic matter export rates

美国 GEOTRACES OCE：测量稳定碳同位素的分布并估算有机物出口率

• 批准号: 2048523
• 负责人: Paul Quay
• 金额: $ 55.39万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2048523&HistoricalAwards=false
• 关键词: US; GEOTRACES; OCE; Measuring; distribution

The goal of this project is to measure the concentration of the rare isotope of carbon (13C) present in the carbon dioxide (CO2) molecules dissolved in seawater of the South Pacific Ocean. 13C atoms make up only 1% of the carbon atoms on earth whereas atoms with the common carbon isotope (12C) make up 99% of the carbon atoms. Variations in the concentration of 13C atoms are represented relative to the concentration of 12C atoms and expressed as the 13C/12C ratio. The utility of measuring spatial variations in the 13C/12C of CO2 in the ocean results from two observations. First, during photosynthesis the 13C/12C of the plant (phytoplankton in the ocean) is distinctly different from the 13C/12C of CO2 consumed during photosynthesis. Second, the 13C/12C of CO2 molecules produced during the combustion of fossil fuels (coal, oil, natural gas) is measurably different from the 13C/12C of CO2 in the atmosphere and ocean. As a result, measuring the spatial variations of 13C/12C of CO2 in the ocean can be used to estimate variations in the rate of photosynthesis and the rate at which CO2 produced by fossil fuel combustion is being adsorbed by the ocean. Estimating variations in these two rates are goals of this project. The 13C/12C of CO2 in the ocean depends in large part on the rates of photosynthesis and respiration, which results in spatial covariations in the 13C/12C of CO2, concentrations of primary nutrients (nitrate and phosphate) and trace elements that are used by phytoplankton (e.g., Cadmium). In this project, the planned measurements of the 13C/12C of CO2, nutrients and trace elements during the GEOTRACES GP17 cruise will be used to determine how the north-south variations in biological productivity (photosynthesis and respiration), elemental composition of sinking particles and water mass mixing control the regional variations in the 13C/12C of CO2, nutrients and bioactive trace element distributions in the S. Pacific Ocean. An improved understanding of the biological, chemical and physical processes that control spatial variations of 13C/12C of CO2, bioactive trace elements and nutrient distributions in the modern ocean will improve our ability to use 13C/12C and trace elements measurements on CaCO3 preserved in the sedimentary record to reconstruct past changes in the ocean circulation and CO2 cycling in the paleo ocean. The project will involve undergraduate students in the research activities and carry out public outreach through University of Washington, Program on Climate Change (PCC).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.

该项目的目标是测量溶解在南太平洋海水中的二氧化碳（CO2）分子中存在的稀有碳同位素（13C）的浓度。13C原子仅占地球碳原子的1%，而具有常见碳同位素（12C）的原子占碳原子的99%。13C原子浓度的变化是相对于12C原子的浓度来表示的，用13C/12C比值表示。测量海洋中二氧化碳13C/12C的空间变化的效用来自两个观测结果。首先，在光合作用过程中，植物（海洋中的浮游植物）的13C/12C与光合作用过程中消耗的二氧化碳的13C/12C明显不同。其次，化石燃料（煤、石油、天然气）燃烧过程中产生的二氧化碳分子的13C/12C与大气和海洋中二氧化碳的13C/12C有明显的不同。因此，测量海洋中二氧化碳13C/12C的空间变化可以用来估计光合作用速率的变化以及化石燃料燃烧产生的二氧化碳被海洋吸附的速率。估算这两个比率的变化是这个项目的目标。海洋中二氧化碳的13C/12C在很大程度上取决于光合作用和呼吸作用的速率，这导致了二氧化碳13C/12C的空间协变，主要营养物质（硝酸盐和磷酸盐）和浮游植物使用的微量元素（如镉）的浓度。在本项目中，GEOTRACES GP17巡航期间计划测量的二氧化碳13C/12C、营养物质和微量元素将用于确定南太平洋生物生产力（光合作用和呼吸作用）、下沉颗粒元素组成和水质量混合的南北变化如何控制二氧化碳13C/12C、营养物质和生物活性微量元素分布的区域变化。对控制现代海洋中13C/12C CO2空间变化、生物活性微量元素和营养物分布的生物、化学和物理过程的进一步了解，将提高我们利用沉积记录中保存的CaCO3的13C/12C和微量元素测量来重建古海洋环流和CO2循环的过去变化的能力。该项目将让本科生参与研究活动，并通过华盛顿大学气候变化项目（PCC）开展公众宣传。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。