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

该项目的目标是测量南太平洋海水中溶解的二氧化碳（CO2）分子中存在的稀有碳同位素（13 C）的浓度。碳13原子仅占地球上碳原子的1%，而具有常见碳同位素（12 C）的原子占碳原子的99%。 13 C原子浓度的变化相对于12 C原子浓度表示，并表示为13 C/12 C比。 测量海洋中CO2的13 C/12 C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13 C/12 C与光合作用过程中消耗的CO2的13 C/12 C明显不同。 第二，化石燃料（煤、石油、天然气）燃烧过程中产生的CO2分子的13 C/12 C与大气和海洋中的CO2分子的13 C/12 C有很大不同。 因此，测量海洋中CO2的13 C/12 C的空间变化可以用来估计光合作用速率和化石燃料燃烧产生的CO2被海洋吸收的速率的变化。 估计这两个速率的变化是本项目的目标。海洋中CO2的13 C/12 C在很大程度上取决于光合作用和呼吸作用的速率，这导致CO2的13 C/12 C、主要营养物（硝酸盐和磷酸盐）的浓度和浮游植物（例如，镉）。在该项目中，GEOTRACES GP 17巡航期间计划对CO2、营养物和微量元素的13 C/12 C进行的测量将用于确定生物生产力的南北差异（光合作用和呼吸作用）、沉降颗粒的元素组成和水团混合控制了CO2的13 C/12 C的区域变化，营养成分和微量元素的分布。太平洋更好地了解控制现代海洋中CO2 13 C/12 C空间变化、生物活性微量元素和营养盐分布的生物、化学和物理过程，将提高我们使用13 C/12 C和微量元素测量保存在沉积记录中的CaCO 3的能力，以重建过去海洋环流和古海洋中CO2循环的变化。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NSF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。

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.