Collaborative Research: Experimental and Modeling Study of Ecosystem-Atmosphere Oxygen Isotopic Fluxes and Discrimination Mechanisms

合作研究：生态系统-大气氧同位素通量和判别机制的实验和模拟研究本项目的目标是研究控制陆地植被与大气之间二氧化碳和水中氧同位素(18O和16O)交换的过程。大豆和玉米将被用作C3和C4植物的模型系统。可调谐半导体激光吸收光谱将与微气象方法相结合，在生态系统尺度上同时、近乎连续地测量二氧化碳和水蒸气的同位素混合比和同位素通量以及18O辨别系数。确定生态系统规模18O区分度的能力对于一些与大气碳收支和生态系统过程有关的基础科学问题至关重要。拟议活动的更广泛影响包括获取用于验证大气碳预算模型的独特数据集。创新的研究方法将增强全球碳和能源流量观测网络的能力，并促进大学科学家和私营行业工程师之间的合作。在该项目期间获得的新知识将通过一次特别会议以及对本科生和研究生的培训，转移到更大的科学界。最后，关于通过18O同位素进行二氧化碳和水的耦合交换的总体战略应该为以真正综合的方式研究碳循环和水循环开辟一个新的层面。

Collaborative Research: Experimental and Modeling Study of Ecosystem-Atmosphere Oxygen Isotopic Fluxes and Discrimination MechanismsThe goal of this project is to investigate processes that control the exchange of oxygen isotopes (18O and 16O) in CO2 and H2O between terrestrial vegetation and the atmosphere. Soybean and corn will be used as model systems for C3 and C4 plants. Tunable diode laser absorption spectroscopy will be combined with the micrometeorological methods to provide simultaneous, near-continuous measurement of isotopomer mixing ratios and isotopic fluxes of CO2 and water vapor, and 18O discrimination factors at the ecosystem scale. The ability to determine the ecosystem-scale 18O discrimination is essential to a number of fundamental science questions relevant to atmospheric carbon budget and ecosystem processes. The broader impacts of the proposed activity include the acquisition of unique datasets for validation of atmospheric carbon budget models. The innovative research methods will enhance the capacity of the global carbon and energy flux observational network and foster collaboration between university scientists and engineers in a private industry. The new knowledge gained during the project will be transferred to the greater scientific community through a special conference session and training of undergraduate and graduate students. Finally, the overall strategy on the coupled exchanges of CO2 and water through the 18O isotopes should open a new dimension for investigating the carbon and water cycles in a truly integrated manner.