Development of portable carbon isotope observation system to evaluate carbon cycle in ecosystems

二氧化碳同位素组成的通量和浓度不仅提供了碳平衡信息，而且还提供了生态系统生理过程及其对环境变化的响应信息。为了在不同时间尺度上连续测量二氧化碳同位素组成，测试了可调谐二极管激光光谱仪（TDLS）的性能。利用该TDLS研制了便携式碳同位素观测系统，实现了野外二氧化碳碳同位素组成的连续观测。大气二氧化碳的碳同位素组成随二氧化碳浓度的变化而波动，土壤呼吸二氧化碳碳同位素信号的波动未被检测到，尽管基林样地估算土壤同位素信号非常敏感，但结果非常分散，特别是在冬季。

Fluxes and concentrations of carbon dioxide isotope compositions provide information about not only carbon balance but also ecosystem physiological processes and their response to environmental variation. For continuous measurement of carbon dioxide isotopic composition over various time-scales using a tunable diode laser spectrometer (TDLS), the performance of a TDLS was tested. Using this TDLS, we developed portable carbon isotope observation system, and continuously observed carbon isotopic composition of carbon dioxide in a field. The carbon isotopic composition of the atmospheric carbon dioxide was fluctuated according the changes of carbon dioxide concentration and fluctuations of the carbon isotope signal from soil respired carbon dioxide was not detected, although Keeling plots to estimate isotope signal from the soil were very sensitive and the results were very scattered especially in winter.