18:15 〜 19:30
[AAS22-P30] 中赤外レーザー分光法を用いたCO2安定同位体の測定：都市のCO2循環の解析
キーワード：CO2, 都市域, CO2循環, 中赤外レーザー分光法
CO2 concentration has been increasing from the range of 275 ppmv (parts per million by volume) to 285 ppmv in the previous industrial period to about 400 ppmv in 2013. IPCC reported that CO2 has the most effective on the positive radiative force. The insight of CO2 emission and absorption flux helps us to estimate the variation of radiative forcing and atmospheric environment. CO2 concentration changed with the anthropogenic and biogenic emission and absorption. The stable isotope ratio of CO2 (δ13C and δ18O) is associated with the CO2 source such as combustion and biogenic respiration. The contribution of each CO2 source in the urban area was estimated by using the stable isotope ratio of CO2.
We conducted the continuous measurement for CO2 concentration and stable isotope ratio of CO2 using the mid-inferred absorption spectrometry which can obtain CO2 concentration and its isotope ratio with high time resolution. The water vapor and stable isotope ratios of water vapor (δD and δ18O-H2O) were measured to show the relationship between H2O and CO2 due to the isotopic exchange reaction. CO and NOx concentrations were obtained as a tracer of anthropogenic emission. The measurement was conducted for two weeks in summer and winter. The seasonal variation of CO2 source was shown according to the comparison of CO2 concentration and stable isotope ratio. Especially, we focused on the contribution of biogenic process to CO2 concentration variation in the urban area.
CO2 concentration and stable isotope ratio of CO2 in the summer showed the diurnal variation. On the other hand, those in the winter had no diurnal variation. CO2 concentration variation in the winter was correlated with CO concentration variation. These results suppose that CO2 concentration variation in the winter was mainly dominated by the anthropogenic emission and that in the summer was related with biogenic process as well as anthropogenic emission. We will discuss the relationship between stable isotope ratio and meteorological condition or water vapor isotope ratio to identify the detail of CO2 source.
We conducted the continuous measurement for CO2 concentration and stable isotope ratio of CO2 using the mid-inferred absorption spectrometry which can obtain CO2 concentration and its isotope ratio with high time resolution. The water vapor and stable isotope ratios of water vapor (δD and δ18O-H2O) were measured to show the relationship between H2O and CO2 due to the isotopic exchange reaction. CO and NOx concentrations were obtained as a tracer of anthropogenic emission. The measurement was conducted for two weeks in summer and winter. The seasonal variation of CO2 source was shown according to the comparison of CO2 concentration and stable isotope ratio. Especially, we focused on the contribution of biogenic process to CO2 concentration variation in the urban area.
CO2 concentration and stable isotope ratio of CO2 in the summer showed the diurnal variation. On the other hand, those in the winter had no diurnal variation. CO2 concentration variation in the winter was correlated with CO concentration variation. These results suppose that CO2 concentration variation in the winter was mainly dominated by the anthropogenic emission and that in the summer was related with biogenic process as well as anthropogenic emission. We will discuss the relationship between stable isotope ratio and meteorological condition or water vapor isotope ratio to identify the detail of CO2 source.