J. C. Turnb0ull, A. Karion, M. L. Fischer, I. Faloona, T. Guilderson, S. J. Lehman, B. R. Miller, J. B. Miller, S. Montzka, T. Sherwood, S. Saripalli, C. Sweeney, and P. P. TansAbstract:
Stable isotope analysis of hydrogen (δ2H) and oxygen (δ18O) can well indicate the source of water in beverages, but traditional isotope analysis only focuses on pure water or extracted water. The isotope composition of the extracted beverage water was determined by infrared spectroscopy (IRIS) and isotope mass spectrometry (IRMS). The samples of beer, soda, fruit juice and milk (without water extraction) were also analyzed by IRIS. For the IRIS analyzer, four needles were injected into each sample, and memory effects were corrected by three methods: (a) 1-4 needle data, (b) 2-4 needle data, and (c) 3-4 needle data. The results show that the values of δ2H and δ18O calculated by the three methods are much different from those of pure water. The memory effect was the smallest when only 3-4 needles were used. Except for fruit juice, the values of δ2H and δ18O of other beverage water conform to the atmospheric precipitation line. Comparing the results of IRIS and IRMS, except for the difference of δ2H in soda water and fruit juice, the difference of δ18O in beer is not significant. The correlation coefficients of δ2H and δ18O values of beer, soda, juice and milk extracts and complex beverages are 0.998 and 0.997 respectively, which are suitable for 1:1 line. Our conclusion is that IRIS can be used directly for the analysis of complex beverages without water extraction, but caution must be taken because the beverage contains sugar, which may clog syringes and increase memory effects. Alcohol in beverages can also interfere with spectral analysis.
Direct quantitative determination of carbon dioxide (CO2ff) from chemical fuel combustion can be used to assess carbon cycle and air quality. In the spring of 2009, we flew two times over Sacramento, California, to measure CO2, CO and CH4 in the boundary layer and troposphere in situ, while collecting samples in sample bottles. Samples in sample bottles are used to analyze 14CO2 and CO2 to determine the recently increased molar fraction of CO2. At the same time, a series of greenhouse gases and trace gases, including hydrocarbons and halogens, were determined with the sample. We observed a strong correlation between CO2 FF and many trace gases in urban emissions. Based on the correlation, we estimate the emission rates of CO2 FF and these trace gases and compare them with the previous emission rates. Carbon monoxide (CO) and benzene emission rates at county level obtained from the California Air Resources Committee's CEPAM database in recent years are in good agreement with our measurements, but previous emissions seem to have overestimated one or two indicators. For most other trace gases, our measurements are quite different from previous estimates (200-500%). On the first flight, we combined the emission rate of CO:CO 2 of 14±2 ppb CO/ppm CO 2 monitored on-line in situ to obtain the estimated value of the molar fraction of CO 2 ff. The carbon dioxide mixing ratio (CO2 bio) of the biosphere is estimated from the difference between total carbon dioxide emissions and fossil combustion emissions. The results show that CO2 bio varies greatly in different places. From the urban area up to 8 + 2 ppm to -6±1 ppm of ambient boundary layer air. Finally, based on the above molar fraction of CO2 ff, the total CO2 emissions from fossil combustion in Sacramento area are calculated by mass balance method. There are one or two uncertainties in the emission calculated by this method: the uncertainties of wind speed and boundary layer height. However, this attempt to use atmospheric radiocarbon to estimate urban-scale CO2 FF emissions shows that the CO2ff can be used to validate and improve previously estimated anthropogenic errors, respectively, in the biosphere, and that if transport uncertainty decreases, CO2ff emissions may be limited.
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