AIRCRAFT MEASUREMENTS OF THE CONCENTRATIONS OF CO2, CH4, N2O, AND CO AND THE CARBON AND OXYGEN ISOTOPIC-RATIOS OF CO2 IN THE TROPOSPHERE OVER RUSSIA

About 370 air samples were collected using aircraft in the troposphere over Russia in the summers of 1992, 1993, and 1994. These were then a nalyzed for the CO2, CH4, N2O and CO concentrations, as well as for de lta(13)C and delta(18)O of CO2. Measured vertical profiles of troposph eric CO2 showed that the concentration increased with height over all locations. In the lower troposphere over the wetland and taiga regions , extremely low CO2 concentrations of 335-345 parts per million by vol ume (ppmv) were often observed. Measured values of delta(13)C and the CO2 concentration were negatively correlated with each other, the rate of change in delta(13)C with respect to the CO2 concentration being a bout -0.05 parts per thousand/ppmv. This implies that the variations i n the CO2 concentration observed over Russia in the summer are primari ly caused by terrestrial biospheric activities. In the middle and uppe r troposphere, the CO2 concentration and delta(13)C showed systematic differences between each other in 1992, 1993, and 1994, probably due t o their secular changes. The delta(18)O and CO2 observed in the lowest part of the troposphere over east and west Siberia were also negative ly correlated with each other, with the rate of change in delta(18)O w ith respect to CO2 estimated to be about -0.11 parts per thousand/ppmv . This relation may be caused by isotopic equilibrium of oxygen in CO2 with soil water through respiration of living plants and decompositio n of organic matter and with chloroplast water in leaves through photo synthesis of living plants. In contrast to CO2, the CH4 concentration decreased with height. Extremely high CH4 concentrations were observed over the west Siberian lowland, owing to a large amount of CH4 emitte d from wetlands. The N2O concentrations were fairly constant through t he troposphere over all locations covered by this study, with an avera ge value of about 311 parts per billion by volume(ppbv). The CO concen trations also showed vertical profiles, with a small gradient over nat ural wetlands, taiga, and tundra. High values of the CH4, CO, and CO2 concentrations were observed over Moscow, owing to emissions of the re spective gases by human activities in an urban area. It was also found that over natural wetlands and tundra the CO2 and CH4 concentrations were negatively correlated with each other, reflecting a strong biosph eric CO2 uptake and CH4 emissions from wetlands. The relationship betw een the CH4 and CO concentrations was strongly positive over areas wit h their anthropogenic and natural sources; the relationship was only s lightly positive over wetlands, possibly due to CO emissions from wetl ands and/or photochemically produced CO.