Trace gas measurements between Moscow and Vladivostok using the Trans-Siberian Railroad

Using a laboratory wagon traveling along the Trans-Siberian railroad, O-3, NO, NO2, CO, CH4, SF6 and black carbon aerosol have been measured during the summer of 1996. The expedition from Niznij Novgorod (500 km east of Moscow) to Vladivostok (and back to Moscow) has shown the great potential of the train method; here the first results are presented and discussed. A wealth of boundary layer air data was obtained during the over 18000 lan travel without serious contamination problems from the electric train itself. The diurnal O-3 cycle peaked generally below 50 nmole/mole, showed the effects of changes in J(NO2), and often dropped to a few nmole/mole at night time during inversions. Over the vast Siberian lowlands situated between the Ural mountains and the river Yenisey, CH4 levels were consistently elevated at around 1.95 mu mole/mole, which we mainly attribute to wetland emissions. Over eastern Siberia, however, CH4 levels were generally lower at 1.85 mu mole/mole. In contrast, over the west Siberian lowlands, CO levels were relatively low, often reaching values of only 110 nmole/mole, whereas over eastern Siberia CO levels were higher. Very high CO levels were detected over a 2000 km section east of Chita, along the river Amur, which represented an enormous polluted air mass. C-14 analysis performed on several CO samples confirms that the origin was biomass burning. SF6, which was measured as a general conserved tracer, showed an eastward attenuation from 4.0 to 3.9 pmole/mole, with peaks in a number of places due to local Russian emissions.