Molecular Hydrogen and Other Reactive Trace Gases Measured by TROICA in Siberia in winter

Abstract

As a part of the TROICA-8 campaign, air samples were collected in the low-land area of Siberia on March 20, 2004. The mixing ratios of H2, CO, CH4, non-methane hydrocarbons, O3, and NOx, and the stable isotope ratios of H2 and CH4 were measured to define source of the air masses in the remote Siberian region. For the region where samples were collected, most air masses appear to have been highly polluted with isolated peaks being detected. The emission ratios (ER) of the gases calculated relative to CO of the background air masses suggest the source of the pollution in the air masses to be biomass fuel or coal combustion, suspecting the wintertime heating system as a major source of the observed chemical compounds. Applying an inverse relation of H2 and its D/H ratio points to the &#61540

D of the source H2 as -294 ‰, which is lower than the &#61540

D value of the H2 from biomass burning. As the ERs indicate, we do not expect a unique source to govern the distribution of H2 observed in the mid-Siberia, but most likely several sources would have contributed.