ABSTRACT

Atmospheric He, Ne and H₂ have been determined simultaneously by gas chromatography without any pre-purification procedures for enrichment. Repeated analyses of atmospheric air samples collected in Matsuyama, Japan from 1982 through 1984 have given the following average values with respective standard deviations; 5.20 ± 0.02ppm for He, 18.4 ± 0.1 ppm for Ne and 0.83 ± 0.02ppm for H₂. The obtained average values for the atmospheric He and Ne are in good agreement with the commonly accepted values. The concentration of H₂, however, is considerably fluctuating even in a short duration less than half an hour, and is affected by meteorological conditions. In particular, the H₂ concentration negatively correlates with wind velocity. This trend is clearly seen in rainy days. Exhaust gases from automobile engines are highly enriched in H₂, on the order of a percent by volume. The H₂-rich exhaust gases are being diluted by less polluted air, and the rate of dilution seems to depend strongly on the wind velocity and precipitation. The average value of H₂ concentrations measured in Matsuyama is definitely higher than the background value in surface air of Northern Hemisphere of 0.584 ppm, but comparable to that in the polluted air in Mainz, West Germany reported ten years ago.