A simple measurement method of atmospheric nitrogen dioxide and sulfur dioxide in mountains using passive samplers

Passive samplers for the determination of NO2 and SO2 in the ambient air of mountains were investigated and applied to. a spatial analysis of air pollutants along the slope of Mt. Hiei. Yanagisawa-type samplers were used for determining the atmospheric NO2. After they were exposed for 24 h, the absorbed NO2 was measured colorimetrically by the Saltzman method. However, SO2 samplers comprising an absorbent filter containing sodium carbonate solution were made and exposed for 20 days. The absorbed SO2 was oxidized to SO42- With a H2O2 solution and determined by ion chromatography. Samplers were set up in 13 locations at Mt. Hiei and also at an air-pollution monitoring station of Kyoto city. The relative standard deviation for NO2 and SO2 determinations by these gas samplers were 1.5 similar to 4.0% and 3 similar to 10%, respectively. The average concentration of atmospheric NO2 at Mt. Hiei was about 7 ppb. The NO2 concentration and its distribution along the slope of Mt. Hiei changed considerably both daily and seasonally. However, the concentration of atmospheric SO2 at Mt. Hiei, with a mean value of about 3 ppb, was lower than that of NO2, and scarcely changed.