[AAS04-P22] Measurement on the 17O-excess of tropospheric nitrogen oxides
Keywords:nitrogen oxides, troposphere, triple oxygen isotope
Δ17O value of NO2 was determined, together with Δ17O value of HONO, by combining sensitive determination method on isotope compositions of NO2-(Komatsu et al., 2008; Tsunogai et al., 2010) with a slightly modified filter-pack method (Noguchi et al., 2007), in which both NO2 and HONO were collected simultaneously as NO2-on triethanolamine (TEA)-coated filter and alkaline (K2CO3) impregnated filter, respectively. Periodical sampling of atmospheric NO2 and HONO was carried out at Hokkaido Institute of Environmental Sciences, Sapporo and at Nagoya University, which is located in a suburban area of Nagoya City. The sample collection period was fixed to one week with a flow rate of 10 L/min. In order to determine diurnal variation in Δ17O value of NO2 and HONO, an automated system for time-interval air sampling equipped with 6 four-stage-filter-packs were made and used it to collect atmospheric samples every 4 hours.The Δ17O values of NO2 and HONO showed similar diurnal variations; higher value on the day time than the night time. The result suggests that the atmospheric HONO is formed mainly by chemical reaction of NOx in the urban atmosphere.