Japan Geoscience Union Meeting 2014

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Oral

Symbol A (Atmospheric, Ocean, and Environmental Sciences) » A-AS Atmospheric Sciences, Meteorology & Atmospheric Environment

[A-AS22_1PM2] Atmospheric Chemistry

Thu. May 1, 2014 4:15 PM - 6:00 PM 511 (5F)

Convener:*Nobuyuki Takegawa(Research Center for Advanced Science and Technology, University of Tokyo), Yousuke Sawa(Geochemical Research Department, Meteorological Research Institute), Yugo Kanaya(Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology), Kenshi Takahashi(Research Institute for Sustainable Humanosphere, Kyoto University), Hiroshi Tanimoto(National Institute for Environmental Studies), Chair:Nobuyuki Takegawa(Research Center for Advanced Science and Technology, University of Tokyo)

4:15 PM - 4:30 PM

[AAS22-P19_PG] Development of a continuous measurement system of PANs and alkyl nitrates in the atmosphere and observations at Suzu, th

3-min talk in an oral session

*Ryo TAKAJI1, Ayana ISHIYAMA1, Yasuhiro SADANAGA1, Atsushi MATSUKI2, Keiichi SATO3, Kazuo OSADA4, Hiroshi BANDOW1 (1.Osaka Prefecture University, 2.Kanazawa University, 3.Asia Center for Air Pollution Research, 4.Nagoya University)

Keywords:peroxyacyl nitrates (PANs), alkyl nitrates, total odd nitrogen species, cavity attenuated phase shift spectroscopy

Peroxyacyl nitrates (PANs) and alkyl nitrates (ANs) are generated in the atmosphere by oxidation of NOx in the presence of solar ultraviolet. They have a comparatively long lifetime, and are important as transboundary air pollutants. On the other hand, PANs and ANs act as the reservoirs of NOx. In order to clarify transboundary pollution of nitrogen oxides, comprehensive measurements of total odd nitrogen species (NOy), including PANs and ANs, are required. In this research, a continuous measurement system of total PANs and ANs has been developed by a thermal dissociation / cavity attenuated phase shift spectroscopy (TD/CAPS) method.This instrument consists of heated quartz tubes to decompose PANs and ANs into NO2, and a CAPS-NO2 analyzer. This system has three intake lines; NO2, PANs and ANs lines. The NO2 line equip of a quartz tube without heating. The PANs and ANs line equip quartz tubes heated at 433 K and 633 K, respectively for thermally decomposing them into NO2. Concentrations of NO2, NO2 + PANs and NO2 + PANs + ANs can be obtained from the NO2, PANs and ANs lines, respectively. These concentrations are sequentially measured by switching solenoid valves and then NO2, PANs and ANs concentrations are obtained. Since a part of HNO3 is pyrolyzed in the ANs line, annular denuder coated with NaCl to remove HNO3 is set before the heated quartz tube in the ANs line. The decomposition efficiencies of PANs and ANs were calibrated to be 100 and 95%, respectively, for all kinds of PANs and ANs examined.Continuous field observations of PANs and ANs have been being performed at NOTOGRO (Noto ground-based Research observatory) supersite in Suzu, the Noto Peninsula, since November 2012. Continuous measurements of NOx, NOy, T.NO3 (the sum of gaseous nitric acid and particulate nitrate) O3, and CO have also been being conducted. NOy concentrations were in agreement with the sum of observed NOy components (= NOx + T.NO3 + PANs + ANs) regardless of seasons. NOx fractions were the highest in NOy constituents. Fractions of T.NO3 in January and February were lower than those in other months. This reflects that wet deposition of T.NO3 would be accelerated in winter due to snowfall. On the other hand, PANs fractions in spring and summer were smaller than those in winter. This suggests that temperature increasing promotes decomposition of PANs.