HR: 1340h
AN: A33A-0835    [Abstracts]
TI: Three-Year Observation of Levoglucosan Over Chichi-jima Island in the Northwestern Pacific
AU: * Mochida, M
EM: mochida@iar.nagoya-u.ac.jp
AF: Institute of Low Temperature Science, Hokkaido University, N19 W8, Kita-ku, Sapporo, 060- 0819, Japan
AU: * Mochida, M
EM: mochida@iar.nagoya-u.ac.jp
AF: Present Address: Institute for Advanced Research, Nagoya University, Furo-cho, Chikusa- ku, Nagoya, 464-8601, Japan
AU: Umemoto, N
AF: Institute of Low Temperature Science, Hokkaido University, N19 W8, Kita-ku, Sapporo, 060- 0819, Japan
AU: Kurokawa, A
AF: Institute of Low Temperature Science, Hokkaido University, N19 W8, Kita-ku, Sapporo, 060- 0819, Japan
AU: Kawamura, K
EM: kawamura@lowtem.hokudai.ac.jp
AF: Institute of Low Temperature Science, Hokkaido University, N19 W8, Kita-ku, Sapporo, 060- 0819, Japan
AB: Levoglucosan (1,6-anhydro-β-D-glucopyranose) is a major constituent of biomass burning aerosol particles, and has been suggested to be useful as a tracer of biomass burning aerosols in the atmosphere. In this study, we analyzed levoglucosan in aerosol samples collected in Chichi-jima Island, the northwestern Pacific from January 2001 to January 2004. Aerosol samples (n = 149) were collected on quartz fiber filters using a high volume air sampler. Levoglucosan and other organics on a filter cut were extracted with methanol/dichloromethane and derivatized with BSTFA. The derivatives were injected to GC-MS for quantification. A clear seasonal variation of the concentration of levoglucosan was observed with a maximum in autumn to spring. The highest concentration was above 10 ng m^-3. The mean concentration of levoglucosan in the period from January to March (2 ng m^-3) was one order of magnitude higher than that in the period from July to September (0.2 ng m^-3). The ratios of levoglucosan carbon (levoglucosan-C) to organic carbon (OC) were in most cases above 1 × 10^-3 in winter season (October - March), whereas the ratios were in many cases below 1 × 10^-4 in summer season (April - September). The higher ratio in winter suggests a relatively larger contribution of biomass burning to OC during the period, nevertheless the ratio is two orders of magnitude lower than that of freshly emitted biomass burning particles. Given that the transport of biomass burning aerosols from Asia to the Pacific is expected to be substantial, the low [levoglucosan-C]/OC ratio may be explained by the decomposition of levoglucosan and/or the secondary production of OC during the long-range transport. While the variation of the concentration of levoglucosan probably represents the change in the contribution of biomass burning aerosols over Chichi-jima, more analyses are required to quantitatively understand the observed low levoglucosan abundance.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting