[AAS06-P15] Seasonal variations of triple oxygen isotopes of atmospheric nitrate and sulfate at Noto Peninsula, Japan
Keywords:Triple oxygen isotopes, Sulfate, Nitrate, Aerosol, Anthropogenic activity, Atmospheric oxidants
The Δ17O values of nitrate showed the clear seasonal variations with summer minimum and winter maximum. This trend is resulted from the seasonal changes in the O3 / HOx ratios decreasing in summer by ozone destruction and HOX production (e.g. OH, HO 2 radicals) via UV irradiance. Although correlation between delta18O and Delta17O values were observed throughout the year, slope between delta18O and Delta17O values for coarse particle for winter-spring period is only different from other seasons and fine particles. Possible explanation of this different isotope pattern for winter and spring period are discussed.
For the Delta17O values of sulfate, clear seasonal variation is not observed but the Delta17O values of sulfate ranged from 0.7 to 1.9‰, being slightly higher than those observed in previous studies for Wuhan (Li et al., 2013) and haze event in Beijing (He et al., 2017), China. This difference of Delta17O values of sulfate between China and Japan may indicate that there is different thermodynamic state of aerosols (stable or metastable) and its influence to aerosol pH during long-distance transportation of SO2.