Mono- and di-carboxylic acids under long-range transport of air pollution in central Japan

Behavior of mono- and di-carboxylic acids during the long-range transport of photochemical air pollution from the metropolitan, large emission source area along the Tokyo Bay to the inland mountainous region in central Japan was investigated as a part of a cooperative field observation of meteorology and chemistry in summers, 1983 and 1986. Measurements were made for every 3 h at inland sites along the transport route of the polluted air mass. Concentrations of acetic acid, propionic acid and n-butyric acid increased to the ranges of 4—8 ppb (V/V), 0.3—0.7 ppb and 0.1—0.3 ppb, respectively in the daytime. In particular, during day, they increased significantly when the polluted air mass arrived at the sampling sites, while they decreased at night. These diurnal variations were similar to that of ozone. Of the di-carboxylic acids, succinic acid was the most abundant species, followed by phthalic acid and malonic acid. Concentrations ranged from 20—130 ng m-3 in the daytime, and were much higher in the daytime than at night. These diurnal variations were similar to those of ozone. These facts suggest that most of mono- and di-carboxylic acids were produced by photo-oxidation of anthropogenic compounds during long-range transport.