Secondary organic aerosol in the urban atmosphere is an important issue from a viewpoint of not only air pollution but also regional and global atmospheric environment. To better understand the production of water-soluble organic aerosols, we analyzed atmospheric particles collected in time-series in Tokyo for dicarboxylic acids (C2-C10), ketocarboxylic acids (C2-C4) and a-dicarbonyls (C2-C3) using a GC and GC/MS. Here, we report, for the first time, diurnal distributions of dicarboxylic acids, ketoacids and dicarbonys in the urban atmosphere. Oxalic acid was found as the most abundant species, followed by malonic, succinic, pyruvic and glyoxylic acids. Total diacids showed a concentration maximum in daytime (11-14 h) with a dynamic change in their molecular composition especially in summer samples. Relative abundances of unsaturated (maleic, methylmaleic and phthalic) and some saturated (methylsuccinic and adipic) species increased in the morning (8-11 h) whereas those of oxalic acid decreased down to 35 % in 8-11 h but increased up to 58 % toward 17-20 h. The diurnal variations are interpreted by photochemical production of diacids, where unsaturated and some saturated species are preferentially generated early in the morning via photo-oxidation of aromatic hydrocarbons and cyclic olefins and further oxidized to oxalic acid in the afternoon

An homologous series of low molecular weight dicarboxylic acids (C2–C11) have been measured in the arctic aerosol samples collected from July 1987 to June 1988 in Alert. Oxalic acid (C2) was found as the dominant species followed by malonic (C3) or succinic (C4 acid. At the time of polar sunrise, certain dicarboxylic acids in arctic haze aerosols became 5 to 20 times more abundant than in the preceding dark winter months. Furthermore, they are correlated with tropospheric ozone depletion events marked by particulate bromine. Here, we report, for the first time, observations of dicarboxylic acids in the polar atmosphere and discuss the formation of these organic acids in terms of photochemical oxidation of pollutant precursors that reach the Arctic by long range atmospheric transport from mid‐latitudes.