The state of the art on the chemical characterization of diesel particulates in Japan.

In this paper, the state of the art of the chemical characterization of diesel particulates in Japan is presented. However, some of these results are only preliminary. The principal contents may be summarized as follows: Characterization of Diesel Particulates; Examples of the application of the chemical characterization to various studies are described. Measurements for elemental composition and distributions of molecular weight and boiling point of diesel particulates and related samples were carried out to gain a better understanding of the main components of diesel particulates. Determinations of carbonaceous components, elemental carbon and organic carbon, in diesel particulates were made by a thermal carbon analyzer, and these results were applied to the study of the relations between such components and the driving conditions of diesel vehicles and to the estimate of emission rates of carbonaceous components from on-road diesel vehicles in a highway tunnel. It seems that the thermal carbon analyzer can be used to advantage in the determination of such carbonaceous components. Artifacts of PAH and 1-NP during Collection of Diesel Particulates; In order to minimize the artifacts of PAH during collection of diesel particulates, three methods were investigated for the artifacts of BkF, BaP and BghiP; two methods incorporated the removal of reactive gaseous components such as NO2, with an ACF method and an impinger method, and the third was a high dilution sampling method. These results suggest that the high dilution sampling method is very promising. From the results of various studies including model experiments, it is clear that the artifact formation of 1-NP is of first order dependence on total amounts of nitrate on carbon black and diesel particulates, not on gaseous nitric acid, although second order dependence of the artifact formation on NO2 concentration is ambiguous. Aside from the above studies, the relation between 1-NP concentrations in diesel exhaust and NO2 concentrations in the dilution tunnel with changing the dilution ratio at a fixed driving condition was utilized for an estimate of the artifact formation of 1-NP, and the estimated results are discussed in connection with the reaction order of the artifact formation on NO2 concentration. Concentrations of Various Components in Diesel Exhaust and Ambient Air; Analytical results are presented for the PAH, mononitro-PAH and dinitro-PAH in particulate samples collected from the exhaust of both IDI and DI diesel vehicles and the ambient air in several areas in Japan and China.(ABSTRACT TRUNCATED AT 400 WORDS)