Characterization of the Atmospheric Particulate Matter Observed at the Sites near the Heavy Traffic Road in Tokyo.
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The particulate matter (PM) emissions from motor vehicles were studied by measuring the atmospheric PM at the sites near the heavy traffic road in Tokyo. Measurements were performed in December 1997 and in June 1998, and each period was about two weeks.<BR>Size segregated PM samples were collected using the Andersen samplers at two sites, Hatsudai and Matsubara-bashi in December and Hatsudai and Wakamiya in June. Obtained samples were chemically analyzed by applying instrumental neutron activation analysis for elemental measurements, ion chromatography for water soluble ions, and thermal oxidation method for organic and elemental carbon.<BR>Continuous cumulative frequency functions were derived at first from the discrete cumulative percent values obtained experimentally for PM and various chemical components, and there size distributions were determined secondly as the derivatives of the cumulative frequency functions. Size distributions of PM were bimodal pattern with a valley around 1-2 micro-meter of aerodynamic diameter. On the other hand, for chemical components, each size distribution was distinctive reFLecting its emission sources and particle formation processes.<BR>The effect of motor vehicles on the concentration of atmospheric PM was mainly caused by exhaust particles emitted from diesel vehicles which occupied around 30% of traveling vehicles. Exhaust particles from diesel vehicle were dominated by elemental carbon. Approximately 80% of elemental carbon was in fi ne particle fraction, and its size distribution was remarkably one-sided toward small size. Because of resuspended soil and street dust, and emission of tires and brakes abrasion particles, crustal elements like Al, and some elements, Cu, Au, Mo, Sb, Ba, and Hf, attributed to the abrasion particles of tires and brakes were enriched in coarse particle fraction.<BR>Water soluble ions were second to carbonaceous component in atmospheric concentration among analyzed various chemical components, and these occupied considerable concentration in fine particle fraction especially in winter. Motor vehicles were the remarkable emission source of NO which is precursor of nitrate. Diesel exhaust particles contributed few to atmospheric sulfate even at the site near the remarkably heavy traffic road in Tokyo, because the diesel fuel with sulfur content of below 0.05 wt.% has been supplied already at that time.
- 社団法人 大気環境学会の論文
社団法人 大気環境学会 | 論文
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