Characteristics of the hourly and seasonal high concentration frequency pattern of SO_2, NO_x, OX and SPM in Yamaguchi Prefecture, Chugoku region, Western Japan

摘要

The distributions of SO_2 NO_x, OX and SPM concentrations for 1991 - 96 in four different cities in the Yamaguchi Prefecture were analyzed to depict the air pollution conditions in this region. The trends of annual pattern of the mean concentrations show an increasing trends in SO_2 and OX concentrations in all the four cities. For NO_x in Yamaguchi city and in Kokusetsu Ube, it shows a little increasing trends, but in Ube city office, Shimonoseki city and Tokuyama city it is decreasing. The seasonoal pattern shows that in Spring and in Winter, the concentrations of pollutants are high. Among the pollutants, the concentration of NO_x is higher in winter only, while OX and SO_2 have their higher concentrations in spring and winter. In smmer, the concentrations of NOx, OX and SO_2 are the least, though the highest values of SPM varied differently according to the city and seasons.