Fig.l Study area with 6 observation 
points in Osaka Bay. 
Fig. 2 Flow chart of analysis adopted 
in this study(bold line). 
Fig.3 Chromaticity diagram at 6 
stations in Osaka Bay from 
1983 to 1992. 
Fig.4 Chromaticity diagram with 
definitions of main wavelength 
and purity. 
43