1. The hydrocarbons of sediments were analyzed with gas-liquid chromatography. The biogenetic hydrocarbons (pristane and squalene) as well as n-alkanes were detected.
2. Considering the distribution of pristane plus squalene/n-alkanes ratio and the fact that this ratio was coincident with that of lipid content, it is recognized that the hydrocarbons of mud were mainly derived from the organisms in this area.
3. It is supposed that this area was not too polluted to give petroleum odour in fish as of summer of 1973 and winter of 1974.