Studies of the oil pollution on the fishing ground in Seto Inland Sea -II. Distribution of the oily wastes in the mud of sea bottom

The present work deals with the pollution of sea bottom by wastes from oil factories, as indicated by ether-extractable substances, ignition loss, COD and sulfide in the bottom mud. The distribution of ignition loss and ether-extractable substances are shown in Figs. 1 and 2, and relation between their values presented in Fig. 3. The marked correlations between them were observed in the regions of Osaka and Shimotsu, both of which have semicolosed geographical features. The appearance of visible spots or odor of oily waste was observed on the mud which contained ether-extractable substances more than 4mg/g, and located within the limits of 1Km from the out-fall of oily waste. The distribution of sulfide and COD in the mud are shown in Figs. 4 and 5. The relation between ether-extractable substances and sulfide or COD in the mud are given in Figs. 6 and 7. respectively. Both sulfide amounts and COD values increased with increment of ether-extractable substances. This tendency observed in the Shimotsu area, where oily wastes are mainly discharged, may indicate that the oil pollution brings about the increases of sulfide amounts and COD values in the mud.