Abstract
On core samples taken from 907 meter boring penetrating the Quaternary-the middle Tertiary sediments at Tanakamoto-machi, Minato-ku, Osaka, total organic carbon, alkaline soluble organic carbon, humic acid, and fluvic acid have been analysed. The absorption spectra of humic acids extracted from those samples have been examined. The results obtained are as follows: 1) Except for samples containing substantial amount of plant residues, total organic carbon contents of core samples ranged from 0.1 per cent to 1.5 per cent, of which values had little difference compared with those of recent sediments in Osaka Bay. These results were not closely related to the increasing depth or facies of sediments. Accordingly it could be concluded that total organic carbon content in sediments might strongly reflect autochthonous organic matter content supplied into the sediments. 2) Alkaline soluble organic carbon contents, with a mean of 0.26 per cent, did not vary with an increase in depth. 3) There was a slight decrease in amounts of humic acid but not in amounts of fluvic acid with depth. 4) Sediments contained more fluvic acids than humic acids in quantity. 5) The patterns of absorption curve of the humic acids extracted from these sediments were roughly similar to those from soils. 6) Values of RF of humic acids varied from 49 to 145. Values of Δlog K of humic acids (log K_<400>-log K_<600>) ranged from 0.5 to 0.9 with a mean of 0.7. Supposing the degree of humification of humic acid indicated by these values, humic acids extracted from core samples are considered to have been moderately humified.
