A new method of evaluating the rate of mineralization of photoassimilated organic matter is described. This method enables us to compare the rate of direct mineralization of particulate organic carbon (POC) to CO₂ with the rate of solubilization of photoassimilated organic carbon followed by the mineralization of the resultant dissolved organic carbon (DOC) under the same conditions. The direct mineralization of photoassimilated carbon from POC to CO₂ is a more significant process compared with the mineralization of extracellular released organic carbon. The first-order rate coefficients range from 0.132 to 0.434 day^-1 for direct mineralization and 0.034 to 0.189 day-1 for solubilization.

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Backscatter cross-sections of microwaves from the sea surface are calculated by using the facet model and are compared with JONSWAP '75 experimental results. The principal features obtained are:(1) asymmetry of backscatter cross-sections between upwind and downwind directions is attributable to the modulation of the short gravity-capillary wave spectrum by a larger wave, and the non-Gaussian wave slope distribution has a tendency to cancel this effect, (2) angular spreading of the energy spectrum in the higher frequency range should have a narrower band than a simple cosine distribution, (3) the facet model itself should begin to break down at a larger incident angle than previously supposed.

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The vertical transport of PCBs and chlorinated hydrocarbon pesticides such as DDT compounds and HCH (BHC) isomers in the deep sea are discussed on basis of their vertical profiles and the proportion of their adsorbed and dissolved fractions in surface water surveyed in the Western Pacific, Eastern Indian and Antarctic Oceans.
All chlorinated hydrocarbons determined were detected with measurable concentrations throughout the water column, even at depths of several thousand meters. The vertical distributions of PCBs and DDT compounds were found to show small variations in concentration throughout the water column, whereas HCH isomer concentrations decreased systematically with depth. A large portion of DDT compounds in surface water was adsorbed on suspended solids, while most of the HCH isomers were present in the filtered water. The proportion of PCBs adsorbed on suspended solids was smaller than the proportion of DDT compounds, but was much greater than that of HCH isomers. These observations suggest that HCH isomers have been slowly scavenged from the surface to the deeper layers in the water column, while PCBs and DDT compounds have been rapidly and abundantly transported downward by sinking particles.
The percentages of chlorinated hydrocarbons adsorbed on suspended solids in surface water increased towards the high latitude locations, and the percentage seemed to be proportional to the concentration of suspended solids in the surface water. This implies that the residence time of chlorinated hydrocarbons in the water column will differ significantly among oceans that differ in primary productivity. According to our estimation based on the data presented in this study, the residence time of ΣHCH in the euphotic zone, the top 100 m of the water column, is more than 2 years, whereas those of PCBs and ΣDDT are less than 1 year. The longest residence time, of from 5 to 10 years, was obtained for ΣHCH in oligotrophic water of the western North Pacific. The shortest value, only 11 to 19 days, was estimated for ΣDDT in the Antarctic Ocean.

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The mechanism and rate of water exchange were investigated in Kabira Cove, Ishigaki Island, in the southernmost part of Japanese islands, near Taiwan. During observations in the summers of 1976 and 1977, a larger proportion of the salt transport into the bay was derived from the so-called “tidal trapping effect”. In the latter period of observation carried out after heavy rain brought by a seasonal typhoon under annual mean tidal conditions, the turnover time, i. e. the scale of replacement of the whole bay water with the open sea water, is estimated to be 3.6 days.
Based on these observational results, a concept of the tidal trapping due to coupling of the actions of tides and buoyancy in a vertical two-dimensional field with a sill at the bay mouth is proposed. Considering the topographical, hydrometeorological and geographical conditions of the cove, it is inferred that this water exchange process tends to be formed in Kabira Cove in summer except during neap tides.

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Hydrographic data taken at 25 equally spaced stations along 35°N in April 1976 and again in July 1977 are compared for the longitude range 139-163°W and the depth range 0-1, 000m. A continuous subsurface layer is found, centered at 100 m and extending more than 2, 000 km in the east-west direction, in which the temperature and salinity were significantly lower and the density and concentrations of oxygen and three nutrients were higher in the summer of 1977 than in the spring of 1976. In the upper 50 m the temperature and salinity were higher and the density and concentrations of oxygen and nutrients were lower in the summer of 1977 than in the spring of 1976. These relationships are concluded to be due to an annual variation by association with other existing data sets in the same region. The annual variation of hydrographic properties in the upper 200 m can be qualitatively explained by an annual variation in the north-south component of the permanent circulation, which is caused by an annual variation in the large-scale north-south pressure gradient (related to the northward temperature gradient). The observations are consistent with a northward current near the surface and a southward current near 100 m which are both faster in summer than in winter (and spring).

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Sedimentation rates were determined with the ²¹⁰Pb technique in six sediment cores from Harima Nada (Harima Sound), Seto Inland Sea. The rate of deposition varies from 0.11 g cm^-2y^-1 in the northern part to 0.33 g cm^-2y^-1 in, the southern part of the basin. A marked increase in copper and zinc content was observed above a depth in the core corresponding to about 1900 A. D. as a result of increasing human activities. Anthropogenic input of copper and zinc decreased slightly after 1970. Natural background levels of copper and zinc in the sediment in this sound are 11-16 ppm and 100-120 ppm, respectively. The total amounts of anthropogenic. copper and zinc in the sediments were estimated to be 110-180μg cm^-2 and 610-1, 280μg cm^-2, respectively. These values constitute 40-50 % of the total sedimentary input of copper and zinc in the sediments since about 1900 A. D.

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