Two piston core samples were collected from the northern basin in the Japan Sea. The J-2 core showed sediment accumulated stratifically without disturbances. The J-3 core collected 60 km south of the J-2 site showed two thick turbidite layers. From the vertical profiles of the major composition, pronounced concentration peaks of manganese were found in both the core samples. One of the layers was enriched with only manganese in the J-2 core. This manganese rich layer may be formed during the early diagenesis processes. The other type of manganese rich layers was associated with the concentration peaks of calcium. This type of layers seemed to be characterized by the formation of the authigenic manganese oxides and the biological scavenging processes in the water column, while the environment of the Japan Sea changed from an anoxic to an oxic condition during the period from 10000 to 8000 yrs ago. The manganese concentration of seawater at the time before the transition period was estimated to be 110 μg/l, and the anoxic condition lasted over 15000 years by that period.

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The tidal data analysis from 1989 to 1994 in Hiratsuka revealed that the long period variation of sea level was influenced by variability of the Kuroshio, which flows in the neighborhood of the southern part of Sagami Bay. The spectral analysis for the Hiratsuka tidal data showed strong well-separated spectral peaks with typical time scales of 1 year, 80 days, 50 days, 33 days, and 24 days. The variability of 80 days is induced by the mesoscale variation of the Kuroshio and propagates from the southern part: Hachijyo and Miyake islands. The sea level affected by the variation with this period rises as the Kuroshio approaches to the Nojimazaki, to the Irozaki and vice versa. This result suggests that the oceanic conditions of Sagami Bay are affected from down stream side of the Kuroshio. In particular, when the Kuroshio front approaches to the Nojimazaki in wrinter, the rapid temperature rise occurs: the sea level rises rapidly before the rapid rise of the temperature. In this case, the strong westward currents were observed in Hiratsuka. This phenomena developed to the "Kyuu-Chou", which damaged the Yellowtail fixed nets, in January 9, 1994. When the Kuroshio front is away from the Nojimazaki in summer, the sea level falls with the fall of the temperature. These phenomena may propagate to Hiratsuka as the Kelvin waves and may play an important role for the mixing in Sagami Bay.

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Marine microorganisms transform a wide variety of organic compounds in the way as follows: Firstly, the turnover times of easily metabolizable constituents have been shown to be less than a few days in hypereutrophic waters, a few days in eutrophic waters, between a few days and several tens of days in mesotrophic waters, and several tens of days in the surface layer of oligotrophic waters. Secondly, the turnover times of moderately resistant constituents have been shown to be between several days and several tens of days in hypereutrophic waters, between several tens of days and several months in eutrophic waters, several months in mesotrophic waters, and a few years in the surface layer of oligotrophic waters. Finally, the decomposition rates of most refractory constituents of organic materials are regulating the outside cycling rim of turnover of biological elements as a whole; i. e., the turnover times of refractory constituents, both in dissolved and particulate form, have been shown to be between half a year and one year in hypereutrophic waters, several years in eutrophic waters, several tens of years in mesotrophic waters, and between several tens of years and hundreds of years in the surface layer of oligotrophic waters, and possibly several thousands of years in the deep layer of oligotrophic waters.

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