Temporal and spatial variations of hydrogen peroxide, organic peroxide, carbon monoxide, Fe(III) and Fe(II), which are crucial species to control the photochemical processes in coastal seawater, are investigated in the western part of the Seto Inland Sea on May 15-19, 1995. Concentrations of hydrogen peroxide and carbon monoxide wee higher at the surface and decreased with depth, while the vertical distributions of organic peroxide and soluble Fe(II) were found to be almost uniform or a little higher at the bottom layer. Soluble Fe(III) increased with depth and the concentrations at the sampling point near the mouse of the river were higher than those far from river and land, suggesting that suspended matter supplied from river and bottom of the sea was the source of soluble Fe(III). Concentrations of hydrogen peroxide, carbon monoxide and soluble Fe(II) in surface water tended to increase with solar radiation. Especially, diurnal variation of carbon monoxide was clearly in accordance with solar radiation. These results strongly suggest the photochemical formation of hydrogen peroxide, carbon monoxide an soluble Fe(II) in the surface and near-surface waters. Diurnal change of organic peroxide was the reverse of that, the concentrations of organic peroxide in the daytime were lower than those during the nighttime.

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Seasonal variation of Soya Current along the Hokkaido coast in the Sea of Okhotsk was investigated both by the long-term current record obtained at the moored station off Sarufutsu and adjusted sea level record at the tidal stations along the Hokkaido coast. The current record shows significant seasonal variation, i.e., strong in summer and weak in winter. The current variation is closely correlated with the sea level difference between by high sea level in the Japan Sea compared with that in Sea of Okhotsk, while the weak current in winter is due to small difference of the sea level between both seas. This fact strongly depends on the unique seasonal variation of the sea level along the Hokkaido coast in the Sea of Okhotsk, i.e., maximum in winter and minimum in spring. The high sea level in winter is retained by the low salinity water in the subsurface layer of the southern part of the Sea of Okhotsk (Ito, 1997) and found along the southern coast of Hokkaido. The interannual variation of sea level along the Hokkaido coast in the Sea of Okhotsk in winter correlates with the Monsoon-Index (MOI) variation defined as difference of atmosphere pressure between Irkutsk in Russia and Nemuro in Hokkaido.

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Afterslip of the 1978 Off-Miyagi Prefecture Earthquake occurred in June 12 1978, which was originally detected by a seismologist using coastal sea level data, is reanalyzed by means of different detection procedures. Time series of sea level difference between two tidal stations shows the short period variations which seem to be oceanic origin. It is found that in order to obtain the plausible crustal movement, the median filter with the window of several ten days to a hundred days is appropriate. In the coastal sea level data, mixed signals of oceanic variations and crustal movements exist, and in order to precisely detect each of them as much as possible, close collaboration between the researchers of both fields should be done in future.

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