Research Study and Suggestion on the Regeneration of Tidal Flat Environment at Fujimae Tidal Flat in Nagoya Port

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There is a basin with 150m width, 400m length and 6m depth in the Fujimae tidal flat. Water in the basin is so strongly stratified during summer season that anoxic water is accumulated in the basin. But a strong turbulence such as a typhoon would spill out the basin water with poor dissolved oxygen into the surrounding tidal flat. In this study I estimated the effect of meteorological turbulence on the stratification of the basin water and also on the tidal flat environment. Another environmental problem in the Ise-Mikawa Bay is the persistence of poor oxygen environment in the bottom layer of more than half area of the Bay during summer.This environmental deterioration is due to the reclamation of tidal flat and shallow marine region. So that I have researched and monitored changes in water qualities after the reclamation of Chubu International Air Port Island (580ha) and Mae-Jima Island (130ha) at Tokoname shore, co-working with other research on the changes of bottom sediment qualit … More y and benthic fauna.From the results of observation at Fujimae basin on 22 August in 2002, it was confirmed that a meteorological turbulence by typhoon No.13 mixed the water column of the basin and resulted 10-15% of oxygen saturation which affected severe damage on the surrounding tidal flat environment. On the other hand, on 12 August, just after the typhoon No.10 approached nearest to Ise-Bay, no turbulence was observed at the basin. In this case, the typhoon passed through from Osaka-Bay to Hokuriku region and brought the southern wind which did not make large turbulence in the Ise-Bay.Sediment pore water was sampled before and after the low tide at Fujimae tidal flat in order to estimate microbial activities such as nitrification, de-nitrification, sulfate reduction and sulfur oxidation. Analysis of pore water showed that sulfate reduction became major microbial decomposition process in the tidal mud from spring to summer with increase of organic matter supply. Analysis of sediment pore water also showed NH_4+ decreases and PO_4^<3->increases after the low tide which suggested that ammonium oxidation and organic matter degradation should be stimulated during the low tideWater quality observations around the Air Port Island off Tokoname suggested a deterioration of marine environments after the reclamation of Air Port Island. In spite of the beginning of water column mixing at the middle of October in 2002, one station with a depth of 12m (St.K1) showed 50% of oxygen saturation at the bottom. But at the same period in 2003, oxygen saturation at two more stations with a depth of 12m (St.K2) and 15m (St.A10) decreased to 50%. From these environmental deterioration by the reclamation of Air Port Islands, it is strongly recommended to regenerate lost tidal flats or shallow marine regions in Ise and Mikawa Bay. Less