TERRAPUB Journal of Oceanography

Journal of Oceanography, Vol. 55 (No. 3), pp. 427-437, 1999

Current and Material Transport at Tomogashima Strait, Japan

Akira Hoshika, Terumi Tanimoto and Yasufumi Mishima

Chugoku National Industrial Research Institute, 2-2-2 Hiro-Suehiro, Kure 737-0179, Japan

(Received 14 July 1998; in revised form 18 January 1999; accepted 18 January 1999)

Abstract: Tomogashima Strait, which is an entrance of Osaka Bay, is a very important area for material transport because a large volume of pollutant-rich water in Osaka Bay is transported through this strait. We have investigated the cross sectional structures of current and material fluxes at Tomogashima Strait, Osaka Bay. Tidal current and residual flow patterns in cross section at Tomogashima Strait during summer and winter are almost the same, and residual flow in summer is stronger than that in winter. However, the net water exchange through the strait in summer was almost the same volume as that in winter. At Tomogashima Strait, total suspended matter (TSM) and particulate organic carbon (POC), and individual nitrogen and phosphorus compartments in Osaka Bay always flowed out except particulate organic nitrogen (PON). The average outflows of total nitrogen (TN) and total phosphorus (TP) at Tomogashima Strait over a year were calculated to be 145 ton/d and 30 ton/d, respectively. The average outflow of DIN and DIP at Tomogashima Strait over a year were 95 ton/d and 13 ton/d (DIN/DIP = 16), respectively. Residence times of both DIN and DIP in Osaka Bay were estimated to be about two months.

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