Study of Sumida River, Part-1; Its COD and EC characteristics from data collected in spring, 2021

The Sumida River, a typical urban river in Tokyo, has been recognized as a site for fostering Tokyo’s urbanlife that serves as a venue of leisure and relaxation for its residents. As the Teikyo University of Science(TUS) is located near the Sumida River, students spend a lot of time nearby. Clarifying the characteristics ofSumida River, and teaching it to students, are important not only for enhancing environmental awarenessamong students, but also local environment conservation. In this study, chemical oxygen demand (COD)and electric conductivity (EC) data, major sources of contamination, and the characteristics of the river wereanalyzed and interpreted as follows. 1) Although our COD and EC data showed that Sumida River wasaffected by tidal movement, the river water in our research area (from Otakebashi Bridge to Senju-OhashiBridge) might exhibit backward and forward movements, and it was slightly affected by sea water from theTokyo Bay. 2) Major chemical contaminant sources of investigated area were determined to be the Miyagiwastewater purification facility (WPF) and the Mikawajima WPF at the upstream and downstream sides ofthe TUS, respectively. 3) We presume a two-fraction zone in the Sumida River from our analytical resultsand public data, including a "high COD zone" with an upstream stagnant zone upper the Shirahige Bridge,and a "low COD zone" with a downstream flush zone under the Shirahige Bridge. Raising environmentalawareness concerning the urban river among its residents presumably might contribute to maintaining itsclean and safe environment. We came to conclusion that the importance of educating the citizens aboutkeeping urban rivers environmentally clean and safe for the future generations