Water Pollution in Tokyo Bay, Osaka Bay, Lake Biwa and Kasumigaura - 2020s

Water Pollution in Tokyo Bay, Osaka Bay, Lake Biwa and Kasumigaura - 2020s

In the 2020s, water pollution in Japan remains a serious problem, with Tokyo Bay, Osaka Bay, Lake Biwa, and Kasumigaura being particularly polluted; in the 2020s, chemical oxygen demand (COD) in Tokyo Bay and Osaka Bay reached 7.4 mg/L and 6.9 mg/L, respectively, far exceeding standards. In Lake Biwa, total nitrogen and phosphorus concentrations reached 1.5 to 2.0 mg/L and 0.10 to 0.12 mg/L, respectively, indicating that eutrophication is ongoing. Kasumigaura is the most polluted with a COD of 10.5 mg/L. The main causes of these pollutions are untreated wastewater from households and wastewater from factories such as ENEOS Holdings and Showa Denko around Kawasaki City. Furthermore, according to a 2022 survey, 0.8 microplastics per square meter were detected along the coast of Tokyo Bay, seriously affecting the marine ecosystem and food chain.