摘要
Japan experienced severe water pollution throughout the period of high economic growth in the 1960s. With the concentration of population and industries in coastal regions, large quantities of pollutants such as chemicals, organic matters and nutrients flowed into the sea, and these caused health hazard and harmful algae blooms which damage fishery and living environment. To cope with this situation, the Water Pollution Control Law and various other laws and systems for pollutant control were established, and the installation of sewage systems and wastewater treatment facilities has been promoted. Total Pollutant Load Control System (TPLCS) has been implemented in Tokyo bay, Ise Bay, and the Seto Inland Sea. The TPLCS is designed to reduce the total amount of pollutant loads (target item; chemical oxygen demand, total nitrogen, total phosphorus) flowing into enclosed ocean. In the Seto Inland Sea, the largest enclosed coastal sea in Japan, the concentrations of nitrogen and phosphorus came to meet Environmental Quality Standards in almost all areas as a result of 40 year efforts including the TPLCS. However, some enclosed coastal sea areas in our country are still suffering from frequent generation of algae blooms and oxygen deficient water masses due to eutrophication. In other areas, on the other hand, the reduction of nutrient loads, hindering the circulation of nutrients to organisms of higher trophic levels in food chain, is considered to have changed the balance of ecosystem and caused a decline in fishery resources. For such areas, it is necessary to rebalance the circulation of nutrients through the entire cycle from land to sea areas. To deal with these problems, efficient and effective management policies for a smooth circulation of nutrients through land and sea areas should be specifically established for respective coastal sea areas. For this purpose, the Ministry of the Environment (MOE) has had discussions to develop “Action Plan for Healthy Material Circulation in Ocean-for 3 years since 2010. In addition, the MOE supports the restoration efforts of the regions affected by the Great East Japan Earthquake on March 11th of 2011. The environments of such areas were greatly damaged by landform changes in coastal lines and sea bottoms as well as disappearance of seaweed beds. We have assisted the environmental recovery, using the method and the knowhow of Sato-umi Creation. Sato-umi is defined as a coastal zone where the livelihood of human beings and the blessings of nature coexist harmoniously through human works with coastal area eco-systems. Under such circumstances, Central Environment Council submitted a report last October on Desirable Future Vision of the Seto Inland Sea. According to the report, the sea has multifunctional roles/values likened to “Garden- “Farm-and “Seaway- In addition, the report set out a vision of “Bountiful Seto Inland Sea-where these three functions are maximized in harmony with the environmental conservation for the sustainable use of the ecosystem service in the future. In response to the report, we will revise the master plan for the environmental conservation of the Seto Inland sea (Ministry of the Environment, 2000). Keywords Coastal management policy Enclosed coastal seas The total pollutant load control system Sato-umi Bountiful sea The healthy plan