Performance and design of artificial lagoons for controlling diffuse pollution in Lake Kasumigaura, Japan

摘要: Abstract Artificial lagoons (ALs) are unique wetland treatment areas for lakes. They use enclosed river mouth to retain pollutants, and they mimic the small natural rimming large lakes, functioning as habitats limiting entry of diffuse (non-point-source) pollutants from basins. Four ALs have been installed in Lake Kasumigaura (∼60 km northeast Tokyo) since 1998. We evaluated performance these facilities. Rates removal ranged 8.2% 44% chemical oxygen demand (COD Mn ), 0.9% 8.7% TN, 9% 55% TP. The long-term rate pollutant was proportional average hydraulic retention time declined exponentially with increasing loading (annual discharge/area) load/area). ratio AL surface area watershed also correlated performance, occurs stormwater wetlands, although ratios were much smaller than those wetlands. Our results can be used preliminary design tools ALs, on understanding that data obtained only should therefore applied carefully.