Abstract
To clarify long-term trend of pollutant loads into Tokyo Bay from its watershed, we analyze the temporal changes of freshwater discharge and T-P, T-N and COD fluxes through rivers, sewages, industries and precipitation. Although the freshwater discharge through the rivers was dominant, sewages, industries and precipitation were also found to be important sources of freshwater. The trend analysis of pollutant loads indicates that although the pollutant loads in winter decreases appreciably, the declining trend of the pollutant loads was not found in summer, showing the appreciable differences of long-term trend of pollutant load between winter and summer. Note that the pollutant loads in summer are significantly larger than those analyzed by a unit effluent load.
