Abstract
To clarify the behavior of 1,4-dioxane in a water environment, concentrations and loads of 1,4-dioxane in water in the Tama River and its inflow rivers were investigated. Contamination of 1,4-dioxane was observed at every sampling point. The level of 1,4-dioxane in the river increased because of the inflow of the branches and especially inflows of those carrying effluent from sewage treatment plants. The cumulative load of 1,4-dioxane from catchments along the river stream from Nagata Bridge, as the uppermost point in this study, closely resembled the measured load at each sampling point in the Tama River. These results indicate that 1,4-dioxane was scarcely degraded, volatilized, or absorbed during flow down the river. The respective contribution rates of the loads of the branches and the sewage were estimated as 25 % and 75 %. Furthermore, the measured load of inflow was 30 times higher than the estimated loads based on Pollutant Release and Transfer Register system (PRTR) in the Tama River Basin. These findings suggest that the present PRTR has never covered the 1,4-dioxane emission sources completely.
