Abstract
The amounts of changes in loadings and concentrations of pollutant matters, during flowing down in an irrigation channel without influx and efflux to outside, were estimated from the view point of mass balances under the ordinary loading condition by three diurnal observations and a daily observation. The diurnal means of flowing down rates for the conservative dissolved matter were nearly about 1.0, but most particulate organic matters ranged from 0.7 to 1.0. In an urban river where the concentrations of P04-P and SS were high, dissolved P04-P became particulate phosphorus with the adsorption to the suspended solids. But in the channel where both concentrations and the ratio of P04-P/SS were lower than urban rivers such changes were small and inconspicuous. The inclusive self-purification coefficients of organic matter including sedimentation and adsorption became larger than that by the conventional method using impulse injection of refined organic matter of high concentration. In the regular rectangular channel where the discharge and the water quality were stable, the removal of organic matter with sedimentation and adsorption was made clear to play an important roll in the inclusive self-purification as well as a river.
