中小都市河川における有機汚濁物質の分解と蓄積

抄録

Organic carbon balance model was utilized to describe the variations of SS, DOC and sediment in urban polluted rivers. This model incorporates dispersion, convection, sedimentation, aerobic decomposition, anaerobic decomposition and growth of benthic biomass.
The calculation based on this model is compared with the observed values in the Nogawa River - one of the tributaries of the Tama River - a shallow and polluted river with approximate flow rate of 0.46 m³/sec at midreaches.
The model shows that considerable fraction of suspended solid is accumulated in sediment of the river. This is the reason why apparent high selfpurification constants are observed in midreaches. The sediment is flushed out during showers and heavy rains. Run off of organic carbon (3.3 ton) was observed during a shower on July 13, 1981. The estimated value from the model reasonably explains this result which assures the plausibility of the model proposed.