Abstract
Our previous investigation had revealed various interesting aspects on tiny air bubbles found on the Abukuma river bed. The gas composition of the tiny bubbles were 99.8% of nitrogen, and it had been concluded that the river had been undergoing self-purification process of nitrogen. For the purpose of better evaluations of the microorganism activities related with nitrogen on the river bed, field research was carried out for two months from March to April 1995. On the other hand, we carried out batch tests with bed biofilms taken from the Abukuma river in which the initial NH4+- N and NO3--N concentration were adjusted as 10mg/l. In the tests, we found that the biofilms supplied the NH4+- N and NO3--N when the bacterial activities were low. In this report, we revealed the relationship between bacterial activities and nitrification and denitrification rate on the river bed.
