Abstract
Prior to instigation of the experimental work, a number of relevant topics were examined in detail in order to provide a perspective in which the experimental work could be viewed. Investigations were made based on the hypothesis that, assuming continuous plug-flow, the dynamics of the planktonic phase in a river are identical to those found in batch culture. The experimental procedure was applied to samples from two mildly polluted rivers; the River Wey at Guildford and the River Mole at Dorking. Nitrogen transformations were monitored together with changes in the bacterial community. The limitations of the experimental method were examined critically, especially with relevance to the problems of surface colonization, and detailed consideration was given to the efficacy of the microbiological and chemical techniques employed. The results showed that a quantitatively significant and qualitatively diverse community became established on the walls of the sample vessel. Also interesting relationships were observed between fluxes in the nitrogen cycle, particularly nitrification, and the structure of the bacterial community in the main body of the sample.