Studies on development of new method for water quality assessment using microcosm system

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Tne aim of this study is to establish a new method for water quality assessment with the experimental examination about the development of an aquatic microcosm system as one of model ecosystems which consist of bacteria as decomposer, algae as producer, and protozoa and micro metazoa as consumer, and which shows very high reproductivity and reflectivity of natural eco-system, and about the prosperity and decay of these microbiota with addition of surfactant such as detargent, chemical pesticide, and/or genetically engineered microorganisms such as micribial pesticide. This year, environmental assessment of these matters using microcosm system was attempted.In the case of surfactant addition such as LAS, soap and composit soap, it was made clear that the effective concentration to the microbiota of micricism system was lower that that of EC_<50> which was employed usually, and a possibility of analysis of gas balance in matter cycle with closed micricism system was showrd.In the case of … More chemical pesticide addition such as symadine and benziocurb, it was made clear that the effect to micribiota was different by the sort of pesticide, and that herbicide has no effect with the concentration of the environmental standard, and that micricism system is able to be one of essential method to decide the ranking of effectiveness to ecosystem.In the case of genetically engineered microorganism addition such as microbial pesticide, it was made clear that predation of protozoa and micro metazoa very affected to the prosperity and decay of genetically engineered microorganisms, and the pattern of prosperity and decay of these bacteria in microcosm system was controled by the combinetion of host bacterial strain and plasmid DNA.From these results obtained from this study, it was made clear that our aquatic microcosm system is expected to be one of a valid method for environmental assessment, and that more correct assessment will be possible with the combination of monoxenic culture test, flask-size microcosm test and natural lake model ecosystem as tier test method. Less