Studies on alga pollution and its toxicity of municipal water supplies

：Algae are the most frequently used biological monitoring indicators of waters eutrophication. In order to understand the status of algae pollution of municipal water supplies, monitoring of six times in a year for the main water supplies source algae in the city and the bioassay of toxic element extracted from lyophillized algal cell were performed. The results showed that the algae had polluted the water source at different level. 4 species of the algae were identified. Extracts from lyophillized algal cell posed hepatotoxicity through injection of rat stomach. The LD50 was 68.39-114.02mg lyophillized algal cell per kilogram body weight. It is suggested that algae should be a regular monitoring index indicating water quality, in order to supply basis for chosing the water source reasonably.