[Studies on algae and microcystin pollution in source water of Yellow River in Zhengzhou city].

OBJECTIVE: To study the law of development of pollution with algae and microcystin (MC) in source water of Yellow River in Zhengzhou city. METHODS: Algae and MC were detected continuously for source water samples collected from B and S Water Works of Zhengzhou in 1998. Microcystin was determined with high-sensitive ELISA. RESULTS: Monthly average density of algae was 1,439 x 10(4)/L in source water of B Water Works of Zhengzhou, with peak algae density of 4,762 x 10(4)/L in August, and that of S Water Works was 1,071 x 10(4)/L. Blue-algae of higher toxicity has become dominant species in source water from S water Works. Detection rate of microcystin was 70.83% in 24 samples collected from the two water works. CONCLUSION: According to Carlson's trophic state index (TSI), as well as other indices, such as total nitrogen, total phosphorus, chemical oxygen demands (COD) and algae density in water, source water in Zhengzhou has presented characteristics of eutrophication.