In Hsinsan water reservoir, located in northern Taiwan, Microcystis bloom was found to occur periodically in late spring. A long-term monitoring, from 2005 to 2009, was conducted to study the relationship of this event with the physico-chemical variables in waters. The results of correlation analysis showed that Microcystis bloom was more closely correlated with those chemical variables such as organic carbon, organic nitrogen, ammonium, and biochemical oxygen demand than others. These variables were originated from the pollutants partly of the input from input of surface waters (i.e. riverine origin) and others from the reservoir interior caused by an overturn of reservoir water, which occurred usually in winter. As a result of such overturn, the hypolimnion water containing high concentrations of pollutants would be brought to epilimnion and thus favorable for the outgrowth of Microcystis in subsequent time there, when water temperature and irradiation were elevated. A control of the depth of river water input was proven to have successfully depressed the occurrence of Microcystis bloom in late spring and summer.
展开▼
