Inlake algal bloom control with enclosure ecosystem bags

The enclosure ecosystem bags are used to study the control of algal bloom with the chemical and biomanipulation method and to test the phosphorus threshold value for algal growth．The bags with a value of 2．8 m3 are filled with lake water and closely simulate the natural lake environment．The results showed that the application of aluminum and iron salts made the Microcystis colonies sink to the lake bottom and gradually die off,and as synergists，could greatly enhance the control of algicide．Salvinia，a kind of floating macrophyte，could also have inhibitmT effects on the growth of Microcystis．0．019 mg/L orthophosphate are regard as the threshold of Microcystis development．The mechanism of the effects of iron and aluminum salts were also discussed in the study．