Environmental and ecological engineering on control and remediation of eutrophicated waterbodies: by using ameliorated alum plasma and fishes to control blue-green blooms of qiaodun reservoir

The blue green algae bloom broke out in the summer of 1997 and 1998 in Qiaodun reservoir. The emergency dealing with the “bloom" by insufflating ameliorated alum plasm of 38.8?g each square meter of water was carried out in Sept. of 1998 and the “bloom" disappeared this year. 1200 seedlings of silver carp and bighead with individual weight of 20?g per hectare water were cultured in the waterbody during the end of 1998 to the beginning of 1999. The cell number of Cyanophyceae in Aug. of 1999 descended by 77 7 percent and the transparency heightened 1 5 meters according to the corresponding period of 1998. The blue green bloom appeared no longer in 2000 and 2001, and the sight of water meliorated apparently. Compared with the corresponding period of 1998, The transparency in Aug. of 2000 heightened 2 4 meters, of T N and T P decreased by 61 1 and 59 4 percent respectively. The cell number of Cyanophyceae dropped to 143 3×10 4 per liter from 10435 5×10 4 per liter of 1998. The number proportion of Cyanophyceae dropped to 31 5 percent from 99 2 percent of 1998. The water status of eutrophication got back to medium dystrophic type from medium eutrophic type of 1998.