| Title |
A study on water quality variations on the artificial aeration in water supply system ( Lake Dalbang ) |
| Authors |
허우명(Woo Myung Heo),김재옥(Jae Ok Kim),김범철(Bom Chul Kim) |
| Abstract |
The effect of aeration on the water quality was investigated in a reservoir, Lake Dalbang, which is utilized for the water supply to Donghae City. Water quality has been getting worse from the beginning of impoundment and recently it showed the indication of eutrophication, such as the increase of cyanobacterial density and odor problem in drinking water. Six aerators were installed to improve water quality in 1996. Phytoplankton community and the concentrations of chlorophyll a, total phosphorus, and total nitrogen were measured from April, 1995 to December, 1997. The thermal stratification was destroyed after the onset of aeration. DO of September and October increased from 4-6 ㎎O₂/L before aeration in 1995 to 7-8 ㎎O₂/L in 1996 and 1997 after the destratification. The whole lake became isothermal at 18-20℃. Total phosphorus concentration of the water column decreased slightly from 15-40 ㎎P/㎥ in 1995 to 15-30 ㎎P/㎥ in 1997. The total algal biomass of growing season increased from 178 ㎎Chl.a/㎡ in 1995 to 1150 ㎎Chl.a/㎡ in 1997. But cyanobacterial cell density decreased from 20,640 cells/mL in August 1995 to 20-50 cells/mL in August 1997. Blue-green and green algae showed rapid decreasing trend since 1995, while diatom increased in 1996 and 1997. The dominant species in warm seasons of 1995 was Anabaena macrospora(occasionally Microcystis sp.). It was replaced by Asterionella formosa and Melosira granulara in 1997. From the result it can be concluded that total phytoplankton biomass increased by aeration. |