Effects of light and aeration on competition between Microcystis aeruginosa and Scenedesmus quadricauda and phosphorus release at the water-sediment interface
光照与通气方式对蓝、绿藻竞争生长和磷的水沉积物界面过程的影响

Competition between Microcystis aeruginosa and Scenedesmus quadricauda and phosphorus release at the water-sediment interface were studied in laboratory simulation experiments where lighting and aeration were varied. The results showed that Microcystis aeruginosa was dominant in both aerobic and anoxic experimental conditions. The sequence of phosphorus concentration in overlying water was: no light irradiation > light irradiation, anoxic condition > aerobic condition, and the changes were related to algal growth. The bioactivity of algae and microorganisms was increased under light irradiation, which stimulated the release of bio-available phosphorus from sediments. So the quantity of phosphorus released from sediments under light irradiation and aerobic conditions was much higher than that in an anoxic environment. In the anoxic condition, the main released fraction of phosphorus in the sediment was Fe-P, and the concentration of Ca-P increased only a little. However, under aerobic conditions, the concentration of Fe-P had no obvious changes, and Ca-P declined slightly in the light. No obvious changes were found for the concentration of total phosphorus, organic or residual phosphorus.