[Effects of illumination on overlying water quality and on phosphate adsorption by sediment].
By the method of laboratory simulation, this paper studied the effects of illumination on the quality of overlying water and on the phosphate adsorption by sediment in a clean lake region. The results showed that under anaerobic condition, illumination could increase the pH value and the dissolved oxygen (DO) concentration of overlying water, while under aerobic condition, the concentration of dissolved inorganic phosphate (DIP) in overlying water declined fast at the beginning of the experiment, which indicated that DIP concentration was controlled by the DO concentration at the water-sediment interface. With the time went on, the DIP concentration in overlying water was much lower in the light than in the dark, indicating that illumination was the dominant controlling factor to the DIP concentration in overlying water. Phosphate could be adsorbed by the sediment with continuously loading, and the adsorbed amount varied with different environmental conditions. The effect of illumination on the phosphate adsorption by sediment was limited by the environment whether being aerobic or anaerobic.