Abstract
The impact of coexistent metal cations on the survival of diatom in the presence of polynuclear hydroxyl-aluminium ion was studied through the cultivation of Nitzschia palea under a weakly acidic condition (pH=6) and the monitoring of chlorophyll a. The presence of Zn higher than 0.2mg/l inhibited the survival of Nitzschia palea without Al. The presence of polynuclear hydroxyl-aluminium ion higher than 0.4mg/l inhibited the survival of Nitzschia palea without Zn. However, the survival of Nitzschia palea was adversely affected by the coexistence with lower level of Zn (0.03mg/l), even though the concentration of polynuclear hydroxyl-aluminium ion was 0.1mg/l. These results indicated that the coexistence of low levels of polynuclear hydroxyl-aluminium and Zn would cause the complex ecological effect on aquatic attached diatom. On the other hand, the coexistence with Ca or Mg higher than 10mg/l attenuated the adverse effect of polynuclear hydroxyl-aluminium ion on the survival of Nitzschia palea. However, the effect of Ca or Mg would be insignificant because their concentrations are lower than 10mg/l in water environment such as rivers.
