Studies on Dissolved Metalloenzymes in Lake Water. III. Correlation between Dissolved Alkaline Phosphatase and Orthophosphate in Lake Water

Alkaline phosphatase activity (both dissolved and total) in Lake Kasumigaura was determined periodically together with concentrations of phosphorus compounds therein. Distinct negative correlation was found between the dissolved alkaline phosphatase activity and the orthophosphate concentration during the phosphorus-limited season. The decrease of the concentration of dissolved alkaline phosphatase was observed at the level of 1 ng ml−1 of orthophosphate. The present results suggest that both alkaline phosphatase in vivo and dissolved alkaline phosphatase in the lake water play important roles in phosphorus cycles in natural water.