Tóm tắt
Alkaline phosphatase activities were determined in water samples taken from three depths at a central point in Lake Kinneret (Lake Tiberias). Seasonal fluctuations were shown, and also indications of induction‐repression or activation and inhibition mechanisms, or both, with respect to total phosphorus, and, during stratification, the existence of a metalimnetic layer of intense activity. Phosphatase activities with “natural” substrates and estimates of phosphorus availabilities were derived by measuring release of soluble inorganic orthophosphate from samples saturated with chloroform. Phosphorus, which appeared to be adequate during the main bloom season, may have become limiting from the end of summer until overturn. In epilimnetic waters 30–66% of total phosphorus was hydrolyzed with a turnover time of 3–6 days.
