Abstract
Fluctuations of alkaline phosphatase activities in two streams and in reservoirs receiving the stream waters located in two adjacent but not connected watersheds were investigated from January to December in 2000. Alkaline phosphatase activities (APA) remained nearly constant in both streams, whereas in reservoirs they increased during the summer season. No relation was found between APA and soluble reactive phosphorus concentration. At one sampling station located in the stream, phosphorus concentration extraordinarily increased later in the study, but there were no related change observed in APA. An examination of size-fractionated samples suggested that most the APA in stream could be attributed to dissolved enzymes, whereas in reservoir most APA was related to bacterial particles. It assumed that APA is not indicative of phosphorus status of aquatic microorganisms.
