Effect of lake sediments of different trophic states on alkaline phosphatase activity.

Samples of sediments, interstitial water and overlying water were collected monthly under temperature-controlled conditions to determine the effects of sediment types on the alkaline phosphatase activity (APA) in lake systems. The relationship between the total alkaline phosphatase activity (TAPA) and soluble reactive phosphorus (SRP) concentration also was examined. The study results indicate the variations of TAPA in the overlying water, and the interstitial water in different layers from different sediments was similar over time. They were influenced not only by the phosphate concentrations, but also were correlated with submerged plant and phytoplankton biomass. The direct effects of the sediment types on the APA were not readily obvious. Although the higher APA in sediment was probably responsible for the enzymatic response to the characteristics of sediments, other factors (e.g. growth of submerged plants and phytoplankton) also should be considered. The peak of the maximum velocity of the enzyme reactions (Vmax) at deeper sediment layers suggests another stratum in which the enzymatically mediated phosphorus regeneration was active. This finding contributes to our understanding of phosphorus cycling in lake sediments. [ABSTRACT FROM AUTHOR]