Phosphatase in sediments in Lake Donghu, Wuhan can be classified as alkaline phosphatase, showing a higher activity at alkaline pH ranges.The kinetics of alkaline phosphatase exhibited a distinct spatial heterogeneity in sediments of Lake Donghu and Yanxihu, which is not significantly correlated with the concentrations of soluble reactive phosphorus in interstitial water, overlying water and surface water.Furthermore, it varied greatly in vertical profiles, and peaked both at surface and in a middle layer (8-12 cm beneath the surface).The latter added a new dimension in which P cycling mediated by some biochemical mechanisms is active.