A study was initiated to observe the concentrations of different nitrogen species in pore water and the solid phases of sediments. Additionally, nitrogen release, ammonium desorption, and denitrification rates in lake sediments were experimentally performed. For an eutrophic lake, the average denitrification rate was approx 14.6 mg N/m2·h within a 5‐cm layer of the sediment; the rates decreased with an increase in sediment depth. By considering adsorption, desorption, and denitrification processes, a model was developed to describe the transformation of nitrogen species between the sediment and the aqueous solution and to predict the effects of nitrogen forms in sediments on the water quality of the overlying water bodies.