The occurrence of vertical nutrient mixing in central Long Island Sound was simulated for the period from July 23 to August 29, 1986 using a one-dimensional mixed-layer model based on Mellor and Yamada (1974)'s level 2 turbulence closure scheme. During most of the study period, the water column was stratified and the nutrient fluxes through the thermocline were driven by the combined effect of the wind and the tidal mixing. The nutrient entrainment at the bottom of the thermocline was tidally induced, while that at the top of the thermocline had a pulsating character resulting from the interaction of the wind stress and wind-generated inertial currents. Near the end of the summer, the combination of strong wind stress, surface cooling and spring tide completely broke down the stratification. The relieved upward nutrient transport was an order of magnitude larger than during the stratified period, which could result in the observed phytoplankton bloom. Model results agreed well with observations, suggesting that the mixed-layer model can be used for prediction of vertical fluxes of nutrients and other dissolved materials in Long Island Sound.