The effect of turbulence, induced by diffused bubble aeration, on mass transfer at the water surface of a pilot aeration basin was investigated. The mass transfer of ammonia from an enclosed headspace over the basin to acidified water was measured when different diffuser air flow rates were applied. Oxygen transfer tests were conducted immediately following each ammonia transfer test. Increasing air flow rates through fine and coarse bubble diffusers had a significant effect on the ammonia mass transfer rate; no effect of diffuser type on ammonia transfer could be determined. This infers an impact on oxygen transfer into the water at the surface, as well as potential transfer of VOCs from the water, if present. The results of the ammonia mass transfer experiments suggested that adjustments to the existing mass transfer correlations for surface volatilization from aeration basins may be in order. This will have the greatest impact upon predictions for the less volatile compounds under conditions of low off-gas flow rates.