Profiles of eddy diffusivity and the rate of dissipation of temperature variance were inferred from temperature microstructure measurements near a bubble plume at the center of a tank with a diameter of 13.7 m and a maximum depth of 8.3 m. Measurements occurred outside the bubbly part of the flow. Profiles of eddy diffusivity were estimated with two methods: one based on the equation for turbulent kinetic energy and one based on the equation for temperature variance. The eddy diffusivities showed nonmonotonic behavior with distance from the plume axis, as in numerical simulations. Eddy diffusivities estimated with the two methods match well, except for one data set with strong turbulence and weak stratification. The estimates of the eddy diffusivity allow two empirical formulas for the bulk, or tank-averaged, effective diffusivity to be evaluated; the bulk diffusivity is within the range of values predicted by the models.