Dispersion from a continuous line source located at the wall of a turbulent channel and transport over a step change in wall heat flux are studied for fluids with Prandtl numbers between 0.1 and 2400. Direct Numerical Simulation is used to develop the velocity flow field, which is then coupled with a particle tracking algorithm to describe the behavior of heat or mass markers released from instantaneous sources on the wall. The positions in time and space of these markers, which have been available as a database created by Papavassiliou and Hanratty [Int. J. Heat Mass Transfer 40 (6) (1997) 1303], are used as the building block for the study of passive scalar transport from the wall of the channel. Qualitative and quantitative results are obtained with particular emphasis on transport parameters from the wall.