Hello,
It depends how you want to model it. Perhaps you can explain more exactly what you want to do.
If modelling tracer in Eulerian way, you can find examples with TRACERS in the TELEMAC-2D and TELEMAC-3D examples and validation manuals (e.g. telemac2d/flume_tracer, telemac2d/pildepon, telemac3d/pildepon, telemac3d/source). Basic ones are e.g. in pildepon (2D or 3D).
If modelling tracer in Lagrangian way, you can find examples with DROGUES, ALGAE or OIL SPILL, e.g. telemac2d/flotteurs, telemac2d/canalalgae, telemac2d/2Dcoupling_algae, telemac2d/riv_art, telemac3d/particles).
Basic is drogues (rather than algae or oil spill), hence flotteur in 2D or particles in 3D.
Hope this helps,
Chi-Tuan