The session is devoted to mixing and transport in geophysical and environmental flows. The transport includes that of passive tracers (e.g. oil, volcanic dust, chemical and biological constituents) and also active ones (e.g. density and vorticity). Theoretical, experimental and modelling results are all of interest, as are methodologies which can be used across traditional disciplines. The goal is that such studies will yield greater understanding of the turbulent processes occurring in the atmosphere and ocean.