A separations tray assembly for use in a fluid-fluid exchange column. The separations tray assembly is of the type where a first fluid, in a continuous phase, is directed across successive trays in a serpentine flow path. A second fluid, in a dispersed phase ascends through apertures in the tray thus inducing interaction and mass transfer with the first fluid. In accordance with one aspect of the present invention, the separations tray further includes a diffuser skirt, having apertures disposed therein, operatively coupled to a fluid channel. The diffuser skirt is operable to direct the first fluid to cover substantially an entire volumetric cross-flow window between successive separations trays and to induce stirring and mixing of the first fluid and the second fluid to effect efficient mass transfer.