Liquid foam or foam is potentially capable of overcoming the intrinsic challenges associated with liquid-based delivery of engineered nanoparticles in the unsaturated zone. Foam is a particular kind of colloidal dispersion in which a gas is dispersed in a continuous liquid phase.  The focus of this research project is to investigate the capability of foam to transport NPs in unsaturated media. Below is an image of the experimental set-up (left) and a BTC figure (right) showing the NP (brown) and tracer (green) concentrations.