Abstract: The invention provides novel environmental remediants and methods for remediating contaminated soils, earth, ground, or groundwater, particularly subsurface sites. The environmental remediants comprise a chemically or biologically active material, in the form of a particles which are on average less than about one micron, and a carrier which is interactive with an environmentally acceptable solvent. The carrier is capable of maintaining the particles in a persistent suspension which can permeate soil pores due to it small size, thereby delivering the remediant to the subsurface contamination. Significant advantages over prior art methods, particularly for metallic nanoparticles, are avoiding agglomeration, ease of application, and delivery to subsurface sites.