Compositions and methods for in situ ground water remediation. The compositions comprise a colloidal biomatrix comprised of sorbent particles, such as zeolites, organoclays and activated carbon, dispersed in aqueous solution that are injectable into the permeable zones of an aquifer to be treated. Once deposited into the permeable zones of the aquifer, the groundwater concentrations of contaminants in those zones are depleted, thus increasing the rate of diffusion of contaminants of the less permeable zones. The compositions and methods of the present invention can be used to treat any organic contaminants and provide rapid remediation of contaminated ground water by adsorption and biodegradation of such contaminants.