Colloid-facilitated Contaminant Transport in Natural Porous Media: Experimental Studies and Modelling

Mobile colloidal particles have been identified to be involved in a broad variety of environmentally relevant processes. A considerable number of these processes may have hazardous consequences. Most recently, mobile colloidal particles have been reported to be a potentially relevant transport pathway for strongly sorbing contaminants. Thereby the colloidal particles act as highly mobile contaminant carries and enhance in such a way the spreading of sorbing pollutants in subsurface systems. Therefore, considering potential hazardous incidents due to mobilized colloidal particles should represent a critical task in risk assessment of any subsurface contamination problem, in the development of remediation strategies, as well as in recharge and waste water management. In order to judge or predict the susceptibility of a subsurface system to the phenomena of enhanced contaminant transport by mobile colloidal particles, a detailed understanding of the following processes is required: (i) the generation of mobile colloidal particles, (ii) the life-time of these particles within the system, and (iii) the association of the contaminant with the mobile particles. In the present paper various aspects of the diverse problem of enhanced contaminant transport by in-situ mobilized colloid particles will be addressed.