Small Particles - Big Change? Engineered Nanomaterial Effects on Soil Subsurface Properties

A large number of research papers on the fate of engineered nanomaterials (ENMs) in the soil-water system have appeared in recent years, focusing on ENM transport, persistence and toxicological impact. However, very few studies have examined the impact of ENMs on the natural soil-subsurface matrix and its properties. Potential irreversible changes to natural soil-subsurface systems that originate from contact with other chemical contaminants of anthropogenic origin have been noted previously. Such changes are considered to have a substantial impact on the liquid phase and solid matrix properties. ENMs reach the land surface through many pathways during and after their beneficial use. Once in the soil, ENMs move as suspended particles in aqueous solution. Dissolution, aggregation and deposition are the primary processes governing their interaction with the soil solid phase and their redistribution from the land surface to the groundwater. We argue that irreversible deposition of ENMs occurring under specific conditions (e.g., in arid and semi-arid environments) may lead to irreversible changes in soil matrix structure and properties. Results from our research on metal and metal oxides ENMs (e.g., CuO, Ag) and from literature on carbon based nanomaterials will be presented in support of our hypothesis.