Transport and mobilization of engineered nanoparticles in the vadose zone and groundwater

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The increased use of engineered nanomaterials in the past few decades has resulted in release of engineered nanoparticles to subsurface environments. Many engineered nanoparticles are highly reactive and can cause extensive damage to humans and other organisms. To evaluate the scope of nanoparticle contamination in soil and near-surface sediments, and the potential risk of nanoparticle contamination of groundwater aquifers that are used as drinking water sources, a better understanding of how nanoparticles are mobilized and transported in subsurface environments is essential. In the last few years, some progress has been made in understanding nanoparticle transport in groundwater (water-saturated media). However, we know little about how nanoparticles are mobilized and transported in soil and partially-saturated sediments (i.e., the vadose zone). The overall objectives of my research program is to identify the major factors that control nanoparticle mobilization and transport in the vadose zone and groundwater, and to develop a mathematical model to predict nanoparticle migration in subsurface. My short-term objectives include doing laboratory column experiments and theoretical modeling studies to: (i) examine how nanoparticle transport in uniformly-packed porous medium is influenced by porous medium type, moisture content, nanoparticle properties, and pore water flow and chemistry, and (ii) investigate the role of non-steady state flow and chemical conditions in nanoparticle mobilization. In the long term, the influence of soil texture and mineralogical components, as well as porous medium structure (e.g., macropores), will be investigated in packed columns and intact natural sediment cores. Eventually nanoparticle mobilization and transport will be studied at a number of field sites. This research will provide valuable knowledge on nanoparticle migration in subsurface environments and help address concerns over environmental risks associated with nanomaterial usage. The knowledge gained from this research will offer guidance to the Canadian government for developing proper regulations that are aimed at minimizing negative environmental impacts of nanotechnology.