Role of Environmental Nanoparticles in Phosphorous-Rich Agricultural Soils.

In the environment, nanoparticles (diameter = 1 – 100 nm) and colloids are present naturally as the smallest fraction of particulate matter in the soil.  These particles act as dispersed particulate matter in aqueous systems such as surface- and ground- water.  This study will investigate the importance of nano-sized particles as nutrient/contaminant carriers, focusing on the essential plant nutrient phosphorus (P), through soil-water environment.   These small particles will behave differently than larger clay particles, which are a few microns in diameter, due to their extremely high surface area to volume ratio.  This may have an effect on the ability and rate of P adsorption and desorption from the colloidal surfaces.  Additionally, the small size of these particles may provide for easier transport through complex surface- and subsurface-matrices.  The objective of this study is to determine the reactivity of environmental nanoparticles in P-rich agricultural surface soils in South Carolina, as well as the role of these nanoparticles in nutrient/contaminant transport.  Agricultural surface soils are often treated with animal based or synthetic fertilizers high in P.  Transport of P into surface- and ground-water has adverse effects on water quality.  This transport is relatively well understood at the scale of larger clay particles, however, the transport of P with environmental nanoparticles has not been well studied.  To understand the reactivity of P in environmental nanoparticles, we will use bench-scale desorption studies, coupled with a series of colloidal separations.  Colloids will be characterized using chemical digestion and electron microscopy, both SEM and TEM.  External structure of these particles, as well as chemical make-up will be analyzed.