TRANSPORT OF NAPROXEN AND IBUPROFEN IN HOMOGENEOUSLY-PACKED QUARTZ SAND COLUMNS

Emerging contaminants such as pharmaceuticals and personal care products (PPCP’s) have recently become a concern due to the potential threat they pose in the environment and to human health. Low PPCP (and related compounds)-concentrations in natural waters have been shown to adversely affect aquatic and non-aquatic organisms. Environmental fate of these compounds is largely unknown, but main degradation mechanisms in natural waters include microbial degradation, photodegradation, and sorption to suspended and stream-bottom sediments and soils. Mineral surfaces in soils, including clays and oxides of Fe, Al, and Mn, and reactive fractions of natural organic matter (OM) can potentially sorb PPCPs. Complex chemical structure of PPCPs include nonpolar (aryl) and ionic (carboxylic and amine) functional groups that can interact with reactive fractions in soils and sediment. The purpose of this study was to investigate the geochemical fate of two PPCPs, ibuprofen and naproxen in porous media. A simple one-dimensional flow model was constructed using a well-sorted, homogeneous coarse-to-fine sand, and was then completely saturated with deionized water to simulate a phreatic-zone environment. Tracer solutions of nitrate, ibuprofen, and naproxen were prepared at concentrations of 20, 15, and 50 mg/L respectively, and injected into homogeneously-packed sand column at a constant rate. The breakthrough curves for each tracer were used to determine the isotherm that best described the sorption/desorption of the pharmaceuticals. Preliminary data suggested that sorption of these compounds could be best described by nonlinear sorption isotherms. In addition, the slightly skewed breakthrough curve associated with the advection of the compounds shows a slower desorption component which implies sorption of the compounds to the sand surfaces. We expect that this preliminary transport data will help us develop better insights into transport of pharmaceutical chemicals in soils and groundwater.