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Quantifying the Effect of Physical and Geochemical Heterogeneity on Virus and Nitrate Transport in Aquifers

Zhengtao Cui and Claire Welty,
Department of Civil and Environmental Engineering and Center for Urban Environmental Research and Education (CUERE)


Rehmann et al. (1999), Ren et al. (2000), Ren et al. (2001), and Maxwell et al. (2003) evaluated the effect of physical (geologic) heterogeneity on virus transport in aquifers. The first part of the study would extend their work to incorporate the dditional effects of geochemical heterogeneity. Within the framework of colloid filtration theory, the aquifer geochemical heterogeneity is described mathematically by the bulk specific area of the grains covered by mineral coatings, which is then correlated to the hydraulic conductivity and effective porosity. A stochastic explicit random walk particle tracking approach will be used to simulate the virus transport in three-dimensional physically and geochemically heterogeneous sandy aquifers. It will be applied to the U.S. Geological Survey Cape Cod site to test the hypothesis. Results from this work will improve current understanding of virus transport mechanisms in physically and geochemically heterogeneous aquifers.

Recent years, elevated virus and nitrogen concentration in underlying aquifers have been linked to septic tank effluent and sewer line leakages (Lodder et al. 2005 and Shields et al. 2008). I will conduct hypothetical numerical simulations of virus transport and nitrogen migration in fractured rock domain underlying a septic tank system of a residential site. A hypothetical heterogeneous fractured rock aquifer in the Piedmont province will be designed. The stochastic modeling framework mentioned above will be enhanced to study the effect of aquifer heterogeneity on the fate and transport of virus and nitrogen. The results of this research will help understand the heavy rainfall events flush effects on virus and nitrogen transport on sites served by septic systems.