A Comparative Analysis on Transport of Pollutants Through Soils to Ground Water

Effect of Molecular Diffusivity on Pollutant Transport through Soils to Groundwater

Abstract

Three simplistic models are developed for evaluating thetransport of organic pollutants through soil to ground water. The modelsconsider mobility and first-order degradation. The first calculates linearsorption/desorption of the pollutant and first-order degradation withoutconsidering dispersion. The second is similar to the first but also considersdispersion. A quantitative understanding of the transport ofpollutants in groundwater is of great importance from the environmentalperspective. Some environmental pollution scenarios involving groundwatercontamination are very real. For example, one may encounter a situation wherean underground storage tank is leaking hydrocarbons into an aquifer at aconstant rate. Similarly, an overturned oil tanker spilling fuel that mightflow through the sandy soil and find its way to the groundwater aquifer leadingto its contamination. The main focus of the present experimental study was toinvestigate the effect of the molecular diffusivity of the tracer on thedispersive transport or the spread of the pollutant. This was achieved usingtwo different salt tracers of significantly different diffusivities. Pulseinjections of tracers were made and their concentrations were monitored in situ downstream with the help ofspecially designed conductivity probes.