In-situ modeling experiments on the transport of pollutants from the Shaziying garbage dump field in an aquifer in the Chaoyang District, Beijing, China

The water quality of shallow aquifers that have direct relationships to human heath and ecological safety has been seriously threatened by the widespread dumps of industrial solid waste and urban and rural garbage. The authors chose a garbage dump field with typical hydrogeological and environmental-geological characteristics in the Beijing plain to construct a hydrogeological model. Then after part of parameters for calculations were obtained using the collected data, they found the parameters such as the dispersion coefficient of the aquifer by performing in-situ dispersion experiments and conducting investigations and sample tests; the equation of solute transport in 2D unsteady flow was used for modeling and calculation of the processes and rates of transport/diffusion and pollution scope of garbage pollutants in the aquifer. In addition, in-situ drilling and sample analysis were carried out to evaluate the actual pollution situation in the aquifer. The modeling experiments and in-situ investigations show that: the transport/diffusion processes of pollutants in the aquifer follow the equation of solute migration in the 2D unsteady flow field; the rate of migration of pollutants in the aquifer is about 86.25 m/a; the pollutant migration and diffusion mainly occur in the upward groundwater flow; and the width of the lateral groundwater diffusion is very small, being 1/17 of the upward groundwater flow.