Assessment of landfill leachate in Nam Son, Hanoi using 3D electrical imaging and self-potential data

Abstract

The main objective of this study was to assess the environmental impact of the Nam Son landãll on the subsurĩace geological structure studied using 3D electrical imaging and self-potential investigations. The map of the equipotential was based on self-potential data and was indicative of concentrations of redox-active components, and the map of the electrical conductivity provided intormatỉon about the mineralỉzation of the groundwater. The electrical conductivity of the subsurface was obtaỉned from 3D-electrical imaging analysis conducted using a Wenner-based array conhguration. An ỉnversion of the data was carried out using 3D regularixed least-squares optimization methods with robust model constraints. Three prohles of 3D electrical imaging and 180 setf- potential data points, scattered within the study area near the disposal site, were implemented. The self-potential method supports the results of the geoelectrical method relating to a contaminated zone in the survey area with a large negative seư-potential anomaly of ~-260 mV with respect to the reĩerence of a contamỉnant plume. Interpretations of geophysical data showed a low resistivity zone (<10 Í2 m), which appeared to be a íiilly saturated zone with leachate from the Nam Son open dumpsite. The correlation between geophysical investigations and hydrochemical analysis proved to show high conductivity zones related with landbll leachate.