Polluted soil leaching: unsaturated conditions and flow rate effects

Abstract

In this study, soil samples are extracted from a polluted site at different depths. Soilstexture and pollutant presence are different with depth. Preliminary analyzes showedpollution by heavy metals. To simulate soil leaching operation in static condition, aseries of leaching tests are conducted in laboratory column under conditions of upflowunsaturated soil. Electrical conductivity and pH measurements on the recoveredleachate are performed. Different flow rates are tested. Comparison of different profilesshows that the dissolved pollutants are concentrated in the upper soil levels anddisperse weakly in the lower parts which confirm the nature of anthropogenicpollution of heavy metals. Water mobilizes a high amount of dissolved ionic substancesup to 80% of the initial concentration. The increase in flow rate requires more porevolume injected to achieve the maximum clearance rate. The down flow conditionextracts a small amount of dissolved substances.