Transport of arsenic in some affected soils of Indian subtropics

An experiment on transport of aqueous arsenic (As) from both affected and unaffected soils of West Bengal, India, was conducted with the help of double-chambered columns in the laboratory. In the vertical column study, the sigmoid shape of breakthrough curves (BTCs) suggests hydrodynamic dispersion, whereas the inflexion of BTCs at a much lesser relative concentration indicates retention of As in the affected soils. In the horizontal column study, the affected soils showed lower mechanical filtration capacity and solute permeability and higher reflection coefficient, indicating greater As retention in these soils. The frictional coefficients for soil-water solute derived from the horizontal flow also indicate As retention by the affected soils. The As retention capacity of these soils was attributed to the greater clay content, illitic minerals, organic matter, specific surface area, and amorphous iron and aluminium content.