Heavy Metal Leaching in Coastal Loamy Soil of the Field Treated with Municipal Solid Waste at Puducherry (Pondicherry), India

Leaching of Pb (lead), Mn (manganese), Cu (copper), Zn (zinc) and Cd (cadmium) in coastal loamy field soil treated with Municipal Solid Waste at 10, 20, 50, 75, and 100 t/ha was assessed at Puducherry in relation to the native soil without treatment. The concentrations (ppm) of the heavy metals on the soil surface (0 cm), 10, 20 and 30cm sub-layers across the treatments and native soil showed that the Pb and Mn concentrations were higher in surface layer and gradually decreased in 10 and 20cm layers, and was low in 30cm layer across the treatments. However, the concentrations of Cu, Zn, and Cd were less in the surface layer and gradually increased in the sub- layers of the soil and were high at 30 cm layer. Among the leached heavy metals, Cu was in higher concentration in the surface layer and the ranking order was Cu > Cd > Zn > Mn > Pb in surface layer across the treatments. The ranking order of the metals at 30 cm depth was same as that of surface with the same ranking order. Thus, the leaching was higher in Cu, Cd and Zn than in Mn and Pb, the latter two being almost immobile and more concentrated in the surface layer. The concentrations of these heavy metals in different layers across the treatments were significantly different from each other (P < 0.01) and higher compared to that of the native soil.