A Study of Heavy Metal Contamination in the Urban Soil of Dindigul Town, Tamil Nadu

Levels of iron, manganese, zinc, copper, lead, cadmium and chromium were determined by Atomic Absorption Spectroscopy to assess the heavy metal contamination of urban soil of Dindigul town. Soil samples were collected from the residential site, traffic site and industrial site at the depth of 0-20 cm, 20-40 cm and 40-60 cm, respectively. A comparison of heavy metal concentrations between polluted and control site exhibited significantly higher concentration at the polluted sites. The mean concentration of Fe, Mn, Zn, Cu, Pb, Cd and Cr at the industrial site were 9.087 mg/kg, 10.443 mg/kg, 2.49 mg/kg, 8.657 mg/kg, 0.072 mg/kg, 2.85 mg/kg, respectively. Soil profile samples showed that Fe, Mn, Zn, Cu, Pb, Cd and Cr concentration were higher in the top soil of (0-20 cm), but decreased with increase in depth. Correlation co-efficient of all the heavy metals showed significant correlation except Mn. Heavy Metal Index (HMI) for the control, traffic and industrial sites were 14.27, 21.13 and 24.39, respectively. Traffic and industrial sites were found to be highly polluted. Comparing heavy metal concentration in soils of different sampling sites show that urban soil was affected by the human impact. However, the heavy metal content in the soil compared with international standards do not give cause for the concern but continued urbanization and industrialization will ultimately place human health and environmental targets at risk.